Currently the last_trans_committed field of struct btrfs_fs_info is
modified and read without any locking or other protection. For example
early in the fsync path, skip_inode_logging() is called which reads
fs_info->last_trans_committed, but at the same time we can have a
transaction commit completing and updating that field.
In the case of an fsync this is harmless and any data race should be
rare and at most cause an unnecessary logging of an inode.
To avoid data race warnings from tools like KCSAN and other issues such
as load and store tearing (amongst others, see [1]), create helpers to
access the last_trans_committed field of struct btrfs_fs_info using
READ_ONCE() and WRITE_ONCE(), and use these helpers everywhere.
[1] https://lwn.net/Articles/793253/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently the generation field of struct btrfs_fs_info is always modified
while holding fs_info->trans_lock locked. Most readers will access this
field without taking that lock but while holding a transaction handle,
which is safe to do due to the transaction life cycle.
However there are other readers that are neither holding the lock nor
holding a transaction handle open:
1) When reading an inode from disk, at btrfs_read_locked_inode();
2) When reading the generation to expose it to sysfs, at
btrfs_generation_show();
3) Early in the fsync path, at skip_inode_logging();
4) When creating a hole at btrfs_cont_expand(), during write paths,
truncate and reflinking;
5) In the fs_info ioctl (btrfs_ioctl_fs_info());
6) While mounting the filesystem, in the open_ctree() path. In these
cases it's safe to directly read fs_info->generation as no one
can concurrently start a transaction and update fs_info->generation.
In case of the fsync path, races here should be harmless, and in the worst
case they may cause a fsync to log an inode when it's not really needed,
so nothing bad from a functional perspective. In the other cases it's not
so clear if functional problems may arise, though in case 1 rare things
like a load/store tearing [1] may cause the BTRFS_INODE_NEEDS_FULL_SYNC
flag not being set on an inode and therefore result in incorrect logging
later on in case a fsync call is made.
To avoid data race warnings from tools like KCSAN and other issues such
as load and store tearing (amongst others, see [1]), create helpers to
access the generation field of struct btrfs_fs_info using READ_ONCE() and
WRITE_ONCE(), and use these helpers where needed.
[1] https://lwn.net/Articles/793253/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Space for block group item insertions, necessary after allocating a new
block group, is reserved in the delayed refs block reserve. Currently we
do this by incrementing the transaction handle's delayed_ref_updates
counter and then calling btrfs_update_delayed_refs_rsv(), which will
increase the size of the delayed refs block reserve by an amount that
corresponds to the same amount we use for delayed refs, given by
btrfs_calc_delayed_ref_bytes().
That is an excessive amount because it corresponds to the amount of space
needed to insert one item in a btree (btrfs_calc_insert_metadata_size())
times 2 when the free space tree feature is enabled. All we need is an
amount as given by btrfs_calc_insert_metadata_size(), since we only need to
insert a block group item in the extent tree (or block group tree if this
feature is enabled). By using btrfs_calc_insert_metadata_size() we will
need to reserve 2 times less space when using the free space tree, putting
less pressure on space reservation.
So use helpers to reserve and release space for block group item
insertions that use btrfs_calc_insert_metadata_size() for calculation of
the space.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The btrfs_defrag_root() function does not really belong in the
transaction.{c,h} module and as we have a defrag.{c,h} nowadays,
move it to there instead. This also allows to stop exporting
btrfs_defrag_leaves(), so we can make it static.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ rename info to fs_info for consistency ]
Signed-off-by: David Sterba <dsterba@suse.com>
The root argument for btrfs_update_inode_fallback() always matches the
root of the given inode, so remove the root argument and get it from the
inode argument.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Consider the following sequence:
- enable quotas
- create subvol S id 256 at dir outer/
- create a qgroup 1/100
- add 0/256 (S's auto qgroup) to 1/100
- create subvol T id 257 at dir outer/inner/
With full qgroups, there is no relationship between 0/257 and either of
0/256 or 1/100. There is an inherit feature that the creator of inner/
can use to specify it ought to be in 1/100.
Simple quotas are targeted at container isolation, where such automatic
inheritance for not necessarily trusted/controlled nested subvol
creation would be quite helpful. Therefore, add a new default behavior
for simple quotas: when you create a nested subvol, automatically
inherit as parents any parents of the qgroup of the subvol the new inode
is going in.
In our example, 257/0 would also be under 1/100, allowing easy control
of a total quota over an arbitrary hierarchy of subvolumes.
I think this _might_ be a generally useful behavior, so it could be
interesting to put it behind a new inheritance flag that simple quotas
always use while traditional quotas let the user specify, but this is a
minimally intrusive change to start.
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
Pull creating the qgroup earlier in the snapshot. This allows simple
quotas qgroups to see all the metadata writes related to the snapshot
being created and to be born with the root node accounted.
Note this has an impact on transaction commit where the qgroup creation
can do a lot of work, allocate memory and take locks. The change is done
for correctness, potential performance issues will be fixed in the
future.
Signed-off-by: Boris Burkov <boris@bur.io>
[ add note ]
Signed-off-by: David Sterba <dsterba@suse.com>
Add a new quota mode called "simple quotas". It can be enabled by the
existing quota enable ioctl via a new command, and sets an incompat
bit, as the implementation of simple quotas will make backwards
incompatible changes to the disk format of the extent tree.
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
We sync the kernel files to userspace and the 'errno' symbol is defined
by standard library, which does not matter in kernel but the parameters
or local variables could clash. Rename them all.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When starting a transaction (or joining an existing one with
btrfs_start_transaction()), we reserve space for the number of items we
want to insert in a btree, but we don't do it for the delayed refs we
will generate while using the transaction to modify (COW) extent buffers
in a btree or allocate new extent buffers. Basically how it works:
1) When we start a transaction we reserve space for the number of items
the caller wants to be inserted/modified/deleted in a btree. This space
goes to the transaction block reserve;
2) If the delayed refs block reserve is not full, its size is greater
than the amount of its reserved space, and the flush method is
BTRFS_RESERVE_FLUSH_ALL, then we attempt to reserve more space for
it corresponding to the number of items the caller wants to
insert/modify/delete in a btree;
3) The size of the delayed refs block reserve is increased when a task
creates delayed refs after COWing an extent buffer, allocating a new
one or deleting (freeing) an extent buffer. This happens after the
the task started or joined a transaction, whenever it calls
btrfs_update_delayed_refs_rsv();
4) The delayed refs block reserve is then refilled by anyone calling
btrfs_delayed_refs_rsv_refill(), either during unlink/truncate
operations or when someone else calls btrfs_start_transaction() with
a 0 number of items and flush method BTRFS_RESERVE_FLUSH_ALL;
5) As a task COWs or allocates extent buffers, it consumes space from the
transaction block reserve. When the task releases its transaction
handle (btrfs_end_transaction()) or it attempts to commit the
transaction, it releases any remaining space in the transaction block
reserve that it did not use, as not all space may have been used (due
to pessimistic space calculation) by calling btrfs_block_rsv_release()
which will try to add that unused space to the delayed refs block
reserve (if its current size is greater than its reserved space).
That transferred space may not be enough to completely fulfill the
delayed refs block reserve.
Plus we have some tasks that will attempt do modify as many leaves
as they can before getting -ENOSPC (and then reserving more space and
retrying), such as hole punching and extent cloning which call
btrfs_replace_file_extents(). Such tasks can generate therefore a
high number of delayed refs, for both metadata and data (we can't
know in advance how many file extent items we will find in a range
and therefore how many delayed refs for dropping references on data
extents we will generate);
6) If a transaction starts its commit before the delayed refs block
reserve is refilled, for example by the transaction kthread or by
someone who called btrfs_join_transaction() before starting the
commit, then when running delayed references if we don't have enough
reserved space in the delayed refs block reserve, we will consume
space from the global block reserve.
Now this doesn't make a lot of sense because:
1) We should reserve space for delayed references when starting the
transaction, since we have no guarantees the delayed refs block
reserve will be refilled;
2) If no refill happens then we will consume from the global block reserve
when running delayed refs during the transaction commit;
3) If we have a bunch of tasks calling btrfs_start_transaction() with a
number of items greater than zero and at the time the delayed refs
reserve is full, then we don't reserve any space at
btrfs_start_transaction() for the delayed refs that will be generated
by a task, and we can therefore end up using a lot of space from the
global reserve when running the delayed refs during a transaction
commit;
4) There are also other operations that result in bumping the size of the
delayed refs reserve, such as creating and deleting block groups, as
well as the need to update a block group item because we allocated or
freed an extent from the respective block group;
5) If we have a significant gap between the delayed refs reserve's size
and its reserved space, two very bad things may happen:
1) The reserved space of the global reserve may not be enough and we
fail the transaction commit with -ENOSPC when running delayed refs;
2) If the available space in the global reserve is enough it may result
in nearly exhausting it. If the fs has no more unallocated device
space for allocating a new block group and all the available space
in existing metadata block groups is not far from the global
reserve's size before we started the transaction commit, we may end
up in a situation where after the transaction commit we have too
little available metadata space, and any future transaction commit
will fail with -ENOSPC, because although we were able to reserve
space to start the transaction, we were not able to commit it, as
running delayed refs generates some more delayed refs (to update the
extent tree for example) - this includes not even being able to
commit a transaction that was started with the goal of unlinking a
file, removing an empty data block group or doing reclaim/balance,
so there's no way to release metadata space.
In the worst case the next time we mount the filesystem we may
also fail with -ENOSPC due to failure to commit a transaction to
cleanup orphan inodes. This later case was reported and hit by
someone running a SLE (SUSE Linux Enterprise) distribution for
example - where the fs had no more unallocated space that could be
used to allocate a new metadata block group, and the available
metadata space was about 1.5M, not enough to commit a transaction
to cleanup an orphan inode (or do relocation of data block groups
that were far from being full).
So improve on this situation by always reserving space for delayed refs
when calling start_transaction(), and if the flush method is
BTRFS_RESERVE_FLUSH_ALL, also try to refill the delayed refs block
reserve if it's not full. The space reserved for the delayed refs is added
to a local block reserve that is part of the transaction handle, and when
a task updates the delayed refs block reserve size, after creating a
delayed ref, the space is transferred from that local reserve to the
global delayed refs reserve (fs_info->delayed_refs_rsv). In case the
local reserve does not have enough space, which may happen for tasks
that generate a variable and potentially large number of delayed refs
(such as the hole punching and extent cloning cases mentioned before),
we transfer any available space and then rely on the current behaviour
of hoping some other task refills the delayed refs reserve or fallback
to the global block reserve.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently when reserving space for deleting the csum items for a data
extent, when adding or updating a delayed ref head, we determine how
many leaves of csum items we can have and then pass that number to the
helper btrfs_calc_delayed_ref_bytes(). This helper is used for calculating
space for all tree modifications we need when running delayed references,
however the amount of space it computes is excessive for deleting csum
items because:
1) It uses btrfs_calc_insert_metadata_size() which is excessive because
we only need to delete csum items from the csum tree, we don't need
to insert any items, so btrfs_calc_metadata_size() is all we need (as
it computes space needed to delete an item);
2) If the free space tree is enabled, it doubles the amount of space,
which is pointless for csum deletion since we don't need to touch the
free space tree or any other tree other than the csum tree.
So improve on this by tracking how many csum deletions we have and using
a new helper to calculate space for csum deletions (just a wrapper around
btrfs_calc_metadata_size() with a comment). This reduces the amount of
space we need to reserve for csum deletions by a factor of 4, and it helps
reduce the number of times we have to block space reservations and have
the reclaim task enter the space flushing algorithm (flush delayed items,
flush delayed refs, etc) in order to satisfy tickets.
