Commit Graph

137 Commits

Author SHA1 Message Date
Gao Xiang
1a0ac8bd7a erofs: fix erofs_insert_workgroup() lockref usage
As Linus pointed out [1], lockref_put_return() is fundamentally
designed to be something that can fail.  It behaves as a fastpath-only
thing, and the failure case needs to be handled anyway.

Actually, since the new pcluster was just allocated without being
populated, it won't be accessed by others until it is inserted into
XArray, so lockref helpers are actually unneeded here.

Let's just set the proper reference count on initializing.

[1] https://lore.kernel.org/r/CAHk-=whCga8BeQnJ3ZBh_Hfm9ctba_wpF444LpwRybVNMzO6Dw@mail.gmail.com

Fixes: 7674a42f35 ("erofs: use struct lockref to replace handcrafted approach")
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20231031060524.1103921-1-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-10-31 18:59:49 +08:00
Jingbo Xu
91b1ad0815 erofs: release ztailpacking pclusters properly
Currently ztailpacking pclusters are chained with FOLLOWED_NOINPLACE and
not recorded into the managed_pslots XArray.

After commit 7674a42f35 ("erofs: use struct lockref to replace
handcrafted approach"), ztailpacking pclusters won't be freed with
erofs_workgroup_put() anymore, which will cause the following issue:

BUG erofs_pcluster-1 (Tainted: G           OE     ): Objects remaining in erofs_pcluster-1 on __kmem_cache_shutdown()

Use z_erofs_free_pcluster() directly to free ztailpacking pclusters.

Fixes: 7674a42f35 ("erofs: use struct lockref to replace handcrafted approach")
Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230822110530.96831-1-jefflexu@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-08-23 23:57:03 +08:00
Gao Xiang
c33ad3b2b7 erofs: adapt folios for z_erofs_read_folio()
It's a straight-forward conversion and no logic changes (except that
it renames the corresponding tracepoint.)

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230817083942.103303-1-hsiangkao@linux.alibaba.com
2023-08-23 23:47:33 +08:00
Gao Xiang
491b1105a8 erofs: adapt folios for z_erofs_readahead()
It's a straight-forward conversion except that readahead_folio()
will do folio_put() in advance but it doesn't matter since folios
are still locked.

As before, since file-backed folios (pages for now) are locked, so
we could temporarily use folio->private as an internal counter to
indicate split parts of each folio for the corresponding pclusters
to decompress.

When such counter becomes zero, the folio will be finally unlocked
(see compress.h and z_erofs_onlinepage_endio()).

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230817082813.81180-7-hsiangkao@linux.alibaba.com
2023-08-23 23:47:18 +08:00
Gao Xiang
06ec03660d erofs: get rid of fe->backmost for cache decompression
EROFS_MAP_FULL_MAPPED is more accurate to decide if caching the last
incomplete pcluster for later read or not.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230817082813.81180-6-hsiangkao@linux.alibaba.com
2023-08-23 23:46:42 +08:00
Gao Xiang
9a05c6a8bc erofs: drop z_erofs_page_mark_eio()
It can be folded into z_erofs_onlinepage_endio() to simplify the code.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230817082813.81180-5-hsiangkao@linux.alibaba.com
2023-08-23 23:45:49 +08:00
Gao Xiang
e4c1cf523d erofs: tidy up z_erofs_do_read_page()
- Fix a typo: spiltted => split;

 - Move !EROFS_MAP_MAPPED and EROFS_MAP_FRAGMENT upwards;

 - Increase `split` in advance to avoid unnecessary repeats.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230817082813.81180-4-hsiangkao@linux.alibaba.com
2023-08-23 23:43:42 +08:00
Gao Xiang
aeebae9d77 erofs: move preparation logic into z_erofs_pcluster_begin()
Some preparation logic should be part of z_erofs_pcluster_begin()
instead of z_erofs_do_read_page().  Let's move now.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230817082813.81180-3-hsiangkao@linux.alibaba.com
2023-08-23 23:43:15 +08:00
Gao Xiang
dcba1b232e erofs: avoid obsolete {collector,collection} terms
{collector,collection} were once reserved in order to indicate different
runtime logical extent instance of multi-reference pclusters.

However, de-duplicated decompression has been landed in a more flexable
way, thus `struct z_erofs_collection` was formally removed in commit
87ca34a706 ("erofs: get rid of `struct z_erofs_collection'").

Let's handle the remaining leftovers, for example:
    `z_erofs_collector_begin` => `z_erofs_pcluster_begin`
    `z_erofs_collector_end` => `z_erofs_pcluster_end`

as well as some comments.  No logic changes.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230817082813.81180-2-hsiangkao@linux.alibaba.com
2023-08-23 23:42:03 +08:00
Gao Xiang
8b00be163f erofs: simplify z_erofs_read_fragment()
A trivial cleanup to make the fragment handling logic more clear.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230817082813.81180-1-hsiangkao@linux.alibaba.com
2023-08-23 23:41:39 +08:00
Ferry Meng
e3157bb55d erofs: refine warning messages for zdata I/Os
Don't warn users since -EINTR can be returned due to user interruption.
Also suppress warning messages of readmore.

