Support improperly formated device numbers

There are kernel drivers (smblk) which set '-1' as their device major number.
This number is listed in /proc/devices then - but the kernel itself is using
just 12 bits - thus device is accessible via 4095 - there is posted patch
for 3.4 to fix this behavior (0 for auto allocation was mean to be used).

However to still allow using such devices with older kernels add some code
to use same behavior - so cut 12 bits from the major number from /proc/devices.

For now use log_warn() - maybe the severity of the message could be lowered
to just verbose level.

1 files changed, 15 insertions, 2 deletions

diff --git a/lib/filters/filter.c b/lib/filters/filter.c
index aa1e89c3..11b94c15 100644
--- a/lib/filters/filter.c
+++ b/lib/filters/filter.c
@@ -196,7 +196,7 @@ static int _scan_proc_dev(const char *proc, const struct dm_config_node *cn)
 	size_t dev_len = 0;
 	const struct dm_config_value *cv;
 	const char *name;
-
+	char *nl;
 
 	if (!*proc) {
 		log_verbose("No proc filesystem found: using all block device "
@@ -227,7 +227,20 @@ static int _scan_proc_dev(const char *proc, const struct dm_config_node *cn)
 
 		/* If it's not a number it may be name of section */
 		line_maj = atoi(((char *) (line + i)));
-		if ((line_maj <= 0) || (line_maj >= NUMBER_OF_MAJORS)) {
+
+		if (line_maj < 0 || line_maj >= NUMBER_OF_MAJORS) {
+			/*
+			 * Device numbers shown in /proc/devices are actually direct
+			 * numbers passed to registering function, however the kernel
+			 * uses only 12 bits, so use just 12 bits for major.
+			 */
+			if ((nl = strchr(line, '\n'))) *nl = '\0';
+			log_warn("WARNING: /proc/devices line: %s, replacing major with %d.",
+				 line, line_maj & (NUMBER_OF_MAJORS - 1));
+			line_maj &= (NUMBER_OF_MAJORS - 1);
+		}
+
+		if (!line_maj) {
 			blocksection = (line[i] == 'B') ? 1 : 0;
 			continue;
 		}