For example this results in a total time decrease when unlinking (or
truncating) files with many extents, as we end up having to block on space
metadata reservations less often. Example test:
$ cat test.sh
#!/bin/bash
DEV=/dev/nullb0
MNT=/mnt/test
umount $DEV &> /dev/null
mkfs.btrfs -f $DEV
# Use compression to quickly create files with a lot of extents
# (each with a size of 128K).
mount -o compress=lzo $DEV $MNT
# 100G gives at least 983040 extents with a size of 128K.
xfs_io -f -c "pwrite -S 0xab -b 1M 0 120G" $MNT/foobar
# Flush all delalloc and clear all metadata from memory.
umount $MNT
mount -o compress=lzo $DEV $MNT
start=$(date +%s%N)
rm -f $MNT/foobar
end=$(date +%s%N)
dur=$(( (end - start) / 1000000 ))
echo "rm took $dur milliseconds"
umount $MNT
Before this change rm took: 7504 milliseconds
After this change rm took: 6574 milliseconds (-12.4%)
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When running delayed references, through btrfs_run_delayed_refs(), we can
specify how many to run, run all existing delayed references and keep
running delayed references while we can find any. This is controlled with
the value of the 'count' argument, where a value of 0 means to run all
delayed references that exist by the time btrfs_run_delayed_refs() is
called, (unsigned long)-1 means to keep running delayed references while
we are able find any, and any other value to run that exact number of
delayed references.
Typically a specific value other than 0 or -1 is used when flushing space
to try to release a certain amount of bytes for a ticket. In this case
we just simply calculate how many delayed reference heads correspond to a
specific amount of bytes, with calc_delayed_refs_nr(). However that only
takes into account the space reserved for the reference heads themselves,
and does not account for the space reserved for deleting checksums from
the csum tree (see add_delayed_ref_head() and update_existing_head_ref())
in case we are going to delete a data extent. This means we may end up
running more delayed references than necessary in case we process delayed
references for deleting a data extent.
So change the logic of btrfs_run_delayed_refs() to take a bytes argument
to specify how many bytes of delayed references to run/release, using the
special values of 0 to mean all existing delayed references and U64_MAX
(or (u64)-1) to keep running delayed references while we can find any.
This prevents running more delayed references than necessary, when we have
delayed references for deleting data extents, but also makes the upcoming
changes/patches simpler and it's preparatory work for them.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We are passing a block reserve argument to btrfs_reserve_metadata_bytes()
which is not really used, all we need is to pass the space_info associated
to the block reserve, we don't change the block reserve at all.
Not only it's pointless to pass the block reserve, it's also confusing as
one might think that the reserved bytes will end up being added to the
passed block reserve, when that's not the case. The pattern for reserving
space and adding it to a block reserve is to first reserve space with
btrfs_reserve_metadata_bytes() and if that succeeds, then add the space to
a block reserve by calling btrfs_block_rsv_add_bytes().
Also the reverse of btrfs_reserve_metadata_bytes(), which is
btrfs_space_info_free_bytes_may_use(), takes a space_info argument and
not a block reserve, so one more reason to pass a space_info and not a
block reserve to btrfs_reserve_metadata_bytes().
So change btrfs_reserve_metadata_bytes() and its callers to pass a
space_info argument instead of a block reserve argument.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Function name in the comment does not bring much value to code not
exposed as API and we don't stick to the kdoc format anymore. Update
formatting of parameter descriptions.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-6.6-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
- delayed refs fixes:
- fix race when refilling delayed refs block reserve
- prevent transaction block reserve underflow when starting
transaction
- error message and value adjustments
- fix build warnings with CONFIG_CC_OPTIMIZE_FOR_SIZE and
-Wmaybe-uninitialized
- fix for smatch report where uninitialized data from invalid extent
buffer range could be returned to the caller
- fix numeric overflow in statfs when calculating lower threshold
for a full filesystem
* tag 'for-6.6-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: initialize start_slot in btrfs_log_prealloc_extents
btrfs: make sure to initialize start and len in find_free_dev_extent
btrfs: reset destination buffer when read_extent_buffer() gets invalid range
btrfs: properly report 0 avail for very full file systems
btrfs: log message if extent item not found when running delayed extent op
btrfs: remove redundant BUG_ON() from __btrfs_inc_extent_ref()
btrfs: return -EUCLEAN for delayed tree ref with a ref count not equals to 1
btrfs: prevent transaction block reserve underflow when starting transaction
btrfs: fix race when refilling delayed refs block reserve
When starting a transaction, with a non-zero number of items, we reserve
metadata space for that number of items and for delayed refs by doing a
call to btrfs_block_rsv_add(), with the transaction block reserve passed
as the block reserve argument. This reserves metadata space and adds it
to the transaction block reserve. Later we migrate the space we reserved
for delayed references from the transaction block reserve into the delayed
refs block reserve, by calling btrfs_migrate_to_delayed_refs_rsv().
btrfs_migrate_to_delayed_refs_rsv() decrements the number of bytes to
migrate from the source block reserve, and this however may result in an
underflow in case the space added to the transaction block reserve ended
up being used by another task that has not reserved enough space for its
own use - examples are tasks doing reflinks or hole punching because they
end up calling btrfs_replace_file_extents() -> btrfs_drop_extents() and
may need to modify/COW a variable number of leaves/paths, so they keep
trying to use space from the transaction block reserve when they need to
COW an extent buffer, and may end up trying to use more space then they
have reserved (1 unit/path only for removing file extent items).
This can be avoided by simply reserving space first without adding it to
the transaction block reserve, then add the space for delayed refs to the
delayed refs block reserve and finally add the remaining reserved space
to the transaction block reserve. This also makes the code a bit shorter
and simpler. So just do that.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-6.6-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
- several fixes for handling directory item (inserting, removing,
iteration, error handling)
- fix transaction commit stalls when auto relocation is running and
blocks other tasks that want to commit
- fix a build error when DEBUG is enabled
- fix lockdep warning in inode number lookup ioctl
- fix race when finishing block group creation
- remove link to obsolete wiki in several files
* tag 'for-6.6-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
MAINTAINERS: remove links to obsolete btrfs.wiki.kernel.org
btrfs: assert delayed node locked when removing delayed item
btrfs: remove BUG() after failure to insert delayed dir index item
btrfs: improve error message after failure to add delayed dir index item
btrfs: fix a compilation error if DEBUG is defined in btree_dirty_folio
btrfs: check for BTRFS_FS_ERROR in pending ordered assert
btrfs: fix lockdep splat and potential deadlock after failure running delayed items
btrfs: do not block starts waiting on previous transaction commit
btrfs: release path before inode lookup during the ino lookup ioctl
btrfs: fix race between finishing block group creation and its item update
Internally I got a report of very long stalls on normal operations like
creating a new file when auto relocation was running. The reporter used
the 'bpf offcputime' tracer to show that we would get stuck in
start_transaction for 5 to 30 seconds, and were always being woken up by
the transaction commit.
Using my timing-everything script, which times how long a function takes
and what percentage of that total time is taken up by its children, I
saw several traces like this
1083 took 32812902424 ns
29929002926 ns 91.2110% wait_for_commit_duration
25568 ns 7.7920e-05% commit_fs_roots_duration
1007751 ns 0.00307% commit_cowonly_roots_duration
446855602 ns 1.36182% btrfs_run_delayed_refs_duration
271980 ns 0.00082% btrfs_run_delayed_items_duration
2008 ns 6.1195e-06% btrfs_apply_pending_changes_duration
9656 ns 2.9427e-05% switch_commit_roots_duration
1598 ns 4.8700e-06% btrfs_commit_device_sizes_duration
4314 ns 1.3147e-05% btrfs_free_log_root_tree_duration
Here I was only tracing functions that happen where we are between
START_COMMIT and UNBLOCKED in order to see what would be keeping us
blocked for so long. The wait_for_commit() we do is where we wait for a
previous transaction that hasn't completed it's commit. This can
include all of the unpin work and other cleanups, which tends to be the
longest part of our transaction commit.
There is no reason we should be blocking new things from entering the
transaction at this point, it just adds to random latency spikes for no
reason.
Fix this by adding a PREP stage. This allows us to properly deal with
multiple committers coming in at the same time, we retain the behavior
that the winner waits on the previous transaction and the losers all
wait for this transaction commit to occur. Nothing else is blocked
during the PREP stage, and then once the wait is complete we switch to
COMMIT_START and all of the same behavior as before is maintained.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-6.6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
"No new features, the bulk of the changes are fixes, refactoring and
cleanups. The notable fix is the scrub performance restoration after
rewrite in 6.4, though still only partial.
Fixes:
- scrub performance drop due to rewrite in 6.4 partially restored:
- do IO grouping by blg_plug/blk_unplug again
- avoid unnecessary tree searches when processing stripes, in
extent and checksum trees
- the drop is noticeable on fast PCIe devices, -66% and restored
to -33% of the original
- backports to 6.4 planned
- handle more corner cases of transaction commit during orphan
cleanup or delayed ref processing
- use correct fsid/metadata_uuid when validating super block
- copy directory permissions and time when creating a stub subvolume
Core:
- debugging feature integrity checker deprecated, to be removed in
6.7
- in zoned mode, zones are activated just before the write, making
error handling easier, now the overcommit mechanism can be enabled
again which improves performance by avoiding more frequent flushing
- v0 extent handling completely removed, deprecated long time ago
- error handling improvements
- tests:
- extent buffer bitmap tests
- pinned extent splitting tests
- cleanups and refactoring:
- compression writeback
- extent buffer bitmap
- space flushing, ENOSPC handling"
* tag 'for-6.6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (110 commits)
btrfs: zoned: skip splitting and logical rewriting on pre-alloc write
btrfs: tests: test invalid splitting when skipping pinned drop extent_map
btrfs: tests: add a test for btrfs_add_extent_mapping
btrfs: tests: add extent_map tests for dropping with odd layouts
btrfs: scrub: move write back of repaired sectors to scrub_stripe_read_repair_worker()
btrfs: scrub: don't go ordered workqueue for dev-replace
btrfs: scrub: fix grouping of read IO
btrfs: scrub: avoid unnecessary csum tree search preparing stripes
btrfs: scrub: avoid unnecessary extent tree search preparing stripes
btrfs: copy dir permission and time when creating a stub subvolume
btrfs: remove pointless empty list check when reading delayed dir indexes
btrfs: drop redundant check to use fs_devices::metadata_uuid
btrfs: compare the correct fsid/metadata_uuid in btrfs_validate_super
btrfs: use the correct superblock to compare fsid in btrfs_validate_super
btrfs: simplify memcpy either of metadata_uuid or fsid
btrfs: add a helper to read the superblock metadata_uuid
btrfs: remove v0 extent handling
btrfs: output extra debug info if we failed to find an inline backref
btrfs: move the !zoned assert into run_delalloc_cow
btrfs: consolidate the error handling in run_delalloc_nocow
...
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Merge tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs timestamp updates from Christian Brauner:
"This adds VFS support for multi-grain timestamps and converts tmpfs,
xfs, ext4, and btrfs to use them. This carries acks from all relevant
filesystems.
The VFS always uses coarse-grained timestamps when updating the ctime
and mtime after a change. This has the benefit of allowing filesystems
to optimize away a lot of metadata updates, down to around 1 per
jiffy, even when a file is under heavy writes.
Unfortunately, this has always been an issue when we're exporting via
NFSv3, which relies on timestamps to validate caches. A lot of changes
can happen in a jiffy, so timestamps aren't sufficient to help the
client decide to invalidate the cache.
Even with NFSv4, a lot of exported filesystems don't properly support
a change attribute and are subject to the same problems with timestamp
granularity. Other applications have similar issues with timestamps
(e.g., backup applications).
If we were to always use fine-grained timestamps, that would improve
the situation, but that becomes rather expensive, as the underlying
filesystem would have to log a lot more metadata updates.
This introduces fine-grained timestamps that are used when they are
actively queried.
This uses the 31st bit of the ctime tv_nsec field to indicate that
something has queried the inode for the mtime or ctime. When this flag
is set, on the next mtime or ctime update, the kernel will fetch a
fine-grained timestamp instead of the usual coarse-grained one.
As POSIX generally mandates that when the mtime changes, the ctime
must also change the kernel always stores normalized ctime values, so
only the first 30 bits of the tv_nsec field are ever used.
Filesytems can opt into this behavior by setting the FS_MGTIME flag in
the fstype. Filesystems that don't set this flag will continue to use
coarse-grained timestamps.
Various preparatory changes, fixes and cleanups are included:
- Fixup all relevant places where POSIX requires updating ctime
together with mtime. This is a wide-range of places and all
maintainers provided necessary Acks.
- Add new accessors for inode->i_ctime directly and change all
callers to rely on them. Plain accesses to inode->i_ctime are now
gone and it is accordingly rename to inode->__i_ctime and commented
as requiring accessors.
- Extend generic_fillattr() to pass in a request mask mirroring in a
sense the statx() uapi. This allows callers to pass in a request
mask to only get a subset of attributes filled in.
