xfs: Fix fall-through warnings for Clang

In preparation to enable -Wimplicit-fallthrough for Clang, fix
the following warnings by replacing /* fall through */ comments,
and its variants, with the new pseudo-keyword macro fallthrough:

fs/xfs/libxfs/xfs_alloc.c:3167:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/libxfs/xfs_da_btree.c:286:3: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/libxfs/xfs_ag_resv.c:346:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/libxfs/xfs_ag_resv.c:388:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/xfs_bmap_util.c:246:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/xfs_export.c:88:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/xfs_export.c:96:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/xfs_file.c:867:3: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/xfs_ioctl.c:562:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/xfs_ioctl.c:1548:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/xfs_iomap.c:1040:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/xfs_inode.c:852:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/xfs_log.c:2627:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/xfs_trans_buf.c:298:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/scrub/bmap.c:275:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/scrub/btree.c:48:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/scrub/common.c:85:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/scrub/common.c:138:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/scrub/common.c:698:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/scrub/dabtree.c:51:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/scrub/repair.c:951:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
fs/xfs/scrub/agheader.c:89:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]

Notice that Clang doesn't recognize /* fall through */ comments as
implicit fall-through markings, so in order to globally enable
-Wimplicit-fallthrough for Clang, these comments need to be
replaced with fallthrough; in the whole codebase.

Link: https://github.com/KSPP/linux/issues/115Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

fs/xfs/libxfs/xfs_ag_resv.c

@@ -354,7 +354,7 @@ xfs_ag_resv_alloc_extent(
 		break;
 	default:
 		ASSERT(0);
-		/* fall through */
+		fallthrough;
 	case XFS_AG_RESV_NONE:
 		field = args->wasdel ? XFS_TRANS_SB_RES_FDBLOCKS :
 				       XFS_TRANS_SB_FDBLOCKS;
@@ -396,7 +396,7 @@ xfs_ag_resv_free_extent(
 		break;
 	default:
 		ASSERT(0);
-		/* fall through */
+		fallthrough;
 	case XFS_AG_RESV_NONE:
 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (int64_t)len);
 		return;

fs/xfs/libxfs/xfs_alloc.c

@@ -3174,7 +3174,7 @@ xfs_alloc_vextent(
 		}
 		args->agbno = XFS_FSB_TO_AGBNO(mp, args->fsbno);
 		args->type = XFS_ALLOCTYPE_NEAR_BNO;
-		/* FALLTHROUGH */
+		fallthrough;
 	case XFS_ALLOCTYPE_FIRST_AG:
 		/*
 		 * Rotate through the allocation groups looking for a winner.

fs/xfs/libxfs/xfs_da_btree.c

@@ -282,7 +282,7 @@ xfs_da3_node_read_verify(
 						__this_address);
 				break;
 			}
-			/* fall through */
+			fallthrough;
 		case XFS_DA_NODE_MAGIC:
 			fa = xfs_da3_node_verify(bp);
 			if (fa)

fs/xfs/scrub/agheader.c

@@ -86,6 +86,7 @@ xchk_superblock(
 	case -ENOSYS:
 	case -EFBIG:
 		error = -EFSCORRUPTED;
+		fallthrough;
 	default:
 		break;
 	}

fs/xfs/scrub/bmap.c

@@ -271,7 +271,7 @@ xchk_bmap_iextent_xref(
 	case XFS_DATA_FORK:
 		if (xfs_is_reflink_inode(info->sc->ip))
 			break;
-		/* fall through */
+		fallthrough;
 	case XFS_ATTR_FORK:
 		xchk_xref_is_not_shared(info->sc, agbno,
 				irec->br_blockcount);

fs/xfs/scrub/btree.c

@@ -44,7 +44,7 @@ __xchk_btree_process_error(
 		/* Note the badness but don't abort. */
 		sc->sm->sm_flags |= errflag;
 		*error = 0;
-		/* fall through */
+		fallthrough;
 	default:
 		if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE)
 			trace_xchk_ifork_btree_op_error(sc, cur, level,

fs/xfs/scrub/common.c

@@ -81,7 +81,7 @@ __xchk_process_error(
 		/* Note the badness but don't abort. */
 		sc->sm->sm_flags |= errflag;
 		*error = 0;
-		/* fall through */
+		fallthrough;
 	default:
 		trace_xchk_op_error(sc, agno, bno, *error,
 				ret_ip);
@@ -134,7 +134,7 @@ __xchk_fblock_process_error(
 		/* Note the badness but don't abort. */
 		sc->sm->sm_flags |= errflag;
 		*error = 0;
-		/* fall through */
+		fallthrough;
 	default:
 		trace_xchk_file_op_error(sc, whichfork, offset, *error,
 				ret_ip);
@@ -694,7 +694,7 @@ xchk_get_inode(
 		if (error)
 			return -ENOENT;
 		error = -EFSCORRUPTED;
-		/* fall through */
+		fallthrough;
 	default:
 		trace_xchk_op_error(sc,
 				XFS_INO_TO_AGNO(mp, sc->sm->sm_ino),

