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Subject[57/71] block: rescan partitions on invalidated devices on -ENOMEDIA too
2.6.38-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Tejun Heo <tj@kernel.org>

commit 02e352287a40bd456eb78df705bf888bc3161d3f upstream.

__blkdev_get() doesn't rescan partitions if disk->fops->open() fails,
which leads to ghost partition devices lingering after medimum removal
is known to both the kernel and userland. The behavior also creates a
subtle inconsistency where O_NONBLOCK open, which doesn't fail even if
there's no medium, clears the ghots partitions, which is exploited to
work around the problem from userland.

Fix it by updating __blkdev_get() to issue partition rescan after
-ENOMEDIA too.

This was reported in the following bz.

https://bugzilla.kernel.org/show_bug.cgi?id=13029

Stable: 2.6.38

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: David Zeuthen <zeuthen@gmail.com>
Reported-by: Martin Pitt <martin.pitt@ubuntu.com>
Reported-by: Kay Sievers <kay.sievers@vrfy.org>
Tested-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/block_dev.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)

--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1099,6 +1099,7 @@ static int __blkdev_get(struct block_dev
if (!bdev->bd_part)
goto out_clear;

+ ret = 0;
if (disk->fops->open) {
ret = disk->fops->open(bdev, mode);
if (ret == -ERESTARTSYS) {
@@ -1114,9 +1115,18 @@ static int __blkdev_get(struct block_dev
mutex_unlock(&bdev->bd_mutex);
goto restart;
}
- if (ret)
- goto out_clear;
}
+ /*
+ * If the device is invalidated, rescan partition
+ * if open succeeded or failed with -ENOMEDIUM.
+ * The latter is necessary to prevent ghost
+ * partitions on a removed medium.
+ */
+ if (bdev->bd_invalidated && (!ret || ret == -ENOMEDIUM))
+ rescan_partitions(disk, bdev);
+ if (ret)
+ goto out_clear;
+
if (!bdev->bd_openers) {
bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
bdi = blk_get_backing_dev_info(bdev);
@@ -1124,8 +1134,6 @@ static int __blkdev_get(struct block_dev
bdi = &default_backing_dev_info;
bdev_inode_switch_bdi(bdev->bd_inode, bdi);
}
- if (bdev->bd_invalidated)
- rescan_partitions(disk, bdev);
} else {
struct block_device *whole;
whole = bdget_disk(disk, 0);
@@ -1152,13 +1160,14 @@ static int __blkdev_get(struct block_dev
put_disk(disk);
disk = NULL;
if (bdev->bd_contains == bdev) {
- if (bdev->bd_disk->fops->open) {
+ ret = 0;
+ if (bdev->bd_disk->fops->open)
ret = bdev->bd_disk->fops->open(bdev, mode);
- if (ret)
- goto out_unlock_bdev;
- }
- if (bdev->bd_invalidated)
+ /* the same as first opener case, read comment there */
+ if (bdev->bd_invalidated && (!ret || ret == -ENOMEDIUM))
rescan_partitions(bdev->bd_disk, bdev);
+ if (ret)
+ goto out_unlock_bdev;
}
}
bdev->bd_openers++;



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