Signed-off-by: Ferry Meng <mengferry@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230809060637.21311-1-mengferry@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-08-23 23:39:01 +08:00
Gao Xiang
94c43de735 erofs: fix wrong primary bvec selection on deduplicated extents
When handling deduplicated compressed data, there can be multiple
decompressed extents pointing to the same compressed data in one shot.

In such cases, the bvecs which belong to the longest extent will be
selected as the primary bvecs for real decompressors to decode and the
other duplicated bvecs will be directly copied from the primary bvecs.

Previously, only relative offsets of the longest extent were checked to
decompress the primary bvecs.  On rare occasions, it can be incorrect
if there are several extents with the same start relative offset.
As a result, some short bvecs could be selected for decompression and
then cause data corruption.

For example, as Shijie Sun reported off-list, considering the following
extents of a file:
 117:   903345..  915250 |   11905 :     385024..    389120 |    4096
...
 119:   919729..  930323 |   10594 :     385024..    389120 |    4096
...
 124:   968881..  980786 |   11905 :     385024..    389120 |    4096

The start relative offset is the same: 2225, but extent 119 (919729..
930323) is shorter than the others.

Let's restrict the bvec length in addition to the start offset if bvecs
are not full.

Reported-by: Shijie Sun <sunshijie@xiaomi.com>
Fixes: 5c2a64252c ("erofs: introduce partial-referenced pclusters")
Tested-by Shijie Sun <sunshijie@xiaomi.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230719065459.60083-1-hsiangkao@linux.alibaba.com
2023-08-01 16:12:17 +08:00
Chunhai Guo
8191213a58 erofs: avoid infinite loop in z_erofs_do_read_page() when reading beyond EOF
z_erofs_do_read_page() may loop infinitely due to the inappropriate
truncation in the below statement. Since the offset is 64 bits and min_t()
truncates the result to 32 bits. The solution is to replace unsigned int
with a 64-bit type, such as erofs_off_t.
    cur = end - min_t(unsigned int, offset + end - map->m_la, end);

    - For example:
        - offset = 0x400160000
        - end = 0x370
        - map->m_la = 0x160370
        - offset + end - map->m_la = 0x400000000
        - offset + end - map->m_la = 0x00000000 (truncated as unsigned int)
    - Expected result:
        - cur = 0
    - Actual result:
        - cur = 0x370

Signed-off-by: Chunhai Guo <guochunhai@vivo.com>
Fixes: 3883a79abd ("staging: erofs: introduce VLE decompression support")
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230710093410.44071-1-guochunhai@vivo.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-07-12 00:50:43 +08:00
Chunhai Guo
936aa701d8 erofs: avoid useless loops in z_erofs_pcluster_readmore() when reading beyond EOF
z_erofs_pcluster_readmore() may take a long time to loop when the page
offset is large enough, which is unnecessary should be prevented.

For example, when the following case is encountered, it will loop 4691368
times, taking about 27 seconds:
    - offset = 19217289215
    - inode_size = 1442672

Signed-off-by: Chunhai Guo <guochunhai@vivo.com>
Fixes: 386292919c ("erofs: introduce readmore decompression strategy")
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230710042531.28761-1-guochunhai@vivo.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-07-12 00:50:33 +08:00
Sandeep Dhavale
12d0a24afd erofs: Fix detection of atomic context
Current check for atomic context is not sufficient as
z_erofs_decompressqueue_endio can be called under rcu lock
from blk_mq_flush_plug_list(). See the stacktrace [1]

In such case we should hand off the decompression work for async
processing rather than trying to do sync decompression in current
context. Patch fixes the detection by checking for
rcu_read_lock_any_held() and while at it use more appropriate
!in_task() check than in_atomic().

Background: Historically erofs would always schedule a kworker for
decompression which would incur the scheduling cost regardless of
the context. But z_erofs_decompressqueue_endio() may not always
be in atomic context and we could actually benefit from doing the
decompression in z_erofs_decompressqueue_endio() if we are in
thread context, for example when running with dm-verity.
This optimization was later added in patch [2] which has shown
improvement in performance benchmarks.

