linux-stable.git/fs/ext4, branch v6.0.2

ext4: fixup possible uninitialized variable access in ext4_mb_choose_next_group_cr1()

2022-09-26T17:21:05+00:00

Variable 'grp' may be left uninitialized if there's no group with
suitable average fragment size (or larger). Fix the problem by
initializing it earlier.

Link: https://lore.kernel.org/r/20220922091542.pkhedytey7wzp5fi@quack3
Fixes: 83e80a6e3543 ("ext4: use buckets for cr 1 block scan instead of rbtree")
Cc: stable@kernel.org
Reported-by: Dan Carpenter 
Signed-off-by: Jan Kara 
Signed-off-by: Theodore Ts'o

ext4: limit the number of retries after discarding preallocations blocks

2022-09-22T14:51:19+00:00

This patch avoids threads live-locking for hours when a large number
threads are competing over the last few free extents as they blocks
getting added and removed from preallocation pools.  From our bug
reporter:

   A reliable way for triggering this has multiple writers
   continuously write() to files when the filesystem is full, while
   small amounts of space are freed (e.g. by truncating a large file
   -1MiB at a time). In the local filesystem, this can be done by
   simply not checking the return code of write (0) and/or the error
   (ENOSPACE) that is set. Over NFS with an async mount, even clients
   with proper error checking will behave this way since the linux NFS
   client implementation will not propagate the server errors [the
   write syscalls immediately return success] until the file handle is
   closed. This leads to a situation where NFS clients send a
   continuous stream of WRITE rpcs which result in ERRNOSPACE -- but
   since the client isn't seeing this, the stream of writes continues
   at maximum network speed.

   When some space does appear, multiple writers will all attempt to
   claim it for their current write. For NFS, we may see dozens to
   hundreds of threads that do this.

   The real-world scenario of this is database backup tooling (in
   particular, github.com/mdkent/percona-xtrabackup) which may write
   large files (>1TiB) to NFS for safe keeping. Some temporary files
   are written, rewound, and read back -- all before closing the file
   handle (the temp file is actually unlinked, to trigger automatic
   deletion on close/crash.) An application like this operating on an
   async NFS mount will not see an error code until TiB have been
   written/read.

   The lockup was observed when running this database backup on large
   filesystems (64 TiB in this case) with a high number of block
   groups and no free space. Fragmentation is generally not a factor
   in this filesystem (~thousands of large files, mostly contiguous
   except for the parts written while the filesystem is at capacity.)

Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org

ext4: fix bug in extents parsing when eh_entries == 0 and eh_depth > 0

2022-09-22T14:50:54+00:00

When walking through an inode extents, the ext4_ext_binsearch_idx() function
assumes that the extent header has been previously validated.  However, there
are no checks that verify that the number of entries (eh->eh_entries) is
non-zero when depth is > 0.  And this will lead to problems because the
EXT_FIRST_INDEX() and EXT_LAST_INDEX() will return garbage and result in this:

