s390-tools/s390-tools-sles15sp4-zdev-Fix-path-resolution-for-multi-mount-point-file-.patch

Subject: [PATCH] [BZ 196440] zdev: Fix path resolution for multi-mount point file systems
From: Peter Oberparleiter <oberpar@linux.ibm.com>

Description:   zdev: Fix path resolution for multi-mount point file systems
Symptom:       Path resolution fails when a device provides multiple mount
               points such as, for example, when using btrfs subvolumes, or
               when mounting the same file system at multiple mount points.
Problem:       The failure is caused by zdev relying on the MOUNTPOINT
               attribute of lsblk's output which only contains a single
               mount point.
Solution:      Fix this by making use of lsblk's MOUNTPOINTS attribute that
               contains the full list of mount points.
Reproduction:  chzdev -f -e <dev_id_a> <dev_id_b> <dev_id_c>: In this case, if
               the rootfs is soread across multiple devices, zdev adds only the
               first device in to the initrd and the system does not boot.
Upstream-ID:   1faa5d2957eb82ab235778959d70a38062b7aa7d
Problem-ID:    196440

Upstream-Description:

              zdev: Fix path resolution for multi-mount point file systems

              zdev provides path resolution logic to determine which z-specific
              devices contribute to the file system mounted at a specific mount point.
              This logic is used by command-line option --by-path, but also to
              determine the list of devices needed to enable the root file system.

              Path resolution fails when a device provides multiple mount points such
              as, for example, when using btrfs subvolumes, or when mounting the same
              file system at multiple mount points. The failure is caused by zdev
              relying on the MOUNTPOINT attribute of lsblk's output which only
              contains a single mount point.

              Fix this by making use of lsblk's MOUNTPOINTS attribute that contains
              the full list of mount points. Note that MOUNTPOINTS was only introduced
              with util-linux v2.37, therefore a fall-back to the old format is
              needed.

              Fixes: https://github.com/ibm-s390-linux/s390-tools/issues/129
              Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
              Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
              Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
              Reviewed-by: Eduard Shishkin <edward6@linux.ibm.com>
              Reported-by: Dan Horak <dan@danny.cz>
              Signed-off-by: Jan Hoeppner <hoeppner@linux.ibm.com>


Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Index: s390-tools-service/zdev/src/blkinfo.c
===================================================================
--- s390-tools-service.orig/zdev/src/blkinfo.c
+++ s390-tools-service/zdev/src/blkinfo.c
@@ -7,6 +7,7 @@
  * it under the terms of the MIT license. See LICENSE for details.
  */
 
+#include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -16,6 +17,7 @@
 #include "misc.h"
 
 #define LSBLK_CMDLINE	"lsblk -P -o NAME,MAJ:MIN,FSTYPE,UUID,MOUNTPOINT,PKNAME 2>/dev/null"
+#define LSBLK_CMDLINE2	"lsblk -P -o NAME,MAJ:MIN,FSTYPE,UUID,MOUNTPOINTS,PKNAME 2>/dev/null"
 
 struct blkinfo {
 	struct devnode *devnode;
@@ -82,6 +84,26 @@ void blkinfo_print(struct blkinfo *blkin
 		printf("%*sparent=%s\n", level, "", blkinfo->parent);
 }
 
+/* Convert each occurrence of '\xnn' in @str to character with hex code <nn>. */
+static void hex_unescape(char *str)
+{
+	unsigned int c;
+
+	while ((str = strstr(str, "\\x"))) {
+		if (isxdigit(str[2]) && isxdigit(str[3]) &&
+		    sscanf(str + 2, "%2x", &c) == 1) {
+			str[0] = (char)c;
+
+			/* Move remainder of str including nul behind <c>. */
+			memmove(str + /* <c> */ 1,
+				str + /* '\xnn' */ 4,
+				strlen(str + 4) + /* <nul> */ 1);
+		}
+
+		str++;
+	}
+}
+
 static char *isolate_keyword(char **line_ptr, const char *keyword)
 {
 	char *start, *end;
@@ -102,9 +124,11 @@ static char *isolate_keyword(char **line
 	return start;
 }
 
-static struct blkinfo *blkinfo_from_line(char *line)
+static void add_blkinfos_from_line(struct util_list *blkinfos,
+				   char *line)
 {
-	char *name, *majmin, *fstype, *uuid, *mountpoint, *parent;
+	char *name, *majmin, *fstype, *uuid, *mountpoint, *mountpoints, *parent;
+	struct blkinfo *blkinfo;
 
 	name		= isolate_keyword(&line, "NAME=\"");
 	majmin		= isolate_keyword(&line, "MAJ:MIN=\"");
@@ -113,21 +137,45 @@ static struct blkinfo *blkinfo_from_line
 	fstype		= isolate_keyword(&line, "FSTYPE=\"");
 	uuid		= isolate_keyword(&line, "UUID=\"");
 	mountpoint	= isolate_keyword(&line, "MOUNTPOINT=\"");
+	mountpoints	= isolate_keyword(&line, "MOUNTPOINTS=\"");
 	parent		= isolate_keyword(&line, "PKNAME=\"");
 
-	return blkinfo_new(name, majmin, fstype, uuid, mountpoint, parent);
+	if (!mountpoints) {
+		/* Handle old lsblk output format. */
+		blkinfo = blkinfo_new(name, majmin, fstype, uuid, mountpoint,
+				      parent);
+		ptrlist_add(blkinfos, blkinfo);
+		return;
+	}
+
+	/* Restore newline mount point separator encoded as hex. */
+	hex_unescape(mountpoints);
+
+	/* Represent each mount point as a separate blkinfo to support
+	 * resolution of multi-mount point file systems like btrfs
+	 * subvolumes. */
+	while ((mountpoint = strsep(&mountpoints, "\n"))) {
+		blkinfo = blkinfo_new(name, majmin, fstype, uuid, mountpoint,
+				      parent);
+		ptrlist_add(blkinfos, blkinfo);
+	}
 }
 
 static struct util_list *blkinfos_read(void)
 {
 	char *output, *curr, *next;
 	struct util_list *blkinfos;
-	struct blkinfo *blkinfo;
 
 	if (cached_blkinfos)
 		return cached_blkinfos;
 
-	output = misc_read_cmd_output(LSBLK_CMDLINE, 0, 1);
+	output = misc_read_cmd_output(LSBLK_CMDLINE2, 0, 1);
+	if (output && !*output) {
+		/* No output might indicate no support for new lsblk command-
+		 * line format - fall back to old format. */
+		free(output);
+		output = misc_read_cmd_output(LSBLK_CMDLINE, 0, 1);
+	}
 	if (!output)
 		return NULL;
 
@@ -136,9 +184,7 @@ static struct util_list *blkinfos_read(v
 	/* Iterate over each line. */
 	next = output;
 	while ((curr = strsep(&next, "\n"))) {
-		blkinfo = blkinfo_from_line(curr);
-		if (blkinfo)
-			ptrlist_add(blkinfos, blkinfo);
+		add_blkinfos_from_line(blkinfos, curr);
 	}
 
 	free(output);