Since EROFS handles decompression in non-atomic contexts due to
uncontrollable decompression latencies and vmap() usage, it tries
to detect atomic contexts and only kicks off a kworker on demand
in order to reduce unnecessary scheduling overhead.
However, the current approach is insufficient and can lead to
sleeping function calls in invalid contexts, causing kernel
warnings and potential system instability. See the stacktrace [1]
and previous discussion [2].
The current implementation only checks rcu_read_lock_any_held(),
which behaves inconsistently across different kernel configurations:
- When CONFIG_DEBUG_LOCK_ALLOC is enabled: correctly detects
RCU critical sections by checking rcu_lock_map
- When CONFIG_DEBUG_LOCK_ALLOC is disabled: compiles to
"!preemptible()", which only checks preempt_count and misses
RCU critical sections
This patch introduces z_erofs_in_atomic() to provide comprehensive
atomic context detection:
1. Check RCU preemption depth when CONFIG_PREEMPTION is enabled,
as RCU critical sections may not affect preempt_count but still
require atomic handling
2. Always use async processing when CONFIG_PREEMPT_COUNT is disabled,
as preemption state cannot be reliably determined
3. Fall back to standard preemptible() check for remaining cases
The function replaces the previous complex condition check and ensures
that z_erofs always uses (kthread_)work in atomic contexts to minimize
scheduling overhead and prevent sleeping in invalid contexts.
[1] Problem stacktrace
[ 61.266692] BUG: sleeping function called from invalid context at kernel/locking/rtmutex_api.c:510
[ 61.266702] in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 107, name: irq/54-ufshcd
[ 61.266704] preempt_count: 0, expected: 0
[ 61.266705] RCU nest depth: 2, expected: 0
[ 61.266710] CPU: 0 UID: 0 PID: 107 Comm: irq/54-ufshcd Tainted: G W O 6.12.17 #1
[ 61.266714] Tainted: [W]=WARN, [O]=OOT_MODULE
[ 61.266715] Hardware name: schumacher (DT)
[ 61.266717] Call trace:
[ 61.266718] dump_backtrace+0x9c/0x100
[ 61.266727] show_stack+0x20/0x38
[ 61.266728] dump_stack_lvl+0x78/0x90
[ 61.266734] dump_stack+0x18/0x28
[ 61.266736] __might_resched+0x11c/0x180
[ 61.266743] __might_sleep+0x64/0xc8
[ 61.266745] mutex_lock+0x2c/0xc0
[ 61.266748] z_erofs_decompress_queue+0xe8/0x978
[ 61.266753] z_erofs_decompress_kickoff+0xa8/0x190
[ 61.266756] z_erofs_endio+0x168/0x288
[ 61.266758] bio_endio+0x160/0x218
[ 61.266762] blk_update_request+0x244/0x458
[ 61.266766] scsi_end_request+0x38/0x278
[ 61.266770] scsi_io_completion+0x4c/0x600
[ 61.266772] scsi_finish_command+0xc8/0xe8
[ 61.266775] scsi_complete+0x88/0x148
[ 61.266777] blk_mq_complete_request+0x3c/0x58
[ 61.266780] scsi_done_internal+0xcc/0x158
[ 61.266782] scsi_done+0x1c/0x30
[ 61.266783] ufshcd_compl_one_cqe+0x12c/0x438
[ 61.266786] __ufshcd_transfer_req_compl+0x2c/0x78
[ 61.266788] ufshcd_poll+0xf4/0x210
[ 61.266789] ufshcd_transfer_req_compl+0x50/0x88
[ 61.266791] ufshcd_intr+0x21c/0x7c8
[ 61.266792] irq_forced_thread_fn+0x44/0xd8
[ 61.266796] irq_thread+0x1a4/0x358
[ 61.266799] kthread+0x12c/0x138
[ 61.266802] ret_from_fork+0x10/0x20
[2] https://lore.kernel.org/r/58b661d0-0ebb-4b45-a10d-c5927fb791cd@paulmck-laptop
Signed-off-by: Junli Liu <liujunli@lixiang.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250805011957.911186-1-liujunli@lixiang.com
[ Gao Xiang: Use the original trace in v1. ]
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Thanks to the meta buffer infrastructure, metadata-compressed inodes are
just read from the metabox inode instead of the blockdevice (or backing
file) inode.
