diff options
| author | Filipe Manana <fdmanana@suse.com> | 2023-10-04 11:38:51 +0100 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2023-10-12 16:44:17 +0200 |
| commit | 0124855ff18b9bdfe6aec87f7b29d3fdc6f575db (patch) | |
| tree | 9efcc94b959df93a18e6fecc165546b1f99f3fad /fs/btrfs/fs.h | |
| parent | 4a4f8fe2b0230c22aba40c9f8ea7b9c6fcfc8417 (diff) | |
btrfs: add and use helpers for reading and writing last_trans_committed
Currently the last_trans_committed field of struct btrfs_fs_info is
modified and read without any locking or other protection. For example
early in the fsync path, skip_inode_logging() is called which reads
fs_info->last_trans_committed, but at the same time we can have a
transaction commit completing and updating that field.
In the case of an fsync this is harmless and any data race should be
rare and at most cause an unnecessary logging of an inode.
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_trans_committed field of struct btrfs_fs_info 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/fs.h')
| -rw-r--r-- | fs/btrfs/fs.h | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h index d04b729cbdf3..318df6f9d9cb 100644 --- a/fs/btrfs/fs.h +++ b/fs/btrfs/fs.h @@ -423,6 +423,10 @@ struct btrfs_fs_info { * Should always be updated using btrfs_set_fs_generation(). */ u64 generation; + /* + * Always use btrfs_get_last_trans_committed() and + * btrfs_set_last_trans_committed() to read and update this field. + */ u64 last_trans_committed; /* * Generation of the last transaction used for block group relocation @@ -833,6 +837,16 @@ static inline void btrfs_set_fs_generation(struct btrfs_fs_info *fs_info, u64 ge WRITE_ONCE(fs_info->generation, gen); } +static inline u64 btrfs_get_last_trans_committed(const struct btrfs_fs_info *fs_info) +{ + return READ_ONCE(fs_info->last_trans_committed); +} + +static inline void btrfs_set_last_trans_committed(struct btrfs_fs_info *fs_info, u64 gen) +{ + WRITE_ONCE(fs_info->last_trans_committed, gen); +} + static inline void btrfs_set_last_root_drop_gen(struct btrfs_fs_info *fs_info, u64 gen) { |