xfs: ignore discard return value

__blkdev_issue_discard() always returns 0, making all error checking
in XFS discard functions dead code.

Change xfs_discard_extents() return type to void, remove error variable,
error checking, and error logging for the __blkdev_issue_discard() call
in same function.

Update xfs_trim_perag_extents() and xfs_trim_rtgroup_extents() to
ignore the xfs_discard_extents() return value and error checking
code.

Update xfs_discard_rtdev_extents() to ignore __blkdev_issue_discard()
return value and error checking code.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chaitanya Kulkarni <ckulkarnilinux@gmail.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: ChaitanayaKulkarni

fs/xfs/xfs_discard.c

@@ -108,15 +108,14 @@ xfs_discard_endio(
  * list. We plug and chain the bios so that we only need a single completion
  * call to clear all the busy extents once the discards are complete.
  */
-int
+void
 xfs_discard_extents(
 	struct xfs_mount	*mp,
 	struct xfs_busy_extents	*extents)
 {
 	struct xfs_extent_busy	*busyp;
 	struct bio		*bio = NULL;
 	struct blk_plug		plug;
-	int			error = 0;
 
 	blk_start_plug(&plug);
 	list_for_each_entry(busyp, &extents->extent_list, list) {
@@ -126,18 +125,10 @@ xfs_discard_extents(
 
 		trace_xfs_discard_extent(xg, busyp->bno, busyp->length);
 
-		error = __blkdev_issue_discard(btp->bt_bdev,
+		__blkdev_issue_discard(btp->bt_bdev,
 				xfs_gbno_to_daddr(xg, busyp->bno),
 				XFS_FSB_TO_BB(mp, busyp->length),
 				GFP_KERNEL, &bio);
-		if (error && error != -EOPNOTSUPP) {
-			xfs_info(mp,
-	 "discard failed for extent [0x%llx,%u], error %d",
-				 (unsigned long long)busyp->bno,
-				 busyp->length,
-				 error);
-			break;
-		}
 	}
 
 	if (bio) {
@@ -148,8 +139,6 @@ xfs_discard_extents(
 		xfs_discard_endio_work(&extents->endio_work);
 	}
 	blk_finish_plug(&plug);
-
-	return error;
 }
 
 /*
@@ -385,9 +374,7 @@ xfs_trim_perag_extents(
 		 * list  after this function call, as it may have been freed by
 		 * the time control returns to us.
 		 */
-		error = xfs_discard_extents(pag_mount(pag), extents);
-		if (error)
-			break;
+		xfs_discard_extents(pag_mount(pag), extents);
 
 		if (xfs_trim_should_stop())
 			break;
@@ -496,12 +483,10 @@ xfs_discard_rtdev_extents(
 
 		trace_xfs_discard_rtextent(mp, busyp->bno, busyp->length);
 
-		error = __blkdev_issue_discard(bdev,
+		__blkdev_issue_discard(bdev,
 				xfs_rtb_to_daddr(mp, busyp->bno),
 				XFS_FSB_TO_BB(mp, busyp->length),
 				GFP_NOFS, &bio);
-		if (error)
-			break;
 	}
 	xfs_discard_free_rtdev_extents(tr);
 
@@ -741,9 +726,7 @@ xfs_trim_rtgroup_extents(
 		 * list  after this function call, as it may have been freed by
 		 * the time control returns to us.
 		 */
-		error = xfs_discard_extents(rtg_mount(rtg), tr.extents);
-		if (error)
-			break;
+		xfs_discard_extents(rtg_mount(rtg), tr.extents);
 
 		low = tr.restart_rtx;
 	} while (!xfs_trim_should_stop() && low <= high);

fs/xfs/xfs_discard.h

@@ -6,7 +6,7 @@ struct fstrim_range;
 struct xfs_mount;
 struct xfs_busy_extents;
 
-int xfs_discard_extents(struct xfs_mount *mp, struct xfs_busy_extents *busy);
+void xfs_discard_extents(struct xfs_mount *mp, struct xfs_busy_extents *busy);
 int xfs_ioc_trim(struct xfs_mount *mp, struct fstrim_range __user *fstrim);
 
 #endif /* XFS_DISCARD_H */