The same is true for shared extended attributes.
When metadata compression is enabled, inode numbers are divided from
on-disk NIDs because of non-LTS 32-bit application compatibility.
Co-developed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Bo Liu (OpenAnolis) <liubo03@inspur.com>
Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250722003229.2121752-1-hsiangkao@linux.alibaba.com
- need_kmap is always true except for a ztailpacking case; thus, just
open-code that one;
- The upcoming metadata compression will add a new boolean, so simplify
this first.
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20250714090907.4095645-1-hsiangkao@linux.alibaba.com
The compressed data for the ztailpacking feature is fetched from
the metadata inode (e.g., bd_inode), which is folio-based.
Therefore, the folio interface should be used instead.
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250626085459.339830-1-hsiangkao@linux.alibaba.com
Fragments aren't limited by Z_EROFS_PCLUSTER_MAX_DSIZE. However, if
a fragment's logical length is larger than Z_EROFS_PCLUSTER_MAX_DSIZE
but the fragment is not the whole inode, it currently returns
-EOPNOTSUPP because m_flags has the wrong EROFS_MAP_ENCODED flag set.
It is not intended by design but should be rare, as it can only be
reproduced by mkfs with `-Eall-fragments` in a specific case.
Let's normalize fragment m_flags using the new EROFS_MAP_FRAGMENT.
Reported-by: Axel Fontaine <axel@axelfontaine.com>
Closes: https://github.com/erofs/erofs-utils/issues/23
Fixes: 7c3ca1838a ("erofs: restrict pcluster size limitations")
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250711195826.3601157-1-hsiangkao@linux.alibaba.com
When attempting to use an archive file, such as APEX on android,
as a file-backed mount source, it fails because EROFS image within
the archive file does not start at offset 0. As a result, a loop
or a dm device is still needed to attach the image file at an
appropriate offset first. Similarly, if an EROFS image within a
block device does not start at offset 0, it cannot be mounted
directly either.
To address this issue, this patch adds a new mount option `fsoffset=x'
to accept a start offset for the primary device. The offset should be
aligned to the block size. EROFS will add this offset before performing
read requests.
Signed-off-by: Sheng Yong <shengyong1@xiaomi.com>
Signed-off-by: Wang Shuai <wangshuai12@xiaomi.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250517090544.2687651-1-shengyong1@xiaomi.com
[ Gao Xiang: minor update on documentation and the error message. ]
Reviewed-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Currently, when EROFS is built with per-CPU workers, the workers are
started and CPU hotplug hooks are registered during module initialization.
This leads to unnecessary worker start/stop cycles during CPU hotplug
events, particularly on Android devices that frequently suspend and resume.
This change defers the initialization of per-CPU workers and the
registration of CPU hotplug hooks until the first EROFS mount. This
ensures that these resources are only allocated and managed when EROFS is
actually in use.
The tear down of per-CPU workers and unregistration of CPU hotplug hooks
still occurs during z_erofs_exit_subsystem(), but only if they were
initialized.
Signed-off-by: Sandeep Dhavale <dhavale@google.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20250506225743.308517-1-dhavale@google.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
When compressed data deduplication is enabled, multiple logical extents
may reference the same compressed physical cluster.
The previous commit 94c43de735 ("erofs: fix wrong primary bvec
selection on deduplicated extents") already avoids using shortened
bvecs. However, in such cases, the extra temporary buffers also
need to be preserved for later use in z_erofs_fill_other_copies() to
to prevent data corruption.
IOWs, extra temporary buffers have to be retained not only due to
varying start relative offsets (`pageofs_out`, as indicated by
`pcl->multibases`) but also because of shortened bvecs.
android.hardware.graphics.composer@2.1.so : 270696 bytes
0: 0.. 204185 | 204185 : 628019200.. 628084736 | 65536
-> 1: 204185.. 225536 | 21351 : 544063488.. 544129024 | 65536
2: 225536.. 270696 | 45160 : 0.. 0 | 0
com.android.vndk.v28.apex : 93814897 bytes
...
