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| author |   David Sterba <dsterba@suse.com> | 2022-09-05 18:32:23 +0200 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2022-09-26 12:28:02 +0200 |
| commit | 748f553c3c4c4f175c6c834358632aff802d72cf (patch) | |
| tree | cab7b8594b9c01f5c6e656dd9f60ba5cdb12c406 /fs/btrfs/block-rsv.h | |
| parent | btrfs: remove useless used space increment during space reservation (diff) | |
| download | linux-dev-748f553c3c4c4f175c6c834358632aff802d72cf.tar.xz linux-dev-748f553c3c4c4f175c6c834358632aff802d72cf.zip | |
btrfs: add KCSAN annotations for unlocked access to block_rsv->full
KCSAN reports that there's unlocked access mixed with locked access,
which is technically correct but is not a bug. To avoid false alerts at
least from KCSAN, add annotation and use a wrapper whenever ->full is
accessed for read outside of lock.
It is used as a fast check and only advisory. In the worst case the
block reserve is found !full and becomes full in the meantime, but
properly handled.
Depending on the value of ->full, btrfs_block_rsv_release decides
where to return the reservation, and block_rsv_release_bytes handles a
NULL pointer for block_rsv and if it's not NULL then it double checks
the full status under a lock.
Link: https://lore.kernel.org/linux-btrfs/CAAwBoOJDjei5Hnem155N_cJwiEkVwJYvgN-tQrwWbZQGhFU=cA@mail.gmail.com/
Link: https://lore.kernel.org/linux-btrfs/YvHU/vsXd7uz5V6j@hungrycats.org
Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/block-rsv.h')
| -rw-r--r-- | fs/btrfs/block-rsv.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/btrfs/block-rsv.h b/fs/btrfs/block-rsv.h index 0c183709be00..578c3497a455 100644 --- a/fs/btrfs/block-rsv.h +++ b/fs/btrfs/block-rsv.h @@ -92,4 +92,13 @@ static inline void btrfs_unuse_block_rsv(struct btrfs_fs_info *fs_info, btrfs_block_rsv_release(fs_info, block_rsv, 0, NULL); } +/* + * Fast path to check if the reserve is full, may be carefully used outside of + * locks. + */ +static inline bool btrfs_block_rsv_full(const struct btrfs_block_rsv *rsv) +{ + return data_race(rsv->full); +} + #endif /* BTRFS_BLOCK_RSV_H */ |