diff options
| author | Christian Brauner <brauner@kernel.org> | 2025-02-07 15:10:33 +0100 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2025-02-21 10:25:32 +0100 |
| commit | da06e3c5179467f9ef7caffb512ef111a70afde1 (patch) | |
| tree | ef35a14c19b2d3f2d364d1ef5b9740e1208c187c /fs/internal.h | |
| parent | 1bb772565f327291b0a463b125c7646dc45ae8b4 (diff) | |
fs: don't needlessly acquire f_lock
Before 2011 there was no meaningful synchronization between
read/readdir/write/seek. Only in commit
ef3d0fd27e90 ("vfs: do (nearly) lockless generic_file_llseek")
synchronization was added for SEEK_CUR by taking f_lock around
vfs_setpos().
Then in 2014 full synchronization between read/readdir/write/seek was
added in commit 9c225f2655e3 ("vfs: atomic f_pos accesses as per POSIX")
by introducing f_pos_lock for regular files with FMODE_ATOMIC_POS and
for directories. At that point taking f_lock became unnecessary for such
files.
So only acquire f_lock for SEEK_CUR if this isn't a file that would have
acquired f_pos_lock if necessary.
Link: https://lore.kernel.org/r/20250207-daten-mahlzeit-99d2079864fb@brauner
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'fs/internal.h')
| -rw-r--r-- | fs/internal.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/internal.h b/fs/internal.h index 84607e7b05dc..1cb85a62c07f 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -338,3 +338,4 @@ static inline bool path_mounted(const struct path *path) return path->mnt->mnt_root == path->dentry; } void file_f_owner_release(struct file *file); +bool file_seek_cur_needs_f_lock(struct file *file); |