md: Remove deprecated CONFIG_MD_MULTIPATH

md-multipath has been marked as deprecated for 2.5 years. Remove it.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Neil Brown <neilb@suse.de>
Cc: Guoqing Jiang <guoqing.jiang@linux.dev>
Cc: Mateusz Grzonka <mateusz.grzonka@intel.com>
Cc: Jes Sorensen <jes@trained-monkey.org>
Signed-off-by: Song Liu <song@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20231214222107.2016042-3-song@kernel.org

drivers/md/Kconfig

@@ -159,17 +159,6 @@ config MD_RAID456
 
 	  If unsure, say Y.
 
-config MD_MULTIPATH
-	tristate "Multipath I/O support (deprecated)"
-	depends on BLK_DEV_MD
-	help
-	  MD_MULTIPATH provides a simple multi-path personality for use
-	  the MD framework.  It is not under active development.  New
-	  projects should consider using DM_MULTIPATH which has more
-	  features and more testing.
-
-	  If unsure, say N.
-
 config MD_FAULTY
 	tristate "Faulty test module for MD (deprecated)"
 	depends on BLK_DEV_MD

drivers/md/Makefile

@@ -29,7 +29,6 @@ dm-zoned-y	+= dm-zoned-target.o dm-zoned-metadata.o dm-zoned-reclaim.o
 
 md-mod-y	+= md.o md-bitmap.o
 raid456-y	+= raid5.o raid5-cache.o raid5-ppl.o
-multipath-y	+= md-multipath.o
 faulty-y	+= md-faulty.o
 
 # Note: link order is important.  All raid personalities
@@ -41,7 +40,6 @@ obj-$(CONFIG_MD_RAID0)		+= raid0.o
 obj-$(CONFIG_MD_RAID1)		+= raid1.o
 obj-$(CONFIG_MD_RAID10)		+= raid10.o
 obj-$(CONFIG_MD_RAID456)	+= raid456.o
-obj-$(CONFIG_MD_MULTIPATH)	+= multipath.o
 obj-$(CONFIG_MD_FAULTY)		+= faulty.o
 obj-$(CONFIG_MD_CLUSTER)	+= md-cluster.o
 obj-$(CONFIG_BCACHE)		+= bcache/

drivers/md/md.c

@@ -1287,17 +1287,11 @@ static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor
 	rdev->sb_size = MD_SB_BYTES;
 	rdev->badblocks.shift = -1;
 
-	if (sb->level == LEVEL_MULTIPATH)
-		rdev->desc_nr = -1;
-	else
 	rdev->desc_nr = sb->this_disk.number;
 
-	/* not spare disk, or LEVEL_MULTIPATH */
-	if (sb->level == LEVEL_MULTIPATH ||
-		(rdev->desc_nr >= 0 &&
-		 rdev->desc_nr < MD_SB_DISKS &&
-		 sb->disks[rdev->desc_nr].state &
-		 ((1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE))))
+	/* not spare disk */
+	if (rdev->desc_nr >= 0 && rdev->desc_nr < MD_SB_DISKS &&
+	    sb->disks[rdev->desc_nr].state & ((1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)))
 		spare_disk = false;
 
 	if (!refdev) {
@@ -1444,20 +1438,19 @@ static int super_90_validate(struct mddev *mddev, struct md_rdev *freshest, stru
 			return 0;
 	}
 
-	if (mddev->level != LEVEL_MULTIPATH) {
 	desc = sb->disks + rdev->desc_nr;
 
 	if (desc->state & (1<<MD_DISK_FAULTY))
 		set_bit(Faulty, &rdev->flags);
-		else if (desc->state & (1<<MD_DISK_SYNC) /* &&
-			    desc->raid_disk < mddev->raid_disks */) {
+	else if (desc->state & (1<<MD_DISK_SYNC)) {
 		set_bit(In_sync, &rdev->flags);
 		rdev->raid_disk = desc->raid_disk;
 		rdev->saved_raid_disk = desc->raid_disk;
 	} else if (desc->state & (1<<MD_DISK_ACTIVE)) {
 		/* active but not in sync implies recovery up to
 		 * reshape position.  We don't know exactly where
-			 * that is, so set to zero for now */
+		 * that is, so set to zero for now
+		 */
 		if (mddev->minor_version >= 91) {
 			rdev->recovery_offset = 0;
 			rdev->raid_disk = desc->raid_disk;
@@ -1467,8 +1460,6 @@ static int super_90_validate(struct mddev *mddev, struct md_rdev *freshest, stru
 		set_bit(WriteMostly, &rdev->flags);
 	if (desc->state & (1<<MD_DISK_FAILFAST))
 		set_bit(FailFast, &rdev->flags);
-	} else /* MULTIPATH are always insync */
-		set_bit(In_sync, &rdev->flags);
 	return 0;
 }
 
