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dnotify: replace dnotify_mark_mutex with mark mutex of dnotify_group 

There is no need to use a special mutex to protect against the
fcntl/close race (see dnotify.c for a description of this race).
Instead the dnotify_groups mark mutex can be used.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Lino Sanfilippo 2013-07-08 15:59:44 -07:00 committed by Linus Torvalds
parent 5e9c070ca0
commit 52f8572980
1 changed files with 13 additions and 12 deletions
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25
fs/notify/dnotify/dnotify.c
View File

@ -31,7 +31,6 @@ int dir_notify_enable __read_mostly = 1;
static struct kmem_cache *dnotify_struct_cache __read_mostly;
static struct kmem_cache *dnotify_mark_cache __read_mostly;
static struct fsnotify_group *dnotify_group __read_mostly;
static DEFINE_MUTEX(dnotify_mark_mutex);
/*
* dnotify will attach one of these to each inode (i_fsnotify_marks) which
@ -183,7 +182,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
return;
dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark);
mutex_lock(&dnotify_mark_mutex);
mutex_lock(&dnotify_group->mark_mutex);
spin_lock(&fsn_mark->lock);
prev = &dn_mark->dn;
@ -199,11 +198,12 @@ void dnotify_flush(struct file *filp, fl_owner_t id)
spin_unlock(&fsn_mark->lock);
/* nothing else could have found us thanks to the dnotify_mark_mutex */
/* nothing else could have found us thanks to the dnotify_groups
mark_mutex */
if (dn_mark->dn == NULL)
fsnotify_destroy_mark(fsn_mark, dnotify_group);
fsnotify_destroy_mark_locked(fsn_mark, dnotify_group);
mutex_unlock(&dnotify_mark_mutex);
mutex_unlock(&dnotify_group->mark_mutex);
fsnotify_put_mark(fsn_mark);
}
@ -326,7 +326,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
new_dn_mark->dn = NULL;
/* this is needed to prevent the fcntl/close race described below */
mutex_lock(&dnotify_mark_mutex);
mutex_lock(&dnotify_group->mark_mutex);
/* add the new_fsn_mark or find an old one. */
fsn_mark = fsnotify_find_inode_mark(dnotify_group, inode);
@ -334,7 +334,8 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark);
spin_lock(&fsn_mark->lock);
} else {
fsnotify_add_mark(new_fsn_mark, dnotify_group, inode, NULL, 0);
fsnotify_add_mark_locked(new_fsn_mark, dnotify_group, inode,
NULL, 0);
spin_lock(&new_fsn_mark->lock);
fsn_mark = new_fsn_mark;
dn_mark = new_dn_mark;
@ -348,9 +349,9 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
/* if (f != filp) means that we lost a race and another task/thread
* actually closed the fd we are still playing with before we grabbed
* the dnotify_mark_mutex and fsn_mark->lock. Since closing the fd is the
* only time we clean up the marks we need to get our mark off
* the list. */
* the dnotify_groups mark_mutex and fsn_mark->lock. Since closing the
* fd is the only time we clean up the marks we need to get our mark
* off the list. */
if (f != filp) {
/* if we added ourselves, shoot ourselves, it's possible that
* the flush actually did shoot this fsn_mark. That's fine too
@ -385,9 +386,9 @@ out:
spin_unlock(&fsn_mark->lock);
if (destroy)
fsnotify_destroy_mark(fsn_mark, dnotify_group);
fsnotify_destroy_mark_locked(fsn_mark, dnotify_group);
mutex_unlock(&dnotify_mark_mutex);
mutex_unlock(&dnotify_group->mark_mutex);
fsnotify_put_mark(fsn_mark);
out_err:
if (new_fsn_mark)