Commit Graph

191 Commits

Author SHA1 Message Date
Johannes Thumshirn
9669fcb77e btrfs: change dump_block_groups() in btrfs_dump_space_info() from int to bool
btrfs_dump_space_info()'s parameter dump_block_groups is used as a boolean
although it is defined as an integer.

Change it from int to bool.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Daniel Vacek <neelx@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-07-21 23:58:05 +02:00
David Sterba
60a8bab08c btrfs: rename err to ret in calc_pct_ratio()
Unify naming of return value to the preferred way.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-07-21 23:53:28 +02:00
Johannes Thumshirn
2a946bf6d6 btrfs: make btrfs_should_periodic_reclaim() static
btrfs_should_periodic_reclaim() is not used outside of space-info.c so
make it static and remove the prototype from space-info.h.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-07-21 23:44:11 +02:00
Naohiro Aota
45a59513b4 btrfs: add support for reclaiming from sub-space space_info
Modify btrfs_async_{data,metadata}_reclaim() to run the reclaim process
on the sub-spaces as well.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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>
2025-05-15 14:30:54 +02:00
Naohiro Aota
cc0517fe77 btrfs: tweak extent/chunk allocation for space_info sub-space
Make the extent allocator and the chunk allocator aware of the sub-space.
It now uses BTRFS_SUB_GROUP_DATA_RELOC sub-space for data relocation block
group, and uses BTRFS_SUB_GROUP_TREELOG for metadata tree-log block group.

And, it needs to check the space_info is the right one when a block group
candidate is given. Also, new block group should now belong to the
specified one.

Now that, block_group->space_info is always set before
btrfs_add_bg_to_space_info(), we no longer need to "find" the space_info.
So, rename the variable name to address that as well.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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>
2025-05-15 14:30:53 +02:00
Naohiro Aota
9a3023b828 btrfs: introduce tree-log sub-space_info
Introduce the tree-log sub-space_info, which is sub-space of
metadata space_info and dedicated for tree-log node allocation.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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>
2025-05-15 14:30:53 +02:00
Naohiro Aota
f92ee31e03 btrfs: introduce btrfs_space_info sub-group
Current code assumes we have only one space_info for each block group type
(DATA, METADATA, and SYSTEM). We sometime need multiple space infos to
manage special block groups.

One example is handling the data relocation block group for the zoned mode.
That block group is dedicated for writing relocated data and we cannot
allocate any regular extent from that block group, which is implemented in
the zoned extent allocator. This block group still belongs to the normal
data space_info. So, when all the normal data block groups are full and
there is some free space in the dedicated block group, the space_info
looks to have some free space, while it cannot allocate normal extent
anymore. That results in a strange ENOSPC error. We need to have a
space_info for the relocation data block group to represent the situation
properly.

Adds a basic infrastructure for having a "sub-group" of a space_info:
creation and removing. A sub-group space_info belongs to one of the
primary space_infos and has the same flags as its parent.

This commit first introduces the relocation data sub-space_info, and the
next commit will introduce tree-log sub-space_info. In the future, it could
be useful to implement tiered storage for btrfs e.g. by implementing a
sub-group space_info for block groups resides on a fast storage.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:53 +02:00
Naohiro Aota
098a442d5b btrfs: add space_info argument to btrfs_chunk_alloc()
Take a btrfs_space_info argument in btrfs_chunk_alloc(). New block group
will belong to that space_info.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:53 +02:00
Naohiro Aota
4ec06a9ddb btrfs: factor out do_async_reclaim_{data,metadata}_space()
Factor out the main part of btrfs_async_reclaim_data_space() to
do_async_reclaim_data_space(), so it can take data space_info parameter
it is working on. Do the same for metadata. There is no functional change.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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>
2025-05-15 14:30:53 +02:00
Naohiro Aota
ac5578fef3 btrfs: factor out init_space_info() from create_space_info()
Factor out initialization of the space_info struct, which is used in a
later patch. There is no functional change.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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>
2025-05-15 14:30:53 +02:00
Naohiro Aota
5d39fda880 btrfs: pass btrfs_space_info to btrfs_reserve_data_bytes()
Pass struct btrfs_space_info to btrfs_reserve_data_bytes() to allow
reserving the data from multiple data space_info candidates.

