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block: revert block_dev read-only check 

This reverts commit 75f1dc0d07 ("block: check bdev_read_only() from
blkdev_get()").  That commit added stricter checking to make sure
devices that were being used read-only were actually opened in that
mode.

It turns out that the change breaks a bunch of kernel code that opens
block devices.  Affected systems include dm, md, and the loop device.
Because strict checking for read-only opens of block devices was not
done before this, the code that opens the devices was opening them
read-write even if they were being used read-only.  Auditing all that
code will take time, and new userspace packages for dm, mdadm, etc.
will also be required.

Signed-off-by: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Chuck Ebbert 2011-02-16 18:11:53 -05:00 committed by Linus Torvalds
parent a2640111d5
commit e51900f7d3
1 changed files with 5 additions and 6 deletions
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11
fs/block_dev.c
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@ -1215,12 +1215,6 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
res = __blkdev_get(bdev, mode, 0);
/* __blkdev_get() may alter read only status, check it afterwards */
if (!res && (mode & FMODE_WRITE) && bdev_read_only(bdev)) {
__blkdev_put(bdev, mode, 0);
res = -EACCES;
}
if (whole) {
/* finish claiming */
mutex_lock(&bdev->bd_mutex);
@ -1298,6 +1292,11 @@ struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
if (err)
return ERR_PTR(err);
if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
blkdev_put(bdev, mode);
return ERR_PTR(-EACCES);
}
return bdev;
}
EXPORT_SYMBOL(blkdev_get_by_path);