==============================================
[1] Problem stacktrace
[name:core&]BUG: sleeping function called from invalid context at kernel/locking/mutex.c:291
[name:core&]in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 1615, name: CpuMonitorServi
[name:core&]preempt_count: 0, expected: 0
[name:core&]RCU nest depth: 1, expected: 0
CPU: 7 PID: 1615 Comm: CpuMonitorServi Tainted: G S      W  OE      6.1.25-android14-5-maybe-dirty-mainline #1
Hardware name: MT6897 (DT)
Call trace:
 dump_backtrace+0x108/0x15c
 show_stack+0x20/0x30
 dump_stack_lvl+0x6c/0x8c
 dump_stack+0x20/0x48
 __might_resched+0x1fc/0x308
 __might_sleep+0x50/0x88
 mutex_lock+0x2c/0x110
 z_erofs_decompress_queue+0x11c/0xc10
 z_erofs_decompress_kickoff+0x110/0x1a4
 z_erofs_decompressqueue_endio+0x154/0x180
 bio_endio+0x1b0/0x1d8
 __dm_io_complete+0x22c/0x280
 clone_endio+0xe4/0x280
 bio_endio+0x1b0/0x1d8
 blk_update_request+0x138/0x3a4
 blk_mq_plug_issue_direct+0xd4/0x19c
 blk_mq_flush_plug_list+0x2b0/0x354
 __blk_flush_plug+0x110/0x160
 blk_finish_plug+0x30/0x4c
 read_pages+0x2fc/0x370
 page_cache_ra_unbounded+0xa4/0x23c
 page_cache_ra_order+0x290/0x320
 do_sync_mmap_readahead+0x108/0x2c0
 filemap_fault+0x19c/0x52c
 __do_fault+0xc4/0x114
 handle_mm_fault+0x5b4/0x1168
 do_page_fault+0x338/0x4b4
 do_translation_fault+0x40/0x60
 do_mem_abort+0x60/0xc8
 el0_da+0x4c/0xe0
 el0t_64_sync_handler+0xd4/0xfc
 el0t_64_sync+0x1a0/0x1a4

[2] Link: https://lore.kernel.org/all/20210317035448.13921-1-huangjianan@oppo.com/

Reported-by: Will Shiu <Will.Shiu@mediatek.com>
Suggested-by: Gao Xiang <xiang@kernel.org>
Signed-off-by: Sandeep Dhavale <dhavale@google.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Link: https://lore.kernel.org/r/20230621220848.3379029-1-dhavale@google.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-06-22 21:16:02 +08:00
Gao Xiang
43d86ec936 erofs: use poison pointer to replace the hard-coded address
It's safer and cleaner to replace such hard-coded illegal pointer
with poison pointers.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Link: https://lore.kernel.org/r/20230526201459.128169-7-hsiangkao@linux.alibaba.com
2023-06-18 12:10:53 +08:00
Gao Xiang
7674a42f35 erofs: use struct lockref to replace handcrafted approach
Let's avoid the current handcrafted lockref although `struct lockref`
inclusion usually increases extra 4 bytes with an explicit spinlock if
CONFIG_DEBUG_SPINLOCK is off.

Apart from the size difference, note that the meaning of refcount is
also changed to active users. IOWs, it doesn't take an extra refcount
for XArray tree insertion.

I don't observe any significant performance difference at least on
our cloud compute server but the new one indeed simplifies the
overall codebase a bit.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Link: https://lore.kernel.org/r/20230529123727.79943-1-hsiangkao@linux.alibaba.com
2023-06-18 12:10:47 +08:00
Gao Xiang
7b4e372c36 erofs: adapt managed inode operations into folios
This patch gets rid of erofs_try_to_free_cached_page() and fold it
into .release_folio().

It also moves managed inode operations into zdata.c, which simplifies
the code a bit.  No logic changes.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Link: https://lore.kernel.org/r/20230526201459.128169-5-hsiangkao@linux.alibaba.com
2023-05-29 23:06:03 +08:00
Gao Xiang
967c28b23f erofs: kill hooked chains to avoid loops on deduplicated compressed images
After heavily stressing EROFS with several images which include a
hand-crafted image of repeated patterns for more than 46 days, I found
two chains could be linked with each other almost simultaneously and
form a loop so that the entire loop won't be submitted.  As a
consequence, the corresponding file pages will remain locked forever.

It can be _only_ observed on data-deduplicated compressed images.
For example, consider two chains with five pclusters in total:
	Chain 1:  2->3->4->5    -- The tail pcluster is 5;
        Chain 2:  5->1->2       -- The tail pcluster is 2.

Chain 2 could link to Chain 1 with pcluster 5; and Chain 1 could link
to Chain 2 at the same time with pcluster 2.

Since hooked chains are all linked locklessly now, I have no idea how
to simply avoid the race.  Instead, let's avoid hooked chains completely
until I could work out a proper way to fix this and end users finally
tell us that it's needed to add it back.

Actually, this optimization can be found with multi-threaded workloads
(especially even more often on deduplicated compressed images), yet I'm
not sure about the overall system impacts of not having this compared
with implementation complexity.

Fixes: 267f2492c8 ("erofs: introduce multi-reference pclusters (fully-referenced)")
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Link: https://lore.kernel.org/r/20230526201459.128169-4-hsiangkao@linux.alibaba.com
2023-05-29 23:05:43 +08:00
Gao Xiang
6ab5eed600 erofs: avoid on-stack pagepool directly passed by arguments
On-stack pagepool is used so that short-lived temporary pages could be
shared within a single I/O request (e.g. among multiple pclusters).