This is a preparation for the following commits and there is no functional
change.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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>
2025-05-15 14:30:52 +02:00
Mark Harmstone
846b534075 btrfs: fix typo in space info explanation
There's an explanation of how space info works at the top of
fs/btrfs/space-info.c, which makes reference to a variable called
bytes_may_reserve.  There's nothing called that in the code, and wasn't
at time the comment was written; as far I can tell this is a typo, and
it should actually be bytes_may_use.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Mark Harmstone <maharmstone@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-05-15 14:30:39 +02:00
David Sterba
6149c82bda btrfs: update include and forward declarations in headers
Pass over all header files and add missing forward declarations,
includes or fix include types.

Signed-off-by: David Sterba <dsterba@suse.com>
2025-03-18 20:35:43 +01:00
Naohiro Aota
453a73c306 btrfs: zoned: reclaim unused zone by zone resetting
On the zoned mode, once used and freed region is still not reusable after the
freeing. The underlying zone needs to be reset before reusing. Btrfs resets a
zone when it removes a block group, and then new block group is allocated on
the zones to reuse the zones. But, it is sometime too late to catch up with a
write side.

This commit introduces a new space-info reclaim method ZONE_RESET. That will
pick a block group from the unused list and reset its zone to reuse the
zone_unusable space. It is faster than removing the block group and re-creating
a new block group on the same zones.

For the first implementation, the ZONE_RESET is only applied to a block group
whose region is fully zone_unusable. Reclaiming partial zone_unusable block
group could be implemented later.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2025-01-13 14:53:14 +01:00
Naohiro Aota
7de9ca1f30 btrfs: drop fs_info argument from btrfs_update_space_info_*()
Since commit e1e577aafe41 ("btrfs: store fs_info in space_info"), we have
the fs_info in a space_info. So, we can drop fs_info argument from
btrfs_update_space_info_*. There is no behavior change.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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>
2025-01-13 14:53:14 +01:00
Naohiro Aota
3704db1013 btrfs: factor out btrfs_return_free_space()
Factor out a part of unpin_extent_range() that returns space back to the
space info, prioritizing global block reserve.  Also, move the "len"
variable into the loop to clarify we don't need to carry it beyond an
iteration.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.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>
2025-01-13 14:53:14 +01:00
David Sterba
343a63594b btrfs: drop unused parameter fs_info from do_reclaim_sweep()
The parameter is unused and we can get it from space info if needed.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11 14:34:15 +01:00
David Sterba
a6563fa06a btrfs: drop unused parameter fs_info from wait_reserve_ticket()
The parameter is not used, we can also reach it from the space info if
needed in the future.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11 14:34:15 +01:00
Shen Lichuan
2144e1f23f btrfs: correct typos in multiple comments across various files
Fix some confusing spelling errors that were currently identified,
the details are as follows:

	block-group.c: 2800: 	uncompressible 	==> incompressible
	extent-tree.c: 3131:	EXTEMT		==> EXTENT
	extent_io.c: 3124: 	utlizing 	==> utilizing
	extent_map.c: 1323: 	ealier		==> earlier
	extent_map.c: 1325:	possiblity	==> possibility
	fiemap.c: 189:		emmitted	==> emitted
	fiemap.c: 197:		emmitted	==> emitted
	fiemap.c: 203:		emmitted	==> emitted
	transaction.h: 36:	trasaction	==> transaction
	volumes.c: 5312:	filesysmte	==> filesystem
	zoned.c: 1977:		trasnsaction	==> transaction

Signed-off-by: Shen Lichuan <shenlichuan@vivo.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-11-11 14:34:14 +01:00
David Sterba
ca283ea992 btrfs: constify more pointer parameters
Continue adding const to parameters.  This is for clarity and minor
addition to safety. There are some minor effects, in the assembly code
and .ko measured on release config.

Signed-off-by: David Sterba <dsterba@suse.com>
2024-09-10 16:51:22 +02:00
Filipe Manana
ecb54277cb btrfs: fix uninitialized return value from btrfs_reclaim_sweep()
The return variable 'ret' at btrfs_reclaim_sweep() is never assigned if
none of the space infos is reclaimable (for example if periodic reclaim
is disabled, which is the default), so we return an undefined value.

