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| 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/disk-io.c | |
| parent | a5b8a5f9f8355d27a4f8d0afa93427f16d2f3c1e (diff) | |
| download | linux-f9850787969953552266da579d0f1fbf2c2e1c10.tar.gz linux-f9850787969953552266da579d0f1fbf2c2e1c10.tar.bz2 linux-f9850787969953552266da579d0f1fbf2c2e1c10.zip | |
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/disk-io.c')
| -rw-r--r-- | fs/btrfs/disk-io.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index ff3802986b3e..fe18c54cec10 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -677,7 +677,7 @@ static void __setup_root(struct btrfs_root *root, struct btrfs_fs_info *fs_info, atomic_set(&root->nr_swapfiles, 0); root->log_transid = 0; root->log_transid_committed = -1; - root->last_log_commit = 0; + btrfs_set_root_last_log_commit(root, 0); root->anon_dev = 0; if (!dummy) { extent_io_tree_init(fs_info, &root->dirty_log_pages, @@ -1006,7 +1006,7 @@ int btrfs_add_log_tree(struct btrfs_trans_handle *trans, root->log_root = log_root; root->log_transid = 0; root->log_transid_committed = -1; - root->last_log_commit = 0; + btrfs_set_root_last_log_commit(root, 0); return 0; } |