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From:   Thiago Becker <tbecker@redhat.com>
To:     linux-nfs@vger.kernel.org, steved@redhat.com
Cc:     trbecker@gmail.com, Thiago Becker <tbecker@redhat.com>
Subject: [PATCH] nfsrahead: fix oops caused by non-starndard naming schemes
Date:   Mon, 25 Apr 2022 16:59:49 -0300
Message-Id: <20220425195948.2627428-1-tbecker@redhat.com>
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brtfs uses a non standard naming scheme for its fs structures, which
causes nfsrahead to take a long time scanning all the memory
available and then crashes. This causes the udev to take forever to
quiesce and delays the system startup.

This t=patch refactors the way the device number is obtained to handle
this situation.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2078147
Signed-off-by: Thiago Becker <tbecker@redhat.com>
---
 tools/nfsrahead/main.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/tools/nfsrahead/main.c b/tools/nfsrahead/main.c
index b3af3aa8..83a389f7 100644
--- a/tools/nfsrahead/main.c
+++ b/tools/nfsrahead/main.c
@@ -26,27 +26,31 @@ struct device_info {
 };
 
 /* Convert a string in the format n:m to a device number */
-static dev_t dev_from_arg(const char *device_number)
+static int fill_device_number(struct device_info *info)
 {
-	char *s = strdup(device_number), *p;
+	char *s = strdup(info->device_number), *p;
 	char *maj_s, *min_s;
 	unsigned int maj, min;
-	dev_t dev;
+	int err = -EINVAL;
 
 	maj_s = p = s;
-	for ( ; *p != ':'; p++)
+	for ( ; *p != ':' && *p != '\0'; p++)
 		;
 
+	if (*p == '\0')
+		goto out_free;
+
+	err = 0;
 	*p = '\0';
 	min_s = p + 1;
 
 	maj = strtol(maj_s, NULL, 10);
 	min = strtol(min_s, NULL, 10);
 
-	dev = makedev(maj, min);
-
+	info->dev = makedev(maj, min);
+out_free:
 	free(s);
-	return dev;
+	return err;
 }
 
 #define sfree(ptr) if (ptr) free(ptr)
@@ -55,7 +59,7 @@ static dev_t dev_from_arg(const char *device_number)
 static void init_device_info(struct device_info *di, const char *device_number)
 {
 	di->device_number = strdup(device_number);
-	di->dev = dev_from_arg(device_number);
+	di->dev = 0;
 	di->mountpoint = NULL;
 	di->fstype = NULL;
 }
@@ -76,6 +80,8 @@ static int get_mountinfo(const char *device_number, struct device_info *device_i
 	char *target;
 
 	init_device_info(device_info, device_number);
+	if ((ret = fill_device_number(device_info)) < 0)
+		goto out_free_device_info;
 
 	mnttbl = mnt_new_table();
 
@@ -101,6 +107,7 @@ out_free_fs:
 	mnt_free_fs(fs);
 out_free_tbl:
 	mnt_free_table(mnttbl);
+out_free_device_info:
 	free(device_info->device_number);
 	device_info->device_number = NULL;
 	return ret;
-- 
2.35.1