[dm-devel] [PATCH] multipath: remove unnecessary fds from alias code

[Benjamin Marzinski <bmarzins redhat com>]

Originally, the alias code duped the bindings file fd so that a stream could
be opened on it, and then closed without closing the original fd. Later,
closing the stream was moved to the end of the function, to avoid a locking
bug.  Because of this, there isn't any point to duping the fd.  Also, since
the stream is still opened when the original fd is used, the stream
should be flushed after its done being used.

Signed-off-by: Benjamin Marzinski <bmarzins redhat com>
---
 libmultipath/alias.c |   41 +++++++++++------------------------------
 1 file changed, 11 insertions(+), 30 deletions(-)

Index: multipath-tools-120518/libmultipath/alias.c
===================================================================
--- multipath-tools-120518.orig/libmultipath/alias.c
+++ multipath-tools-120518/libmultipath/alias.c
@@ -361,7 +361,7 @@ get_user_friendly_alias(char *wwid, char
 			int bindings_read_only)
 {
 	char *alias;
-	int fd, scan_fd, id;
+	int fd, id;
 	FILE *f;
 	int can_write;
 
@@ -374,19 +374,10 @@ get_user_friendly_alias(char *wwid, char
 	if (fd < 0)
 		return NULL;
 
-	scan_fd = dup(fd);
-	if (scan_fd < 0) {
-		condlog(0, "Cannot dup bindings file descriptor : %s",
-			strerror(errno));
-		close(fd);
-		return NULL;
-	}
-
-	f = fdopen(scan_fd, "r");
+	f = fdopen(fd, "r");
 	if (!f) {
 		condlog(0, "cannot fdopen on bindings file descriptor : %s",
 			strerror(errno));
-		close(scan_fd);
 		close(fd);
 		return NULL;
 	}
@@ -394,8 +385,13 @@ get_user_friendly_alias(char *wwid, char
 	id = lookup_binding(f, wwid, &alias, prefix);
 	if (id < 0) {
 		fclose(f);
-		close(scan_fd);
-		close(fd);
+		return NULL;
+	}
+
+	if (fflush(f) != 0) {
+		condlog(0, "cannot fflush bindings file stream : %s",
+			strerror(errno));
+		fclose(f);
 		return NULL;
 	}
 
@@ -403,8 +399,6 @@ get_user_friendly_alias(char *wwid, char
 		alias = allocate_binding(fd, wwid, id, prefix);
 
 	fclose(f);
-	close(scan_fd);
-	close(fd);
 	return alias;
 }
 
@@ -412,7 +406,7 @@ char *
 get_user_friendly_wwid(char *alias, char *file)
 {
 	char *wwid;
-	int fd, scan_fd, id, unused;
+	int fd, id, unused;
 	FILE *f;
 
 	if (!alias || *alias == '\0') {
@@ -424,19 +418,10 @@ get_user_friendly_wwid(char *alias, char
 	if (fd < 0)
 		return NULL;
 
-	scan_fd = dup(fd);
-	if (scan_fd < 0) {
-		condlog(0, "Cannot dup bindings file descriptor : %s",
-			strerror(errno));
-		close(fd);
-		return NULL;
-	}
-
-	f = fdopen(scan_fd, "r");
+	f = fdopen(fd, "r");
 	if (!f) {
 		condlog(0, "cannot fdopen on bindings file descriptor : %s",
 			strerror(errno));
-		close(scan_fd);
 		close(fd);
 		return NULL;
 	}
@@ -444,13 +429,9 @@ get_user_friendly_wwid(char *alias, char
 	id = rlookup_binding(f, &wwid, alias);
 	if (id < 0) {
 		fclose(f);
-		close(scan_fd);
-		close(fd);
 		return NULL;
 	}
 
 	fclose(f);
-	close(scan_fd);
-	close(fd);
 	return wwid;
 }