Documentation/filesystems/Locking no longer reflects current locking semantics. i_mutex is no longer used for locking, and has been superseded by i_rwsem. Additionally, ->iterate_shared() was not documented. Signed-off-by: Sean Anderson <seanga2@xxxxxxxxx> --- Documentation/filesystems/Locking | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index fe25787ff6d4..b098d2e50b7f 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -69,8 +69,8 @@ prototypes: locking rules: all may block - i_mutex(inode) -lookup: yes + i_rwsem(inode) +lookup: shared create: yes link: yes (both) mknod: yes @@ -92,7 +92,7 @@ atomic_open: yes tmpfile: no - Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on + Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_rwsem on victim. cross-directory ->rename() has (per-superblock) ->s_vfs_rename_sem. @@ -111,7 +111,7 @@ prototypes: locking rules: all may block - i_mutex(inode) + i_rwsem(inode) list: no get: no set: yes @@ -217,7 +217,7 @@ prototypes: locking rules: All except set_page_dirty and freepage may block - PageLocked(page) i_mutex + PageLocked(page) i_rwsem writepage: yes, unlocks (see below) readpage: yes, unlocks writepages: @@ -439,6 +439,7 @@ prototypes: ssize_t (*read_iter) (struct kiocb *, struct iov_iter *); ssize_t (*write_iter) (struct kiocb *, struct iov_iter *); int (*iterate) (struct file *, struct dir_context *); + int (*iterate_shared) (struct file *, struct dir_context *); unsigned int (*poll) (struct file *, struct poll_table_struct *); long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long); long (*compat_ioctl) (struct file *, unsigned int, unsigned long); @@ -480,6 +481,10 @@ mutex or just to use i_size_read() instead. Note: this does not protect the file->f_pos against concurrent modifications since this is something the userspace has to take care about. +->iterate() is called with i_rwsem held. + +->iterate_shared() is called with i_rwsem shared. + ->fasync() is responsible for maintaining the FASYNC bit in filp->f_flags. Most instances call fasync_helper(), which does that maintenance, so it's not normally something one needs to worry about. Return values > 0 will be -- 2.13.2
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