xfs: don't perform discard if the given range length is less than blo…

…ck size

commit f9fd013 upstream.

For discard operation, we should return EINVAL if the given range length
is less than a block size, otherwise it will go through the file system
to discard data blocks as the end range might be evaluated to -1, e.g,
/xfs7: 9811378176 bytes were trimmed

This issue can be triggered via xfstests/generic/288.

Also, it seems to get the request queue pointer via bdev_get_queue()
instead of the hard code pointer dereference is not a bad thing.

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>

Signed-off-by: Jiri Slaby <jslaby@suse.cz>

fs/xfs/xfs_discard.c

@@ -158,7 +158,7 @@ xfs_ioc_trim(
 	struct xfs_mount		*mp,
 	struct fstrim_range __user	*urange)
 {
-	struct request_queue	*q = mp->m_ddev_targp->bt_bdev->bd_disk->queue;
+	struct request_queue	*q = bdev_get_queue(mp->m_ddev_targp->bt_bdev);
 	unsigned int		granularity = q->limits.discard_granularity;
 	struct fstrim_range	range;
 	xfs_daddr_t		start, end, minlen;
@@ -181,7 +181,8 @@ xfs_ioc_trim(
 	 * matter as trimming blocks is an advisory interface.
 	 */
 	if (range.start >= XFS_FSB_TO_B(mp, mp->m_sb.sb_dblocks) ||
-	    range.minlen > XFS_FSB_TO_B(mp, XFS_ALLOC_AG_MAX_USABLE(mp)))
+	    range.minlen > XFS_FSB_TO_B(mp, XFS_ALLOC_AG_MAX_USABLE(mp)) ||
+	    range.len < mp->m_sb.sb_blocksize)
 		return -XFS_ERROR(EINVAL);
 
 	start = BTOBB(range.start);