364: 53869896..54095257 | 225361 : 543997952.. 544063488 | 65536
-> 365: 54095257..54309344 | 214087 : 544063488.. 544129024 | 65536
366: 54309344..54514557 | 205213 : 544129024.. 544194560 | 65536
...
Both 204185 and 54095257 have the same start relative offset of 3481,
but the logical page 55 of `android.hardware.graphics.composer@2.1.so`
ranges from 225280 to 229632, forming a shortened bvec [225280, 225536)
that cannot be used for decompressing the range from 54095257 to
54309344 of `com.android.vndk.v28.apex`.
Since `pcl->multibases` is already meaningless, just mark `be->keepxcpy`
on demand for simplicity.
Again, this issue can only lead to data corruption if `-Ededupe` is on.
Fixes: 94c43de735 ("erofs: fix wrong primary bvec selection on deduplicated extents")
Reviewed-by: Hongbo Li <lihongbo22@huawei.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250506101850.191506-1-hsiangkao@linux.alibaba.com
Remove duplicate code in function z_erofs_register_pcluster()
Signed-off-by: Bo Liu <liubo03@inspur.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250410042048.3044-2-liubo03@inspur.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
We're almost there. It's straight-forward to adapt the current
decompression subsystem to support unaligned encoded (compressed) data.
Note that unaligned data is not encouraged because of worse I/O and
caching efficiency unless the corresponding compressor doesn't support
fixed-sized output compression natively like Zstd.
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Acked-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20250310095459.2620647-10-hsiangkao@linux.alibaba.com
- Rename erofs_init_managed_cache() to z_erofs_init_super();
- Move the initialization of managed_pslots into z_erofs_init_super() too;
- Move z_erofs_init_super() and packed inode preparation upwards, before
the root inode initialization.
Therefore, the root directory can also be compressible.
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Acked-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20250317054840.3483000-1-hsiangkao@linux.alibaba.com
It seems that all compressors need those two values, so just move
them into the common structure.
`struct z_erofs_lz4_decompress_ctx` can be dropped too.
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250305124007.1810731-1-hsiangkao@linux.alibaba.com
Since EROFS_KMAP_ATOMIC is no longer valid, get rid of erofs_kmap_type too.
Signed-off-by: Bo Liu <liubo03@inspur.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20250217093141.2659-1-liubo03@inspur.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
All users of lockref_init() now initialize the count to 1, so hardcode
that and remove the count argument.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Link: https://lore.kernel.org/r/20250130135624.1899988-4-agruenba@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
- Micro-optimize superblock checksum;
- Avoid overly large bvecs[] for file-backed mounts;
- Some leftover folio conversion in z_erofs_bind_cache();
- Minor bugfixes and cleanups.
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Merge tag 'erofs-for-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs
Pull erofs updates from Gao Xiang:
"Still no new features for this cycle, as some ongoing improvements
remain premature for now.
This includes a micro-optimization for the superblock checksum, along
with minor bugfixes and code cleanups, as usual:
- Micro-optimize superblock checksum
- Avoid overly large bvecs[] for file-backed mounts
- Some leftover folio conversion in z_erofs_bind_cache()
- Minor bugfixes and cleanups"
* tag 'erofs-for-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
erofs: refine z_erofs_get_extent_compressedlen()
erofs: remove dead code in erofs_fc_parse_param
erofs: return SHRINK_EMPTY if no objects to free
erofs: convert z_erofs_bind_cache() to folios
erofs: tidy up zdata.c
erofs: get rid of `z_erofs_next_pcluster_t`
erofs: simplify z_erofs_load_compact_lcluster()
erofs: fix potential return value overflow of z_erofs_shrink_scan()
erofs: shorten bvecs[] for file-backed mounts
erofs: micro-optimize superblock checksum
fs: erofs: xattr.c change kzalloc to kcalloc
1) Per-CPU kthreads must stay affine to a single CPU and never execute
relevant code on any other CPU. This is currently handled by smpboot
code which takes care of CPU-hotplug operations. Affinity here is
a correctness constraint.
2) Some kthreads _have_ to be affine to a specific set of CPUs and can't
run anywhere else. The affinity is set through kthread_bind_mask()
and the subsystem takes care by itself to handle CPU-hotplug
operations. Affinity here is assumed to be a correctness constraint.
