--- /dev/null
+From c80e299925d45086b9fc252e3c67c4e98fb5ab65 Mon Sep 17 00:00:00 2001
+From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Date: Mon, 29 Apr 2019 15:56:26 +0200
+Subject: Revert "block/loop: Use global lock for ioctl() operation."
+
+From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+This reverts commit a17189a0e107ee316b3fff61217f5a037357d65e which is
+commit 310ca162d779efee8a2dc3731439680f3e9c1e86 upstream.
+
+Jan Kara has reported seeing problems with this patch applied, as has
+Salvatore Bonaccorso, so let's drop it for now.
+
+Reported-by: Salvatore Bonaccorso <carnil@debian.org>
+Reported-by: Jan Kara <jack@suse.cz>
+Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
+Cc: Jens Axboe <axboe@kernel.dk>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/block/loop.c | 47 +++++++++++++++++++++++------------------------
+ drivers/block/loop.h | 1 +
+ 2 files changed, 24 insertions(+), 24 deletions(-)
+
+--- a/drivers/block/loop.c
++++ b/drivers/block/loop.c
+@@ -81,7 +81,6 @@
+
+ static DEFINE_IDR(loop_index_idr);
+ static DEFINE_MUTEX(loop_index_mutex);
+-static DEFINE_MUTEX(loop_ctl_mutex);
+
+ static int max_part;
+ static int part_shift;
+@@ -1013,7 +1012,7 @@ static int loop_clr_fd(struct loop_devic
+ */
+ if (lo->lo_refcnt > 1) {
+ lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
+- mutex_unlock(&loop_ctl_mutex);
++ mutex_unlock(&lo->lo_ctl_mutex);
+ return 0;
+ }
+
+@@ -1062,12 +1061,12 @@ static int loop_clr_fd(struct loop_devic
+ lo->lo_flags = 0;
+ if (!part_shift)
+ lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
+- mutex_unlock(&loop_ctl_mutex);
++ mutex_unlock(&lo->lo_ctl_mutex);
+ /*
+- * Need not hold loop_ctl_mutex to fput backing file.
+- * Calling fput holding loop_ctl_mutex triggers a circular
++ * Need not hold lo_ctl_mutex to fput backing file.
++ * Calling fput holding lo_ctl_mutex triggers a circular
+ * lock dependency possibility warning as fput can take
+- * bd_mutex which is usually taken before loop_ctl_mutex.
++ * bd_mutex which is usually taken before lo_ctl_mutex.
+ */
+ fput(filp);
+ return 0;
+@@ -1301,7 +1300,7 @@ static int lo_ioctl(struct block_device
+ struct loop_device *lo = bdev->bd_disk->private_data;
+ int err;
+
+- mutex_lock_nested(&loop_ctl_mutex, 1);
++ mutex_lock_nested(&lo->lo_ctl_mutex, 1);
+ switch (cmd) {
+ case LOOP_SET_FD:
+ err = loop_set_fd(lo, mode, bdev, arg);
+@@ -1310,7 +1309,7 @@ static int lo_ioctl(struct block_device
+ err = loop_change_fd(lo, bdev, arg);
+ break;
+ case LOOP_CLR_FD:
+- /* loop_clr_fd would have unlocked loop_ctl_mutex on success */
++ /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
+ err = loop_clr_fd(lo);
+ if (!err)
+ goto out_unlocked;
+@@ -1341,7 +1340,7 @@ static int lo_ioctl(struct block_device
+ default:
+ err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
+ }
+- mutex_unlock(&loop_ctl_mutex);
++ mutex_unlock(&lo->lo_ctl_mutex);
+
+ out_unlocked:
