diff options
| author | Filipe Manana <fdmanana@suse.com> | 2023-10-04 13:38:51 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2023-10-12 17:44:17 +0300 |
| commit | 0124855ff18b9bdfe6aec87f7b29d3fdc6f575db (patch) | |
| tree | 9efcc94b959df93a18e6fecc165546b1f99f3fad /fs/btrfs/disk-io.c | |
| parent | 4a4f8fe2b0230c22aba40c9f8ea7b9c6fcfc8417 (diff) | |
| download | linux-0124855ff18b9bdfe6aec87f7b29d3fdc6f575db.tar.xz | |
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/disk-io.c')
| -rw-r--r-- | fs/btrfs/disk-io.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index c84d32951b26..401ea09ae4b8 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -244,6 +244,7 @@ blk_status_t btree_csum_one_bio(struct btrfs_bio *bbio) struct extent_buffer *eb = bbio->private; struct btrfs_fs_info *fs_info = eb->fs_info; u64 found_start = btrfs_header_bytenr(eb); + u64 last_trans; u8 result[BTRFS_CSUM_SIZE]; int ret; @@ -281,12 +282,12 @@ blk_status_t btree_csum_one_bio(struct btrfs_bio *bbio) * Also check the generation, the eb reached here must be newer than * last committed. Or something seriously wrong happened. */ - if (unlikely(btrfs_header_generation(eb) <= fs_info->last_trans_committed)) { + last_trans = btrfs_get_last_trans_committed(fs_info); + if (unlikely(btrfs_header_generation(eb) <= last_trans)) { ret = -EUCLEAN; btrfs_err(fs_info, "block=%llu bad generation, have %llu expect > %llu", - eb->start, btrfs_header_generation(eb), - fs_info->last_trans_committed); + eb->start, btrfs_header_generation(eb), last_trans); goto error; } write_extent_buffer(eb, result, 0, fs_info->csum_size); @@ -2653,7 +2654,7 @@ static int __cold init_tree_roots(struct btrfs_fs_info *fs_info) /* All successful */ fs_info->generation = btrfs_header_generation(tree_root->node); - fs_info->last_trans_committed = fs_info->generation; + btrfs_set_last_trans_committed(fs_info, fs_info->generation); fs_info->last_reloc_trans = 0; /* Always begin writing backup roots after the one being used */ |