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authorDavid Sterba <dsterba@suse.com>2022-09-05 18:32:23 +0200
committerDavid Sterba <dsterba@suse.com>2022-09-26 12:28:02 +0200
commit748f553c3c4c4f175c6c834358632aff802d72cf (patch)
treecab7b8594b9c01f5c6e656dd9f60ba5cdb12c406 /fs/btrfs/block-rsv.h
parentbtrfs: remove useless used space increment during space reservation (diff)
downloadlinux-748f553c3c4c4f175c6c834358632aff802d72cf.tar.xz
linux-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.h9
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 */