- Rework timestamp updates so it's possible to drop the @now
parameter the update_time() inode operation and associated helpers.
- Add inode_update_timestamps() and convert all filesystems to it
removing a bunch of open-coding"
* tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (107 commits)
btrfs: convert to multigrain timestamps
ext4: switch to multigrain timestamps
xfs: switch to multigrain timestamps
tmpfs: add support for multigrain timestamps
fs: add infrastructure for multigrain timestamps
fs: drop the timespec64 argument from update_time
xfs: have xfs_vn_update_time gets its own timestamp
fat: make fat_update_time get its own timestamp
fat: remove i_version handling from fat_update_time
ubifs: have ubifs_update_time use inode_update_timestamps
btrfs: have it use inode_update_timestamps
fs: drop the timespec64 arg from generic_update_time
fs: pass the request_mask to generic_fillattr
fs: remove silly warning from current_time
gfs2: fix timestamp handling on quota inodes
fs: rename i_ctime field to __i_ctime
selinux: convert to ctime accessor functions
security: convert to ctime accessor functions
apparmor: convert to ctime accessor functions
sunrpc: convert to ctime accessor functions
...
Update the comment for btrfs_join_transaction_nostart() to be more clear
about how it works and how it's different from btrfs_attach_transaction().
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When joining a transaction with TRANS_JOIN_NOSTART, if we don't find a
running transaction we end up creating one. This goes against the purpose
of TRANS_JOIN_NOSTART which is to join a running transaction if its state
is at or below the state TRANS_STATE_COMMIT_START, otherwise return an
-ENOENT error and don't start a new transaction. So fix this to not create
a new transaction if there's no running transaction at or below that
state.
CC: stable@vger.kernel.org # 4.14+
Fixes: a6d155d2e3 ("Btrfs: fix deadlock between fiemap and transaction commits")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_start_transaction reserves metadata space of the PERTRANS type
before it identifies a transaction to start/join. This allows flushing
when reserving that space without a deadlock. However, it results in a
race which temporarily breaks qgroup rsv accounting.
T1 T2
start_transaction
do_stuff
start_transaction
qgroup_reserve_meta_pertrans
commit_transaction
qgroup_free_meta_all_pertrans
hit an error starting txn
goto reserve_fail
qgroup_free_meta_pertrans (already freed!)
The basic issue is that there is nothing preventing another commit from
committing before start_transaction finishes (in fact sometimes we
intentionally wait for it) so any error path that frees the reserve is
at risk of this race.
While this exact space was getting freed anyway, and it's not a huge
deal to double free it (just a warning, the free code catches this), it
can result in incorrectly freeing some other pertrans reservation in
this same reservation, which could then lead to spuriously granting
reservations we might not have the space for. Therefore, I do believe it
is worth fixing.
To fix it, use the existing prealloc->pertrans conversion mechanism.
When we first reserve the space, we reserve prealloc space and only when
we are sure we have a transaction do we convert it to pertrans. This way
any racing commits do not blow away our reservation, but we still get a
pertrans reservation that is freed when _this_ transaction gets committed.
This issue can be reproduced by running generic/269 with either qgroups
or squotas enabled via mkfs on the scratch device.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
CC: stable@vger.kernel.org # 5.10+
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently find_first_extent_bit() returns a 0 if it found a range in the
given io tree and 1 if it didn't find any. There's no need to return any
errors, so make the return value a boolean and invert the logic to make
more sense: return true if it found a range and false if it didn't find
any range.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_attach_transaction_barrier() is used to get a handle pointing to the
current running transaction if the transaction has not started its commit
yet (its state is < TRANS_STATE_COMMIT_START). If the transaction commit
has started, then we wait for the transaction to commit and finish before
returning - however we completely ignore if the transaction was aborted
due to some error during its commit, we simply return ERR_PT(-ENOENT),
which makes the caller assume everything is fine and no errors happened.
This could make an fsync return success (0) to user space when in fact we
had a transaction abort and the target inode changes were therefore not
persisted.
Fix this by checking for the return value from btrfs_wait_for_commit(),
and if it returned an error, return it back to the caller.
Fixes: d4edf39bd5 ("Btrfs: fix uncompleted transaction")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
At btrfs_wait_for_commit() we wait for a transaction to finish and then
always return 0 (success) without checking if it was aborted, in which
case the transaction didn't happen due to some critical error. Fix this
by checking if the transaction was aborted.
Fixes: 462045928b ("Btrfs: add START_SYNC, WAIT_SYNC ioctls")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In later patches, we're going to change how the inode's ctime field is
used. Switch to using accessor functions instead of raw accesses of
inode->i_ctime.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230705190309.579783-27-jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
During the transaction commit path, at create_pending_snapshot(), there
is no need to BUG_ON() in case we fail to get a dir index for the snapshot
in the parent directory. This should fail very rarely because the parent
inode should be loaded in memory already, with the respective delayed
inode created and the parent inode's index_cnt field already initialized.
However if it fails, it may be -ENOMEM like the comment at
create_pending_snapshot() says or any error returned by
btrfs_search_slot() through btrfs_set_inode_index_count(), which can be
pretty much anything such as -EIO or -EUCLEAN for example. So the comment
is not correct when it says it can only be -ENOMEM.
However doing a BUG_ON() here is overkill, since we can instead abort
the transaction and return the error. Note that any error returned by
create_pending_snapshot() will eventually result in a transaction
abort at cleanup_transaction(), called from btrfs_commit_transaction(),
but we can explicitly abort the transaction at this point instead so that
we get a stack trace to tell us that the call to btrfs_set_inode_index()
failed.
So just abort the transaction and return in case btrfs_set_inode_index()
returned an error at create_pending_snapshot().
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When btrfs_redirty_list_add redirties a buffer, it also acquires
an extra reference that is released on transaction commit. But
this is not required as buffers that are dirty or under writeback
are never freed (look for calls to extent_buffer_under_io())).
Remove the extra reference and the infrastructure used to drop it
again.
History behind redirty logic:
In the first place, it used releasing_list to hold all the
to-be-released extent buffers, and decided which buffers to re-dirty at
the commit time. Then, in a later version, the behaviour got changed to
re-dirty a necessary buffer and add re-dirtied one to the list in
btrfs_free_tree_block(). In short, the list was there mostly for the
patch series' historical reason.
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
[ add Naohiro's comment regarding history ]
Signed-off-by: David Sterba <dsterba@suse.com>
The writeback_control structure already passes down the information about
a writeback being synchronous from the core VM code, and thus information
is propagated into the bio REQ_SYNC flag through the wbc_to_write_flags
helper.
Use that information to decide if checksums calculation is offloaded to
a workqueue instead of btrfs_inode::sync_writers field that not only
bloats the inode but also has too wide scope, being inode wide instead
of limited to the actual writeback request.
The sync writes were set in:
- btrfs_do_write_iter - regular IO, sync status is set
- start_ordered_ops - ordered write start, writeback with WB_SYNC_ALL
mode
- btrfs_write_marked_extents - write marked extents, writeback with
WB_SYNC_ALL mode
Reviewed-by: Chris Mason <clm@fb.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>
When starting a transaction, we are assuming the number of bytes used for
each delayed ref update matches the number of bytes used for each item
update, that is the return value of:
btrfs_calc_insert_metadata_size(fs_info, num_items)
However that is not correct when we are using the free space tree, as we
need to multiply that value by 2, since delayed ref updates need to modify
the free space tree besides the extent tree.
So fix this by using btrfs_calc_delayed_ref_bytes() to get the correct
number of bytes used for delayed ref updates.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When starting a transaction we are comparing the result of a call to
btrfs_block_rsv_full() with 0, but the function returns a boolean. While
in practice it is not incorrect, as 0 is equivalent to false, it makes it
a bit odd and less readable. So update the check to not compare against 0
and instead use the logical not (!) operator.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The function should_end_transaction() is very short and only has one
caller, which is btrfs_should_end_transaction(). So move the code from
should_end_transaction() into btrfs_should_end_transaction().
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
Since the introduction of per-fs feature sysfs interface
(/sys/fs/btrfs/<UUID>/features/), the content of that directory is never
updated.
Thus for the following case, that directory will not show the new
features like RAID56:
# mkfs.btrfs -f $dev1 $dev2 $dev3
# mount $dev1 $mnt
# btrfs balance start -f -mconvert=raid5 $mnt
# ls /sys/fs/btrfs/$uuid/features/
extended_iref free_space_tree no_holes skinny_metadata
While after unmount and mount, we got the correct features:
# umount $mnt
# mount $dev1 $mnt
# ls /sys/fs/btrfs/$uuid/features/
extended_iref free_space_tree no_holes raid56 skinny_metadata
[CAUSE]
Because we never really try to update the content of per-fs features/
directory.
We had an attempt to update the features directory dynamically in commit
14e46e0495 ("btrfs: synchronize incompat feature bits with sysfs
files"), but unfortunately it get reverted in commit e410e34fad
("Revert "btrfs: synchronize incompat feature bits with sysfs files"").
The problem in the original patch is, in the context of
btrfs_create_chunk(), we can not afford to update the sysfs group.
The exported but never utilized function, btrfs_sysfs_feature_update()
is the leftover of such attempt. As even if we go sysfs_update_group(),
new files will need extra memory allocation, and we have no way to
specify the sysfs update to go GFP_NOFS.
[FIX]
This patch will address the old problem by doing asynchronous sysfs
update in the cleaner thread.
This involves the following changes:
- Make __btrfs_(set|clear)_fs_(incompat|compat_ro) helpers to set
BTRFS_FS_FEATURE_CHANGED flag when needed
- Update btrfs_sysfs_feature_update() to use sysfs_update_group()
And drop unnecessary arguments.
- Call btrfs_sysfs_feature_update() in cleaner_kthread
If we have the BTRFS_FS_FEATURE_CHANGED flag set.
- Wake up cleaner_kthread in btrfs_commit_transaction if we have
BTRFS_FS_FEATURE_CHANGED flag
By this, all the previously dangerous call sites like
btrfs_create_chunk() need no new changes, as above helpers would
have already set the BTRFS_FS_FEATURE_CHANGED flag.
The real work happens at cleaner_kthread, thus we pay the cost of
delaying the update to sysfs directory, but the delayed time should be
small enough that end user can not distinguish though it might get
delayed if the cleaner thread is busy with removing subvolumes or
defrag.
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
While trying to sync messages.[ch] I ended up with this dependency on
messages.h in the rest of btrfs-progs code base because it's where
btrfs_abort_transaction() was now held. We want to keep messages.[ch]
limited to the kernel code, and the btrfs_abort_transaction() code
better fits in the transaction code and not in messages.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ move the __cold attributes ]
Signed-off-by: David Sterba <dsterba@suse.com>
All callers except one pass NULL, so the parameter can be dropped and
the inode::io_tree initialization can be open coded.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The div_factor* helpers calculate fraction or percentage fraction. The
name is a bit confusing, we use it only for percentage calculations and
there are two helpers.
There's a helper mult_frac that's for general fractions, that tries to
be accurate but we multiply and divide by small numbers so we can use
the div_u64 helper.
Rename the div_factor* helpers and use 1..100 percentage range, also drop
the case checking for percentage == 100, it's never hit.
The conversions:
* div_factor calculates tenths and the numbers need to be adjusted
* div_factor_fine is direct replacement
Signed-off-by: David Sterba <dsterba@suse.com>
Move these out of ctree.h into scrub.h to cut down on code in ctree.h.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move these out of ctree.h into relocation.h to cut down on code in
ctree.h
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move these out of ctree.h into ioctl.h to cut down on code in ctree.h.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move these out of ctree.h into uuid-tree.h to cut down on the code in
ctree.h.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move these prototypes out of ctree.h and into their own header file.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that the defrag code is all in one file, create a defrag.h and move
all the defrag related prototypes and helper out of ctree.h and into
defrag.h.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move all the root-tree.c prototypes to root-tree.h, and then update all
the necessary files to include the new header.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move all the extent tree related prototypes to extent-tree.h out of
ctree.h, and then go include it everywhere needed so everything
compiles.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
While struct qstr is more natural without fscrypt, since it's provided
by dentries, struct fscrypt_str is provided by the fscrypt handlers
processing dentries, and is thus more natural in the fscrypt world.
Replace all of the struct qstr uses with struct fscrypt_str.
