Commit e51900f7 authored Feb 16, 2011 by Chuck Ebbert Committed by Linus Torvalds Feb 16, 2011

block: revert block_dev read-only check



This reverts commit 75f1dc0d ("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>

parent a2640111

fs/block_dev.c

+5 −6

Original line number	Diff line number	Diff line
		@@ -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);