fs: mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

This patch fixes the following warnings:

fs/affs/affs.h:124:38: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/configfs/dir.c:1692:11: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/configfs/dir.c:1694:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ceph/file.c:249:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/hash.c:233:15: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/hash.c:246:15: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext2/inode.c:1237:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext2/inode.c:1244:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1182:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1188:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1432:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ext4/indirect.c:1440:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/f2fs/node.c:618:8: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/f2fs/node.c:620:8: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/btrfs/ref-verify.c:522:15: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/gfs2/bmap.c:711:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/gfs2/bmap.c:722:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/jffs2/fs.c:339:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/nfsd/nfs4proc.c:429:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ufs/util.h:62:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/ufs/util.h:43:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/fcntl.c:770:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/seq_file.c:319:10: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/libfs.c:148:11: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/libfs.c:150:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/signalfd.c:178:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
fs/locks.c:1473:16: warning: this statement may fall through [-Wimplicit-fallthrough=]

Warning level 3 was used: -Wimplicit-fallthrough=3

This patch is part of the ongoing efforts to enabling
-Wimplicit-fallthrough.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

fs/affs/super.c

@@ -487,7 +487,7 @@ got_root:
 		break;
 	case MUFS_OFS:
 		affs_set_opt(sbi->s_flags, SF_MUFS);
-		/* fall thru */
+		/* fall through */
 	case FS_OFS:
 		affs_set_opt(sbi->s_flags, SF_OFS);
 		sb->s_flags |= SB_NOEXEC;
@@ -495,6 +495,7 @@ got_root:
 	case MUFS_DCOFS:
 	case MUFS_INTLOFS:
 		affs_set_opt(sbi->s_flags, SF_MUFS);
+		/* fall through */
 	case FS_DCOFS:
 	case FS_INTLOFS:
 		affs_set_opt(sbi->s_flags, SF_INTL);

fs/btrfs/ref-verify.c

@@ -520,6 +520,7 @@ static int process_leaf(struct btrfs_root *root,
 		switch (key.type) {
 		case BTRFS_EXTENT_ITEM_KEY:
 			*num_bytes = key.offset;
+			/* fall through */
 		case BTRFS_METADATA_ITEM_KEY:
 			*bytenr = key.objectid;
 			ret = process_extent_item(fs_info, path, &key, i,

fs/btrfs/volumes.h

@@ -390,6 +390,7 @@ static inline enum btrfs_map_op btrfs_op(struct bio *bio)
 		return BTRFS_MAP_WRITE;
 	default:
 		WARN_ON_ONCE(1);
+		/* fall through */
 	case REQ_OP_READ:
 		return BTRFS_MAP_READ;
 	}

fs/ceph/file.c

@@ -247,6 +247,7 @@ static int ceph_init_file(struct inode *inode, struct file *file, int fmode)
 	case S_IFREG:
 		ceph_fscache_register_inode_cookie(inode);
 		ceph_fscache_file_set_cookie(inode, file);
+		/* fall through */
 	case S_IFDIR:
 		ret = ceph_init_file_info(inode, file, fmode,
 						S_ISDIR(inode->i_mode));

fs/configfs/dir.c

@@ -1690,9 +1690,11 @@ static loff_t configfs_dir_lseek(struct file *file, loff_t offset, int whence)
 	switch (whence) {
 		case 1:
 			offset += file->f_pos;
+			/* fall through */
 		case 0:
 			if (offset >= 0)
 				break;
+			/* fall through */
 		default:
 			return -EINVAL;
 	}

fs/f2fs/node.c

@@ -616,8 +616,10 @@ pgoff_t f2fs_get_next_page_offset(struct dnode_of_data *dn, pgoff_t pgofs)
 	switch (dn->max_level) {
 	case 3:
 		base += 2 * indirect_blks;
+		/* fall through */
 	case 2:
 		base += 2 * direct_blks;
+		/* fall through */
 	case 1:
 		base += direct_index;
 		break;

fs/fcntl.c

@@ -769,7 +769,7 @@ static void send_sigio_to_task(struct task_struct *p,
 			si.si_fd    = fd;
 			if (!do_send_sig_info(signum, &si, p, type))
 				break;
-		/* fall-through: fall back on the old plain SIGIO signal */
+		/* fall-through - fall back on the old plain SIGIO signal */
 		case 0:
 			do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type);
 	}