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Most places where we get a struct qstr, we are doing so from a dentry.
With fscrypt, the dentry's name may be encrypted on-disk, so fscrypt
provides a helper to convert a dentry name to the appropriate disk name
if necessary. Convert each of the dentry name accesses to use
fscrypt_setup_filename(), then convert the resulting fscrypt_name back
to an unencrypted qstr. This does not work for nokey names, but the
specific locations that could spawn nokey names are noted.
At present, since there are no encrypted directories, nothing goes down
the filename encryption paths.
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Many functions throughout btrfs take name buffer and name length
arguments. Most of these functions at the highest level are usually
called with these arguments extracted from a supplied dentry's name.
But the entire name can be passed instead, making each function a little
more elegant.
Each function whose arguments are currently the name and length
extracted from a dentry is herein converted to instead take a pointer to
the name in the dentry. The couple of calls to these calls without a
struct dentry are converted to create an appropriate qstr to pass in.
Additionally, every function which is only called with a name/len
extracted directly from a qstr is also converted.
This change has positive effect on stack consumption, frame of many
functions is reduced but this will be used in the future for fscrypt
related structures.
Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This is a large patch, but because they're all macros it's impossible to
split up. Simply copy all of the item accessors in ctree.h and paste
them in accessors.h, and then update any files to include the header so
everything compiles.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ reformat comments, style fixups ]
Signed-off-by: David Sterba <dsterba@suse.com>
Now that we're not using this code anywhere we can remove it as well as
the member from fs_info.
We don't have any mount options or on/off features that would utilize
the pending infrastructure, the last one was inode_cache.
There was a patchset [1] to enable some features from sysfs that would
break things if it would be set immediately. In case we'll need that
kind of logic again the patch can be reverted, but for the current use
it can be replaced by the single state bit to do the commit.
[1] https://lore.kernel.org/linux-btrfs/1422609654-19519-1-git-send-email-quwenruo@cn.fujitsu.com/
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add note ]
Signed-off-by: David Sterba <dsterba@suse.com>
Currently we are only using fs_info->pending_changes to indicate that we
need a transaction commit. The original users for this were removed
years ago and we don't have more usage in sight, so this is the only
remaining reason to have this field. Add a flag so we can remove this
code.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have several fs wide related helpers in ctree.h. The bulk of these
are the incompat flag test helpers, but there are things such as
btrfs_fs_closing() and the read only helpers that also aren't directly
related to the ctree code. Move these into a fs.h header, which will
serve as the location for file system wide related helpers.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This is local to the transaction code, remove it from ctree.h and
inode.c, create new helpers in the transaction to handle the init work
and move the cachep locally to transaction.c.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We only use this for normal inodes, so don't set it if we're not a
normal inode.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Instead of taking up a whole argument to indicate we're clearing
everything in a range, simply add another EXTENT bit to control this,
and then update all the callers to drop this argument from the
clear_extent_bit variants.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This is only used in the case that we are clearing EXTENT_LOCKED, so
infer this value from the bits passed in instead of taking it as an
argument.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
KCSAN reports that there's unlocked access mixed with locked access,
which is technically correct but is not a bug. To avoid false alerts at
least from KCSAN, add annotation and use a wrapper whenever ->full is
accessed for read outside of lock.
It is used as a fast check and only advisory. In the worst case the
block reserve is found !full and becomes full in the meantime, but
properly handled.
Depending on the value of ->full, btrfs_block_rsv_release decides
where to return the reservation, and block_rsv_release_bytes handles a
NULL pointer for block_rsv and if it's not NULL then it double checks
the full status under a lock.
Link: https://lore.kernel.org/linux-btrfs/CAAwBoOJDjei5Hnem155N_cJwiEkVwJYvgN-tQrwWbZQGhFU=cA@mail.gmail.com/
Link: https://lore.kernel.org/linux-btrfs/YvHU/vsXd7uz5V6j@hungrycats.org
Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Signed-off-by: David Sterba <dsterba@suse.com>
The extent tree v2 needs a new root for storing all block group items,
the whole feature hasn't been finished yet so we can afford to do some
changes.
My initial proposal years ago just added a new tree rootid, and load it
from tree root, just like what we did for quota/free space tree/uuid/extent
roots.
But the extent tree v2 patches introduced a completely new way to store
block group tree root into super block which is arguably wasteful.
Currently there are only 3 trees stored in super blocks, and they all
have their valid reasons:
- Chunk root
Needed for bootstrap.
- Tree root
Really the entry point for all trees.
- Log root
This is special as log root has to be updated out of existing
transaction mechanism.
There is not even any reason to put block group root into super blocks,
the block group tree is updated at the same time as the old extent tree,
no need for extra bootstrap/out-of-transaction update.
So just move block group root from super block into tree root.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
struct btrfs_caching_ctl::progress and struct
btrfs_block_group::last_byte_to_unpin were previously needed to ensure
that unpin_extent_range() didn't return a range to the free space cache
before the caching thread had a chance to cache that range. However, the
commit "btrfs: fix space cache corruption and potential double
allocations" made it so that we always synchronously cache the block
group at the time that we pin the extent, so this machinery is no longer
necessary.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In contrast to the num_writers and num_extwriters wait events, the
condition for the pending ordered wait event is signaled in a different
context from the wait event itself. The condition signaling occurs in
btrfs_remove_ordered_extent() in fs/btrfs/ordered-data.c while the wait
event is implemented in btrfs_commit_transaction() in
fs/btrfs/transaction.c
Thus the thread signaling the condition has to acquire the lockdep map
as a reader at the start of btrfs_remove_ordered_extent() and release it
after it has signaled the condition. In this case some dependencies
might be left out due to the placement of the annotation, but it is
better than no annotation at all.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Add lockdep annotations for the transaction states that have wait
events;
1) TRANS_STATE_COMMIT_START
2) TRANS_STATE_UNBLOCKED
3) TRANS_STATE_SUPER_COMMITTED
4) TRANS_STATE_COMPLETED
The new macros introduced here to annotate the transaction states wait
events have the same effect as the generic lockdep annotation macros.
With the exception of the lockdep annotation for TRANS_STATE_COMMIT_START
the transaction thread has to acquire the lockdep maps for the
transaction states as reader after the lockdep map for num_writers is
released so that lockdep does not complain.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Similarly to the num_writers wait event in fs/btrfs/transaction.c add a
lockdep annotation for the num_extwriters wait event.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Annotate the num_writers wait event in fs/btrfs/transaction.c with
lockdep in order to catch deadlocks involving this wait event.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The chained assignments may be convenient to write, but make readability
a bit worse as it's too easy to overlook that there are several values
set on the same line while this is rather an exception. Making it
consistent everywhere avoids surprises.
The pattern where inode times are initialized reuses the first value and
the order is mtime, ctime. In other blocks the assignments are expanded
so the order of variables is similar to the neighboring code.
Signed-off-by: David Sterba <dsterba@suse.com>
Track several stats about transaction commit, to be later exported via
sysfs:
- number of commits so far
- duration of the last commit in ns
- maximum commit duration seen so far in ns
- total duration for all commits so far in ns
The update of the commit stats occurs after the commit thread has gone
through all the logic that checks if there is another thread committing
at the same time. This means that we only account for actual commit work
in the commit stats we report and not the time the thread spends waiting
until it is ready to do the commit work.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Ioannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This reverts commit 48b36a602a.
Revert the xarray conversion, there's a problem with potential
sleep-inside-spinlock [1] when calling xa_insert that triggers GFP_NOFS
allocation. The radix tree used the preloading mechanism to avoid
sleeping but this is not available in xarray.
Conversion from spin lock to mutex is possible but at time of rc6 is
riskier than a clean revert.
[1] https://lore.kernel.org/linux-btrfs/cover.1657097693.git.fdmanana@suse.com/
Reported-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
… rename it to simply fs_roots and adjust all usages of this object to use
the XArray API, because it is notionally easier to use and understand, as
it provides array semantics, and also takes care of locking for us,
further simplifying the code.
Also do some refactoring, esp. where the API change requires largely
rewriting some functions, anyway.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Gabriel Niebler <gniebler@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently we use a spin lock to protect the red black tree that we use to
track block groups. Most accesses to that tree are actually read only and
for large filesystems, with thousands of block groups, it actually has
a bad impact on performance, as concurrent read only searches on the tree
are serialized.
Read only searches on the tree are very frequent and done when:
1) Pinning and unpinning extents, as we need to lookup the respective
block group from the tree;
2) Freeing the last reference of a tree block, regardless if we pin the
underlying extent or add it back to free space cache/tree;
3) During NOCOW writes, both buffered IO and direct IO, we need to check
if the block group that contains an extent is read only or not and to
increment the number of NOCOW writers in the block group. For those
operations we need to search for the block group in the tree.
Similarly, after creating the ordered extent for the NOCOW write, we
need to decrement the number of NOCOW writers from the same block
group, which requires searching for it in the tree;
4) Decreasing the number of extent reservations in a block group;
5) When allocating extents and freeing reserved extents;
6) Adding and removing free space to the free space tree;
7) When releasing delalloc bytes during ordered extent completion;
8) When relocating a block group;
9) During fitrim, to iterate over the block groups;
10) etc;
Write accesses to the tree, to add or remove block groups, are much less
frequent as they happen only when allocating a new block group or when
deleting a block group.
We also use the same spin lock to protect the list of currently caching
block groups. Additions to this list are made when we need to cache a
block group, because we don't have a free space cache for it (or we have
but it's invalid), and removals from this list are done when caching of
the block group's free space finishes. These cases are also not very
common, but when they happen, they happen only once when the filesystem
is mounted.
So switch the lock that protects the tree of block groups from a spinning
lock to a read/write lock.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We're passing a root around here, but we only really need the fs_info,
so fix up btrfs_clean_one_deleted_snapshot() to take an fs_info instead,
and then fix up all the callers appropriately.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
With extent tree v2 you will be able to create multiple csum, extent,
and free space trees. They will be used based on the block group, which
will now use the block_group_item->chunk_objectid to point to the set of
global roots that it will use. When allocating new block groups we'll
simply mod the gigabyte offset of the block group against the number of
global roots we have and that will be the block groups global id.
>From there we can take the bytenr that we're modifying in the respective
tree, look up the block group and get that block groups corresponding
global root id. From there we can get to the appropriate global root
for that bytenr.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We hit a bug with a recovering relocation on mount for one of our file
systems in production. I reproduced this locally by injecting errors
into snapshot delete with balance running at the same time. This
presented as an error while looking up an extent item
WARNING: CPU: 5 PID: 1501 at fs/btrfs/extent-tree.c:866 lookup_inline_extent_backref+0x647/0x680
CPU: 5 PID: 1501 Comm: btrfs-balance Not tainted 5.16.0-rc8+ #8
RIP: 0010:lookup_inline_extent_backref+0x647/0x680
RSP: 0018:ffffae0a023ab960 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 000000000000000c RDI: 0000000000000000
RBP: ffff943fd2a39b60 R08: 0000000000000000 R09: 0000000000000001
R10: 0001434088152de0 R11: 0000000000000000 R12: 0000000001d05000
R13: ffff943fd2a39b60 R14: ffff943fdb96f2a0 R15: ffff9442fc923000
FS: 0000000000000000(0000) GS:ffff944e9eb40000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1157b1fca8 CR3: 000000010f092000 CR4: 0000000000350ee0
Call Trace:
<TASK>
insert_inline_extent_backref+0x46/0xd0
__btrfs_inc_extent_ref.isra.0+0x5f/0x200
? btrfs_merge_delayed_refs+0x164/0x190
__btrfs_run_delayed_refs+0x561/0xfa0
? btrfs_search_slot+0x7b4/0xb30
? btrfs_update_root+0x1a9/0x2c0
btrfs_run_delayed_refs+0x73/0x1f0
? btrfs_update_root+0x1a9/0x2c0
btrfs_commit_transaction+0x50/0xa50
? btrfs_update_reloc_root+0x122/0x220
prepare_to_merge+0x29f/0x320
relocate_block_group+0x2b8/0x550
btrfs_relocate_block_group+0x1a6/0x350
btrfs_relocate_chunk+0x27/0xe0
btrfs_balance+0x777/0xe60
balance_kthread+0x35/0x50
? btrfs_balance+0xe60/0xe60
kthread+0x16b/0x190
? set_kthread_struct+0x40/0x40
ret_from_fork+0x22/0x30
</TASK>
Normally snapshot deletion and relocation are excluded from running at
the same time by the fs_info->cleaner_mutex. However if we had a
pending balance waiting to get the ->cleaner_mutex, and a snapshot
deletion was running, and then the box crashed, we would come up in a
state where we have a half deleted snapshot.
