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/

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