fs/gfs2/bmap.c

@@ -710,7 +710,7 @@ static int gfs2_iomap_alloc(struct inode *inode, struct iomap *iomap,
 			}
 			if (n == 0)
 				break;
-		/* Branching from existing tree */
+		/* fall through - To branching from existing tree */
 		case ALLOC_GROW_DEPTH:
 			if (i > 1 && i < mp->mp_fheight)
 				gfs2_trans_add_meta(ip->i_gl, mp->mp_bh[i-1]);
@@ -721,7 +721,7 @@ static int gfs2_iomap_alloc(struct inode *inode, struct iomap *iomap,
 				state = ALLOC_DATA;
 			if (n == 0)
 				break;
-		/* Tree complete, adding data blocks */
+		/* fall through - To tree complete, adding data blocks */
 		case ALLOC_DATA:
 			BUG_ON(n > dblks);
 			BUG_ON(mp->mp_bh[end_of_metadata] == NULL);

fs/jffs2/fs.c

@@ -340,6 +340,7 @@ struct inode *jffs2_iget(struct super_block *sb, unsigned long ino)
 			rdev = old_decode_dev(je16_to_cpu(jdev.old_id));
 		else
 			rdev = new_decode_dev(je32_to_cpu(jdev.new_id));
+		/* fall through */
 
 	case S_IFSOCK:
 	case S_IFIFO:

fs/libfs.c

@@ -146,9 +146,11 @@ loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
 	switch (whence) {
 		case 1:
 			offset += file->f_pos;
+			/* fall through */
 		case 0:
 			if (offset >= 0)
 				break;
+			/* fall through */
 		default:
 			return -EINVAL;
 	}

fs/locks.c

@@ -1471,7 +1471,7 @@ static void lease_clear_pending(struct file_lock *fl, int arg)
 	switch (arg) {
 	case F_UNLCK:
 		fl->fl_flags &= ~FL_UNLOCK_PENDING;
-		/* fall through: */
+		/* fall through */
 	case F_RDLCK:
 		fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
 	}

fs/nfsd/nfs4proc.c

@@ -427,6 +427,7 @@ nfsd4_open(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 				goto out;
 			open->op_openowner->oo_flags |= NFS4_OO_CONFIRMED;
 			reclaim = true;
+			/* fall through */
 		case NFS4_OPEN_CLAIM_FH:
 		case NFS4_OPEN_CLAIM_DELEG_CUR_FH:
 			status = do_open_fhandle(rqstp, cstate, open);

fs/nfsd/nfs4state.c

@@ -2576,6 +2576,7 @@ nfsd4_exchange_id(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 		break;
 	default:				/* checked by xdr code */
 		WARN_ON_ONCE(1);
+		/* fall through */
 	case SP4_SSV:
 		status = nfserr_encr_alg_unsupp;
 		goto out_nolock;

fs/ocfs2/cluster/quorum.c

@@ -81,6 +81,7 @@ static void o2quo_fence_self(void)
 	default:
 		WARN_ON(o2nm_single_cluster->cl_fence_method >=
 			O2NM_FENCE_METHODS);
+		/* fall through */
 	case O2NM_FENCE_RESET:
 		printk(KERN_ERR "*** ocfs2 is very sorry to be fencing this "
 		       "system by restarting ***\n");

fs/seq_file.c

@@ -317,6 +317,7 @@ loff_t seq_lseek(struct file *file, loff_t offset, int whence)
 	switch (whence) {
 	case SEEK_CUR:
 		offset += file->f_pos;
+		/* fall through */
 	case SEEK_SET:
 		if (offset < 0)
 			break;

fs/signalfd.c

@@ -176,6 +176,7 @@ static ssize_t signalfd_dequeue(struct signalfd_ctx *ctx, kernel_siginfo_t *info
 		if (!nonblock)
 			break;
 		ret = -EAGAIN;
+		/* fall through */
 	default:
 		spin_unlock_irq(&current->sighand->siglock);
 		return ret;

fs/ufs/util.h

@@ -42,7 +42,7 @@ ufs_get_fs_state(struct super_block *sb, struct ufs_super_block_first *usb1,
 	case UFS_ST_SUNOS:
 		if (fs32_to_cpu(sb, usb3->fs_postblformat) == UFS_42POSTBLFMT)
 			return fs32_to_cpu(sb, usb1->fs_u0.fs_sun.fs_state);
-		/* Fall Through to UFS_ST_SUN */
+		/* Fall Through - to UFS_ST_SUN */
 	case UFS_ST_SUN:
 		return fs32_to_cpu(sb, usb3->fs_un2.fs_sun.fs_state);
 	case UFS_ST_SUNx86:
@@ -63,7 +63,7 @@ ufs_set_fs_state(struct super_block *sb, struct ufs_super_block_first *usb1,
 			usb1->fs_u0.fs_sun.fs_state = cpu_to_fs32(sb, value);
 			break;
 		}
-		/* Fall Through to UFS_ST_SUN */
+		/* Fall Through - to UFS_ST_SUN */
 	case UFS_ST_SUN:
 		usb3->fs_un2.fs_sun.fs_state = cpu_to_fs32(sb, value);
 		break;