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Commit 52f85729 authored by Lino Sanfilippo's avatar Lino Sanfilippo Committed by Linus Torvalds
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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: default avatarLino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5e9c070c

fs/notify/dnotify/dnotify.c

+13 −12
Original line number Diff line number Diff line
@@ -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)