Merge: md: reintroduce md-linear

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/202

JIRA: https://issues.redhat.com/browse/RHEL-74142

Brew: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=66389573

Upstream Status: Commit found in Linus's Git tree.

Signed-off-by: Nigel Croxon <ncroxon@redhat.com>

Approved-by: Xiao Ni <xni@redhat.com>
Approved-by: Heinz Mauelshagen <heinzm@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Jan Stancek <jstancek@redhat.com>

Author: jstancek

drivers/md/Kconfig

@@ -61,6 +61,19 @@ config MD_BITMAP_FILE
 	  various kernel APIs and can only work with files on a file system not
 	  actually sitting on the MD device.
 
+config MD_LINEAR
+	tristate "Linear (append) mode"
+	depends on BLK_DEV_MD
+	help
+	  If you say Y here, then your multiple devices driver will be able to
+	  use the so-called linear mode, i.e. it will combine the hard disk
+	  partitions by simply appending one to the other.
+
+	  To compile this as a module, choose M here: the module
+	  will be called linear.
+
+	  If unsure, say Y.
+
 config MD_RAID0
 	tristate "RAID-0 (striping) mode"
 	depends on BLK_DEV_MD

drivers/md/Makefile

@@ -29,12 +29,14 @@ 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
+linear-y       += md-linear.o
 
 # Note: link order is important.  All raid personalities
 # and must come before md.o, as they each initialise
 # themselves, and md.o may use the personalities when it
 # auto-initialised.
 
+obj-$(CONFIG_MD_LINEAR)		+= linear.o
 obj-$(CONFIG_MD_RAID0)		+= raid0.o
 obj-$(CONFIG_MD_RAID1)		+= raid1.o
 obj-$(CONFIG_MD_RAID10)		+= raid10.o

drivers/md/md-autodetect.c

@@ -49,6 +49,7 @@ static int md_setup_ents __initdata;
  *             instead of just one.  -- KTK
  * 18May2000: Added support for persistent-superblock arrays:
  *             md=n,0,factor,fault,device-list   uses RAID0 for device n
+ *             md=n,-1,factor,fault,device-list  uses LINEAR for device n
  *             md=n,device-list      reads a RAID superblock from the devices
  *             elements in device-list are read by name_to_kdev_t so can be
  *             a hex number or something like /dev/hda1 /dev/sdb
@@ -87,15 +88,18 @@ static int __init md_setup(char *str)
 		md_setup_ents++;
 	switch (get_option(&str, &level)) {	/* RAID level */
 	case 2: /* could be 0 or -1.. */
-		if (level == 0) {
+		if (level == 0 || level == LEVEL_LINEAR) {
 			if (get_option(&str, &factor) != 2 ||	/* Chunk Size */
 					get_option(&str, &fault) != 2) {
 				printk(KERN_WARNING "md: Too few arguments supplied to md=.\n");
 				return 0;
 			}
 			md_setup_args[ent].level = level;
 			md_setup_args[ent].chunk = 1 << (factor+12);
-			pername = "raid0";
+			if (level ==  LEVEL_LINEAR)
+				pername = "linear";
+			else
+				pername = "raid0";
 			break;
 		}
 		fallthrough;