fix #5288: cherry-pick fix for udev-partition links > 16

If a zvol has more than 15 partitions, the minor device number
exhausts the slot count reserved for partitions next to the zvol
itself. As a result, the minor number cannot be used to determine the
partition number for the higher partition, and doing so results in
wrong named symlinks being generated by udev.

Since the partition number is encoded in the block device name anyway,
let's just extract it from there instead.

For upstream issue and PR discussion see:
openzfs/zfs#15970
openzfs/zfs#15904

Signed-off-by: Stoiko Ivanov <[email protected]>
Signed-off-by: Thomas Lamprecht <[email protected]>

Author: Stoiko Ivanov

debian/patches/0012-udev-correctly-handle-partition-16-and-later.patch

@@ -0,0 +1,52 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Fabian=20Gr=C3=BCnbichler?= <[email protected]>
+Date: Wed, 6 Mar 2024 10:39:06 +0100
+Subject: [PATCH] udev: correctly handle partition #16 and later
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+If a zvol has more than 15 partitions, the minor device number exhausts
+the slot count reserved for partitions next to the zvol itself. As a
+result, the minor number cannot be used to determine the partition
+number for the higher partition, and doing so results in wrong named
+symlinks being generated by udev.
+
+Since the partition number is encoded in the block device name anyway,
+let's just extract it from there instead.
+
+Fixes: #15904
+
+Signed-off-by: Fabian Grünbichler <[email protected]>
+Signed-off-by: Stoiko Ivanov <[email protected]>
+---
+ udev/zvol_id.c | 9 +++++----
+ 1 file changed, 5 insertions(+), 4 deletions(-)
+
+diff --git a/udev/zvol_id.c b/udev/zvol_id.c
+index 5960b9787..609349594 100644
+--- a/udev/zvol_id.c
++++ b/udev/zvol_id.c
+@@ -51,7 +51,7 @@ const char *__asan_default_options(void) {
+ int
+ main(int argc, const char *const *argv)
+ {
+-	if (argc != 2) {
++	if (argc != 2 || strncmp(argv[1], "/dev/zd", 7) != 0) {
+ 		fprintf(stderr, "usage: %s /dev/zdX\n", argv[0]);
+ 		return (1);
+ 	}
+@@ -72,9 +72,10 @@ main(int argc, const char *const *argv)
+ 		return (1);
+ 	}
+ 
+-	unsigned int dev_part = minor(sb.st_rdev) % ZVOL_MINORS;
+-	if (dev_part != 0)
+-		sprintf(zvol_name + strlen(zvol_name), "-part%u", dev_part);
++	const char *dev_part = strrchr(dev_name, 'p');
++	if (dev_part != NULL) {
++		sprintf(zvol_name + strlen(zvol_name), "-part%s", dev_part + 1);
++	}
+ 
+ 	for (size_t i = 0; i < strlen(zvol_name); ++i)
+ 		if (isblank(zvol_name[i]))

debian/patches/series

@@ -9,3 +9,4 @@
 0009-arc-stat-summary-guard-access-to-l2arc-MFU-MRU-stats.patch
 0010-Fix-nfs_truncate_shares-without-etc-exports.d.patch
 0011-zpool-status-tighten-bounds-for-noalloc-stat-availab.patch
+0012-udev-correctly-handle-partition-16-and-later.patch