File 0003-btrfs-progs-add-fallback-code-for-multipat... of Package btrfsprogs.24931

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File 0003-btrfs-progs-add-fallback-code-for-multipath-device-d.patch of Package btrfsprogs.24931

From 25867a7715df03031b9d3de046dc13fcc524b9a6 Mon Sep 17 00:00:00 2001
From: Nikolay Borisov <nborisov@suse.com>
Date: Thu, 30 Sep 2021 15:06:34 +0300
Subject: [PATCH 3/3] btrfs-progs: add fallback code for multipath device
 detection for static build

Since libudev doesn't provide a static version of the library for static
build btrfs-progs will have to provide manual fallback. This change does
this by parsing the udev database files hosted at /run/udev/data/.
Under that directory every block device should have a file with the
following name: bMAJ:MIN. So implement the bare minimum code necessary
to parse this file and search for the presence of DM_MULTIPATH_DEVICE_PATH
udev attribute. This could likely be racy since access to the udev
database is done outside of libudev but that's the best that can be
done when implementing this manually and is only for a limited usecase
where static build has to be used.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 utils.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 46 insertions(+), 9 deletions(-)

diff --git a/utils.c b/utils.c
index e63ec84df83a..3ce23aee3adb 100644
--- a/utils.c
+++ b/utils.c
@@ -30,6 +30,7 @@
 #include <sys/stat.h>
 #include <sys/sysinfo.h>
 #include <uuid/uuid.h>
+#include <sys/sysmacros.h>
 #ifdef HAVE_LIBUDEV
 #include <sys/stat.h>
 #include <libudev.h>
@@ -1974,23 +1975,54 @@ int group_profile_max_safe_loss(u64 flags)
 	}
 }
 
-#ifdef HAVE_LIBUDEV
-static bool is_path_device(char *device_path)
+#ifdef STATIC_BUILD
+static bool is_path_device(dev_t device)
+{
+	FILE *file;
+	char *line = NULL;
+	size_t len = 0;
+	ssize_t nread;
+	bool ret = false;
+	int ret2;
+	char path[PATH_MAX];
+
+	ret2 = snprintf(path, sizeof(path), "/run/udev/data/b%u:%u", major(device),
+			minor(device));
+
+	if (ret2 < 0)
+		return false;
+
+	file = fopen(path, "r");
+	if (file == NULL)
+		return false;
+
+	while ((nread = getline(&line, &len, file)) != -1) {
+		if (strstr(line, "DM_MULTIPATH_DEVICE_PATH=1")) {
+			ret = true;
+			break;
+		}
+	}
+
+	if (line)
+		free(line);
+
+	fclose(file);
+
+	return ret;
+}
+#elif defined(HAVE_LIBUDEV)
+static bool is_path_device(dev_t device)
 {
 	struct udev *udev = NULL;
 	struct udev_device *dev = NULL;
-	struct stat dev_stat;
 	const char *val;
 	bool ret = false;
 
-	if (stat(device_path, &dev_stat) < 0)
-		return false;
-
 	udev = udev_new();
 	if (!udev)
 		goto out;
 
-	dev = udev_device_new_from_devnum(udev, 'b', dev_stat.st_rdev);
+	dev = udev_device_new_from_devnum(udev, 'b', device);
 	if (!dev)
 		goto out;
 
@@ -2004,7 +2036,7 @@ static bool is_path_device(char *device_path)
 	return ret;
 }
 #else
-static bool is_path_device(char *device_path)
+static bool is_path_device(dev_t device)
 {
 	return false;
 }
@@ -2032,13 +2064,18 @@ int btrfs_scan_devices(void)
 	iter = blkid_dev_iterate_begin(cache);
 	blkid_dev_set_search(iter, "TYPE", "btrfs");
 	while (blkid_dev_next(iter, &dev) == 0) {
+		struct stat dev_stat;
+
 		dev = blkid_verify(cache, dev);
 		if (!dev)
 			continue;
 		/* if we are here its definitely a btrfs disk*/
 		strncpy_null(path, blkid_dev_devname(dev));
 
-		if (is_path_device(path))
+		if (stat(path, &dev_stat) < 0)
+			continue;
+
+		if (is_path_device(dev_stat.st_rdev))
 			continue;
 
 		fd = open(path, O_RDONLY);
-- 
2.25.1

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