linux/fs/ext4
Ojaswin Mujoo 9d3de7ee19 ext4: fix rbtree traversal bug in ext4_mb_use_preallocated
During allocations, while looking for preallocations(PA) in the per
inode rbtree, we can't do a direct traversal of the tree because
ext4_mb_discard_group_preallocation() can paralelly mark the pa deleted
and that can cause direct traversal to skip some entries. This was
leading to a BUG_ON() being hit [1] when we missed a PA that could satisfy
our request and ultimately tried to create a new PA that would overlap
with the missed one.

To makes sure we handle that case while still keeping the performance of
the rbtree, we make use of the fact that the only pa that could possibly
overlap the original goal start is the one that satisfies the below
conditions:

  1. It must have it's logical start immediately to the left of
  (ie less than) original logical start.

  2. It must not be deleted

To find this pa we use the following traversal method:

1. Descend into the rbtree normally to find the immediate neighboring
PA. Here we keep descending irrespective of if the PA is deleted or if
it overlaps with our request etc. The goal is to find an immediately
adjacent PA.

2. If the found PA is on right of original goal, use rb_prev() to find
the left adjacent PA.

3. Check if this PA is deleted and keep moving left with rb_prev() until
a non deleted PA is found.

4. This is the PA we are looking for. Now we can check if it can satisfy
the original request and proceed accordingly.

This approach also takes care of having deleted PAs in the tree.

(While we are at it, also fix a possible overflow bug in calculating the
end of a PA)

[1] https://lore.kernel.org/linux-ext4/CA+G9fYv2FRpLqBZf34ZinR8bU2_ZRAUOjKAD3+tKRFaEQHtt8Q@mail.gmail.com/