[  135.245946] ------------[ cut here ]------------
[  135.247579] kernel BUG at fs/ext4/extents.c:2258!
[  135.249045] invalid opcode: 0000 [#1] PREEMPT SMP
[  135.250320] CPU: 2 PID: 238 Comm: tmp118 Not tainted 5.19.0-rc8+ #4
[  135.252067] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b-rebuilt.opensuse.org 04/01/2014
[  135.255065] RIP: 0010:ext4_ext_map_blocks+0xc20/0xcb0
[  135.256475] Code:
[  135.261433] RSP: 0018:ffffc900005939f8 EFLAGS: 00010246
[  135.262847] RAX: 0000000000000024 RBX: ffffc90000593b70 RCX: 0000000000000023
[  135.264765] RDX: ffff8880038e5f10 RSI: 0000000000000003 RDI: ffff8880046e922c
[  135.266670] RBP: ffff8880046e9348 R08: 0000000000000001 R09: ffff888002ca580c
[  135.268576] R10: 0000000000002602 R11: 0000000000000000 R12: 0000000000000024
[  135.270477] R13: 0000000000000000 R14: 0000000000000024 R15: 0000000000000000
[  135.272394] FS:  00007fdabdc56740(0000) GS:ffff88807dd00000(0000) knlGS:0000000000000000
[  135.274510] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  135.276075] CR2: 00007ffc26bd4f00 CR3: 0000000006261004 CR4: 0000000000170ea0
[  135.277952] Call Trace:
[  135.278635]  
[  135.279247]  ? preempt_count_add+0x6d/0xa0
[  135.280358]  ? percpu_counter_add_batch+0x55/0xb0
[  135.281612]  ? _raw_read_unlock+0x18/0x30
[  135.282704]  ext4_map_blocks+0x294/0x5a0
[  135.283745]  ? xa_load+0x6f/0xa0
[  135.284562]  ext4_mpage_readpages+0x3d6/0x770
[  135.285646]  read_pages+0x67/0x1d0
[  135.286492]  ? folio_add_lru+0x51/0x80
[  135.287441]  page_cache_ra_unbounded+0x124/0x170
[  135.288510]  filemap_get_pages+0x23d/0x5a0
[  135.289457]  ? path_openat+0xa72/0xdd0
[  135.290332]  filemap_read+0xbf/0x300
[  135.291158]  ? _raw_spin_lock_irqsave+0x17/0x40
[  135.292192]  new_sync_read+0x103/0x170
[  135.293014]  vfs_read+0x15d/0x180
[  135.293745]  ksys_read+0xa1/0xe0
[  135.294461]  do_syscall_64+0x3c/0x80
[  135.295284]  entry_SYSCALL_64_after_hwframe+0x46/0xb0

This patch simply adds an extra check in __ext4_ext_check(), verifying that
eh_entries is not 0 when eh_depth is > 0.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=215941
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216283
Cc: Baokun Li 
Cc: stable@kernel.org
Signed-off-by: Luís Henriques 
Reviewed-by: Jan Kara 
Reviewed-by: Baokun Li 
Link: https://lore.kernel.org/r/20220822094235.2690-1-lhenriques@suse.de
Signed-off-by: Theodore Ts'o

ext4: use buckets for cr 1 block scan instead of rbtree

2022-09-22T02:12:03+00:00

Using rbtree for sorting groups by average fragment size is relatively
expensive (needs rbtree update on every block freeing or allocation) and
leads to wide spreading of allocations because selection of block group
is very sentitive both to changes in free space and amount of blocks
allocated. Furthermore selecting group with the best matching average
fragment size is not necessary anyway, even more so because the
variability of fragment sizes within a group is likely large so average
is not telling much. We just need a group with large enough average
fragment size so that we have high probability of finding large enough
free extent and we don't want average fragment size to be too big so
that we are likely to find free extent only somewhat larger than what we
need.

So instead of maintaing rbtree of groups sorted by fragment size keep
bins (lists) or groups where average fragment size is in the interval
[2^i, 2^(i+1)). This structure requires less updates on block allocation
/ freeing, generally avoids chaotic spreading of allocations into block
groups, and still is able to quickly (even faster that the rbtree)
provide a block group which is likely to have a suitably sized free
space extent.

This patch reduces number of block groups used when untarring archive
with medium sized files (size somewhat above 64k which is default
mballoc limit for avoiding locality group preallocation) to about half
and thus improves write speeds for eMMC flash significantly.

Fixes: 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning")
CC: stable@kernel.org
Reported-and-tested-by: Stefan Wahren 
Tested-by: Ojaswin Mujoo 
Signed-off-by: Jan Kara 
Reviewed-by: Ritesh Harjani (IBM) 
Link: https://lore.kernel.org/all/0d81a7c2-46b7-6010-62a4-3e6cfc1628d6@i2se.com/
Link: https://lore.kernel.org/r/20220908092136.11770-5-jack@suse.cz
Signed-off-by: Theodore Ts'o

ext4: use locality group preallocation for small closed files

2022-09-22T02:12:00+00:00

Curently we don't use any preallocation when a file is already closed
when allocating blocks (from writeback code when converting delayed
allocation). However for small files, using locality group preallocation
is actually desirable as that is not specific to a particular file.
Rather it is a method to pack small files together to reduce
fragmentation and for that the fact the file is closed is actually even
stronger hint the file would benefit from packing. So change the logic
to allow locality group preallocation in this case.