This can be fixed my making btrfs_reclaim_sweep() not return any value
as well as do_reclaim_sweep() because:

1) do_reclaim_sweep() always returns 0, so we can make it return void;

2) The only caller of btrfs_reclaim_sweep() (btrfs_reclaim_bgs()) doesn't
   care about its return value, and in its context there's nothing to do
   about any errors anyway.

Therefore remove the return value from btrfs_reclaim_sweep() and
do_reclaim_sweep().

Fixes: e4ca3932ae ("btrfs: periodic block_group reclaim")
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>
2024-08-27 16:42:09 +02:00
Naohiro Aota
8cd44dd1d1 btrfs: zoned: fix zone_unusable accounting on making block group read-write again
When btrfs makes a block group read-only, it adds all free regions in the
block group to space_info->bytes_readonly. That free space excludes
reserved and pinned regions. OTOH, when btrfs makes the block group
read-write again, it moves all the unused regions into the block group's
zone_unusable. That unused region includes reserved and pinned regions.
As a result, it counts too much zone_unusable bytes.

Fortunately (or unfortunately), having erroneous zone_unusable does not
affect the calculation of space_info->bytes_readonly, because free
space (num_bytes in btrfs_dec_block_group_ro) calculation is done based on
the erroneous zone_unusable and it reduces the num_bytes just to cancel the
error.

This behavior can be easily discovered by adding a WARN_ON to check e.g,
"bg->pinned > 0" in btrfs_dec_block_group_ro(), and running fstests test
case like btrfs/282.

Fix it by properly considering pinned and reserved in
btrfs_dec_block_group_ro(). Also, add a WARN_ON and introduce
btrfs_space_info_update_bytes_zone_unusable() to catch a similar mistake.

Fixes: 169e0da91a ("btrfs: zoned: track unusable bytes for zones")
CC: stable@vger.kernel.org # 5.15+
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-29 19:21:19 +02:00
Naohiro Aota
d89c285d28 btrfs: do not subtract delalloc from avail bytes
The block group's avail bytes printed when dumping a space info subtract
the delalloc_bytes. However, as shown in btrfs_add_reserved_bytes() and
btrfs_free_reserved_bytes(), it is added or subtracted along with
"reserved" for the delalloc case, which means the "delalloc_bytes" is a
part of the "reserved" bytes. So, excluding it to calculate the avail space
counts delalloc_bytes twice, which can lead to an invalid result.

Fixes: e50b122b83 ("btrfs: print available space for a block group when dumping a space info")
CC: stable@vger.kernel.org # 6.6+
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-29 19:21:04 +02:00
Boris Burkov
0e962e755b btrfs: urgent periodic reclaim pass
Periodic reclaim attempts to avoid block_groups seeing active use with a
sweep mark that gets cleared on allocation and set on a sweep. In urgent
conditions where we have very little unallocated space (less than one
chunk used by the threshold calculation for the unallocated target), we
want to be able to override this mechanism.

Introduce a second pass that only happens if we fail to find a reclaim
candidate and reclaim is urgent. In that case, do a second pass where
all block groups are eligible.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11 15:33:27 +02:00
Boris Burkov
813d4c6422 btrfs: prevent pathological periodic reclaim loops
Periodic reclaim runs the risk of getting stuck in a state where it
keeps reclaiming the same block group over and over. This can happen if

1. reclaiming that block_group fails
2. reclaiming that block_group fails to move any extents into existing
   block_groups and just allocates a fresh chunk and moves everything.

Currently, 1. is a very tight loop inside the reclaim worker. That is
critical for edge triggered reclaim or else we risk forgetting about a
reclaimable group. On the other hand, with level triggered reclaim we
can break out of that loop and get it later.

With that fixed, 2. applies to both failures and "successes" with no
progress. If we have done a periodic reclaim on a space_info and nothing
has changed in that space_info, there is not much point to trying again,
so don't, until enough space gets free, which we capture with a
heuristic of needing to net free 1 chunk.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11 15:33:27 +02:00
Boris Burkov
e4ca3932ae btrfs: periodic block_group reclaim
We currently employ a edge-triggered block group reclaim strategy which
marks block groups for reclaim as they free down past a threshold.

