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loop: Split setting of lo_state from loop_clr_fd 

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>
This commit is contained in:
Jan Kara 2018-11-08 14:01:06 +01:00 committed by Jens Axboe
parent a13165441d
commit a2505b799a
1 changed files with 31 additions and 21 deletions
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52
drivers/block/loop.c
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@ -975,7 +975,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
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;
@ -1025,31 +1025,15 @@ loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
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;
@ -1057,7 +1041,6 @@ static int loop_clr_fd(struct loop_device *lo)
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);
@ -1110,6 +1093,30 @@ static int loop_clr_fd(struct loop_device *lo)
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)
{
@ -1691,11 +1698,14 @@ static void lo_release(struct gendisk *disk, fmode_t mode)
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) {