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-rw-r--r--fs/block_dev.c49
1 files changed, 32 insertions, 17 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 4a181fcb5175..fe09ef9c21f3 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1058,6 +1058,27 @@ retry:
return 0;
}
+static struct gendisk *bdev_get_gendisk(struct block_device *bdev, int *partno)
+{
+ struct gendisk *disk = get_gendisk(bdev->bd_dev, partno);
+
+ if (!disk)
+ return NULL;
+ /*
+ * Now that we hold gendisk reference we make sure bdev we looked up is
+ * not stale. If it is, it means device got removed and created before
+ * we looked up gendisk and we fail open in such case. Associating
+ * unhashed bdev with newly created gendisk could lead to two bdevs
+ * (and thus two independent caches) being associated with one device
+ * which is bad.
+ */
+ if (inode_unhashed(bdev->bd_inode)) {
+ put_disk_and_module(disk);
+ return NULL;
+ }
+ return disk;
+}
+
/**
* bd_start_claiming - start claiming a block device
* @bdev: block device of interest
@@ -1094,7 +1115,7 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
* @bdev might not have been initialized properly yet, look up
* and grab the outer block device the hard way.
*/
- disk = get_gendisk(bdev->bd_dev, &partno);
+ disk = bdev_get_gendisk(bdev, &partno);
if (!disk)
return ERR_PTR(-ENXIO);
@@ -1111,8 +1132,7 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
else
whole = bdgrab(bdev);
- module_put(disk->fops->owner);
- put_disk(disk);
+ put_disk_and_module(disk);
if (!whole)
return ERR_PTR(-ENOMEM);
@@ -1407,10 +1427,10 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
{
struct gendisk *disk;
- struct module *owner;
int ret;
int partno;
int perm = 0;
+ bool first_open = false;
if (mode & FMODE_READ)
perm |= MAY_READ;
@@ -1430,14 +1450,14 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
restart:
ret = -ENXIO;
- disk = get_gendisk(bdev->bd_dev, &partno);
+ disk = bdev_get_gendisk(bdev, &partno);
if (!disk)
goto out;
- owner = disk->fops->owner;
disk_block_events(disk);
mutex_lock_nested(&bdev->bd_mutex, for_part);
if (!bdev->bd_openers) {
+ first_open = true;
bdev->bd_disk = disk;
bdev->bd_queue = disk->queue;
bdev->bd_contains = bdev;
@@ -1463,8 +1483,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
bdev->bd_queue = NULL;
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
- put_disk(disk);
- module_put(owner);
+ put_disk_and_module(disk);
goto restart;
}
}
@@ -1524,15 +1543,15 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
if (ret)
goto out_unlock_bdev;
}
- /* only one opener holds refs to the module and disk */
- put_disk(disk);
- module_put(owner);
}
bdev->bd_openers++;
if (for_part)
bdev->bd_part_count++;
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
+ /* only one opener holds refs to the module and disk */
+ if (!first_open)
+ put_disk_and_module(disk);
return 0;
out_clear:
@@ -1546,8 +1565,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
out_unlock_bdev:
mutex_unlock(&bdev->bd_mutex);
disk_unblock_events(disk);
- put_disk(disk);
- module_put(owner);
+ put_disk_and_module(disk);
out:
bdput(bdev);
@@ -1770,8 +1788,6 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
disk->fops->release(disk, mode);
}
if (!bdev->bd_openers) {
- struct module *owner = disk->fops->owner;
-
disk_put_part(bdev->bd_part);
bdev->bd_part = NULL;
bdev->bd_disk = NULL;
@@ -1779,8 +1795,7 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
victim = bdev->bd_contains;
bdev->bd_contains = NULL;
- put_disk(disk);
- module_put(owner);
+ put_disk_and_module(disk);
}
mutex_unlock(&bdev->bd_mutex);
bdput(bdev);
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