diff options
| author | Christian Brauner <brauner@kernel.org> | 2024-08-30 15:04:59 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-09-12 11:58:45 +0200 |
| commit | 5e9b50dea970ae6d3e1309d4254157099734a2af (patch) | |
| tree | 89f9d1704d813436a4125ebc615a4dd0278578a6 | |
| parent | 1146e5a69efca76501378f748388fd7742ad09cf (diff) | |
fs: add f_pipe
Only regular files with FMODE_ATOMIC_POS and directories need
f_pos_lock. Place a new f_pipe member in a union with f_pos_lock
that they can use and make them stop abusing f_version in follow-up
patches.
Link: https://lore.kernel.org/r/20240830-vfs-file-f_version-v1-18-6d3e4816aa7b@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
| -rw-r--r-- | fs/file_table.c | 7 | ||||
| -rw-r--r-- | include/linux/fs.h | 8 |
2 files changed, 14 insertions, 1 deletions
diff --git a/fs/file_table.c b/fs/file_table.c index 3ef558f27a1c..7ce4d5dac080 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -156,6 +156,13 @@ static int init_file(struct file *f, int flags, const struct cred *cred) } spin_lock_init(&f->f_lock); + /* + * Note that f_pos_lock is only used for files raising + * FMODE_ATOMIC_POS and directories. Other files such as pipes + * don't need it and since f_pos_lock is in a union may reuse + * the space for other purposes. They are expected to initialize + * the respective member when opening the file. + */ mutex_init(&f->f_pos_lock); f->f_flags = flags; f->f_mode = OPEN_FMODE(flags); diff --git a/include/linux/fs.h b/include/linux/fs.h index 3e6b3c1afb31..ca4925008244 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1001,6 +1001,7 @@ static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index) * @f_cred: stashed credentials of creator/opener * @f_path: path of the file * @f_pos_lock: lock protecting file position + * @f_pipe: specific to pipes * @f_pos: file position * @f_version: file version * @f_security: LSM security context of this file @@ -1026,7 +1027,12 @@ struct file { const struct cred *f_cred; /* --- cacheline 1 boundary (64 bytes) --- */ struct path f_path; - struct mutex f_pos_lock; + union { + /* regular files (with FMODE_ATOMIC_POS) and directories */ + struct mutex f_pos_lock; + /* pipes */ + u64 f_pipe; + }; loff_t f_pos; u64 f_version; /* --- cacheline 2 boundary (128 bytes) --- */ |