3) Per-node kthreads _prefer_ to be affine to a specific NUMA node. This
is not a correctness constraint but merely a preference in terms of
memory locality. kswapd and kcompactd both fall into this category.
The affinity is set manually like for any other task and CPU-hotplug
is supposed to be handled by the relevant subsystem so that the task
is properly reaffined whenever a given CPU from the node comes up.
Also care should be taken so that the node affinity doesn't cross
isolated (nohz_full) cpumask boundaries.
4) Similar to the previous point except kthreads have a _preferred_
affinity different than a node. Both RCU boost kthreads and RCU
exp kworkers fall into this category as they refer to "RCU nodes"
from a distinctly distributed tree.
Currently the preferred affinity patterns (3 and 4) have at least 4
identified users, with more or less success when it comes to handle
CPU-hotplug operations and CPU isolation. Each of which do it in its own
ad-hoc way.
This is an infrastructure proposal to handle this with the following API
changes:
_ kthread_create_on_node() automatically affines the created kthread to
its target node unless it has been set as per-cpu or bound with
kthread_bind[_mask]() before the first wake-up.
- kthread_affine_preferred() is a new function that can be called right
after kthread_create_on_node() to specify a preferred affinity
different than the specified node.
When the preferred affinity can't be applied because the possible
targets are offline or isolated (nohz_full), the kthread is affine
to the housekeeping CPUs (which means to all online CPUs most of the
time or only the non-nohz_full CPUs when nohz_full= is set).
kswapd, kcompactd, RCU boost kthreads and RCU exp kworkers have been
converted, along with a few old drivers.
Summary of the changes:
* Consolidate a bunch of ad-hoc implementations of kthread_run_on_cpu()
* Introduce task_cpu_fallback_mask() that defines the default last
resort affinity of a task to become nohz_full aware
* Add some correctness check to ensure kthread_bind() is always called
before the first kthread wake up.
* Default affine kthread to its preferred node.
* Convert kswapd / kcompactd and remove their halfway working ad-hoc
affinity implementation
* Implement kthreads preferred affinity
* Unify kthread worker and kthread API's style
* Convert RCU kthreads to the new API and remove the ad-hoc affinity
implementation.
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Merge tag 'kthread-for-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks
Pull kthread updates from Frederic Weisbecker:
"Kthreads affinity follow either of 4 existing different patterns:
1) Per-CPU kthreads must stay affine to a single CPU and never
execute relevant code on any other CPU. This is currently handled
by smpboot code which takes care of CPU-hotplug operations.
Affinity here is a correctness constraint.
2) Some kthreads _have_ to be affine to a specific set of CPUs and
can't run anywhere else. The affinity is set through
kthread_bind_mask() and the subsystem takes care by itself to
handle CPU-hotplug operations. Affinity here is assumed to be a
correctness constraint.
3) Per-node kthreads _prefer_ to be affine to a specific NUMA node.
This is not a correctness constraint but merely a preference in
terms of memory locality. kswapd and kcompactd both fall into this
category. The affinity is set manually like for any other task and
CPU-hotplug is supposed to be handled by the relevant subsystem so
that the task is properly reaffined whenever a given CPU from the
node comes up. Also care should be taken so that the node affinity
doesn't cross isolated (nohz_full) cpumask boundaries.
4) Similar to the previous point except kthreads have a _preferred_
affinity different than a node. Both RCU boost kthreads and RCU
exp kworkers fall into this category as they refer to "RCU nodes"
from a distinctly distributed tree.
Currently the preferred affinity patterns (3 and 4) have at least 4
identified users, with more or less success when it comes to handle
CPU-hotplug operations and CPU isolation. Each of which do it in its
own ad-hoc way.
This is an infrastructure proposal to handle this with the following
API changes:
- kthread_create_on_node() automatically affines the created kthread
to its target node unless it has been set as per-cpu or bound with
kthread_bind[_mask]() before the first wake-up.
- kthread_affine_preferred() is a new function that can be called
right after kthread_create_on_node() to specify a preferred
affinity different than the specified node.