With a dynamic threshold, this is worse than doing it in a
level-triggered fashion periodically. That is because the reclaim
itself happens periodically, so the threshold at that point in time is
what really matters, not the threshold at freeing time. If we mark the
reclaim in a big pass, then sort by usage and do reclaim, we also
benefit from a negative feedback loop preventing unnecessary reclaims as
we crunch through the "best" candidates.

Since this is quite a different model, it requires some additional
support. The edge triggered reclaim has a good heuristic for not
reclaiming fresh block groups, so we need to replace that with a typical
GC sweep mark which skips block groups that have seen an allocation
since the last sweep.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11 15:33:27 +02:00
Boris Burkov
f5ff64ccf7 btrfs: dynamic block_group reclaim threshold
We can currently recover allocated block_groups by:

- explicitly starting balance operations
- "auto reclaim" via bg_reclaim_threshold

The latter works by checking against a fixed threshold on frees. If we
pass from above the threshold to below, relocation triggers and the
block group will get reclaimed by the cleaner thread (assuming it is
still eligible)

Picking a threshold is challenging. Too high, and you end up trying to
reclaim very full block_groups which is quite costly, and you don't do
reclaim on block_groups that don't get quite THAT full, but could still
be quite fragmented and stranding a lot of space. Too low, and you
similarly miss out on reclaim even if you badly need it to avoid running
out of unallocated space, if you have heavily fragmented block groups
living above the threshold.

No matter the threshold, it suffers from a workload that happens to
bounce around that threshold, which can introduce arbitrary amounts of
reclaim waste.

To improve this situation, introduce a dynamic threshold. The basic idea
behind this threshold is that it should be very lax when there is plenty
of unallocated space, and increasingly aggressive as we approach zero
unallocated space. To that end, it sets a target for unallocated space
(10 chunks) and then linearly increases the threshold as the amount of
space short of the target we are increases. The formula is:
(target - unalloc) / target

I tested this by running it on three interesting workloads:

  1. bounce allocations around X% full.
  2. fill up all the way and introduce full fragmentation.
  3. write in a fragmented way until the filesystem is just about full.

1. and 2. attack the weaknesses of a fixed threshold; fixed either works
perfectly or fully falls apart, depending on the threshold. Dynamic
always handles these cases well.

3. attacks dynamic by checking whether it is too zealous to reclaim in
conditions with low unallocated and low unused. It tends to claw back
1GiB of unallocated fairly aggressively, but not much more. Early
versions of dynamic threshold struggled on this test.

Additional work could be done to intelligently ratchet up the urgency of
reclaim in very low unallocated conditions. Existing mechanisms are
already useless in that case anyway.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11 15:33:27 +02:00
Boris Burkov
42f620aec1 btrfs: store fs_info in space_info
This is handy when computing space_info dynamic reclaim thresholds where
we do not have access to a block group. We could add it to the various
functions as a parameter, but it seems reasonable for space_info to have
an fs_info pointer.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11 15:33:27 +02:00
Filipe Manana
ded980eb3f btrfs: add and use helper to commit the current transaction
We have several places that attach to the current transaction with
btrfs_attach_transaction_barrier() and then commit the transaction if
there is one. Add a helper and use it to deduplicate this pattern.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
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>
2024-07-11 15:33:20 +02:00
David Sterba
42317ab440 btrfs: simplify range parameters of btrfs_wait_ordered_roots()
The range is specified only in two ways, we can simplify the case for
the whole filesystem range as a NULL block group parameter.

Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11 15:33:19 +02:00
David Sterba
5100c4eb52 btrfs: remove unused define EXTENT_SIZE_PER_ITEM
This was added  in c61a16a701 ("Btrfs: fix the confusion between
delalloc bytes and metadata bytes") and removed in 03fe78cc29
("btrfs: use delalloc_bytes to determine flush amount for
shrink_delalloc") where the calculation was reworked to use a
non-constant numbers. This was found by 'make W=2'.

Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-11 15:33:19 +02:00
Naohiro Aota
64d2c847ba btrfs: zoned: fix calc_available_free_space() for zoned mode
calc_available_free_space() returns the total size of metadata (or
system) block groups, which can be allocated from unallocated disk
space. The logic is wrong on zoned mode in two places.