Moving the remaining frontend-related uses into
z_erofs_decompress_frontend to avoid too many arguments.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Link: https://lore.kernel.org/r/20230526201459.128169-3-hsiangkao@linux.alibaba.com
2023-05-29 23:05:25 +08:00
Gao Xiang
05b63d2beb erofs: allocate extra bvec pages directly instead of retrying
If non-bootstrap bvecs cannot be kept in place (very rarely), an extra
short-lived page is allocated.

Let's just allocate it immediately rather than do unnecessary -EAGAIN
return first and retry as a cleanup.  Also it's unnecessary to use
__GFP_NOFAIL here since we could gracefully fail out this case instead.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Link: https://lore.kernel.org/r/20230526201459.128169-2-hsiangkao@linux.alibaba.com
2023-05-29 23:04:45 +08:00
Yue Hu
796e9149a2 erofs: clean up z_erofs_pcluster_readmore()
`end` parameter is no needed since it's pointless for !backmost, we can
handle it with backmost internally.  And we only expand the trailing
edge, so the newstart can be replaced with ->headoffset.

Also, remove linux/prefetch.h inclusion since that is not used anymore
after commit 386292919c ("erofs: introduce readmore decompression
strategy").

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230525072605.17857-1-zbestahu@gmail.com
[ Gao Xiang: update commit description. ]
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-05-29 15:54:51 +08:00
Yue Hu
ef4b4b46c6 erofs: remove the member readahead from struct z_erofs_decompress_frontend
The struct member is only used to add REQ_RAHEAD during I/O submission.
So it is cleaner to pass it as a parameter than keep it in the struct.

Also, rename function z_erofs_get_sync_decompress_policy() to
z_erofs_is_sync_decompress() for better clarity and conciseness.

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230524063944.1655-1-zbestahu@gmail.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-05-29 15:54:50 +08:00
Yue Hu
597e2953ae erofs: fold in z_erofs_decompress()
No need this helper since it's just a simple wrapper for decompress
method and only one caller.  So, let's fold in directly instead.

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230426084449.12781-1-zbestahu@gmail.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-05-29 15:54:49 +08:00
Gao Xiang
cf7f2732b4 erofs: use HIPRI by default if per-cpu kthreads are enabled
As Sandeep shown [1], high priority RT per-cpu kthreads are
typically helpful for Android scenarios to minimize the scheduling
latencies.

Switch EROFS_FS_PCPU_KTHREAD_HIPRI on by default if
EROFS_FS_PCPU_KTHREAD is on since it's the typical use cases for
EROFS_FS_PCPU_KTHREAD.

Also clean up unneeded sched_set_normal().

[1] https://lore.kernel.org/r/CAB=BE-SBtO6vcoyLNA9F-9VaN5R0t3o_Zn+FW8GbO6wyUqFneQ@mail.gmail.com

Reviewed-by: Yue Hu <huyue2@coolpad.com>
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/20230522092141.124290-1-hsiangkao@linux.alibaba.com
2023-05-23 16:57:08 +08:00
Gao Xiang
10656f9ca6 erofs: sunset erofs_dbg()
Such debug messages are rarely used now.  Let's get rid of these,
and revert locally if they are needed for debugging.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230414083027.12307-1-hsiangkao@linux.alibaba.com
2023-04-17 01:15:54 +08:00
Gao Xiang
eb2c5e41be erofs: keep meta inode into erofs_buf
So that erofs_read_metadata() can read metadata from other inodes
(e.g. packed inode) as well.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Acked-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230407141710.113882-2-jefflexu@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-04-17 01:15:50 +08:00
Jingbo Xu
3acea5fc33 erofs: avoid hardcoded blocksize for subpage block support
As the first step of converting hardcoded blocksize to that specified in
on-disk superblock, convert all call sites of hardcoded blocksize to
sb->s_blocksize except for:

1) use sbi->blkszbits instead of sb->s_blocksize in
erofs_superblock_csum_verify() since sb->s_blocksize has not been
updated with the on-disk blocksize yet when the function is called.

2) use inode->i_blkbits instead of sb->s_blocksize in erofs_bread(),
since the inode operated on may be an anonymous inode in fscache mode.
Currently the anonymous inode is allocated from an anonymous mount
maintained in erofs, while in the near future we may allocate anonymous
inodes from a generic API directly and thus have no access to the
anonymous inode's i_sb.  Thus we keep the block size in i_blkbits for
anonymous inodes in fscache mode.