Again, in the normal case the snapshot deletion needs to complete before
relocation can start, but in this case relocation could very well start
before the snapshot deletion completes, as we simply add the root to the
dead roots list and wait for the next time the cleaner runs to clean up
the snapshot.
Fix this by setting a bit on the fs_info if we have any DEAD_ROOT's that
had a pending drop_progress key. If they do then we know we were in the
middle of the drop operation and set a flag on the fs_info. Then
balance can wait until this flag is cleared to start up again.
If there are DEAD_ROOT's that don't have a drop_progress set then we're
safe to start balance right away as we'll be properly protected by the
cleaner_mutex.
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When using the flushoncommit mount option, during almost every transaction
commit we trigger a warning from __writeback_inodes_sb_nr():
$ cat fs/fs-writeback.c:
(...)
static void __writeback_inodes_sb_nr(struct super_block *sb, ...
{
(...)
WARN_ON(!rwsem_is_locked(&sb->s_umount));
(...)
}
(...)
The trace produced in dmesg looks like the following:
[947.473890] WARNING: CPU: 5 PID: 930 at fs/fs-writeback.c:2610 __writeback_inodes_sb_nr+0x7e/0xb3
[947.481623] Modules linked in: nfsd nls_cp437 cifs asn1_decoder cifs_arc4 fscache cifs_md4 ipmi_ssif
[947.489571] CPU: 5 PID: 930 Comm: btrfs-transacti Not tainted 95.16.3-srb-asrock-00001-g36437ad63879 #186
[947.497969] RIP: 0010:__writeback_inodes_sb_nr+0x7e/0xb3
[947.502097] Code: 24 10 4c 89 44 24 18 c6 (...)
[947.519760] RSP: 0018:ffffc90000777e10 EFLAGS: 00010246
[947.523818] RAX: 0000000000000000 RBX: 0000000000963300 RCX: 0000000000000000
[947.529765] RDX: 0000000000000000 RSI: 000000000000fa51 RDI: ffffc90000777e50
[947.535740] RBP: ffff888101628a90 R08: ffff888100955800 R09: ffff888100956000
[947.541701] R10: 0000000000000002 R11: 0000000000000001 R12: ffff888100963488
[947.547645] R13: ffff888100963000 R14: ffff888112fb7200 R15: ffff888100963460
[947.553621] FS: 0000000000000000(0000) GS:ffff88841fd40000(0000) knlGS:0000000000000000
[947.560537] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[947.565122] CR2: 0000000008be50c4 CR3: 000000000220c000 CR4: 00000000001006e0
[947.571072] Call Trace:
[947.572354] <TASK>
[947.573266] btrfs_commit_transaction+0x1f1/0x998
[947.576785] ? start_transaction+0x3ab/0x44e
[947.579867] ? schedule_timeout+0x8a/0xdd
[947.582716] transaction_kthread+0xe9/0x156
[947.585721] ? btrfs_cleanup_transaction.isra.0+0x407/0x407
[947.590104] kthread+0x131/0x139
[947.592168] ? set_kthread_struct+0x32/0x32
[947.595174] ret_from_fork+0x22/0x30
[947.597561] </TASK>
[947.598553] ---[ end trace 644721052755541c ]---
This is because we started using writeback_inodes_sb() to flush delalloc
when committing a transaction (when using -o flushoncommit), in order to
avoid deadlocks with filesystem freeze operations. This change was made
by commit ce8ea7cc6e ("btrfs: don't call btrfs_start_delalloc_roots
in flushoncommit"). After that change we started producing that warning,
and every now and then a user reports this since the warning happens too
often, it spams dmesg/syslog, and a user is unsure if this reflects any
problem that might compromise the filesystem's reliability.
We can not just lock the sb->s_umount semaphore before calling
writeback_inodes_sb(), because that would at least deadlock with
filesystem freezing, since at fs/super.c:freeze_super() sync_filesystem()
is called while we are holding that semaphore in write mode, and that can
trigger a transaction commit, resulting in a deadlock. It would also
trigger the same type of deadlock in the unmount path. Possibly, it could
also introduce some other locking dependencies that lockdep would report.
To fix this call try_to_writeback_inodes_sb() instead of
writeback_inodes_sb(), because that will try to read lock sb->s_umount
and then will only call writeback_inodes_sb() if it was able to lock it.
This is fine because the cases where it can't read lock sb->s_umount
are during a filesystem unmount or during a filesystem freeze - in those
cases sb->s_umount is write locked and sync_filesystem() is called, which
calls writeback_inodes_sb(). In other words, in all cases where we can't
take a read lock on sb->s_umount, writeback is already being triggered
elsewhere.
An alternative would be to call btrfs_start_delalloc_roots() with a
number of pages different from LONG_MAX, for example matching the number
of delalloc bytes we currently have, in which case we would end up
starting all delalloc with filemap_fdatawrite_wbc() and not with an
async flush via filemap_flush() - that is only possible after the rather
recent commit e076ab2a2c ("btrfs: shrink delalloc pages instead of
full inodes"). However that creates a whole new can of worms due to new
lock dependencies, which lockdep complains, like for example:
[ 8948.247280] ======================================================
[ 8948.247823] WARNING: possible circular locking dependency detected
[ 8948.248353] 5.17.0-rc1-btrfs-next-111 #1 Not tainted
[ 8948.248786] ------------------------------------------------------
[ 8948.249320] kworker/u16:18/933570 is trying to acquire lock:
[ 8948.249812] ffff9b3de1591690 (sb_internal#2){.+.+}-{0:0}, at: find_free_extent+0x141e/0x1590 [btrfs]
[ 8948.250638]
but task is already holding lock:
[ 8948.251140] ffff9b3e09c717d8 (&root->delalloc_mutex){+.+.}-{3:3}, at: start_delalloc_inodes+0x78/0x400 [btrfs]
[ 8948.252018]
which lock already depends on the new lock.
[ 8948.252710]
the existing dependency chain (in reverse order) is:
[ 8948.253343]
-> #2 (&root->delalloc_mutex){+.+.}-{3:3}:
[ 8948.253950] __mutex_lock+0x90/0x900
[ 8948.254354] start_delalloc_inodes+0x78/0x400 [btrfs]
[ 8948.254859] btrfs_start_delalloc_roots+0x194/0x2a0 [btrfs]
[ 8948.255408] btrfs_commit_transaction+0x32f/0xc00 [btrfs]
[ 8948.255942] btrfs_mksubvol+0x380/0x570 [btrfs]
[ 8948.256406] btrfs_mksnapshot+0x81/0xb0 [btrfs]
[ 8948.256870] __btrfs_ioctl_snap_create+0x17f/0x190 [btrfs]
[ 8948.257413] btrfs_ioctl_snap_create_v2+0xbb/0x140 [btrfs]
[ 8948.257961] btrfs_ioctl+0x1196/0x3630 [btrfs]
[ 8948.258418] __x64_sys_ioctl+0x83/0xb0
[ 8948.258793] do_syscall_64+0x3b/0xc0
[ 8948.259146] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 8948.259709]
-> #1 (&fs_info->delalloc_root_mutex){+.+.}-{3:3}:
[ 8948.260330] __mutex_lock+0x90/0x900
[ 8948.260692] btrfs_start_delalloc_roots+0x97/0x2a0 [btrfs]
[ 8948.261234] btrfs_commit_transaction+0x32f/0xc00 [btrfs]
[ 8948.261766] btrfs_set_free_space_cache_v1_active+0x38/0x60 [btrfs]
[ 8948.262379] btrfs_start_pre_rw_mount+0x119/0x180 [btrfs]
[ 8948.262909] open_ctree+0x1511/0x171e [btrfs]
[ 8948.263359] btrfs_mount_root.cold+0x12/0xde [btrfs]
[ 8948.263863] legacy_get_tree+0x30/0x50
[ 8948.264242] vfs_get_tree+0x28/0xc0
[ 8948.264594] vfs_kern_mount.part.0+0x71/0xb0
[ 8948.265017] btrfs_mount+0x11d/0x3a0 [btrfs]
[ 8948.265462] legacy_get_tree+0x30/0x50
[ 8948.265851] vfs_get_tree+0x28/0xc0
[ 8948.266203] path_mount+0x2d4/0xbe0
[ 8948.266554] __x64_sys_mount+0x103/0x140
[ 8948.266940] do_syscall_64+0x3b/0xc0
[ 8948.267300] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 8948.267790]
-> #0 (sb_internal#2){.+.+}-{0:0}:
[ 8948.268322] __lock_acquire+0x12e8/0x2260
[ 8948.268733] lock_acquire+0xd7/0x310
[ 8948.269092] start_transaction+0x44c/0x6e0 [btrfs]
[ 8948.269591] find_free_extent+0x141e/0x1590 [btrfs]
[ 8948.270087] btrfs_reserve_extent+0x14b/0x280 [btrfs]
[ 8948.270588] cow_file_range+0x17e/0x490 [btrfs]
[ 8948.271051] btrfs_run_delalloc_range+0x345/0x7a0 [btrfs]
[ 8948.271586] writepage_delalloc+0xb5/0x170 [btrfs]
[ 8948.272071] __extent_writepage+0x156/0x3c0 [btrfs]
[ 8948.272579] extent_write_cache_pages+0x263/0x460 [btrfs]
[ 8948.273113] extent_writepages+0x76/0x130 [btrfs]
[ 8948.273573] do_writepages+0xd2/0x1c0
[ 8948.273942] filemap_fdatawrite_wbc+0x68/0x90
[ 8948.274371] start_delalloc_inodes+0x17f/0x400 [btrfs]
[ 8948.274876] btrfs_start_delalloc_roots+0x194/0x2a0 [btrfs]
[ 8948.275417] flush_space+0x1f2/0x630 [btrfs]
[ 8948.275863] btrfs_async_reclaim_data_space+0x108/0x1b0 [btrfs]
[ 8948.276438] process_one_work+0x252/0x5a0
[ 8948.276829] worker_thread+0x55/0x3b0
[ 8948.277189] kthread+0xf2/0x120
[ 8948.277506] ret_from_fork+0x22/0x30
[ 8948.277868]
other info that might help us debug this:
[ 8948.278548] Chain exists of:
sb_internal#2 --> &fs_info->delalloc_root_mutex --> &root->delalloc_mutex
[ 8948.279601] Possible unsafe locking scenario:
[ 8948.280102] CPU0 CPU1
[ 8948.280508] ---- ----
[ 8948.280915] lock(&root->delalloc_mutex);
[ 8948.281271] lock(&fs_info->delalloc_root_mutex);
[ 8948.281915] lock(&root->delalloc_mutex);
[ 8948.282487] lock(sb_internal#2);
[ 8948.282800]
*** DEADLOCK ***
[ 8948.283333] 4 locks held by kworker/u16:18/933570:
[ 8948.283750] #0: ffff9b3dc00a9d48 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1d2/0x5a0
[ 8948.284609] #1: ffffa90349dafe70 ((work_completion)(&fs_info->async_data_reclaim_work)){+.+.}-{0:0}, at: process_one_work+0x1d2/0x5a0
[ 8948.285637] #2: ffff9b3e14db5040 (&fs_info->delalloc_root_mutex){+.+.}-{3:3}, at: btrfs_start_delalloc_roots+0x97/0x2a0 [btrfs]
[ 8948.286674] #3: ffff9b3e09c717d8 (&root->delalloc_mutex){+.+.}-{3:3}, at: start_delalloc_inodes+0x78/0x400 [btrfs]
[ 8948.287596]
stack backtrace:
[ 8948.287975] CPU: 3 PID: 933570 Comm: kworker/u16:18 Not tainted 5.17.0-rc1-btrfs-next-111 #1
[ 8948.288677] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[ 8948.289649] Workqueue: events_unbound btrfs_async_reclaim_data_space [btrfs]
[ 8948.290298] Call Trace:
[ 8948.290517] <TASK>
[ 8948.290700] dump_stack_lvl+0x59/0x73
[ 8948.291026] check_noncircular+0xf3/0x110
[ 8948.291375] ? start_transaction+0x228/0x6e0 [btrfs]
[ 8948.291826] __lock_acquire+0x12e8/0x2260
[ 8948.292241] lock_acquire+0xd7/0x310
[ 8948.292714] ? find_free_extent+0x141e/0x1590 [btrfs]
[ 8948.293241] ? lock_is_held_type+0xea/0x140
[ 8948.293601] start_transaction+0x44c/0x6e0 [btrfs]
[ 8948.294055] ? find_free_extent+0x141e/0x1590 [btrfs]
[ 8948.294518] find_free_extent+0x141e/0x1590 [btrfs]
[ 8948.294957] ? _raw_spin_unlock+0x29/0x40
[ 8948.295312] ? btrfs_get_alloc_profile+0x124/0x290 [btrfs]
[ 8948.295813] btrfs_reserve_extent+0x14b/0x280 [btrfs]
[ 8948.296270] cow_file_range+0x17e/0x490 [btrfs]
[ 8948.296691] btrfs_run_delalloc_range+0x345/0x7a0 [btrfs]
[ 8948.297175] ? find_lock_delalloc_range+0x247/0x270 [btrfs]
[ 8948.297678] writepage_delalloc+0xb5/0x170 [btrfs]
[ 8948.298123] __extent_writepage+0x156/0x3c0 [btrfs]
[ 8948.298570] extent_write_cache_pages+0x263/0x460 [btrfs]
[ 8948.299061] extent_writepages+0x76/0x130 [btrfs]
[ 8948.299495] do_writepages+0xd2/0x1c0
[ 8948.299817] ? sched_clock_cpu+0xd/0x110
[ 8948.300160] ? lock_release+0x155/0x4a0
[ 8948.300494] filemap_fdatawrite_wbc+0x68/0x90
[ 8948.300874] ? do_raw_spin_unlock+0x4b/0xa0
[ 8948.301243] start_delalloc_inodes+0x17f/0x400 [btrfs]
[ 8948.301706] ? lock_release+0x155/0x4a0
[ 8948.302055] btrfs_start_delalloc_roots+0x194/0x2a0 [btrfs]
[ 8948.302564] flush_space+0x1f2/0x630 [btrfs]
[ 8948.302970] btrfs_async_reclaim_data_space+0x108/0x1b0 [btrfs]
[ 8948.303510] process_one_work+0x252/0x5a0
[ 8948.303860] ? process_one_work+0x5a0/0x5a0
[ 8948.304221] worker_thread+0x55/0x3b0
[ 8948.304543] ? process_one_work+0x5a0/0x5a0
[ 8948.304904] kthread+0xf2/0x120
[ 8948.305184] ? kthread_complete_and_exit+0x20/0x20
[ 8948.305598] ret_from_fork+0x22/0x30
[ 8948.305921] </TASK>
It all comes from the fact that btrfs_start_delalloc_roots() takes the
delalloc_root_mutex, in the transaction commit path we are holding a
read lock on one of the superblock's freeze semaphores (via
sb_start_intwrite()), the async reclaim task can also do a call to
btrfs_start_delalloc_roots(), which ends up triggering writeback with
calls to filemap_fdatawrite_wbc(), resulting in extent allocation which
in turn can call btrfs_start_transaction(), which will result in taking
the freeze semaphore via sb_start_intwrite(), forming a nasty dependency
on all those locks which can be taken in different orders by different
code paths.