When the preferred affinity can't be applied because the possible
targets are offline or isolated (nohz_full), the kthread is affine to
the housekeeping CPUs (which means to all online CPUs most of the time
or only the non-nohz_full CPUs when nohz_full= is set).
kswapd, kcompactd, RCU boost kthreads and RCU exp kworkers have been
converted, along with a few old drivers.
Summary of the changes:
- Consolidate a bunch of ad-hoc implementations of
kthread_run_on_cpu()
- Introduce task_cpu_fallback_mask() that defines the default last
resort affinity of a task to become nohz_full aware
- Add some correctness check to ensure kthread_bind() is always
called before the first kthread wake up.
- Default affine kthread to its preferred node.
- Convert kswapd / kcompactd and remove their halfway working ad-hoc
affinity implementation
- Implement kthreads preferred affinity
- Unify kthread worker and kthread API's style
- Convert RCU kthreads to the new API and remove the ad-hoc affinity
implementation"
* tag 'kthread-for-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks:
kthread: modify kernel-doc function name to match code
rcu: Use kthread preferred affinity for RCU exp kworkers
treewide: Introduce kthread_run_worker[_on_cpu]()
kthread: Unify kthread_create_on_cpu() and kthread_create_worker_on_cpu() automatic format
rcu: Use kthread preferred affinity for RCU boost
kthread: Implement preferred affinity
mm: Create/affine kswapd to its preferred node
mm: Create/affine kcompactd to its preferred node
kthread: Default affine kthread to its preferred NUMA node
kthread: Make sure kthread hasn't started while binding it
sched,arm64: Handle CPU isolation on last resort fallback rq selection
arm64: Exclude nohz_full CPUs from 32bits el0 support
lib: test_objpool: Use kthread_run_on_cpu()
kallsyms: Use kthread_run_on_cpu()
soc/qman: test: Use kthread_run_on_cpu()
arm/bL_switcher: Use kthread_run_on_cpu()
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Merge tag 'vfs-6.14-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"Features:
- Support caching symlink lengths in inodes
The size is stored in a new union utilizing the same space as
i_devices, thus avoiding growing the struct or taking up any more
space
When utilized it dodges strlen() in vfs_readlink(), giving about
1.5% speed up when issuing readlink on /initrd.img on ext4
- Add RWF_DONTCACHE iocb and FOP_DONTCACHE file_operations flag
If a file system supports uncached buffered IO, it may set
FOP_DONTCACHE and enable support for RWF_DONTCACHE.
If RWF_DONTCACHE is attempted without the file system supporting
it, it'll get errored with -EOPNOTSUPP
- Enable VBOXGUEST and VBOXSF_FS on ARM64
Now that VirtualBox is able to run as a host on arm64 (e.g. the
Apple M3 processors) we can enable VBOXSF_FS (and in turn
VBOXGUEST) for this architecture.
Tested with various runs of bonnie++ and dbench on an Apple MacBook
Pro with the latest Virtualbox 7.1.4 r165100 installed
Cleanups:
- Delay sysctl_nr_open check in expand_files()
- Use kernel-doc includes in fiemap docbook
- Use page->private instead of page->index in watch_queue
- Use a consume fence in mnt_idmap() as it's heavily used in
link_path_walk()
- Replace magic number 7 with ARRAY_SIZE() in fc_log
- Sort out a stale comment about races between fd alloc and dup2()
- Fix return type of do_mount() from long to int
- Various cosmetic cleanups for the lockref code
Fixes:
- Annotate spinning as unlikely() in __read_seqcount_begin
The annotation already used to be there, but got lost in commit
52ac39e5db ("seqlock: seqcount_t: Implement all read APIs as
statement expressions")
- Fix proc_handler for sysctl_nr_open
- Flush delayed work in delayed fput()
- Fix grammar and spelling in propagate_umount()
- Fix ESP not readable during coredump
In /proc/PID/stat, there is the kstkesp field which is the stack
pointer of a thread. While the thread is active, this field reads
zero. But during a coredump, it should have a valid value
However, at the moment, kstkesp is zero even during coredump
- Don't wake up the writer if the pipe is still full
- Fix unbalanced user_access_end() in select code"
* tag 'vfs-6.14-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (28 commits)
gfs2: use lockref_init for qd_lockref
erofs: use lockref_init for pcl->lockref
dcache: use lockref_init for d_lockref
lockref: add a lockref_init helper
lockref: drop superfluous externs
lockref: use bool for false/true returns
lockref: improve the lockref_get_not_zero description
lockref: remove lockref_put_not_zero
fs: Fix return type of do_mount() from long to int
select: Fix unbalanced user_access_end()
vbox: Enable VBOXGUEST and VBOXSF_FS on ARM64
pipe_read: don't wake up the writer if the pipe is still full
selftests: coredump: Add stackdump test
fs/proc: do_task_stat: Fix ESP not readable during coredump
fs: add RWF_DONTCACHE iocb and FOP_DONTCACHE file_operations flag
fs: sort out a stale comment about races between fd alloc and dup2
fs: Fix grammar and spelling in propagate_umount()
fs: fc_log replace magic number 7 with ARRAY_SIZE()
fs: use a consume fence in mnt_idmap()
file: flush delayed work in delayed fput()
...
