diff options
author | Filipe Manana <fdmanana@suse.com> | 2023-10-04 11:38:48 +0100 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2023-10-12 16:44:17 +0200 |
commit | f9850787969953552266da579d0f1fbf2c2e1c10 (patch) | |
tree | 1ba9afba0fd05be401ac6bcd4e9bd4b99dfd3c31 /fs/btrfs/btrfs_inode.h | |
parent | a5b8a5f9f8355d27a4f8d0afa93427f16d2f3c1e (diff) |
btrfs: add and use helpers for reading and writing last_log_commit
Currently, the last_log_commit of a root can be accessed concurrently
without any lock protection. Readers can be calling btrfs_inode_in_log()
early in a fsync call, which reads a root's last_log_commit, while a
writer can change the last_log_commit while a log tree if being synced,
at btrfs_sync_log(). Any races here should be harmless, and in the worst
case they may cause a fsync to log an inode when it's not really needed,
so nothing bad from a functional perspective.
To avoid data race warnings from tools like KCSAN and other issues such
as load and store tearing (amongst others, see [1]), create helpers to
access the last_log_commit field of a root using READ_ONCE() and
WRITE_ONCE(), and use these helpers everywhere.
[1] https://lwn.net/Articles/793253/
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/btrfs_inode.h')
-rw-r--r-- | fs/btrfs/btrfs_inode.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h index 81bf514d988f..d32ef248828e 100644 --- a/fs/btrfs/btrfs_inode.h +++ b/fs/btrfs/btrfs_inode.h @@ -390,7 +390,7 @@ static inline bool btrfs_inode_in_log(struct btrfs_inode *inode, u64 generation) spin_lock(&inode->lock); if (inode->logged_trans == generation && inode->last_sub_trans <= inode->last_log_commit && - inode->last_sub_trans <= inode->root->last_log_commit) + inode->last_sub_trans <= btrfs_get_root_last_log_commit(inode->root)) ret = true; spin_unlock(&inode->lock); return ret; |