Be noted that this patch only gets rid of the hardcoded blocksize, in
preparation for actually setting the on-disk block size in the following
patch.  The hard limit of constraining the block size to PAGE_SIZE still
exists until the next patch.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230313135309.75269-2-jefflexu@linux.alibaba.com
[ Gao Xiang: fold a patch to fix incorrect truncated offsets. ]
Link: https://lore.kernel.org/r/20230413035734.15457-1-zhujia.zj@bytedance.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-04-17 01:15:44 +08:00
Gao Xiang
647dd2c3f0 erofs: Revert "erofs: fix kvcalloc() misuse with __GFP_NOFAIL"
Let's revert commit 12724ba389 ("erofs: fix kvcalloc() misuse with
__GFP_NOFAIL") since kvmalloc() already supports __GFP_NOFAIL in commit
a421ef3030 ("mm: allow !GFP_KERNEL allocations for kvmalloc").  So
the original fix was wrong.

Actually there was some issue as [1] discussed, so before that mm fix
is landed, the warn could still happen but applying this commit first
will cause less.

[1] https://lore.kernel.org/r/20230305053035.1911-1-hsiangkao@linux.alibaba.com

Fixes: 12724ba389 ("erofs: fix kvcalloc() misuse with __GFP_NOFAIL")
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230309053148.9223-1-hsiangkao@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-03-09 23:36:01 +08:00
Dan Carpenter
8d1b80a794 erofs: fix an error code in z_erofs_init_zip_subsystem()
Return -ENOMEM if alloc_workqueue() fails.  Don't return success.

Fixes: d8a650adf429 ("erofs: add per-cpu threads for decompression as an option")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/Y+4d0FRsUq8jPoOu@kili
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2023-02-16 22:51:53 +08:00
Sandeep Dhavale
3fffb589b9 erofs: add per-cpu threads for decompression as an option
Using per-cpu thread pool we can reduce the scheduling latency compared
to workqueue implementation. With this patch scheduling latency and
variation is reduced as per-cpu threads are high priority kthread_workers.

The results were evaluated on arm64 Android devices running 5.10 kernel.

The table below shows resulting improvements of total scheduling latency
for the same app launch benchmark runs with 50 iterations. Scheduling
latency is the latency between when the task (workqueue kworker vs
kthread_worker) became eligible to run to when it actually started
running.
+-------------------------+-----------+----------------+---------+
|                         | workqueue | kthread_worker |  diff   |
+-------------------------+-----------+----------------+---------+
| Average (us)            |     15253 |           2914 | -80.89% |
| Median (us)             |     14001 |           2912 | -79.20% |
| Minimum (us)            |      3117 |           1027 | -67.05% |
| Maximum (us)            |     30170 |           3805 | -87.39% |
| Standard deviation (us) |      7166 |            359 |         |
+-------------------------+-----------+----------------+---------+

Background: Boot times and cold app launch benchmarks are very
important to the Android ecosystem as they directly translate to
responsiveness from user point of view. While EROFS provides
a lot of important features like space savings, we saw some
performance penalty in cold app launch benchmarks in few scenarios.
Analysis showed that the significant variance was coming from the
scheduling cost while decompression cost was more or less the same.

Having per-cpu thread pool we can see from the above table that this
variation is reduced by ~80% on average. This problem was discussed
at LPC 2022. Link to LPC 2022 slides and talk at [1]

[1] https://lpc.events/event/16/contributions/1338/

[ Gao Xiang: At least, we have to add this until WQ_UNBOUND workqueue
             issue [2] on many arm64 devices is resolved. ]
[2] https://lore.kernel.org/r/CAJkfWY490-m6wNubkxiTPsW59sfsQs37Wey279LmiRxKt7aQYg@mail.gmail.com

Signed-off-by: Sandeep Dhavale <dhavale@google.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230208093322.75816-1-hsiangkao@linux.alibaba.com
2023-02-15 08:11:26 +08:00
Gao Xiang
a9a94d9373 erofs: move zdata.h into zdata.c
Definitions in zdata.h are only used in zdata.c and for internal
use only.  No logic changes.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230204093040.97967-4-hsiangkao@linux.alibaba.com
2023-02-15 08:11:25 +08:00
Gao Xiang
b1ed220c62 erofs: remove tagged pointer helpers
Just open-code the remaining one to simplify the code.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230204093040.97967-3-hsiangkao@linux.alibaba.com
2023-02-15 08:11:25 +08:00
Gao Xiang
cdba55067f erofs: avoid tagged pointers to mark sync decompression
We could just use a boolean in z_erofs_decompressqueue for sync
decompression to simplify the code.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230204093040.97967-2-hsiangkao@linux.alibaba.com
2023-02-15 08:11:24 +08:00
Gao Xiang
12724ba389 erofs: fix kvcalloc() misuse with __GFP_NOFAIL
As reported by syzbot [1], kvcalloc() cannot work with  __GFP_NOFAIL.
Let's use kcalloc() instead.