The managed cache uses a pseudo inode to keep (necessary) compressed
data.
Currently, it still uses zero-order folios, so this is just a trivial
conversion, except that the use of the pagepool is temporarily dropped.
Drop some obsoleted comments too.
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250114034429.431408-4-hsiangkao@linux.alibaba.com
It was originally intended for tagged pointer reservation.
Now all encoded data can be represented uniformally with
`struct z_erofs_pcluster` as described in commit bf1aa03980
("erofs: sunset `struct erofs_workgroup`"), let's drop it too.
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250114034429.431408-2-hsiangkao@linux.alibaba.com
z_erofs_shrink_scan() could return small numbers due to the mistyped
`freed`.
Although I don't think it has any visible impact.
Fixes: 3883a79abd ("staging: erofs: introduce VLE decompression support")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250114040058.459981-1-hsiangkao@linux.alibaba.com
kthread_create() creates a kthread without running it yet. kthread_run()
creates a kthread and runs it.
On the other hand, kthread_create_worker() creates a kthread worker and
runs it.
This difference in behaviours is confusing. Also there is no way to
create a kthread worker and affine it using kthread_bind_mask() or
kthread_affine_preferred() before starting it.
Consolidate the behaviours and introduce kthread_run_worker[_on_cpu]()
that behaves just like kthread_run(). kthread_create_worker[_on_cpu]()
will now only create a kthread worker without starting it.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
kthread_create_on_cpu() uses the CPU argument as an implicit and unique
printf argument to add to the format whereas
kthread_create_worker_on_cpu() still relies on explicitly passing the
printf arguments. This difference in behaviour is error prone and
doesn't help standardizing per-CPU kthread names.
Unify the behaviours and convert kthread_create_worker_on_cpu() to
use the printf behaviour of kthread_create_on_cpu().
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Add a sysfs node to drop compression-related caches, currently used to
drop in-memory pclusters and cached compressed folios.
Signed-off-by: Chunhai Guo <guochunhai@vivo.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20241113041148.749129-1-guochunhai@vivo.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Once a pcluster is fully decompressed and there are no attached cached
folios, its corresponding `struct z_erofs_pcluster` will be freed. This
will significantly reduce the frequency of calls to erofs_shrink_scan()
and the memory allocated for `struct z_erofs_pcluster`.
The tables below show approximately a 96% reduction in the calls to
erofs_shrink_scan() and in the memory allocated for `struct
z_erofs_pcluster` after applying this patch. The results were obtained
by performing a test to copy a 4.1GB partition on ARM64 Android devices
running the 6.6 kernel with an 8-core CPU and 12GB of memory.
1. The reduction in calls to erofs_shrink_scan():
+-----------------+-----------+----------+---------+
| | w/o patch | w/ patch | diff |
+-----------------+-----------+----------+---------+
| Average (times) | 11390 | 390 | -96.57% |
+-----------------+-----------+----------+---------+
2. The reduction in memory released by erofs_shrink_scan():
+-----------------+-----------+----------+---------+
| | w/o patch | w/ patch | diff |
+-----------------+-----------+----------+---------+
| Average (Byte) | 133612656 | 4434552 | -96.68% |
+-----------------+-----------+----------+---------+
Signed-off-by: Chunhai Guo <guochunhai@vivo.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20241112043235.546164-1-guochunhai@vivo.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
`struct erofs_workgroup` was introduced to provide a unique header
for all physically indexed objects. However, after big pclusters and
shared pclusters are implemented upstream, it seems that all EROFS
encoded data (which requires transformation) can be represented with
`struct z_erofs_pcluster` directly.