Fixes: 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning")
CC: stable@kernel.org
Reported-and-tested-by: Stefan Wahren 
Tested-by: Ojaswin Mujoo 
Reviewed-by: Ritesh Harjani (IBM) 
Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/all/0d81a7c2-46b7-6010-62a4-3e6cfc1628d6@i2se.com/
Link: https://lore.kernel.org/r/20220908092136.11770-4-jack@suse.cz
Signed-off-by: Theodore Ts'o

ext4: make directory inode spreading reflect flexbg size

2022-09-22T02:11:55+00:00

Currently the Orlov inode allocator searches for free inodes for a
directory only in flex block groups with at most inodes_per_group/16
more directory inodes than average per flex block group. However with
growing size of flex block group this becomes unnecessarily strict.
Scale allowed difference from average directory count per flex block
group with flex block group size as we do with other metrics.

Tested-by: Stefan Wahren 
Tested-by: Ojaswin Mujoo 
Cc: stable@kernel.org
Link: https://lore.kernel.org/all/0d81a7c2-46b7-6010-62a4-3e6cfc1628d6@i2se.com/
Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/r/20220908092136.11770-3-jack@suse.cz
Signed-off-by: Theodore Ts'o

ext4: avoid unnecessary spreading of allocations among groups

2022-09-22T02:11:41+00:00

mb_set_largest_free_order() updates lists containing groups with largest
chunk of free space of given order. The way it updates it leads to
always moving the group to the tail of the list. Thus allocations
looking for free space of given order effectively end up cycling through
all groups (and due to initialization in last to first order). This
spreads allocations among block groups which reduces performance for
rotating disks or low-end flash media. Change
mb_set_largest_free_order() to only update lists if the order of the
largest free chunk in the group changed.

Fixes: 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning")
CC: stable@kernel.org
Reported-and-tested-by: Stefan Wahren 
Tested-by: Ojaswin Mujoo 
Reviewed-by: Ritesh Harjani (IBM) 
Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/all/0d81a7c2-46b7-6010-62a4-3e6cfc1628d6@i2se.com/
Link: https://lore.kernel.org/r/20220908092136.11770-2-jack@suse.cz
Signed-off-by: Theodore Ts'o

ext4: make mballoc try target group first even with mb_optimize_scan

2022-09-22T02:11:34+00:00

One of the side-effects of mb_optimize_scan was that the optimized
functions to select next group to try were called even before we tried
the goal group. As a result we no longer allocate files close to
corresponding inodes as well as we don't try to expand currently
allocated extent in the same group. This results in reaim regression
with workfile.disk workload of upto 8% with many clients on my test
machine:

                     baseline               mb_optimize_scan
Hmean     disk-1       2114.16 (   0.00%)     2099.37 (  -0.70%)
Hmean     disk-41     87794.43 (   0.00%)    83787.47 *  -4.56%*
Hmean     disk-81    148170.73 (   0.00%)   135527.05 *  -8.53%*
Hmean     disk-121   177506.11 (   0.00%)   166284.93 *  -6.32%*
Hmean     disk-161   220951.51 (   0.00%)   207563.39 *  -6.06%*
Hmean     disk-201   208722.74 (   0.00%)   203235.59 (  -2.63%)
Hmean     disk-241   222051.60 (   0.00%)   217705.51 (  -1.96%)
Hmean     disk-281   252244.17 (   0.00%)   241132.72 *  -4.41%*
Hmean     disk-321   255844.84 (   0.00%)   245412.84 *  -4.08%*

Also this is causing huge regression (time increased by a factor of 5 or
so) when untarring archive with lots of small files on some eMMC storage
cards.

Fix the problem by making sure we try goal group first.

Fixes: 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning")
CC: stable@kernel.org
Reported-and-tested-by: Stefan Wahren 
Tested-by: Ojaswin Mujoo 
Reviewed-by: Ritesh Harjani (IBM) 
Link: https://lore.kernel.org/all/20220727105123.ckwrhbilzrxqpt24@quack3/
Link: https://lore.kernel.org/all/0d81a7c2-46b7-6010-62a4-3e6cfc1628d6@i2se.com/
Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/r/20220908092136.11770-1-jack@suse.cz
Signed-off-by: Theodore Ts'o

Merge tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-08-05T23:32:45+00:00

Pull MM updates from Andrew Morton:
 "Most of the MM queue. A few things are still pending.

