4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jan Kara jack@suse.cz
commit a2505b799a496b7b84d9a4a14ec870ff9e42e11b upstream.
Move setting of lo_state to Lo_rundown out into the callers. That will allow us to unlock loop_ctl_mutex while the loop device is protected from other changes by its special state.
Signed-off-by: Jan Kara jack@suse.cz Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/block/loop.c | 52 ++++++++++++++++++++++++++++++--------------------- 1 file changed, 31 insertions(+), 21 deletions(-)
--- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -976,7 +976,7 @@ static int loop_set_fd(struct loop_devic loop_reread_partitions(lo, bdev);
/* Grab the block_device to prevent its destruction after we - * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev). + * put /dev/loopXX inode. Later in __loop_clr_fd() we bdput(bdev). */ bdgrab(bdev); return 0; @@ -1026,31 +1026,15 @@ loop_init_xfer(struct loop_device *lo, s return err; }
-static int loop_clr_fd(struct loop_device *lo) +static int __loop_clr_fd(struct loop_device *lo) { struct file *filp = lo->lo_backing_file; gfp_t gfp = lo->old_gfp_mask; struct block_device *bdev = lo->lo_device;
- if (lo->lo_state != Lo_bound) + if (WARN_ON_ONCE(lo->lo_state != Lo_rundown)) return -ENXIO;
- /* - * If we've explicitly asked to tear down the loop device, - * and it has an elevated reference count, set it for auto-teardown when - * the last reference goes away. This stops $!~#$@ udev from - * preventing teardown because it decided that it needs to run blkid on - * the loopback device whenever they appear. xfstests is notorious for - * failing tests because blkid via udev races with a losetup - * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d - * command to fail with EBUSY. - */ - if (atomic_read(&lo->lo_refcnt) > 1) { - lo->lo_flags |= LO_FLAGS_AUTOCLEAR; - mutex_unlock(&loop_ctl_mutex); - return 0; - } - if (filp == NULL) return -EINVAL;
@@ -1058,7 +1042,6 @@ static int loop_clr_fd(struct loop_devic blk_mq_freeze_queue(lo->lo_queue);
spin_lock_irq(&lo->lo_lock); - lo->lo_state = Lo_rundown; lo->lo_backing_file = NULL; spin_unlock_irq(&lo->lo_lock);
@@ -1111,6 +1094,30 @@ static int loop_clr_fd(struct loop_devic return 0; }
+static int loop_clr_fd(struct loop_device *lo) +{ + if (lo->lo_state != Lo_bound) + return -ENXIO; + /* + * If we've explicitly asked to tear down the loop device, + * and it has an elevated reference count, set it for auto-teardown when + * the last reference goes away. This stops $!~#$@ udev from + * preventing teardown because it decided that it needs to run blkid on + * the loopback device whenever they appear. xfstests is notorious for + * failing tests because blkid via udev races with a losetup + * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d + * command to fail with EBUSY. + */ + if (atomic_read(&lo->lo_refcnt) > 1) { + lo->lo_flags |= LO_FLAGS_AUTOCLEAR; + mutex_unlock(&loop_ctl_mutex); + return 0; + } + lo->lo_state = Lo_rundown; + + return __loop_clr_fd(lo); +} + static int loop_set_status(struct loop_device *lo, const struct loop_info64 *info) { @@ -1692,11 +1699,14 @@ static void lo_release(struct gendisk *d goto out_unlock;
if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) { + if (lo->lo_state != Lo_bound) + goto out_unlock; + lo->lo_state = Lo_rundown; /* * In autoclear mode, stop the loop thread * and remove configuration after last close. */ - err = loop_clr_fd(lo); + err = __loop_clr_fd(lo); if (!err) return; } else if (lo->lo_state == Lo_bound) {