Move all members into `struct z_erofs_pcluster` for simplicity.
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20241021035323.3280682-3-hsiangkao@linux.alibaba.com
This patch aims to allocate bvpages and short-lived compressed pages
from the reserved pool first.
After applying this patch, there are three benefits.
1. It reduces the page allocation time.
The bvpages and short-lived compressed pages account for about 4% of
the pages allocated from the system in the multi-app launch benchmarks
[1]. It reduces the page allocation time accordingly and lowers the
likelihood of blockage by page allocation in low memory scenarios.
2. The pages in the reserved pool will be allocated on demand.
Currently, bvpages and short-lived compressed pages are short-lived
pages allocated from the system, and the pages in the reserved pool all
originate from short-lived pages. Consequently, the number of reserved
pool pages will increase to z_erofs_rsv_nrpages over time.
With this patch, all short-lived pages are allocated from the reserved
pool first, so the number of reserved pool pages will only increase when
there are not enough pages. Thus, even if z_erofs_rsv_nrpages is set to
a large number for specific reasons, the actual number of reserved pool
pages may remain low as per demand. In the multi-app launch benchmarks
[1], z_erofs_rsv_nrpages is set at 256, while the number of reserved
pool pages remains below 64.
3. When erofs cache decompression is disabled
(EROFS_ZIP_CACHE_DISABLED), all pages will *only* be allocated from
the reserved pool for erofs. This will significantly reduce the memory
pressure from erofs.
[1] For additional details on the multi-app launch benchmarks, please
refer to commit 0f6273ab46 ("erofs: add a reserved buffer pool for lz4
decompression").
Signed-off-by: Chunhai Guo <guochunhai@vivo.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20240906121110.3701889-1-guochunhai@vivo.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
With iterative development, our codebase can now deal with compressed
buffer misses properly if both in-place I/O and compressed buffer
allocation fail.
Note that if readahead fails (with non-uptodate folios), the original
request will then fall back to synchronous read, and `.read_folio()`
should return appropriate errnos; otherwise -EIO will be passed to
user space, which is unexpected.
To simplify rarely encountered failure paths, a mimic decompression
will be just used. Before that, failure reasons are recorded in
compressed_bvecs[] and they also act as placeholders to avoid in-place
pages. They will be parsed just before decompression and then pass
back to `.read_folio()`.
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240905084732.2684515-1-hsiangkao@linux.alibaba.com
Use pseudo bios just like the previous fscache approach since
merged bio_vecs can be filled properly with unique interfaces.
Reviewed-by: Sandeep Dhavale <dhavale@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240830032840.3783206-3-hsiangkao@linux.alibaba.com
Since EROFS only needs to handle read requests in simple contexts,
Just directly use vfs_iocb_iter_read() for data I/Os.
Reviewed-by: Sandeep Dhavale <dhavale@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240905093031.2745929-1-hsiangkao@linux.alibaba.com
syzbot reported a task hang issue due to a deadlock case where it is
waiting for the folio lock of a cached folio that will be used for
cache I/Os.
After looking into the crafted fuzzed image, I found it's formed with
several overlapped big pclusters as below:
Ext: logical offset | length : physical offset | length
0: 0.. 16384 | 16384 : 151552.. 167936 | 16384
1: 16384.. 32768 | 16384 : 155648.. 172032 | 16384
2: 32768.. 49152 | 16384 : 537223168.. 537239552 | 16384
...
Here, extent 0/1 are physically overlapped although it's entirely
_impossible_ for normal filesystem images generated by mkfs.
First, managed folios containing compressed data will be marked as
up-to-date and then unlocked immediately (unlike in-place folios) when
compressed I/Os are complete. If physical blocks are not submitted in
the incremental order, there should be separate BIOs to avoid dependency
issues. However, the current code mis-arranges z_erofs_fill_bio_vec()
and BIO submission which causes unexpected BIO waits.
