summaryrefslogtreecommitdiff
path: root/Documentation/filesystems/Locking
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/filesystems/Locking')
-rw-r--r--Documentation/filesystems/Locking52
1 files changed, 31 insertions, 21 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 75d2d57e2c44..2c391338c675 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -69,31 +69,31 @@ prototypes:
locking rules:
all may block
- i_mutex(inode)
-lookup: yes
-create: yes
-link: yes (both)
-mknod: yes
-symlink: yes
-mkdir: yes
-unlink: yes (both)
-rmdir: yes (both) (see below)
-rename: yes (all) (see below)
+ i_rwsem(inode)
+lookup: shared
+create: exclusive
+link: exclusive (both)
+mknod: exclusive
+symlink: exclusive
+mkdir: exclusive
+unlink: exclusive (both)
+rmdir: exclusive (both)(see below)
+rename: exclusive (all) (see below)
readlink: no
get_link: no
-setattr: yes
+setattr: exclusive
permission: no (may not block if called in rcu-walk mode)
get_acl: no
getattr: no
listxattr: no
fiemap: no
update_time: no
-atomic_open: yes
+atomic_open: exclusive
tmpfile: no
- Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on
-victim.
+ Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_rwsem
+ exclusive on victim.
cross-directory ->rename() has (per-superblock) ->s_vfs_rename_sem.
See Documentation/filesystems/directory-locking for more detailed discussion
@@ -111,10 +111,10 @@ prototypes:
locking rules:
all may block
- i_mutex(inode)
+ i_rwsem(inode)
list: no
get: no
-set: yes
+set: exclusive
--------------------------- super_operations ---------------------------
prototypes:
@@ -217,14 +217,14 @@ 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:
set_page_dirty no
readpages:
-write_begin: locks the page yes
-write_end: yes, unlocks yes
+write_begin: locks the page exclusive
+write_end: yes, unlocks exclusive
bmap:
invalidatepage: yes
releasepage: yes
@@ -439,7 +439,10 @@ 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 *);
- unsigned int (*poll) (struct file *, struct poll_table_struct *);
+ int (*iterate_shared) (struct file *, struct dir_context *);
+ __poll_t (*poll) (struct file *, struct poll_table_struct *);
+ struct wait_queue_head * (*get_poll_head)(struct file *, __poll_t);
+ __poll_t (*poll_mask) (struct file *, __poll_t);
long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
int (*mmap) (struct file *, struct vm_area_struct *);
@@ -470,7 +473,7 @@ prototypes:
};
locking rules:
- All may block.
+ All except for ->poll_mask may block.
->llseek() locking has moved from llseek to the individual llseek
implementations. If your fs is not using generic_file_llseek, you
@@ -480,6 +483,10 @@ 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 exclusive.
+
+->iterate_shared() is called with i_rwsem at least 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
@@ -498,6 +505,9 @@ in sys_read() and friends.
the lease within the individual filesystem to record the result of the
operation
+->poll_mask can be called with or without the waitqueue lock for the waitqueue
+returned from ->get_poll_head.
+
--------------------------- dquot_operations -------------------------------
prototypes:
int (*write_dquot) (struct dquot *);