First, the calculation of data_chunk_size is wrong. We always allocate
one zone as one chunk, and no partial allocation of a zone. So, we
should use zone_size (= data_sinfo->chunk_size) as it is.

Second, the result "avail" may not be zone aligned. Since we always
allocate one zone as one chunk on zoned mode, returning non-zone size
aligned bytes will result in less pressure on the async metadata reclaim
process.

This is serious for the nearly full state with a large zone size device.
Allowing over-commit too much will result in less async reclaim work and
end up in ENOSPC. We can align down to the zone size to avoid that.

Fixes: cb6cbab790 ("btrfs: adjust overcommit logic when very close to full")
CC: stable@vger.kernel.org # 6.9
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-07-02 19:13:11 +02:00
David Sterba
2b712e3bb2 btrfs: remove unused included headers
With help of neovim, LSP and clangd we can identify header files that
are not actually needed to be included in the .c files. This is focused
only on removal (with minor fixups), further cleanups are possible but
will require doing the header files properly with forward declarations,
minimized includes and include-what-you-use care.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-03-04 16:24:46 +01:00
Filipe Manana
e06cc89475 btrfs: fix data races when accessing the reserved amount of block reserves
At space_info.c we have several places where we access the ->reserved
field of a block reserve without taking the block reserve's spinlock
first, which makes KCSAN warn about a data race since that field is
always updated while holding the spinlock.

The reports from KCSAN are like the following:

  [117.193526] BUG: KCSAN: data-race in btrfs_block_rsv_release [btrfs] / need_preemptive_reclaim [btrfs]

  [117.195148] read to 0x000000017f587190 of 8 bytes by task 6303 on cpu 3:
  [117.195172]  need_preemptive_reclaim+0x222/0x2f0 [btrfs]
  [117.195992]  __reserve_bytes+0xbb0/0xdc8 [btrfs]
  [117.196807]  btrfs_reserve_metadata_bytes+0x4c/0x120 [btrfs]
  [117.197620]  btrfs_block_rsv_add+0x78/0xa8 [btrfs]
  [117.198434]  btrfs_delayed_update_inode+0x154/0x368 [btrfs]
  [117.199300]  btrfs_update_inode+0x108/0x1c8 [btrfs]
  [117.200122]  btrfs_dirty_inode+0xb4/0x140 [btrfs]
  [117.200937]  btrfs_update_time+0x8c/0xb0 [btrfs]
  [117.201754]  touch_atime+0x16c/0x1e0
  [117.201789]  filemap_read+0x674/0x728
  [117.201823]  btrfs_file_read_iter+0xf8/0x410 [btrfs]
  [117.202653]  vfs_read+0x2b6/0x498
  [117.203454]  ksys_read+0xa2/0x150
  [117.203473]  __s390x_sys_read+0x68/0x88
  [117.203495]  do_syscall+0x1c6/0x210
  [117.203517]  __do_syscall+0xc8/0xf0
  [117.203539]  system_call+0x70/0x98

  [117.203579] write to 0x000000017f587190 of 8 bytes by task 11 on cpu 0:
  [117.203604]  btrfs_block_rsv_release+0x2e8/0x578 [btrfs]
  [117.204432]  btrfs_delayed_inode_release_metadata+0x7c/0x1d0 [btrfs]
  [117.205259]  __btrfs_update_delayed_inode+0x37c/0x5e0 [btrfs]
  [117.206093]  btrfs_async_run_delayed_root+0x356/0x498 [btrfs]
  [117.206917]  btrfs_work_helper+0x160/0x7a0 [btrfs]
  [117.207738]  process_one_work+0x3b6/0x838
  [117.207768]  worker_thread+0x75e/0xb10
  [117.207797]  kthread+0x21a/0x230
  [117.207830]  __ret_from_fork+0x6c/0xb8
  [117.207861]  ret_from_fork+0xa/0x30