  Liam's maple tree rework didn't make it. This has resulted in a few
  other minor patch series being held over for next time.

  Multi-gen LRU still isn't merged as we were waiting for mapletree to
  stabilize. The current plan is to merge MGLRU into -mm soon and to
  later reintroduce mapletree, with a view to hopefully getting both
  into 6.1-rc1.

  Summary:

   - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe
     Lin, Yang Shi, Anshuman Khandual and Mike Rapoport

   - Some kmemleak fixes from Patrick Wang and Waiman Long

   - DAMON updates from SeongJae Park

   - memcg debug/visibility work from Roman Gushchin

   - vmalloc speedup from Uladzislau Rezki

   - more folio conversion work from Matthew Wilcox

   - enhancements for coherent device memory mapping from Alex Sierra

   - addition of shared pages tracking and CoW support for fsdax, from
     Shiyang Ruan

   - hugetlb optimizations from Mike Kravetz

   - Mel Gorman has contributed some pagealloc changes to improve
     latency and realtime behaviour.

   - mprotect soft-dirty checking has been improved by Peter Xu

   - Many other singleton patches all over the place"

 [ XFS merge from hell as per Darrick Wong in

   https://lore.kernel.org/all/YshKnxb4VwXycPO8@magnolia/ ]

* tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (282 commits)
  tools/testing/selftests/vm/hmm-tests.c: fix build
  mm: Kconfig: fix typo
  mm: memory-failure: convert to pr_fmt()
  mm: use is_zone_movable_page() helper
  hugetlbfs: fix inaccurate comment in hugetlbfs_statfs()
  hugetlbfs: cleanup some comments in inode.c
  hugetlbfs: remove unneeded header file
  hugetlbfs: remove unneeded hugetlbfs_ops forward declaration
  hugetlbfs: use helper macro SZ_1{K,M}
  mm: cleanup is_highmem()
  mm/hmm: add a test for cross device private faults
  selftests: add soft-dirty into run_vmtests.sh
  selftests: soft-dirty: add test for mprotect
  mm/mprotect: fix soft-dirty check in can_change_pte_writable()
  mm: memcontrol: fix potential oom_lock recursion deadlock
  mm/gup.c: fix formatting in check_and_migrate_movable_page()
  xfs: fail dax mount if reflink is enabled on a partition
  mm/memcontrol.c: remove the redundant updating of stats_flush_threshold
  userfaultfd: don't fail on unrecognized features
  hugetlb_cgroup: fix wrong hugetlb cgroup numa stat
  ...

Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2022-08-05T03:13:46+00:00

Pull ext4 updates from Ted Ts'o:
 "Add new ioctls to set and get the file system UUID in the ext4
  superblock and improved the performance of the online resizing of file
  systems with bigalloc enabled.

  Fixed a lot of bugs, in particular for the inline data feature,
  potential races when creating and deleting inodes with shared extended
  attribute blocks, and the handling of directory blocks which are
  corrupted"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (37 commits)
  ext4: add ioctls to get/set the ext4 superblock uuid
  ext4: avoid resizing to a partial cluster size
  ext4: reduce computation of overhead during resize
  jbd2: fix assertion 'jh->b_frozen_data == NULL' failure when journal aborted
  ext4: block range must be validated before use in ext4_mb_clear_bb()
  mbcache: automatically delete entries from cache on freeing
  mbcache: Remove mb_cache_entry_delete()
  ext2: avoid deleting xattr block that is being reused
  ext2: unindent codeblock in ext2_xattr_set()
  ext2: factor our freeing of xattr block reference
  ext4: fix race when reusing xattr blocks
  ext4: unindent codeblock in ext4_xattr_block_set()
  ext4: remove EA inode entry from mbcache on inode eviction
  mbcache: add functions to delete entry if unused
  mbcache: don't reclaim used entries
  ext4: make sure ext4_append() always allocates new block
  ext4: check if directory block is within i_size
  ext4: reflect mb_optimize_scan value in options file
  ext4: avoid remove directory when directory is corrupted
  ext4: aligned '*' in comments
  ...