Second, managed folios will be connected to their own pclusters for
efficient inter-queries. However, this is somewhat hard to implement
easily if overlapped big pclusters exist. Again, these only appear in
fuzzed images so let's simply fall back to temporary short-lived pages
for correctness.
Additionally, it justifies that referenced managed folios cannot be
truncated for now and reverts part of commit 2080ca1ed3 ("erofs: tidy
up `struct z_erofs_bvec`") for simplicity although it shouldn't be any
difference.
Reported-by: syzbot+4fc98ed414ae63d1ada2@syzkaller.appspotmail.com
Reported-by: syzbot+de04e06b28cfecf2281c@syzkaller.appspotmail.com
Reported-by: syzbot+c8c8238b394be4a1087d@syzkaller.appspotmail.com
Tested-by: syzbot+4fc98ed414ae63d1ada2@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/r/0000000000002fda01061e334873@google.com
Fixes: 8e6c8fa9f2 ("erofs: enable big pcluster feature")
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240910070847.3356592-1-hsiangkao@linux.alibaba.com
Smatch complains that:
fs/erofs/zdata.c:1047 z_erofs_scan_folio()
error: uninitialized symbol 'err'.
The issue is if we hit this (!(map->m_flags & EROFS_MAP_MAPPED)) {
condition then "err" isn't set. It's inside a loop so we would have to
hit that condition on every iteration. Initialize "err" to zero to
solve this.
Fixes: 5b9654efb6 ("erofs: teach z_erofs_scan_folios() to handle multi-page folios")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/f78ab50e-ed6d-4275-8dd4-a4159fa565a2@stanley.mountain
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
LZ4 always reuses the decompressed buffer as its LZ77 sliding window
(dynamic dictionary) for optimal performance. However, in specific
cases, the output buffer may not fully contain valid page cache pages,
resulting in the use of short-lived pages for temporary purposes.
Due to the limited sliding window size, LZ4 shortlived bounce pages can
also be reused in a sliding manner, so each bounce page can be vmapped
multiple times in different relative positions by design. In order to
avoiding double frees, currently, reuse counts are recorded via page
refcount, but it will no longer be used as-is in the future world of
Memdescs.
Just maintain a lookup table to check if a shortlived page is reused.
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240711053659.1364989-1-hsiangkao@linux.alibaba.com
After revisiting the design, I believe `struct z_erofs_bvec` should
be page-based instead of folio-based due to the reasons below:
- The minimized memory mapping block is a page;
- Under the certain circumstances, only temporary pages needs to be
used instead of folios since refcount, mapcount for such pages are
unnecessary;
- Decompressors handle all types of pages including temporary pages,
not only folios.
When handling `struct z_erofs_bvec`, all folio-related information
is now accessed using the page_folio() helper.
The final goal of this round adaptation is to eliminate direct
accesses to `struct page` in the EROFS codebase, except for some
exceptions like `z_erofs_is_shortlived_page()` and
`z_erofs_page_is_invalidated()`, which require a new helper to
determine the memdesc type of an arbitrary page.
Actually large folios of compressed files seem to work now, yet I tend
to conduct more tests before officially enabling this for all scenarios.
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240703120051.3653452-4-hsiangkao@linux.alibaba.com
Previously, a folio just contains one page. In order to enable large
folios, z_erofs_scan_folios() needs to handle multi-page folios.
First, this patch eliminates all gotos. Instead, the new loop deal
with multiple parts in each folio. It's simple to handle the parts
which belong to unmapped extents or fragment extents; but for encoded
extents, the page boundaries needs to be considered for `tight` and
`split` to keep inplace I/Os work correctly: when a part crosses the
page boundary, they needs to be reseted properly.
Besides, simplify `tight` derivation since Z_EROFS_PCLUSTER_HOOKED
has been removed for quite a while.
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240703120051.3653452-3-hsiangkao@linux.alibaba.com
... and be more idiomatic when calculating ->pageofs_in.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20240425200017.GF1031757@ZenIV
[ Gao Xiang: don't use `offset_in_page(mptr)` due to EROFS_NO_KMAP. ]
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
just lift the call of erofs_pos() into the callers; it will
collapse in most of them, but that's better done caller-by-caller.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20240425195846.GC1031757@ZenIV
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