So add a helper to get the reserved amount of a block reserve while
holding the lock. The value may be not be up to date anymore when used by
need_preemptive_reclaim() and btrfs_preempt_reclaim_metadata_space(), but
that's ok since the worst it can do is cause more reclaim work do be done
sooner rather than later. Reading the field while holding the lock instead
of using the data_race() annotation is used in order to prevent load
tearing.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2024-02-22 12:15:06 +01:00
Josef Bacik
cb6cbab790 btrfs: adjust overcommit logic when very close to full
A user reported some unpleasant behavior with very small file systems.
The reproducer is this

  $ mkfs.btrfs -f -m single -b 8g /dev/vdb
  $ mount /dev/vdb /mnt/test
  $ dd if=/dev/zero of=/mnt/test/testfile bs=512M count=20

This will result in usage that looks like this

  Overall:
      Device size:                   8.00GiB
      Device allocated:              8.00GiB
      Device unallocated:            1.00MiB
      Device missing:                  0.00B
      Device slack:                  2.00GiB
      Used:                          5.47GiB
      Free (estimated):              2.52GiB      (min: 2.52GiB)
      Free (statfs, df):               0.00B
      Data ratio:                       1.00
      Metadata ratio:                   1.00
      Global reserve:                5.50MiB      (used: 0.00B)
      Multiple profiles:                  no

  Data,single: Size:7.99GiB, Used:5.46GiB (68.41%)
     /dev/vdb        7.99GiB

  Metadata,single: Size:8.00MiB, Used:5.77MiB (72.07%)
     /dev/vdb        8.00MiB

  System,single: Size:4.00MiB, Used:16.00KiB (0.39%)
     /dev/vdb        4.00MiB

  Unallocated:
     /dev/vdb        1.00MiB

As you can see we've gotten ourselves quite full with metadata, with all
of the disk being allocated for data.

On smaller file systems there's not a lot of time before we get full, so
our overcommit behavior bites us here.  Generally speaking data
reservations result in chunk allocations as we assume reservation ==
actual use for data.  This means at any point we could end up with a
chunk allocation for data, and if we're very close to full we could do
this before we have a chance to figure out that we need another metadata
chunk.

Address this by adjusting the overcommit logic.  Simply put we need to
take away 1 chunk from the available chunk space in case of a data
reservation.  This will allow us to stop overcommitting before we
potentially lose this space to a data allocation.  With this fix in
place we properly allocate a metadata chunk before we're completely
full, allowing for enough slack space in metadata.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12 16:44:16 +02:00
Filipe Manana
8a526c44da btrfs: allow to run delayed refs by bytes to be released instead of count
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>
2023-10-12 16:44:06 +02:00
Filipe Manana
03551d651e btrfs: pass a space_info argument to btrfs_reserve_metadata_bytes()
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>
2023-10-12 16:44:05 +02:00
David Sterba
9580503bcb btrfs: reformat remaining kdoc style comments
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>
2023-10-12 16:44:04 +02:00
Naohiro Aota
5b135b382a btrfs: zoned: re-enable metadata over-commit for zoned mode
Now that, we can re-enable metadata over-commit. As we moved the activation
from the reservation time to the write time, we no longer need to ensure
all the reserved bytes is properly activated.

Without the metadata over-commit, it suffers from lower performance because
it needs to flush the delalloc items more often and allocate more block
groups. Re-enabling metadata over-commit will solve the issue.

Fixes: 79417d040f ("btrfs: zoned: disable metadata overcommit for zoned")
CC: stable@vger.kernel.org # 6.1+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21 14:52:19 +02:00
Naohiro Aota
5a7d107e5e btrfs: zoned: don't activate non-DATA BG on allocation
Now that a non-DATA block group is activated at write time, don't
activate it on allocation time.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21 14:52:19 +02:00
Filipe Manana
2ee70ed19c btrfs: avoid starting and committing empty transaction when flushing space
When flushing space and we are in the COMMIT_TRANS state, we join a
transaction with btrfs_join_transaction() and then commit the returned
transaction. However btrfs_join_transaction() starts a new transaction if
there is none currently open, which is pointless since comitting a new,
empty transaction, doesn't achieve anything, it only wastes time, IO and
creates an unnecessary rotation of the backup roots.

