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Commit 10f6327b authored by Al Viro's avatar Al Viro
Browse files

btrfs: fix a deadlock in btrfs_scan_one_device() 



pathname resolution under a global mutex, taken on some paths in ->mount()
is a Bad Idea(tm) - think what happens if said pathname resolution triggers
automount of some btrfs instance and walks into attempt to grab the same
mutex.  Deadlock - we are waiting for daemon to finish walking the path,
daemon is waiting for us to release the mutex...

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 6de1d09d

fs/btrfs/volumes.c

+2 −3
Original line number Diff line number Diff line
@@ -706,8 +706,6 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, 
	u64 devid;

	u64 transid;



	mutex_lock(&uuid_mutex);



	flags |= FMODE_EXCL;

	bdev = blkdev_get_by_path(path, flags, holder);
@@ -716,6 +714,7 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, 
		goto error;

	}



	mutex_lock(&uuid_mutex);

	ret = set_blocksize(bdev, 4096);

	if (ret)

		goto error_close;
@@ -737,9 +736,9 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder, 


	brelse(bh);

error_close:

	mutex_unlock(&uuid_mutex);

	blkdev_put(bdev, flags);

error:

	mutex_unlock(&uuid_mutex);

	return ret;

}