+ return err;
+@@ -1474,16 +1473,16 @@ static int lo_compat_ioctl(struct block_
+
+ switch(cmd) {
+ case LOOP_SET_STATUS:
+- mutex_lock(&loop_ctl_mutex);
++ mutex_lock(&lo->lo_ctl_mutex);
+ err = loop_set_status_compat(
+ lo, (const struct compat_loop_info __user *) arg);
+- mutex_unlock(&loop_ctl_mutex);
++ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ case LOOP_GET_STATUS:
+- mutex_lock(&loop_ctl_mutex);
++ mutex_lock(&lo->lo_ctl_mutex);
+ err = loop_get_status_compat(
+ lo, (struct compat_loop_info __user *) arg);
+- mutex_unlock(&loop_ctl_mutex);
++ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ case LOOP_SET_CAPACITY:
+ case LOOP_CLR_FD:
+@@ -1514,9 +1513,9 @@ static int lo_open(struct block_device *
+ goto out;
+ }
+
+- mutex_lock(&loop_ctl_mutex);
++ mutex_lock(&lo->lo_ctl_mutex);
+ lo->lo_refcnt++;
+- mutex_unlock(&loop_ctl_mutex);
++ mutex_unlock(&lo->lo_ctl_mutex);
+ out:
+ mutex_unlock(&loop_index_mutex);
+ return err;
+@@ -1526,7 +1525,7 @@ static void __lo_release(struct loop_dev
+ {
+ int err;
+
+- mutex_lock(&loop_ctl_mutex);
++ mutex_lock(&lo->lo_ctl_mutex);
+
+ if (--lo->lo_refcnt)
+ goto out;
+@@ -1548,7 +1547,7 @@ static void __lo_release(struct loop_dev
+ }
+
+ out:
+- mutex_unlock(&loop_ctl_mutex);
++ mutex_unlock(&lo->lo_ctl_mutex);
+ }
+
+ static void lo_release(struct gendisk *disk, fmode_t mode)
+@@ -1594,10 +1593,10 @@ static int unregister_transfer_cb(int id
+ struct loop_device *lo = ptr;
+ struct loop_func_table *xfer = data;
+
+- mutex_lock(&loop_ctl_mutex);
++ mutex_lock(&lo->lo_ctl_mutex);
+ if (lo->lo_encryption == xfer)
+ loop_release_xfer(lo);
+- mutex_unlock(&loop_ctl_mutex);
++ mutex_unlock(&lo->lo_ctl_mutex);
+ return 0;
+ }
+
+@@ -1678,7 +1677,7 @@ static int loop_add(struct loop_device *
+ if (!part_shift)
+ disk->flags |= GENHD_FL_NO_PART_SCAN;
+ disk->flags |= GENHD_FL_EXT_DEVT;
+- mutex_init(&loop_ctl_mutex);
++ mutex_init(&lo->lo_ctl_mutex);
+ lo->lo_number = i;
+ lo->lo_thread = NULL;
+ init_waitqueue_head(&lo->lo_event);
+@@ -1790,19 +1789,19 @@ static long loop_control_ioctl(struct fi
+ ret = loop_lookup(&lo, parm);
+ if (ret < 0)
+ break;
+- mutex_lock(&loop_ctl_mutex);
++ mutex_lock(&lo->lo_ctl_mutex);
+ if (lo->lo_state != Lo_unbound) {
+ ret = -EBUSY;
+- mutex_unlock(&loop_ctl_mutex);
++ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ }
+ if (lo->lo_refcnt > 0) {
+ ret = -EBUSY;
+- mutex_unlock(&loop_ctl_mutex);
++ mutex_unlock(&lo->lo_ctl_mutex);
+ break;
+ }
+ lo->lo_disk->private_data = NULL;
+- mutex_unlock(&loop_ctl_mutex);
++ mutex_unlock(&lo->lo_ctl_mutex);
+ idr_remove(&loop_index_idr, lo->lo_number);
+ loop_remove(lo);
+ break;
+--- a/drivers/block/loop.h
++++ b/drivers/block/loop.h
+@@ -55,6 +55,7 @@ struct loop_device {
+ struct bio_list lo_bio_list;
+ unsigned int lo_bio_count;
+ int lo_state;
++ struct mutex lo_ctl_mutex;
+ struct task_struct *lo_thread;
+ wait_queue_head_t lo_event;
+ /* wait queue for incoming requests */