On Tue, Oct 25 2016 at 9:07P -0400, Christoph Hellwig <h...@infradead.org> wrote:
> I think the right fix is to kill off the BLKFLSBUF special case in > brd. Yes, it break compatibility - but in this case the compatibility > breaks more than it helps. Jens, please pick up this patch: From: Mike Snitzer <snit...@redhat.com> Date: Tue, 25 Oct 2016 10:25:07 -0400 Subject: [PATCH] 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: Mikulas Patocka <mpato...@redhat.com> Suggested-by: Christoph Hellwig <h...@infradead.org> Signed-off-by: Mike Snitzer <snit...@redhat.com> --- drivers/block/brd.c | 35 ----------------------------------- 1 file changed, 35 deletions(-) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 0c76d40..45c998a 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -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, }; -- 2.8.4 (Apple Git-73) -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html