[1] https://lore.kernel.org/r/0000000000007796bd05f1852ec2@google.com

Reported-by: syzbot+c3729cda01706a04fb98@syzkaller.appspotmail.com
Fixes: fe3e5914e6 ("erofs: try to leave (de)compressed_pages on stack if possible")
Fixes: 4f05687fd7 ("erofs: introduce struct z_erofs_decompress_backend")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230110074927.41651-1-hsiangkao@linux.alibaba.com
2023-01-10 16:41:45 +08:00
Chen Zhongjin
c42c0ffe81 erofs: Fix pcluster memleak when its block address is zero
syzkaller reported a memleak:
https://syzkaller.appspot.com/bug?id=62f37ff612f0021641eda5b17f056f1668aa9aed

unreferenced object 0xffff88811009c7f8 (size 136):
  ...
  backtrace:
    [<ffffffff821db19b>] z_erofs_do_read_page+0x99b/0x1740
    [<ffffffff821dee9e>] z_erofs_readahead+0x24e/0x580
    [<ffffffff814bc0d6>] read_pages+0x86/0x3d0
    ...

syzkaller constructed a case: in z_erofs_register_pcluster(),
ztailpacking = false and map->m_pa = zero. This makes pcl->obj.index be
zero although pcl is not a inline pcluster.

Then following path adds refcount for grp, but the refcount won't be put
because pcl is inline.

z_erofs_readahead()
  z_erofs_do_read_page() # for another page
    z_erofs_collector_begin()
      erofs_find_workgroup()
        erofs_workgroup_get()

Since it's illegal for the block address of a non-inlined pcluster to
be zero, add check here to avoid registering the pcluster which would
be leaked.

Fixes: cecf864d3d ("erofs: support inline data decompression")
Reported-by: syzbot+6f8cd9a0155b366d227f@syzkaller.appspotmail.com
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/Y42Kz6sVkf+XqJRB@debian
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2022-12-07 10:56:31 +08:00
Gao Xiang
1282dea37b erofs: clean up cached I/O strategies
After commit 4c7e42552b ("erofs: remove useless cache strategy of
DELAYEDALLOC"), only one cached I/O allocation strategy is supported:

  When cached I/O is preferred, page allocation is applied without
  direct reclaim.  If allocation fails, fall back to inplace I/O.

Let's get rid of z_erofs_cache_alloctype.  No logical changes.

Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Yue Hu <huyue2@coolpad.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20221206060352.152830-1-xiang@kernel.org
2022-12-07 10:56:20 +08:00
Linus Torvalds
81e7cfa3a9 Changes since last update:
- Fix packed_inode invalid access when reading fragments on crafted
    images;
 
  - Add a missing erofs_put_metabuf() in an error path in fscache mode;
 
  - Fix incorrect `count' for unmapped extents in fscache mode;
 
  - Fix use-after-free of fsid and domain_id string when remounting;
 
  - Fix missing xas_retry() in fscache mode.
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Merge tag 'erofs-for-6.1-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs

Pull erofs fixes from Gao Xiang:
 "Most patches randomly fix error paths or corner cases in fscache mode
  reported recently. One fixes an invalid access relating to fragments
  on crafted images.

  Summary:

   - Fix packed_inode invalid access when reading fragments on crafted
     images

   - Add a missing erofs_put_metabuf() in an error path in fscache mode

   - Fix incorrect `count' for unmapped extents in fscache mode

   - Fix use-after-free of fsid and domain_id string when remounting

   - Fix missing xas_retry() in fscache mode"

* tag 'erofs-for-6.1-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  erofs: fix missing xas_retry() in fscache mode
  erofs: fix use-after-free of fsid and domain_id string
  erofs: get correct count for unmapped range in fscache mode
  erofs: put metabuf in error path in fscache mode
  erofs: fix general protection fault when reading fragment
2022-11-15 10:30:34 -08:00
Johannes Weiner
82e60d00b7 fs: fix leaked psi pressure state
When psi annotations were added to to btrfs compression reads, the psi
state tracking over add_ra_bio_pages and btrfs_submit_compressed_read was
faulty.  A pressure state, once entered, is never left.  This results in
incorrectly elevated pressure, which triggers OOM kills.

pflags record the *previous* memstall state when we enter a new one.  The
code tried to initialize pflags to 1, and then optimize the leave call
when we either didn't enter a memstall, or were already inside a nested
stall.  However, there can be multiple PageWorkingset pages in the bio, at
which point it's that path itself that enters repeatedly and overwrites
pflags.  This causes us to miss the exit.

Enter the stall only once if needed, then unwind correctly.

erofs has the same problem, fix that up too.  And move the memstall exit
past submit_bio() to restore submit accounting originally added by
b8e24a9300 ("block: annotate refault stalls from IO submission").

