zram: cut trailing newline in algorithm name

Supplied sysfs values sometimes contain new-line symbols (echo vs.  echo
-n), which we also copy as a compression algorithm name.  it works fine
when we lookup for compression algorithm, because we use sysfs_streq()
which takes care of new line symbols.  however, it doesn't look nice when
we print compression algorithm name if zcomp_create() failed:

 zram: Cannot initialise LXZ
            compressing backend

cut trailing new-line, so the error string will look like

  zram: Cannot initialise LXZ compressing backend

we also now can replace sysfs_streq() in zcomp_available_show() with
strcmp().

Change-Id: If20e9c6253a9d810e0a15c3df78284145c05c424
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/block/zram/zcomp.c

@@ -282,7 +282,7 @@ ssize_t zcomp_available_show(const char *comp, char *buf)
 	int i = 0;
 
 	while (backends[i]) {
-		if (sysfs_streq(comp, backends[i]->name))
+		if (!strcmp(comp, backends[i]->name))
 			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
 					"[%s] ", backends[i]->name);
 		else

drivers/block/zram/zram_drv.c

@@ -271,13 +271,21 @@ static ssize_t comp_algorithm_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
 	struct zram *zram = dev_to_zram(dev);
+	size_t sz;
+
 	down_write(&zram->init_lock);
 	if (init_done(zram)) {
 		up_write(&zram->init_lock);
 		pr_info("Can't change algorithm for initialized device\n");
 		return -EBUSY;
 	}
 	strlcpy(zram->compressor, buf, sizeof(zram->compressor));
+
+	/* ignore trailing newline */
+	sz = strlen(zram->compressor);
+	if (sz > 0 && zram->compressor[sz - 1] == '\n')
+		zram->compressor[sz - 1] = 0x00;
+
 	up_write(&zram->init_lock);
 	return len;
 }