Cc: stable@kernel.org # 6.4
Fixes: 3872778664 ("ext4: Use rbtrees to manage PAs instead of inode i_prealloc_list")
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reviewed-by: Ritesh Harjani (IBM) ritesh.list@gmail.com
Tested-by: Ritesh Harjani (IBM) ritesh.list@gmail.com
Link: https://lore.kernel.org/r/edd2efda6a83e6343c5ace9deea44813e71dbe20.1690045963.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2023-07-23 08:21:14 -04:00
..
.kunitconfig ext4: add .kunitconfig fragment to enable ext4-specific tests 2021-02-11 23:16:30 -05:00
acl.c fs: port acl to mnt_idmap 2023-01-19 09:24:28 +01:00
acl.h fs: port ->set_acl() to pass mnt_idmap 2023-01-19 09:24:27 +01:00
balloc.c ext4: drop the call to ext4_error() from ext4_get_group_info() 2023-06-14 22:24:05 -04:00
bitmap.c ext4: remove useless conditional branch code 2023-04-19 23:39:08 -04:00
block_validity.c ext4: add ext4_sb_block_valid() refactored out of ext4_inode_block_valid() 2022-02-25 21:34:56 -05:00
crypto.c ext4: refactor and move ext4_ioctl_get_encryption_pwsalt() 2022-05-21 22:24:24 -04:00
dir.c ext4: fix spelling errors in comments 2022-05-11 15:19:06 -04:00
ext4_extents.h ext4: fix sparse warnings 2021-08-30 23:36:50 -04:00
ext4_jbd2.c ext4: split ext4_journal_start trace for debug 2022-12-01 10:46:54 -05:00
ext4_jbd2.h ext4: split ext4_journal_start trace for debug 2022-12-01 10:46:54 -05:00
ext4.h Various cleanups and bug fixes in ext4's extent status tree, 2023-06-29 13:18:36 -07:00
extents_status.c ext4: make ext4_es_insert_extent() return void 2023-06-26 19:35:12 -04:00
extents_status.h ext4: make ext4_es_insert_extent() return void 2023-06-26 19:35:12 -04:00
extents.c ext4: make ext4_zeroout_es() return void 2023-06-26 19:35:12 -04:00
fast_commit.c ext4: use ext4_fc_tl_mem in fast-commit replay path 2023-02-09 10:43:23 -05:00
fast_commit.h ext4: add missing validation of fast-commit record lengths 2022-12-08 21:49:24 -05:00
file.c Various cleanups and bug fixes in ext4's extent status tree, 2023-06-29 13:18:36 -07:00
fsmap.c ext4: fix another off-by-one fsmap error on 1k block filesystems 2023-03-07 20:20:48 -05:00
fsmap.h ext4: fsmap: fix the block/inode bitmap comment 2021-06-24 09:48:29 -04:00
fsync.c \n 2023-06-29 13:39:51 -07:00
hash.c ext4: improve error handling from ext4_dirhash() 2023-05-13 18:05:05 -04:00
ialloc.c ext4: allow ext4_get_group_info() to fail 2023-05-13 18:02:46 -04:00
indirect.c ext4: only update i_reserved_data_blocks on successful block allocation 2023-06-26 19:34:56 -04:00
inline.c ext4: make ext4_es_remove_extent() return void 2023-06-26 19:35:12 -04:00
inode-test.c fs: ext4: Modify inode-test.c to use KUnit parameterized testing feature 2020-12-02 16:07:25 -07:00
inode.c Various cleanups and bug fixes in ext4's extent status tree, 2023-06-29 13:18:36 -07:00
ioctl.c Various cleanups and bug fixes in ext4's extent status tree, 2023-06-29 13:18:36 -07:00
Kconfig ext: EXT4_KUNIT_TESTS should depend on EXT4_FS instead of selecting it 2021-02-11 23:12:59 -05:00
Makefile ext4: move ext4 crypto code to its own file crypto.c 2022-05-21 22:24:24 -04:00
mballoc.c ext4: fix rbtree traversal bug in ext4_mb_use_preallocated 2023-07-23 08:21:14 -04:00
mballoc.h ext4: Give symbolic names to mballoc criterias 2023-06-26 19:34:56 -04:00
migrate.c ext4: avoid deadlock in fs reclaim with page writeback 2023-05-13 18:05:04 -04:00
mmp.c ext4: fix lockdep warning when enabling MMP 2023-05-07 21:11:18 -04:00
move_extent.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
namei.c ext4: Remove ext4 locking of moved directory 2023-06-02 14:55:32 +02:00
orphan.c ext4: remove trailing newline from ext4_msg() message 2022-12-08 21:49:23 -05:00
page-io.c ext4: remove unneeded check of nr_to_submit 2023-04-19 23:38:33 -04:00
readpage.c ext4: Call fsverity_verify_folio() 2023-06-15 00:02:10 -04:00
resize.c ext4: remove unused group parameter in ext4_block_bitmap_csum_set 2023-03-23 23:00:08 -04:00
super.c Various cleanups and bug fixes in ext4's extent status tree, 2023-06-29 13:18:36 -07:00
symlink.c fs: port ->getattr() to pass mnt_idmap 2023-01-19 09:24:25 +01:00
sysfs.c ext4: Give symbolic names to mballoc criterias 2023-06-26 19:34:56 -04:00
truncate.h ext4: Convert to use mapping->invalidate_lock 2021-07-13 14:29:00 +02:00
verity.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
xattr_hurd.c fs: port xattr to mnt_idmap 2023-01-19 09:24:28 +01:00
xattr_security.c fs: port xattr to mnt_idmap 2023-01-19 09:24:28 +01:00
xattr_trusted.c fs: port xattr to mnt_idmap 2023-01-19 09:24:28 +01:00
xattr_user.c fs: port xattr to mnt_idmap 2023-01-19 09:24:28 +01:00
xattr.c ext4: correct inline offset when handling xattrs in inode body 2023-07-23 08:21:05 -04:00
xattr.h ext4: remove EA inode entry from mbcache on inode eviction 2022-08-02 23:56:25 -04:00