Link: https://lkml.kernel.org/r/Y2UHRqthNUwuIQGS@cmpxchg.org
Fixes: 4088a47e78 ("btrfs: add manual PSI accounting for compressed reads")
Fixes: 99486c511f ("erofs: add manual PSI accounting for the compressed address space")
Fixes: 118f3663fb ("block: remove PSI accounting from the bio layer")
Link: https://lore.kernel.org/r/d20a0a85-e415-cf78-27f9-77dd7a94bc8d@leemhuis.info/
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Thorsten Leemhuis <linux@leemhuis.info>
Tested-by: Thorsten Leemhuis <linux@leemhuis.info>
Cc: Chao Yu <chao@kernel.org>
Cc: Chris Mason <clm@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Sterba <dsterba@suse.com>
Cc: Gao Xiang <xiang@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-11-08 15:57:25 -08:00
Yue Hu
e5126de138 erofs: fix general protection fault when reading fragment
As syzbot reported [1], the fragment feature sb flag is not set, so
packed_inode != NULL needs to be checked in z_erofs_read_fragment().

[1] https://lore.kernel.org/all/0000000000002e7a8905eb841ddd@google.com/

Reported-by: syzbot+3faecbfd845a895c04cb@syzkaller.appspotmail.com
Fixes: b15b2e307c ("erofs: support on-disk compressed fragments data")
Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20221021085325.25788-1-zbestahu@gmail.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2022-11-08 14:44:13 +08:00
Gao Xiang
e7933278b4 erofs: fix up inplace decompression success rate
Partial decompression should be checked after updating length.
It's a new regression when introducing multi-reference pclusters.

Fixes: 2bfab9c0ed ("erofs: record the longest decompressed size in this round")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20221014064915.8103-1-hsiangkao@linux.alibaba.com
2022-10-17 06:55:49 +08:00
Gao Xiang
63bbb85658 erofs: shouldn't churn the mapping page for duplicated copies
If other duplicated copies exist in one decompression shot, should
leave the old page as is rather than replace it with the new duplicated
one.  Otherwise, the following cold path to deal with duplicated copies
will use the invalid bvec.  It impacts compressed data deduplication.

Also, shift the onlinepage EIO bit to avoid touching the signed bit.

Fixes: 267f2492c8 ("erofs: introduce multi-reference pclusters (fully-referenced)")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20221012045056.13421-1-hsiangkao@linux.alibaba.com
2022-10-17 06:55:49 +08:00
Linus Torvalds
513389809e for-6.1/block-2022-10-03
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Merge tag 'for-6.1/block-2022-10-03' of git://git.kernel.dk/linux

Pull block updates from Jens Axboe:

 - NVMe pull requests via Christoph:
      - handle number of queue changes in the TCP and RDMA drivers
        (Daniel Wagner)
      - allow changing the number of queues in nvmet (Daniel Wagner)
      - also consider host_iface when checking ip options (Daniel
        Wagner)
      - don't map pages which can't come from HIGHMEM (Fabio M. De
        Francesco)
      - avoid unnecessary flush bios in nvmet (Guixin Liu)
      - shrink and better pack the nvme_iod structure (Keith Busch)
      - add comment for unaligned "fake" nqn (Linjun Bao)
      - print actual source IP address through sysfs "address" attr
        (Martin Belanger)
      - various cleanups (Jackie Liu, Wolfram Sang, Genjian Zhang)
      - handle effects after freeing the request (Keith Busch)
      - copy firmware_rev on each init (Keith Busch)
      - restrict management ioctls to admin (Keith Busch)
      - ensure subsystem reset is single threaded (Keith Busch)
      - report the actual number of tagset maps in nvme-pci (Keith
        Busch)
      - small fabrics authentication fixups (Christoph Hellwig)
      - add common code for tagset allocation and freeing (Christoph
        Hellwig)
      - stop using the request_queue in nvmet (Christoph Hellwig)
      - set min_align_mask before calculating max_hw_sectors (Rishabh
        Bhatnagar)
      - send a rediscover uevent when a persistent discovery controller
        reconnects (Sagi Grimberg)
      - misc nvmet-tcp fixes (Varun Prakash, zhenwei pi)

 - MD pull request via Song:
      - Various raid5 fix and clean up, by Logan Gunthorpe and David
        Sloan.
      - Raid10 performance optimization, by Yu Kuai.

 - sbitmap wakeup hang fixes (Hugh, Keith, Jan, Yu)

 - IO scheduler switching quisce fix (Keith)

 - s390/dasd block driver updates (Stefan)

 - support for recovery for the ublk driver (ZiyangZhang)

 - rnbd drivers fixes and updates (Guoqing, Santosh, ye, Christoph)

 - blk-mq and null_blk map fixes (Bart)

 - various bcache fixes (Coly, Jilin, Jules)

 - nbd signal hang fix (Shigeru)

 - block writeback throttling fix (Yu)

 - optimize the passthrough mapping handling (me)

 - prepare block cgroups to being gendisk based (Christoph)

 - get rid of an old PSI hack in the block layer, moving it to the
   callers instead where it belongs (Christoph)

 - blk-throttle fixes and cleanups (Yu)

