[PATCH 1/2] block: Avoid dead request queue too early removal

[Jarkko Lavinen]

If disk is removed while file system is still mounted, the disk
removal can release the dead request queue too early while
file system is still trying to sumit requests.

Signed-off-by: Jarkko Lavinen <jarkko.lavinen@xxxxxxxxx>
---
 fs/block_dev.c |   24 ++++++++++++++++++++----
 1 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 9cf4b92..91f2fc3 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1165,6 +1165,8 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 	int ret;
 	int partno;
 	int perm = 0;
+	int q_ref = 0;
+	struct module *owner;
 
 	if (mode & FMODE_READ)
 		perm |= MAY_READ;
@@ -1187,6 +1189,11 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 	if (!disk)
 		goto out_unlock_kernel;
 
+	if (blk_get_queue(disk->queue))
+		goto out_unlock_kernel;
+	else
+		q_ref = 1;
+
 	mutex_lock_nested(&bdev->bd_mutex, for_part);
 	if (!bdev->bd_openers) {
 		bdev->bd_disk = disk;
@@ -1248,8 +1255,10 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
 			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
 		}
 	} else {
+		owner = disk->fops->owner;
+		blk_put_queue(disk->queue);
 		put_disk(disk);
-		module_put(disk->fops->owner);
+		module_put(owner);
 		disk = NULL;
 		if (bdev->bd_contains == bdev) {
 			if (bdev->bd_disk->fops->open) {
@@ -1281,9 +1290,15 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
  out_unlock_kernel:
 	unlock_kernel();
 
-	if (disk)
-		module_put(disk->fops->owner);
-	put_disk(disk);
+	if (disk) {
+		owner = disk->fops->owner;
+		if (q_ref)
+			blk_put_queue(disk->queue);
+
+		put_disk(disk);
+		module_put(owner);
+	}
+
 	bdput(bdev);
 
 	return ret;
@@ -1360,6 +1375,7 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
 	if (!bdev->bd_openers) {
 		struct module *owner = disk->fops->owner;
 
+		blk_put_queue(disk->queue);
 		put_disk(disk);
 		module_put(owner);
 		disk_put_part(bdev->bd_part);
-- 
1.6.3.3

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