So just adopt the simple approach of calling try_to_writeback_inodes_sb()
at btrfs_start_delalloc_flush().
Link: https://lore.kernel.org/linux-btrfs/20220130005258.GA7465@cuci.nl/
Link: https://lore.kernel.org/linux-btrfs/43acc426-d683-d1b6-729d-c6bc4a2fff4d@gmail.com/
Link: https://lore.kernel.org/linux-btrfs/6833930a-08d7-6fbc-0141-eb9cdfd6bb4d@gmail.com/
Link: https://lore.kernel.org/linux-btrfs/20190322041731.GF16651@hungrycats.org/
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
[ add more link reports ]
Signed-off-by: David Sterba <dsterba@suse.com>
At ioctl.c:create_snapshot(), we allocate a pending snapshot structure and
then attach it to the transaction's list of pending snapshots. After that
we call btrfs_commit_transaction(), and if that returns an error we jump
to 'fail' label, where we kfree() the pending snapshot structure. This can
result in a later use-after-free of the pending snapshot:
1) We allocated the pending snapshot and added it to the transaction's
list of pending snapshots;
2) We call btrfs_commit_transaction(), and it fails either at the first
call to btrfs_run_delayed_refs() or btrfs_start_dirty_block_groups().
In both cases, we don't abort the transaction and we release our
transaction handle. We jump to the 'fail' label and free the pending
snapshot structure. We return with the pending snapshot still in the
transaction's list;
3) Another task commits the transaction. This time there's no error at
all, and then during the transaction commit it accesses a pointer
to the pending snapshot structure that the snapshot creation task
has already freed, resulting in a user-after-free.
This issue could actually be detected by smatch, which produced the
following warning:
fs/btrfs/ioctl.c:843 create_snapshot() warn: '&pending_snapshot->list' not removed from list
So fix this by not having the snapshot creation ioctl directly add the
pending snapshot to the transaction's list. Instead add the pending
snapshot to the transaction handle, and then at btrfs_commit_transaction()
we add the snapshot to the list only when we can guarantee that any error
returned after that point will result in a transaction abort, in which
case the ioctl code can safely free the pending snapshot and no one can
access it anymore.
CC: stable@vger.kernel.org # 5.10+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We don't allow send and balance/relocation to run in parallel in order
to prevent send failing or silently producing some bad stream. This is
because while send is using an extent (specially metadata) or about to
read a metadata extent and expecting it belongs to a specific parent
node, relocation can run, the transaction used for the relocation is
committed and the extent gets reallocated while send is still using the
extent, so it ends up with a different content than expected. This can
result in just failing to read a metadata extent due to failure of the
validation checks (parent transid, level, etc), failure to find a
backreference for a data extent, and other unexpected failures. Besides
reallocation, there's also a similar problem of an extent getting
discarded when it's unpinned after the transaction used for block group
relocation is committed.
The restriction between balance and send was added in commit 9e967495e0
("Btrfs: prevent send failures and crashes due to concurrent relocation"),
kernel 5.3, while the more general restriction between send and relocation
was added in commit 1cea5cf0e6 ("btrfs: ensure relocation never runs
while we have send operations running"), kernel 5.14.
Both send and relocation can be very long running operations. Relocation
because it has to do a lot of IO and expensive backreference lookups in
case there are many snapshots, and send due to read IO when operating on
very large trees. This makes it inconvenient for users and tools to deal
with scheduling both operations.
For zoned filesystem we also have automatic block group relocation, so
send can fail with -EAGAIN when users least expect it or send can end up
delaying the block group relocation for too long. In the future we might
also get the automatic block group relocation for non zoned filesystems.
This change makes it possible for send and relocation to run in parallel.
This is achieved the following way:
1) For all tree searches, send acquires a read lock on the commit root
semaphore;
2) After each tree search, and before releasing the commit root semaphore,
the leaf is cloned and placed in the search path (struct btrfs_path);
3) After releasing the commit root semaphore, the changed_cb() callback
is invoked, which operates on the leaf and writes commands to the pipe
(or file in case send/receive is not used with a pipe). It's important
here to not hold a lock on the commit root semaphore, because if we did
we could deadlock when sending and receiving to the same filesystem
using a pipe - the send task blocks on the pipe because it's full, the
receive task, which is the only consumer of the pipe, triggers a
transaction commit when attempting to create a subvolume or reserve
space for a write operation for example, but the transaction commit
blocks trying to write lock the commit root semaphore, resulting in a
deadlock;
4) Before moving to the next key, or advancing to the next change in case
of an incremental send, check if a transaction used for relocation was
committed (or is about to finish its commit). If so, release the search
path(s) and restart the search, to where we were before, so that we
don't operate on stale extent buffers. The search restarts are always
possible because both the send and parent roots are RO, and no one can
add, remove of update keys (change their offset) in RO trees - the
only exception is deduplication, but that is still not allowed to run
in parallel with send;
5) Periodically check if there is contention on the commit root semaphore,
which means there is a transaction commit trying to write lock it, and
release the semaphore and reschedule if there is contention, so as to
avoid causing any significant delays to transaction commits.
This leaves some room for optimizations for send to have less path
releases and re searching the trees when there's relocation running, but
for now it's kept simple as it performs quite well (on very large trees
with resulting send streams in the order of a few hundred gigabytes).
Test case btrfs/187, from fstests, stresses relocation, send and
deduplication attempting to run in parallel, but without verifying if send
succeeds and if it produces correct streams. A new test case will be added
that exercises relocation happening in parallel with send and then checks
that send succeeds and the resulting streams are correct.
A final note is that for now this still leaves the mutual exclusion
between send operations and deduplication on files belonging to a root
used by send operations. A solution for that will be slightly more complex
but it will eventually be built on top of this change.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We don't set SHAREABLE on the extent root, we don't need to have this
safety check here.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When we start having multiple extent roots we'll need to use a helper to
get to the correct extent_root. Rename fs_info->extent_root to
_extent_root and convert all of the users of the extent root to using
the btrfs_extent_root() helper. This will allow us to easily clean up
the remaining direct accesses in the future.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This is a leftover from when we used to independently swap the extent
root's commit root and the fs tree commit roots. At the time I simply
changed the helper to a list_add. There's actually no reason to not add
the extent root to the switch commit root at this point, we don't care
about the order we do the switching since it's all done under the
commit_root_sem.
If we re-mark the extent root dirty after adding it to the
switch_commits list we'll see that BTRFS_ROOT_DIRTY isn't set and then
list_move it back onto the dirty list, and then we'll redo the tree
update and everything will be ok.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nobody is using this anymore, remove it.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The root on the trans->root can be anything, and generally we're
committing from the transaction kthread so it's usually the tree_root.
Change this to just take an fs_info, and to maintain compatibility
simply put the ROOT_TREE_OBJECTID as the root objectid for the
tracepoint. This will allow use to remove trans->root.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Currently we do this awful thing where we get another ref on a trans
handle, async off that handle and commit the transaction from that work.
Because we do this we have to mess with current->journal_info and the
freeze counting stuff.
We already have an async thing to kick for the transaction commit, the
transaction kthread. Replace this work struct with a flag on the
fs_info to tell the kthread to go ahead and commit even if it's before
our timeout. Then we can drastically simplify the async transaction
commit path.
Note: this can be simplified and functionality based on the pending
operation COMMIT.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add note ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We used to need the root for btrfs_reserve_metadata_bytes to check the
orphan cleanup state, but we no longer need that, we simply need the
fs_info. Change btrfs_reserve_metadata_bytes() to use the fs_info, and
change both btrfs_block_rsv_refill() and btrfs_block_rsv_add() to do the
same as they simply call btrfs_reserve_metadata_bytes() and then
manipulate the block_rsv that is being used.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In the transaction commit path we are acquiring the tree log mutex too
early and we have a stale comment because:
1) It mentions a function named btrfs_commit_tree_roots(), which does not
exists anymore, it was the old name of commit_cowonly_roots(), renamed
a very long time ago by commit 5d4f98a28c ("Btrfs: Mixed back
reference (FORWARD ROLLING FORMAT CHANGE)"));
2) It mentions that we need to acquire the tree log mutex at that point
to ensure we have no running log writers. That is not correct anymore,
for many years at least, since we are guaranteed that we do not have
any log writers at that point simply because we have set the state of
the transaction to TRANS_STATE_COMMIT_DOING and have waited for all
writers to complete - meaning no one can log until we change the state
of the transaction to TRANS_STATE_UNBLOCKED. Any attempts to join the
transaction or start a new one will block until we do that state
transition;
3) The comment mentions a "trans mutex" which doesn't exists since 2011,
commit a4abeea41a ("Btrfs: kill trans_mutex") removed it;
4) The current use of the tree log mutex is to ensure proper serialization
of super block writes - if someone started a new transaction and uses it
for logging, it will wait for the previous transaction to write its
super block before writing the super block when attempting to sync the
log.
So acquire the tree log mutex only when it's absolutely needed, before
setting the transaction state to TRANS_STATE_UNBLOCKED, fix and move the
stale comment, add some assertions and new comments where appropriate.