 - misc fixes and cleanups (Liu Shixin, Liu Song, Miaohe, Pankaj,
   Ping-Xiang, Wolfram, Saurabh, Li Jinlin, Li Lei, Lin, Li zeming,
   Miaohe, Bart, Coly, Gaosheng

* tag 'for-6.1/block-2022-10-03' of git://git.kernel.dk/linux: (162 commits)
  sbitmap: fix lockup while swapping
  block: add rationale for not using blk_mq_plug() when applicable
  block: adapt blk_mq_plug() to not plug for writes that require a zone lock
  s390/dasd: use blk_mq_alloc_disk
  blk-cgroup: don't update the blkg lookup hint in blkg_conf_prep
  nvmet: don't look at the request_queue in nvmet_bdev_set_limits
  nvmet: don't look at the request_queue in nvmet_bdev_zone_mgmt_emulate_all
  blk-mq: use quiesced elevator switch when reinitializing queues
  block: replace blk_queue_nowait with bdev_nowait
  nvme: remove nvme_ctrl_init_connect_q
  nvme-loop: use the tagset alloc/free helpers
  nvme-loop: store the generic nvme_ctrl in set->driver_data
  nvme-loop: initialize sqsize later
  nvme-fc: use the tagset alloc/free helpers
  nvme-fc: store the generic nvme_ctrl in set->driver_data
  nvme-fc: keep ctrl->sqsize in sync with opts->queue_size
  nvme-rdma: use the tagset alloc/free helpers
  nvme-rdma: store the generic nvme_ctrl in set->driver_data
  nvme-tcp: use the tagset alloc/free helpers
  nvme-tcp: store the generic nvme_ctrl in set->driver_data
  ...
2022-10-07 09:19:14 -07:00
Gao Xiang
5c2a64252c erofs: introduce partial-referenced pclusters
Due to deduplication for compressed data, pclusters can be partially
referenced with their prefixes.

Together with the user-space implementation, it enables EROFS
variable-length global compressed data deduplication with rolling
hash.

Link: https://lore.kernel.org/r/20220923014915.4362-1-hsiangkao@linux.alibaba.com
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2022-09-26 23:55:43 +08:00
Yue Hu
b15b2e307c erofs: support on-disk compressed fragments data
Introduce on-disk compressed fragments data feature.

This approach adds a new field called `h_fragmentoff' in the per-file
compression header to indicate the fragment offset of each tail pcluster
or the whole file in the special packed inode.

Similar to ztailpacking, it will also find and record the 'headlcn'
of the tail pcluster when initializing per-inode zmap for making
follow-on requests more easy.

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/YzHKxcFTlHGgXeH9@B-P7TQMD6M-0146.local
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
2022-09-26 23:55:39 +08:00
Christoph Hellwig
99486c511f erofs: add manual PSI accounting for the compressed address space
erofs uses an additional address space for compressed data read from disk
in addition to the one directly associated with the inode.  Reading into
the lower address space is open coded using add_to_page_cache_lru instead
of using the filemap.c helper for page allocation micro-optimizations,
which means it is not covered by the MM PSI annotations for ->read_folio
and ->readahead, so add manual ones instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220915094200.139713-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-20 08:24:38 -06:00
Gao Xiang
267f2492c8 erofs: introduce multi-reference pclusters (fully-referenced)
Let's introduce multi-reference pclusters at runtime. In details,
if one pcluster is requested by multiple extents at almost the same
time (even belong to different files), the longest extent will be
decompressed as representative and the other extents are actually
copied from the longest one in one round.

After this patch, fully-referenced extents can be correctly handled
and the full decoding check needs to be bypassed for
partial-referenced extents.

Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220715154203.48093-17-hsiangkao@linux.alibaba.com
2022-07-22 21:44:27 +08:00
Gao Xiang
2bfab9c0ed erofs: record the longest decompressed size in this round
Currently, `pcl->length' records the longest decompressed length
as long as the pcluster itself isn't reclaimed.  However, such
number is unneeded for the general cases since it doesn't indicate
the exact decompressed size in this round.

Instead, let's record the decompressed size for this round instead,
thus `pcl->nr_pages' can be completely dropped and pageofs_out is
also designed to be kept in sync with `pcl->length'.

Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220715154203.48093-16-hsiangkao@linux.alibaba.com
2022-07-21 22:55:44 +08:00
Gao Xiang
3fe96ee0f9 erofs: introduce z_erofs_do_decompressed_bvec()
Both out_bvecs and in_bvecs share the common logic for decompressed
buffers. So let's make a helper for this.

Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220715154203.48093-15-hsiangkao@linux.alibaba.com
2022-07-21 22:55:37 +08:00
Gao Xiang
fe3e5914e6 erofs: try to leave (de)compressed_pages on stack if possible
For the most cases, small pclusters can be decompressed with page
arrays on stack.

Try to leave both (de)compressed_pages on stack if possible as before.

Acked-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220715154203.48093-14-hsiangkao@linux.alibaba.com
2022-07-21 22:55:30 +08:00