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path: root/drivers/block/loop.c
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Diffstat (limited to 'drivers/block/loop.c')
-rw-r--r--drivers/block/loop.c82
1 files changed, 52 insertions, 30 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index d7173cb1ea76..40580dc7f41c 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -86,8 +86,6 @@ static DEFINE_MUTEX(loop_index_mutex);
static int max_part;
static int part_shift;
-static struct workqueue_struct *loop_wq;
-
static int transfer_xor(struct loop_device *lo, int cmd,
struct page *raw_page, unsigned raw_off,
struct page *loop_page, unsigned loop_off,
@@ -476,6 +474,28 @@ static int loop_flush(struct loop_device *lo)
return loop_switch(lo, NULL);
}
+static void loop_reread_partitions(struct loop_device *lo,
+ struct block_device *bdev)
+{
+ int rc;
+
+ /*
+ * bd_mutex has been held already in release path, so don't
+ * acquire it if this function is called in such case.
+ *
+ * If the reread partition isn't from release path, lo_refcnt
+ * must be at least one and it can only become zero when the
+ * current holder is released.
+ */
+ if (!atomic_read(&lo->lo_refcnt))
+ rc = __blkdev_reread_part(bdev);
+ else
+ rc = blkdev_reread_part(bdev);
+ if (rc)
+ pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
+ __func__, lo->lo_number, lo->lo_file_name, rc);
+}
+
/*
* loop_change_fd switched the backing store of a loopback device to
* a new file. This is useful for operating system installers to free up
@@ -524,7 +544,7 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
fput(old_file);
if (lo->lo_flags & LO_FLAGS_PARTSCAN)
- ioctl_by_bdev(bdev, BLKRRPART, 0);
+ loop_reread_partitions(lo, bdev);
return 0;
out_putf:
@@ -725,6 +745,12 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
size = get_loop_size(lo, file);
if ((loff_t)(sector_t)size != size)
goto out_putf;
+ error = -ENOMEM;
+ lo->wq = alloc_workqueue("kloopd%d",
+ WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 16,
+ lo->lo_number);
+ if (!lo->wq)
+ goto out_putf;
error = 0;
@@ -755,7 +781,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
if (part_shift)
lo->lo_flags |= LO_FLAGS_PARTSCAN;
if (lo->lo_flags & LO_FLAGS_PARTSCAN)
- ioctl_by_bdev(bdev, BLKRRPART, 0);
+ 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).
@@ -827,7 +853,7 @@ static int loop_clr_fd(struct loop_device *lo)
* <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
* command to fail with EBUSY.
*/
- if (lo->lo_refcnt > 1) {
+ if (atomic_read(&lo->lo_refcnt) > 1) {
lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
mutex_unlock(&lo->lo_ctl_mutex);
return 0;
@@ -836,6 +862,9 @@ static int loop_clr_fd(struct loop_device *lo)
if (filp == NULL)
return -EINVAL;
+ /* freeze request queue during the transition */
+ blk_mq_freeze_queue(lo->lo_queue);
+
spin_lock_irq(&lo->lo_lock);
lo->lo_state = Lo_rundown;
lo->lo_backing_file = NULL;
@@ -867,11 +896,15 @@ static int loop_clr_fd(struct loop_device *lo)
lo->lo_state = Lo_unbound;
/* This is safe: open() is still holding a reference. */
module_put(THIS_MODULE);
+ blk_mq_unfreeze_queue(lo->lo_queue);
+
if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
- ioctl_by_bdev(bdev, BLKRRPART, 0);
+ loop_reread_partitions(lo, bdev);
lo->lo_flags = 0;
if (!part_shift)
lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
+ destroy_workqueue(lo->wq);
+ lo->wq = NULL;
mutex_unlock(&lo->lo_ctl_mutex);
/*
* Need not hold lo_ctl_mutex to fput backing file.
@@ -943,7 +976,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
!(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
lo->lo_flags |= LO_FLAGS_PARTSCAN;
lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
- ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
+ loop_reread_partitions(lo, lo->lo_device);
}
lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
@@ -1324,9 +1357,7 @@ static int lo_open(struct block_device *bdev, fmode_t mode)
goto out;
}
- mutex_lock(&lo->lo_ctl_mutex);
- lo->lo_refcnt++;
- mutex_unlock(&lo->lo_ctl_mutex);
+ atomic_inc(&lo->lo_refcnt);
out:
mutex_unlock(&loop_index_mutex);
return err;
@@ -1337,11 +1368,10 @@ static void lo_release(struct gendisk *disk, fmode_t mode)
struct loop_device *lo = disk->private_data;
int err;
- mutex_lock(&lo->lo_ctl_mutex);
-
- if (--lo->lo_refcnt)
- goto out;
+ if (atomic_dec_return(&lo->lo_refcnt))
+ return;
+ mutex_lock(&lo->lo_ctl_mutex);
if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
/*
* In autoclear mode, stop the loop thread
@@ -1358,7 +1388,6 @@ static void lo_release(struct gendisk *disk, fmode_t mode)
loop_flush(lo);
}
-out:
mutex_unlock(&lo->lo_ctl_mutex);
}
@@ -1425,9 +1454,13 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
{
struct loop_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
+ struct loop_device *lo = cmd->rq->q->queuedata;
blk_mq_start_request(bd->rq);
+ if (lo->lo_state != Lo_bound)
+ return -EIO;
+
if (cmd->rq->cmd_flags & REQ_WRITE) {
struct loop_device *lo = cmd->rq->q->queuedata;
bool need_sched = true;
@@ -1441,9 +1474,9 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
spin_unlock_irq(&lo->lo_lock);
if (need_sched)
- queue_work(loop_wq, &lo->write_work);
+ queue_work(lo->wq, &lo->write_work);
} else {
- queue_work(loop_wq, &cmd->read_work);
+ queue_work(lo->wq, &cmd->read_work);
}
return BLK_MQ_RQ_QUEUE_OK;
@@ -1455,9 +1488,6 @@ static void loop_handle_cmd(struct loop_cmd *cmd)
struct loop_device *lo = cmd->rq->q->queuedata;
int ret = -EIO;
- if (lo->lo_state != Lo_bound)
- goto failed;
-
if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY))
goto failed;
@@ -1594,6 +1624,7 @@ static int loop_add(struct loop_device **l, int i)
disk->flags |= GENHD_FL_NO_PART_SCAN;
disk->flags |= GENHD_FL_EXT_DEVT;
mutex_init(&lo->lo_ctl_mutex);
+ atomic_set(&lo->lo_refcnt, 0);
lo->lo_number = i;
spin_lock_init(&lo->lo_lock);
disk->major = LOOP_MAJOR;
@@ -1711,7 +1742,7 @@ static long loop_control_ioctl(struct file *file, unsigned int cmd,
mutex_unlock(&lo->lo_ctl_mutex);
break;
}
- if (lo->lo_refcnt > 0) {
+ if (atomic_read(&lo->lo_refcnt) > 0) {
ret = -EBUSY;
mutex_unlock(&lo->lo_ctl_mutex);
break;
@@ -1806,13 +1837,6 @@ static int __init loop_init(void)
goto misc_out;
}
- loop_wq = alloc_workqueue("kloopd",
- WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0);
- if (!loop_wq) {
- err = -ENOMEM;
- goto misc_out;
- }
-
blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
THIS_MODULE, loop_probe, NULL, NULL);
@@ -1850,8 +1874,6 @@ static void __exit loop_exit(void)
blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
unregister_blkdev(LOOP_MAJOR, "loop");
- destroy_workqueue(loop_wq);
-
misc_deregister(&loop_misc);
}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.