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block: rescan partitions on invalidated devices on -ENOMEDIA too

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__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>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Tejun Heo 2011-04-29 10:15:20 +02:00 committed by Jens Axboe
parent bf2253a6f0
commit 02e352287a
1 changed files with 18 additions and 9 deletions
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23
fs/block_dev.c
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@ -1102,6 +1102,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
if (!bdev->bd_part)
goto out_clear;
ret = 0;
if (disk->fops->open) {
ret = disk->fops->open(bdev, mode);
if (ret == -ERESTARTSYS) {
@ -1118,9 +1119,18 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
put_disk(disk);
goto restart;
}
}
/*
* 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);
@ -1128,8 +1138,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
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);
@ -1153,14 +1161,15 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
}
} else {
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);
/* 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;
}
if (bdev->bd_invalidated)
rescan_partitions(bdev->bd_disk, bdev);
}
/* only one opener holds refs to the module and disk */
module_put(disk->fops->owner);
put_disk(disk);