Also, this has no effect on concurrency or performance, since the new
start of the critical section is still when the transaction is in the
state TRANS_STATE_COMMIT_DOING.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have a few flags that are inconsistently used to describe the fs in
different states of failure. As of 5963ffcaf3 ("btrfs: always abort
the transaction if we abort a trans handle") we will always set
BTRFS_FS_STATE_ERROR if we abort, so we don't have to check both ABORTED
and ERROR to see if things have gone wrong. Add a helper to check
BTRFS_FS_STATE_ERROR and then convert all checkers of FS_STATE_ERROR to
use the helper.
The TRANS_ABORTED bit check was added in af72273381 ("Btrfs: clean up
resources during umount after trans is aborted") but is not actually
specific.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit eafa4fd0ad ("btrfs: fix exhaustion of the system chunk array
due to concurrent allocations") fixed a problem that resulted in
exhausting the system chunk array in the superblock when there are many
tasks allocating chunks in parallel. Basically too many tasks enter the
first phase of chunk allocation without previous tasks having finished
their second phase of allocation, resulting in too many system chunks
being allocated. That was originally observed when running the fallocate
tests of stress-ng on a PowerPC machine, using a node size of 64K.
However that commit also introduced a deadlock where a task in phase 1 of
the chunk allocation waited for another task that had allocated a system
chunk to finish its phase 2, but that other task was waiting on an extent
buffer lock held by the first task, therefore resulting in both tasks not
making any progress. That change was later reverted by a patch with the
subject "btrfs: fix deadlock with concurrent chunk allocations involving
system chunks", since there is no simple and short solution to address it
and the deadlock is relatively easy to trigger on zoned filesystems, while
the system chunk array exhaustion is not so common.
This change reworks the chunk allocation to avoid the system chunk array
exhaustion. It accomplishes that by making the first phase of chunk
allocation do the updates of the device items in the chunk btree and the
insertion of the new chunk item in the chunk btree. This is done while
under the protection of the chunk mutex (fs_info->chunk_mutex), in the
same critical section that checks for available system space, allocates
a new system chunk if needed and reserves system chunk space. This way
we do not have chunk space reserved until the second phase completes.
The same logic is applied to chunk removal as well, since it keeps
reserved system space long after it is done updating the chunk btree.
For direct allocation of system chunks, the previous behaviour remains,
because otherwise we would deadlock on extent buffers of the chunk btree.
Changes to the chunk btree are by large done by chunk allocation and chunk
removal, which first reserve chunk system space and then later do changes
to the chunk btree. The other remaining cases are uncommon and correspond
to adding a device, removing a device and resizing a device. All these
other cases do not pre-reserve system space, they modify the chunk btree
right away, so they don't hold reserved space for a long period like chunk
allocation and chunk removal do.
The diff of this change is huge, but more than half of it is just addition
of comments describing both how things work regarding chunk allocation and
removal, including both the new behavior and the parts of the old behavior
that did not change.
CC: stable@vger.kernel.org # 5.12+
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Tested-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Tested-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When a task attempting to allocate a new chunk verifies that there is not
currently enough free space in the system space_info and there is another
task that allocated a new system chunk but it did not finish yet the
creation of the respective block group, it waits for that other task to
finish creating the block group. This is to avoid exhaustion of the system
chunk array in the superblock, which is limited, when we have a thundering
herd of tasks allocating new chunks. This problem was described and fixed
by commit eafa4fd0ad ("btrfs: fix exhaustion of the system chunk array
due to concurrent allocations").
However there are two very similar scenarios where this can lead to a
deadlock:
1) Task B allocated a new system chunk and task A is waiting on task B
to finish creation of the respective system block group. However before
task B ends its transaction handle and finishes the creation of the
system block group, it attempts to allocate another chunk (like a data
chunk for an fallocate operation for a very large range). Task B will
be unable to progress and allocate the new chunk, because task A set
space_info->chunk_alloc to 1 and therefore it loops at
btrfs_chunk_alloc() waiting for task A to finish its chunk allocation
and set space_info->chunk_alloc to 0, but task A is waiting on task B
to finish creation of the new system block group, therefore resulting
in a deadlock;
2) Task B allocated a new system chunk and task A is waiting on task B to
finish creation of the respective system block group. By the time that
task B enter the final phase of block group allocation, which happens
at btrfs_create_pending_block_groups(), when it modifies the extent
tree, the device tree or the chunk tree to insert the items for some
new block group, it needs to allocate a new chunk, so it ends up at
btrfs_chunk_alloc() and keeps looping there because task A has set
space_info->chunk_alloc to 1, but task A is waiting for task B to
finish creation of the new system block group and release the reserved
system space, therefore resulting in a deadlock.
In short, the problem is if a task B needs to allocate a new chunk after
it previously allocated a new system chunk and if another task A is
currently waiting for task B to complete the allocation of the new system
chunk.
Unfortunately this deadlock scenario introduced by the previous fix for
the system chunk array exhaustion problem does not have a simple and short
fix, and requires a big change to rework the chunk allocation code so that
chunk btree updates are all made in the first phase of chunk allocation.
And since this deadlock regression is being frequently hit on zoned
filesystems and the system chunk array exhaustion problem is triggered
in more extreme cases (originally observed on PowerPC with a node size
of 64K when running the fallocate tests from stress-ng), revert the
changes from that commit. The next patch in the series, with a subject
of "btrfs: rework chunk allocation to avoid exhaustion of the system
chunk array" does the necessary changes to fix the system chunk array
exhaustion problem.
Reported-by: Naohiro Aota <naohiro.aota@wdc.com>
Link: https://lore.kernel.org/linux-btrfs/20210621015922.ewgbffxuawia7liz@naota-xeon/
Fixes: eafa4fd0ad ("btrfs: fix exhaustion of the system chunk array due to concurrent allocations")
CC: stable@vger.kernel.org # 5.12+
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Tested-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Tested-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing a send we don't expect the task to ever start a transaction
after the initial check that verifies if commit roots match the regular
roots. This is because after that we set current->journal_info with a
stub (special value) that signals we are in send context, so that we take
a read lock on an extent buffer when reading it from disk and verifying
it is valid (its generation matches the generation stored in the parent).
This stub was introduced in 2014 by commit a26e8c9f75 ("Btrfs: don't
clear uptodate if the eb is under IO") in order to fix a concurrency issue
between send and balance.
However there is one particular exception where we end up needing to start
a transaction and when this happens it results in a crash with a stack
trace like the following:
[60015.902283] kernel: WARNING: CPU: 3 PID: 58159 at arch/x86/include/asm/kfence.h:44 kfence_protect_page+0x21/0x80
[60015.902292] kernel: Modules linked in: uinput rfcomm snd_seq_dummy (...)
[60015.902384] kernel: CPU: 3 PID: 58159 Comm: btrfs Not tainted 5.12.9-300.fc34.x86_64 #1
[60015.902387] kernel: Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./F2A88XN-WIFI, BIOS F6 12/24/2015
[60015.902389] kernel: RIP: 0010:kfence_protect_page+0x21/0x80
[60015.902393] kernel: Code: ff 0f 1f 84 00 00 00 00 00 55 48 89 fd (...)
[60015.902396] kernel: RSP: 0018:ffff9fb583453220 EFLAGS: 00010246
[60015.902399] kernel: RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff9fb583453224
[60015.902401] kernel: RDX: ffff9fb583453224 RSI: 0000000000000000 RDI: 0000000000000000
[60015.902402] kernel: RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[60015.902404] kernel: R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002
[60015.902406] kernel: R13: ffff9fb583453348 R14: 0000000000000000 R15: 0000000000000001
[60015.902408] kernel: FS: 00007f158e62d8c0(0000) GS:ffff93bd37580000(0000) knlGS:0000000000000000
[60015.902410] kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[60015.902412] kernel: CR2: 0000000000000039 CR3: 00000001256d2000 CR4: 00000000000506e0
[60015.902414] kernel: Call Trace:
[60015.902419] kernel: kfence_unprotect+0x13/0x30
[60015.902423] kernel: page_fault_oops+0x89/0x270
[60015.902427] kernel: ? search_module_extables+0xf/0x40
[60015.902431] kernel: ? search_bpf_extables+0x57/0x70
[60015.902435] kernel: kernelmode_fixup_or_oops+0xd6/0xf0
[60015.902437] kernel: __bad_area_nosemaphore+0x142/0x180
[60015.902440] kernel: exc_page_fault+0x67/0x150
[60015.902445] kernel: asm_exc_page_fault+0x1e/0x30
[60015.902450] kernel: RIP: 0010:start_transaction+0x71/0x580
[60015.902454] kernel: Code: d3 0f 84 92 00 00 00 80 e7 06 0f 85 63 (...)
[60015.902456] kernel: RSP: 0018:ffff9fb5834533f8 EFLAGS: 00010246
[60015.902458] kernel: RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000000
[60015.902460] kernel: RDX: 0000000000000801 RSI: 0000000000000000 RDI: 0000000000000039
[60015.902462] kernel: RBP: ffff93bc0a7eb800 R08: 0000000000000001 R09: 0000000000000000
[60015.902463] kernel: R10: 0000000000098a00 R11: 0000000000000001 R12: 0000000000000001
[60015.902464] kernel: R13: 0000000000000000 R14: ffff93bc0c92b000 R15: ffff93bc0c92b000
[60015.902468] kernel: btrfs_commit_inode_delayed_inode+0x5d/0x120
[60015.902473] kernel: btrfs_evict_inode+0x2c5/0x3f0
[60015.902476] kernel: evict+0xd1/0x180
[60015.902480] kernel: inode_lru_isolate+0xe7/0x180
[60015.902483] kernel: __list_lru_walk_one+0x77/0x150
[60015.902487] kernel: ? iput+0x1a0/0x1a0
[60015.902489] kernel: ? iput+0x1a0/0x1a0
[60015.902491] kernel: list_lru_walk_one+0x47/0x70
[60015.902495] kernel: prune_icache_sb+0x39/0x50
[60015.902497] kernel: super_cache_scan+0x161/0x1f0
[60015.902501] kernel: do_shrink_slab+0x142/0x240
[60015.902505] kernel: shrink_slab+0x164/0x280
[60015.902509] kernel: shrink_node+0x2c8/0x6e0
[60015.902512] kernel: do_try_to_free_pages+0xcb/0x4b0
[60015.902514] kernel: try_to_free_pages+0xda/0x190
[60015.902516] kernel: __alloc_pages_slowpath.constprop.0+0x373/0xcc0
[60015.902521] kernel: ? __memcg_kmem_charge_page+0xc2/0x1e0
[60015.902525] kernel: __alloc_pages_nodemask+0x30a/0x340
[60015.902528] kernel: pipe_write+0x30b/0x5c0
[60015.902531] kernel: ? set_next_entity+0xad/0x1e0
[60015.902534] kernel: ? switch_mm_irqs_off+0x58/0x440
[60015.902538] kernel: __kernel_write+0x13a/0x2b0
[60015.902541] kernel: kernel_write+0x73/0x150
[60015.902543] kernel: send_cmd+0x7b/0xd0
[60015.902545] kernel: send_extent_data+0x5a3/0x6b0
[60015.902549] kernel: process_extent+0x19b/0xed0
[60015.902551] kernel: btrfs_ioctl_send+0x1434/0x17e0
[60015.902554] kernel: ? _btrfs_ioctl_send+0xe1/0x100
[60015.902557] kernel: _btrfs_ioctl_send+0xbf/0x100
[60015.902559] kernel: ? enqueue_entity+0x18c/0x7b0
[60015.902562] kernel: btrfs_ioctl+0x185f/0x2f80
[60015.902564] kernel: ? psi_task_change+0x84/0xc0
[60015.902569] kernel: ? _flat_send_IPI_mask+0x21/0x40
[60015.902572] kernel: ? check_preempt_curr+0x2f/0x70
[60015.902576] kernel: ? selinux_file_ioctl+0x137/0x1e0
[60015.902579] kernel: ? expand_files+0x1cb/0x1d0
[60015.902582] kernel: ? __x64_sys_ioctl+0x82/0xb0
[60015.902585] kernel: __x64_sys_ioctl+0x82/0xb0
[60015.902588] kernel: do_syscall_64+0x33/0x40
[60015.902591] kernel: entry_SYSCALL_64_after_hwframe+0x44/0xae
[60015.902595] kernel: RIP: 0033:0x7f158e38f0ab
[60015.902599] kernel: Code: ff ff ff 85 c0 79 9b (...)
