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Commit ff269568 authored by Mike Snitzer's avatar Mike Snitzer Committed by Jens Axboe
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brd: remove support for BLKFLSBUF 



Discontinue having the brd driver destructively free all pages in the
ramdisk in response to the BLKFLSBUF ioctl.  Doing so allows a BLKFLSBUF
ioctl issued to a logical partition to destroy pages of the parent brd
device (and all other partitions of that brd device).

This change breaks compatibility - but in this case the compatibility
breaks more than it helps.

Reported-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Suggested-by: default avatarChristoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 366f4aea

drivers/block/brd.c

+0 −35
Original line number Diff line number Diff line
@@ -395,44 +395,9 @@ static long brd_direct_access(struct block_device *bdev, sector_t sector, 
#define brd_direct_access NULL

#endif



static int brd_ioctl(struct block_device *bdev, fmode_t mode,

			unsigned int cmd, unsigned long arg)

{

	int error;

	struct brd_device *brd = bdev->bd_disk->private_data;



	if (cmd != BLKFLSBUF)

		return -ENOTTY;



	/*

	 * ram device BLKFLSBUF has special semantics, we want to actually

	 * release and destroy the ramdisk data.

	 */

	mutex_lock(&brd_mutex);

	mutex_lock(&bdev->bd_mutex);

	error = -EBUSY;

	if (bdev->bd_openers <= 1) {

		/*

		 * Kill the cache first, so it isn't written back to the

		 * device.

		 *

		 * Another thread might instantiate more buffercache here,

		 * but there is not much we can do to close that race.

		 */

		kill_bdev(bdev);

		brd_free_pages(brd);

		error = 0;

	}

	mutex_unlock(&bdev->bd_mutex);

	mutex_unlock(&brd_mutex);



	return error;

}



static const struct block_device_operations brd_fops = {

	.owner =		THIS_MODULE,

	.rw_page =		brd_rw_page,

	.ioctl =		brd_ioctl,

	.direct_access =	brd_direct_access,

};