@@ -1758,9 +1749,6 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_
 	    && rdev->new_data_offset < sb_start + (rdev->sb_size/512))
 		return -EINVAL;
 
-	if (sb->level == cpu_to_le32(LEVEL_MULTIPATH))
-		rdev->desc_nr = -1;
-	else
 	rdev->desc_nr = le32_to_cpu(sb->dev_number);
 
 	if (!rdev->bb_page) {
@@ -1814,12 +1802,10 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_
 	    sb->level != 0)
 		return -EINVAL;
 
-	/* not spare disk, or LEVEL_MULTIPATH */
-	if (sb->level == cpu_to_le32(LEVEL_MULTIPATH) ||
-		(rdev->desc_nr >= 0 &&
-		rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
+	/* not spare disk */
+	if (rdev->desc_nr >= 0 && rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
 	    (le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < MD_DISK_ROLE_MAX ||
-		 le16_to_cpu(sb->dev_roles[rdev->desc_nr]) == MD_DISK_ROLE_JOURNAL)))
+	     le16_to_cpu(sb->dev_roles[rdev->desc_nr]) == MD_DISK_ROLE_JOURNAL))
 		spare_disk = false;
 
 	if (!refdev) {
@@ -1862,6 +1848,7 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *freshest, struc
 {
 	struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
 	__u64 ev1 = le64_to_cpu(sb->events);
+	int role;
 
 	rdev->raid_disk = -1;
 	clear_bit(Faulty, &rdev->flags);
@@ -1977,8 +1964,7 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *freshest, struc
 			/* just a hot-add of a new device, leave raid_disk at -1 */
 			return 0;
 	}
-	if (mddev->level != LEVEL_MULTIPATH) {
-		int role;
+
 	if (rdev->desc_nr < 0 ||
 	    rdev->desc_nr >= le32_to_cpu(sb->max_dev)) {
 		role = MD_DISK_ROLE_SPARE;
@@ -2015,7 +2001,7 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *freshest, struc
 	} else {
 		role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
 	}
-		switch(role) {
+	switch (role) {
 	case MD_DISK_ROLE_SPARE: /* spare */
 		break;
 	case MD_DISK_ROLE_FAULTY: /* faulty */
@@ -2057,8 +2043,6 @@ static int super_1_validate(struct mddev *mddev, struct md_rdev *freshest, struc
 		set_bit(FailFast, &rdev->flags);
 	if (le32_to_cpu(sb->feature_map) & MD_FEATURE_REPLACEMENT)
 		set_bit(Replacement, &rdev->flags);
-	} else /* MULTIPATH are always insync */
-		set_bit(In_sync, &rdev->flags);
 
 	return 0;
 }
@@ -2876,10 +2860,6 @@ void md_update_sb(struct mddev *mddev, int force_change)
 		} else
 			pr_debug("md: %pg (skipping faulty)\n",
 				 rdev->bdev);
-
-		if (mddev->level == LEVEL_MULTIPATH)
-			/* only need to write one superblock... */
-			break;
 	}
 	if (md_super_wait(mddev) < 0)
 		goto rewrite;
@@ -3880,12 +3860,7 @@ static int analyze_sbs(struct mddev *mddev)
 				continue;
 			}
 		}
-		if (mddev->level == LEVEL_MULTIPATH) {
-			rdev->desc_nr = i++;
-			rdev->raid_disk = rdev->desc_nr;
-			set_bit(In_sync, &rdev->flags);
-		} else if (rdev->raid_disk >=
-			    (mddev->raid_disks - min(0, mddev->delta_disks)) &&
+		if (rdev->raid_disk >= (mddev->raid_disks - min(0, mddev->delta_disks)) &&
 		    !test_bit(Journal, &rdev->flags)) {
 			rdev->raid_disk = -1;
 			clear_bit(In_sync, &rdev->flags);

include/uapi/linux/raid/md_p.h

@@ -233,7 +233,7 @@ struct mdp_superblock_1 {
 	char	set_name[32];	/* set and interpreted by user-space */
 
 	__le64	ctime;		/* lo 40 bits are seconds, top 24 are microseconds or 0*/
-	__le32	level;		/* -4 (multipath), 0,1,4,5 */
+	__le32	level;		/* 0,1,4,5 */
 	__le32	layout;		/* only for raid5 and raid10 currently */
 	__le64	size;		/* used size of component devices, in 512byte sectors */
 

include/uapi/linux/raid/md_u.h

@@ -104,7 +104,6 @@ typedef struct mdu_array_info_s {
 } mdu_array_info_t;
 
 /* non-obvious values for 'level' */
-#define	LEVEL_MULTIPATH		(-4)
 #define	LEVEL_FAULTY		(-5)
 
 /* we need a value for 'no level specified' and 0