tree-wide: convert open calls to remove spaces to skip_spaces() lib function

Makes use of skip_spaces() defined in lib/string.c for removing leading
spaces from strings all over the tree.

It decreases lib.a code size by 47 bytes and reuses the function tree-wide:
   text    data     bss     dec     hex filename
  64688     584     592   65864   10148 (TOTALS-BEFORE)
  64641     584     592   65817   10119 (TOTALS-AFTER)

Also, while at it, if we see (*str && isspace(*str)), we can be sure to
remove the first condition (*str) as the second one (isspace(*str)) also
evaluates to 0 whenever *str == 0, making it redundant. In other words,
"a char equals zero is never a space".

Julia Lawall tried the semantic patch (http://coccinelle.lip6.fr) below,
and found occurrences of this pattern on 3 more files:
    drivers/leds/led-class.c
    drivers/leds/ledtrig-timer.c
    drivers/video/output.c

@@
expression str;
@@

( // ignore skip_spaces cases
while (*str &&  isspace(*str)) { \(str++;\|++str;\) }
|
- *str &&
isspace(*str)
)

Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com>
Cc: Julia Lawall <julia@diku.dk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: David Howells <dhowells@redhat.com>
Cc: <linux-ext4@vger.kernel.org>
Cc: Samuel Ortiz <samuel@sortiz.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 4 insertions, 7 deletions

diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index 4618516dd994..c2413561ea75 100644
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -21,6 +21,7 @@
 #include <linux/mount.h>
 #include <linux/statfs.h>
 #include <linux/ctype.h>
+#include <linux/string.h>
 #include <linux/fs_struct.h>
 #include "internal.h"
 
@@ -257,8 +258,7 @@ static ssize_t cachefiles_daemon_write(struct file *file,
 		if (args == data)
 			goto error;
 		*args = '\0';
-		for (args++; isspace(*args); args++)
-			continue;
+		args = skip_spaces(++args);
 	}
 
 	/* run the appropriate command handler */
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 768c111a77ec..827bde1f2594 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2137,11 +2137,8 @@ static int parse_strtoul(const char *buf,
 {
 	char *endp;
 
-	while (*buf && isspace(*buf))
-		buf++;
-	*value = simple_strtoul(buf, &endp, 0);
-	while (*endp && isspace(*endp))
-		endp++;
+	*value = simple_strtoul(skip_spaces(buf), &endp, 0);
+	endp = skip_spaces(endp);
 	if (*endp || *value > max)
 		return -EINVAL;