xfs: don't bother reporting blocks trimmed via FITRIM

Don't bother reporting the number of bytes that we "trimmed" because the
underlying storage isn't required to do anything(!) and failed discard
IOs aren't reported to the caller anyway. It's not like userspace can
use the reported value for anything useful like adjusting the offset
parameter of the next call, and it's not like anyone ever wrote a
manpage about FITRIM's out parameters.

Signed-off-by: Darrick J. Wong <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Tested-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Chandan Babu R <[e-mail]>

fs/xfs/xfs_discard.c

···
 xfs_trim_gather_extents(
 	struct xfs_perag	*pag,
 	struct xfs_trim_cur	*tcur,
-	struct xfs_busy_extents	*extents,
-	uint64_t		*blocks_trimmed)
+	struct xfs_busy_extents	*extents)
 {
 	struct xfs_mount	*mp = pag->pag_mount;
 	struct xfs_trans	*tp;
···
 
 		xfs_extent_busy_insert_discard(pag, fbno, flen,
 				&extents->extent_list);
-		*blocks_trimmed += flen;
 next_extent:
 		if (tcur->by_bno)
 			error = xfs_btree_increment(cur, 0, &i);
···
 	struct xfs_perag	*pag,
 	xfs_agblock_t		start,
 	xfs_agblock_t		end,
-	xfs_extlen_t		minlen,
-	uint64_t		*blocks_trimmed)
+	xfs_extlen_t		minlen)
 {
 	struct xfs_trim_cur	tcur = {
 		.start		= start,
···
 		extents->owner = extents;
 		INIT_LIST_HEAD(&extents->extent_list);
 
-		error = xfs_trim_gather_extents(pag, &tcur, extents,
-				blocks_trimmed);
+		error = xfs_trim_gather_extents(pag, &tcur, extents);
 		if (error) {
 			kfree(extents);
 			break;
···
 	struct xfs_mount	*mp,
 	xfs_daddr_t		start,
 	xfs_daddr_t		end,
-	xfs_extlen_t		minlen,
-	uint64_t		*blocks_trimmed)
+	xfs_extlen_t		minlen)
 {
 	xfs_agnumber_t		start_agno, end_agno;
 	xfs_agblock_t		start_agbno, end_agbno;
···
 
 		if (start_agno == end_agno)
 			agend = end_agbno;
-		error = xfs_trim_perag_extents(pag, start_agbno, agend, minlen,
-				blocks_trimmed);
+		error = xfs_trim_perag_extents(pag, start_agbno, agend, minlen);
 		if (error)
 			last_error = error;
 
···
 struct xfs_trim_rtdev {
 	/* list of rt extents to free */
 	struct list_head	extent_list;
-
-	/* pointer to count of blocks trimmed */
-	uint64_t		*blocks_trimmed;
 
 	/* minimum length that caller allows us to trim */
 	xfs_rtblock_t		minlen_fsb;
···
 	busyp->length = rlen;
 	INIT_LIST_HEAD(&busyp->list);
 	list_add_tail(&busyp->list, &tr->extent_list);
-	*tr->blocks_trimmed += rlen;
 
 	tr->restart_rtx = rec->ar_startext + rec->ar_extcount;
 	return 0;
···
 	struct xfs_mount	*mp,
 	xfs_daddr_t		start,
 	xfs_daddr_t		end,
-	xfs_daddr_t		minlen,
-	uint64_t		*blocks_trimmed)
+	xfs_daddr_t		minlen)
 {
 	struct xfs_rtalloc_rec	low = { };
 	struct xfs_rtalloc_rec	high = { };
 	struct xfs_trim_rtdev	tr = {
-		.blocks_trimmed	= blocks_trimmed,
 		.minlen_fsb	= XFS_BB_TO_FSB(mp, minlen),
 	};
 	struct xfs_trans	*tp;
···
 	return error;
 }
 #else
-# define xfs_trim_rtdev_extents(m,s,e,n,b)	(-EOPNOTSUPP)
+# define xfs_trim_rtdev_extents(...)	(-EOPNOTSUPP)
 #endif /* CONFIG_XFS_RT */
 
 /*
···
 	xfs_daddr_t		start, end;
 	xfs_extlen_t		minlen;
 	xfs_rfsblock_t		max_blocks;
-	uint64_t		blocks_trimmed = 0;
 	int			error, last_error = 0;
 
 	if (!capable(CAP_SYS_ADMIN))
···
 	end = start + BTOBBT(range.len) - 1;
 
 	if (bdev_max_discard_sectors(mp->m_ddev_targp->bt_bdev)) {
-		error = xfs_trim_datadev_extents(mp, start, end, minlen,
-				&blocks_trimmed);
+		error = xfs_trim_datadev_extents(mp, start, end, minlen);
 		if (error)
 			last_error = error;
 	}
 
 	if (rt_bdev && !xfs_trim_should_stop()) {
-		error = xfs_trim_rtdev_extents(mp, start, end, minlen,
-				&blocks_trimmed);
+		error = xfs_trim_rtdev_extents(mp, start, end, minlen);
 		if (error)
 			last_error = error;
 	}
···
 	if (last_error)
 		return last_error;
 
-	range.len = XFS_FSB_TO_B(mp, blocks_trimmed);
+	range.len = min_t(unsigned long long, range.len,
+			  XFS_FSB_TO_B(mp, max_blocks));
 	if (copy_to_user(urange, &range, sizeof(range)))
 		return -EFAULT;
 	return 0;