So use btrfs_attach_transaction_barrier() to avoid starting a new
transaction. This also waits for any ongoing transaction that is
committing (state >= TRANS_STATE_COMMIT_DOING) to fully complete, and
therefore wait for all the extents that were pinned during the
transaction's lifetime to be unpinned.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21 14:52:18 +02:00
Filipe Manana
2391245ac2 btrfs: avoid starting new transaction when flushing delayed items and refs
When flushing space we join a transaction to flush delayed items and
delayed references, in order to try to release space. However using
btrfs_join_transaction() not only joins an existing transaction as well
as it starts a new transaction if there is none open. If there is no
transaction open, we don't have neither delayed items nor delayed
references, so creating a new transaction is a waste of time, IO and
creates an unnecessary rotation of the backup roots without gaining any
benefits (including releasing space).

So use btrfs_join_transaction_nostart() when attempting to flush delayed
items and references.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21 14:52:18 +02:00
Filipe Manana
7e3bfd146e btrfs: fail priority metadata ticket with real fs error
At priority_reclaim_metadata_space(), if we were not able to satisfy the
the ticket after going through the various flushing states and we notice
the fs went into an error state, likely due to a transaction abort during
the flushing, set the ticket's error to the error that caused the
transaction abort instead of an unconditional -EROFS.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21 14:52:18 +02:00
Filipe Manana
1b6948acb8 btrfs: don't steal space from global rsv after a transaction abort
When doing a priority metadata space reclaim, while we are going through
the flush states and running their respective operations, it's possible
that a transaction abort happened, for example when running delayed refs
we hit -ENOSPC or in the critical section of transaction commit we failed
with -ENOSPC or some other error. In these cases a transaction was aborted
and the fs turned into error state. If that happened, then it makes no
sense to steal from the global block reserve and return success to the
caller if the stealing was successful - the caller will later get an
error when attempting to modify the fs. Instead make the ticket fail if
we have the fs in error state and don't attempt to steal from the global
rsv, as it's not only it's pointless, it also simplifies debugging some
-ENOSPC problems.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21 14:52:17 +02:00
Filipe Manana
1ff9fee3bd btrfs: print available space across all block groups when dumping space info
When dumping a space info also sum the available space for all block
groups and then print it. This often useful for debugging -ENOSPC
related problems.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21 14:52:17 +02:00
Filipe Manana
e50b122b83 btrfs: print available space for a block group when dumping a space info
When dumping a space info, we iterate over all its block groups and then
print their size and the amounts of bytes used, reserved, pinned, etc.
When debugging -ENOSPC problems it's also useful to know how much space
is available (free), so calculate that and print it as well.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21 14:52:17 +02:00
Filipe Manana
b92e8f5472 btrfs: print block group super and delalloc bytes when dumping space info
When dumping a space info's block groups, also print the number of bytes
used for super blocks and delalloc. This is often useful for debugging
-ENOSPC problems.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21 14:52:17 +02:00
Filipe Manana
0e55a54502 btrfs: add helper to calculate space for delayed references
Instead of duplicating the logic for calculating how much space is
required for a given number of delayed references, add an inline helper
to encapsulate that logic and use it everywhere we are calculating the
space required.

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>
2023-04-17 18:01:19 +02:00
Filipe Manana
f4160ee878 btrfs: constify fs_info argument for the reclaim items calculation helpers
Now that btrfs_calc_insert_metadata_size() can take a const fs_info
argument, make the fs_info argument of calc_reclaim_items_nr() and of
calc_delayed_refs_nr() const as well.

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>
2023-04-17 18:01:19 +02:00
Filipe Manana
007145ff64 btrfs: accurately calculate number of delayed refs when flushing
When flushing a limited number of delayed references (FLUSH_DELAYED_REFS_NR
state), we are assuming each delayed reference is holding a number of bytes
matching the needed space for inserting for a single metadata item (the
result of btrfs_calc_insert_metadata_size()). That is not correct when
using the free space tree, as in that case we have to multiply that value
by 2 since we need to touch the free space tree as well. This is the same
computation as we do at btrfs_update_delayed_refs_rsv() and at
btrfs_delayed_refs_rsv_release().

So correct the computation for the amount of delayed references we need to
flush in case we have the free space tree. This does not fix a functional
issue, instead it makes the flush code flush less delayed references, only
the minimum necessary to satisfy a ticket.

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>
2023-04-17 18:01:19 +02:00