[60015.902602] kernel: RSP: 002b:00007ffcb2519bf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[60015.902605] kernel: RAX: ffffffffffffffda RBX: 00007ffcb251ae00 RCX: 00007f158e38f0ab
[60015.902607] kernel: RDX: 00007ffcb2519cf0 RSI: 0000000040489426 RDI: 0000000000000004
[60015.902608] kernel: RBP: 0000000000000004 R08: 00007f158e297640 R09: 00007f158e297640
[60015.902610] kernel: R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000
[60015.902612] kernel: R13: 0000000000000002 R14: 00007ffcb251aee0 R15: 0000558c1a83e2a0
[60015.902615] kernel: ---[ end trace 7bbc33e23bb887ae ]---
This happens because when writing to the pipe, by calling kernel_write(),
we end up doing page allocations using GFP_HIGHUSER | __GFP_ACCOUNT as the
gfp flags, which allow reclaim to happen if there is memory pressure. This
allocation happens at fs/pipe.c:pipe_write().
If the reclaim is triggered, inode eviction can be triggered and that in
turn can result in starting a transaction if the inode has a link count
of 0. The transaction start happens early on during eviction, when we call
btrfs_commit_inode_delayed_inode() at btrfs_evict_inode(). This happens if
there is currently an open file descriptor for an inode with a link count
of 0 and the reclaim task gets a reference on the inode before that
descriptor is closed, in which case the reclaim task ends up doing the
final iput that triggers the inode eviction.
When we have assertions enabled (CONFIG_BTRFS_ASSERT=y), this triggers
the following assertion at transaction.c:start_transaction():
/* Send isn't supposed to start transactions. */
ASSERT(current->journal_info != BTRFS_SEND_TRANS_STUB);
And when assertions are not enabled, it triggers a crash since after that
assertion we cast current->journal_info into a transaction handle pointer
and then dereference it:
if (current->journal_info) {
WARN_ON(type & TRANS_EXTWRITERS);
h = current->journal_info;
refcount_inc(&h->use_count);
(...)
Which obviously results in a crash due to an invalid memory access.
The same type of issue can happen during other memory allocations we
do directly in the send code with kmalloc (and friends) as they use
GFP_KERNEL and therefore may trigger reclaim too, which started to
happen since 2016 after commit e780b0d1c1 ("btrfs: send: use
GFP_KERNEL everywhere").
The issue could be solved by setting up a NOFS context for the entire
send operation so that reclaim could not be triggered when allocating
memory or pages through kernel_write(). However that is not very friendly
and we can in fact get rid of the send stub because:
1) The stub was introduced way back in 2014 by commit a26e8c9f75
("Btrfs: don't clear uptodate if the eb is under IO") to solve an
issue exclusive to when send and balance are running in parallel,
however there were other problems between balance and send and we do
not allow anymore to have balance and send run concurrently since
commit 9e967495e0 ("Btrfs: prevent send failures and crashes due
to concurrent relocation"). More generically the issues are between
send and relocation, and that last commit eliminated only the
possibility of having send and balance run concurrently, but shrinking
a device also can trigger relocation, and on zoned filesystems we have
relocation of partially used block groups triggered automatically as
well. The previous patch that has a subject of:
"btrfs: ensure relocation never runs while we have send operations running"
Addresses all the remaining cases that can trigger relocation.
2) We can actually allow starting and even committing transactions while
in a send context if needed because send is not holding any locks that
would block the start or the commit of a transaction.
So get rid of all the logic added by commit a26e8c9f75 ("Btrfs: don't
clear uptodate if the eb is under IO"). We can now always call
clear_extent_buffer_uptodate() at verify_parent_transid() since send is
the only case that uses commit roots without having a transaction open or
without holding the commit_root_sem.
Reported-by: Chris Murphy <lists@colorremedies.com>
Link: https://lore.kernel.org/linux-btrfs/CAJCQCtRQ57=qXo3kygwpwEBOU_CA_eKvdmjP52sU=eFvuVOEGw@mail.gmail.com/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
qgroup_account_snapshot() is trying to unlock the not taken
tree_log_mutex in a error path. Since ret != 0 in this case, we can
just return from here.
Fixes: 2a4d84c11a ("btrfs: move delayed ref flushing for qgroup into qgroup helper")
CC: stable@vger.kernel.org # 5.12+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Function wait_current_trans_commit_start is now fairly trivial so it can
be inlined in its only caller.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There's only one caller left btrfs_ioctl_start_sync that passes 0, so we
can remove the switch in btrfs_commit_transaction_async.
A cleanup 9babda9f33 ("btrfs: Remove async_transid from
btrfs_mksubvol/create_subvol/create_snapshot") removed calls that passed
1, so this is a followup.
As this removes last call of wait_current_trans_commit_start_and_unblock,
remove the function as well.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The defrag loop processes leaves in batches and starting transaction for
each. The whole defragmentation on a given root is protected by a bit
but in case the transaction fails, the bit is not cleared
In case the transaction fails the bit would prevent starting
defragmentation again, so make sure it's cleared.
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
While stress testing our error handling I noticed that sometimes we
would still commit the transaction even though we had aborted the
transaction.
Currently we track if a trans handle has dirtied any metadata, and if it
hasn't we mark the filesystem as having an error (so no new transactions
can be started), but we will allow the current transaction to complete
as we do not mark the transaction itself as having been aborted.
This sounds good in theory, but we were not properly tracking IO errors
in btrfs_finish_ordered_io, and thus committing the transaction with
bogus free space data. This isn't necessarily a problem per-se with the
free space cache, as the other guards in place would have kept us from
accepting the free space cache as valid, but highlights a real world
case where we had a bug and could have corrupted the filesystem because
of it.
This "skip abort on empty trans handle" is nice in theory, but assumes
we have perfect error handling everywhere, which we clearly do not.
Also we do not allow further transactions to be started, so all this
does is save the last transaction that was happening, which doesn't
necessarily gain us anything other than the potential for real
corruption.
Remove this particular bit of code, if we decide we need to abort the
transaction then abort the current one and keep us from doing real harm
to the file system, regardless of whether this specific trans handle
dirtied anything or not.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There is a race between a task aborting a transaction during a commit,
a task doing an fsync and the transaction kthread, which leads to an
use-after-free of the log root tree. When this happens, it results in a
stack trace like the following:
BTRFS info (device dm-0): forced readonly
BTRFS warning (device dm-0): Skipping commit of aborted transaction.
BTRFS: error (device dm-0) in cleanup_transaction:1958: errno=-5 IO failure
BTRFS warning (device dm-0): lost page write due to IO error on /dev/mapper/error-test (-5)
BTRFS warning (device dm-0): Skipping commit of aborted transaction.
BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0xa4e8 len 4096 err no 10
BTRFS error (device dm-0): error writing primary super block to device 1
BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e000 len 4096 err no 10
BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e008 len 4096 err no 10
BTRFS warning (device dm-0): direct IO failed ino 261 rw 0,0 sector 0x12e010 len 4096 err no 10
BTRFS: error (device dm-0) in write_all_supers:4110: errno=-5 IO failure (1 errors while writing supers)
BTRFS: error (device dm-0) in btrfs_sync_log:3308: errno=-5 IO failure
general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b68: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
CPU: 2 PID: 2458471 Comm: fsstress Not tainted 5.12.0-rc5-btrfs-next-84 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
RIP: 0010:__mutex_lock+0x139/0xa40
Code: c0 74 19 (...)
RSP: 0018:ffff9f18830d7b00 EFLAGS: 00010202
RAX: 6b6b6b6b6b6b6b68 RBX: 0000000000000001 RCX: 0000000000000002
RDX: ffffffffb9c54d13 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff9f18830d7bc0 R08: 0000000000000000 R09: 0000000000000000
R10: ffff9f18830d7be0 R11: 0000000000000001 R12: ffff8c6cd199c040
R13: ffff8c6c95821358 R14: 00000000fffffffb R15: ffff8c6cbcf01358
FS: 00007fa9140c2b80(0000) GS:ffff8c6fac600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa913d52000 CR3: 000000013d2b4003 CR4: 0000000000370ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
? __btrfs_handle_fs_error+0xde/0x146 [btrfs]
? btrfs_sync_log+0x7c1/0xf20 [btrfs]
? btrfs_sync_log+0x7c1/0xf20 [btrfs]
btrfs_sync_log+0x7c1/0xf20 [btrfs]
btrfs_sync_file+0x40c/0x580 [btrfs]
do_fsync+0x38/0x70
__x64_sys_fsync+0x10/0x20
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fa9142a55c3
Code: 8b 15 09 (...)
RSP: 002b:00007fff26278d48 EFLAGS: 00000246 ORIG_RAX: 000000000000004a
RAX: ffffffffffffffda RBX: 0000563c83cb4560 RCX: 00007fa9142a55c3
RDX: 00007fff26278cb0 RSI: 00007fff26278cb0 RDI: 0000000000000005
RBP: 0000000000000005 R08: 0000000000000001 R09: 00007fff26278d5c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000340
R13: 00007fff26278de0 R14: 00007fff26278d96 R15: 0000563c83ca57c0
Modules linked in: btrfs dm_zero dm_snapshot dm_thin_pool (...)
---[ end trace ee2f1b19327d791d ]---
The steps that lead to this crash are the following:
1) We are at transaction N;
2) We have two tasks with a transaction handle attached to transaction N.
Task A and Task B. Task B is doing an fsync;
3) Task B is at btrfs_sync_log(), and has saved fs_info->log_root_tree
into a local variable named 'log_root_tree' at the top of
btrfs_sync_log(). Task B is about to call write_all_supers(), but
before that...
4) Task A calls btrfs_commit_transaction(), and after it sets the
transaction state to TRANS_STATE_COMMIT_START, an error happens before
it waits for the transaction's 'num_writers' counter to reach a value
of 1 (no one else attached to the transaction), so it jumps to the
label "cleanup_transaction";
5) Task A then calls cleanup_transaction(), where it aborts the
transaction, setting BTRFS_FS_STATE_TRANS_ABORTED on fs_info->fs_state,
setting the ->aborted field of the transaction and the handle to an
errno value and also setting BTRFS_FS_STATE_ERROR on fs_info->fs_state.
After that, at cleanup_transaction(), it deletes the transaction from
the list of transactions (fs_info->trans_list), sets the transaction
to the state TRANS_STATE_COMMIT_DOING and then waits for the number
of writers to go down to 1, as it's currently 2 (1 for task A and 1
for task B);
6) The transaction kthread is running and sees that BTRFS_FS_STATE_ERROR
is set in fs_info->fs_state, so it calls btrfs_cleanup_transaction().
There it sees the list fs_info->trans_list is empty, and then proceeds
into calling btrfs_drop_all_logs(), which frees the log root tree with
a call to btrfs_free_log_root_tree();
7) Task B calls write_all_supers() and, shortly after, under the label
'out_wake_log_root', it deferences the pointer stored in
'log_root_tree', which was already freed in the previous step by the
transaction kthread. This results in a use-after-free leading to a
crash.
Fix this by deleting the transaction from the list of transactions at
cleanup_transaction() only after setting the transaction state to
TRANS_STATE_COMMIT_DOING and waiting for all existing tasks that are
attached to the transaction to release their transaction handles.
This makes the transaction kthread wait for all the tasks attached to
the transaction to be done with the transaction before dropping the
log roots and doing other cleanups.
Fixes: ef67963dac ("btrfs: drop logs when we've aborted a transaction")
CC: stable@vger.kernel.org # 5.10+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_update_reloc_root will will return errors in the future, so handle
the error properly in commit_fs_roots.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We can create a reloc root when we record the root in the trans, which
can fail for all sorts of different reasons. Propagate this error up
the chain of callers. Future patches will fix the callers of
btrfs_record_root_in_trans() to handle the error.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
record_root_in_trans can currently fail, so handle this failure
properly.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
record_root_in_trans can fail currently, handle this failure properly.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
record_root_in_trans can fail currently, so handle this failure
properly.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_record_root_in_trans will return errors in the future, so handle
the error properly in start_transaction.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add comment ]
Signed-off-by: David Sterba <dsterba@suse.com>