fs/xfs/scrub/dabtree.c

@@ -47,7 +47,7 @@ xchk_da_process_error(
 		/* Note the badness but don't abort. */
 		sc->sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT;
 		*error = 0;
-		/* fall through */
+		fallthrough;
 	default:
 		trace_xchk_file_op_error(sc, ds->dargs.whichfork,
 				xfs_dir2_da_to_db(ds->dargs.geo,

fs/xfs/scrub/repair.c

@@ -947,7 +947,7 @@ xrep_ino_dqattach(
 			xrep_force_quotacheck(sc, XFS_DQTYPE_GROUP);
 		if (XFS_IS_PQUOTA_ON(sc->mp) && !sc->ip->i_pdquot)
 			xrep_force_quotacheck(sc, XFS_DQTYPE_PROJ);
-		/* fall through */
+		fallthrough;
 	case -ESRCH:
 		error = 0;
 		break;

fs/xfs/xfs_bmap_util.c

@@ -242,7 +242,7 @@ xfs_bmap_count_blocks(
 		 */
 		*count += btblocks - 1;
 
-		/* fall through */
+		fallthrough;
 	case XFS_DINODE_FMT_EXTENTS:
 		*nextents = xfs_bmap_count_leaves(ifp, count);
 		break;

fs/xfs/xfs_export.c

@@ -84,7 +84,7 @@ xfs_fs_encode_fh(
 	case FILEID_INO32_GEN_PARENT:
 		fid->i32.parent_ino = XFS_I(parent)->i_ino;
 		fid->i32.parent_gen = parent->i_generation;
-		/*FALLTHRU*/
+		fallthrough;
 	case FILEID_INO32_GEN:
 		fid->i32.ino = XFS_I(inode)->i_ino;
 		fid->i32.gen = inode->i_generation;
@@ -92,7 +92,7 @@ xfs_fs_encode_fh(
 	case FILEID_INO32_GEN_PARENT | XFS_FILEID_TYPE_64FLAG:
 		fid64->parent_ino = XFS_I(parent)->i_ino;
 		fid64->parent_gen = parent->i_generation;
-		/*FALLTHRU*/
+		fallthrough;
 	case FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG:
 		fid64->ino = XFS_I(inode)->i_ino;
 		fid64->gen = inode->i_generation;

fs/xfs/xfs_file.c

@@ -863,7 +863,7 @@ xfs_break_layouts(
 			error = xfs_break_dax_layouts(inode, &retry);
 			if (error || retry)
 				break;
-			/* fall through */
+			fallthrough;
 		case BREAK_WRITE:
 			error = xfs_break_leased_layouts(inode, iolock, &retry);
 			break;

fs/xfs/xfs_inode.c

@@ -848,7 +848,7 @@ xfs_init_new_inode(
 			xfs_inode_inherit_flags(ip, pip);
 		if (pip && (pip->i_diflags2 & XFS_DIFLAG2_ANY))
 			xfs_inode_inherit_flags2(ip, pip);
-		/* FALLTHROUGH */
+		fallthrough;
 	case S_IFLNK:
 		ip->i_df.if_format = XFS_DINODE_FMT_EXTENTS;
 		ip->i_df.if_bytes = 0;

fs/xfs/xfs_ioctl.c

@@ -558,7 +558,7 @@ xfs_ioc_attrmulti_one(
 	case ATTR_OP_REMOVE:
 		value = NULL;
 		*len = 0;
-		/* fall through */
+		fallthrough;
 	case ATTR_OP_SET:
 		error = mnt_want_write_file(parfilp);
 		if (error)
@@ -1544,7 +1544,7 @@ xfs_ioc_getbmap(
 	switch (cmd) {
 	case XFS_IOC_GETBMAPA:
 		bmx.bmv_iflags = BMV_IF_ATTRFORK;
-		/*FALLTHRU*/
+		fallthrough;
 	case XFS_IOC_GETBMAP:
 		/* struct getbmap is a strict subset of struct getbmapx. */
 		recsize = sizeof(struct getbmap);

fs/xfs/xfs_iomap.c

@@ -1036,7 +1036,7 @@ xfs_buffered_write_iomap_begin(
 			prealloc_blocks = 0;
 			goto retry;
 		}
-		/*FALLTHRU*/
+		fallthrough;
 	default:
 		goto out_unlock;
 	}

fs/xfs/xfs_log.c

@@ -2626,6 +2626,7 @@ xlog_covered_state(
 	case XLOG_STATE_COVER_IDLE:
 		if (iclogs_changed == 1)
 			return XLOG_STATE_COVER_IDLE;
+		fallthrough;
 	case XLOG_STATE_COVER_NEED:
 	case XLOG_STATE_COVER_NEED2:
 		break;

fs/xfs/xfs_trans_buf.c

@@ -294,7 +294,7 @@ xfs_trans_read_buf_map(
 	default:
 		if (tp && (tp->t_flags & XFS_TRANS_DIRTY))
 			xfs_force_shutdown(tp->t_mountp, SHUTDOWN_META_IO_ERROR);
-		/* fall through */
+		fallthrough;
 	case -ENOMEM:
 	case -EAGAIN:
 		return error;