zram: return error-valued pointer from zcomp_create()

Instead of returning just NULL, return ERR_PTR from zcomp_create() if
compressing backend creation has failed.  ERR_PTR(-EINVAL) for unsupported
compression algorithm request, ERR_PTR(-ENOMEM) for allocation (zcomp or
compression stream) error.

Perform IS_ERR() check of returned from zcomp_create() value in
disksize_store() and set return code to PTR_ERR().

Change suggested by Jerome Marchand.

[akpm@linux-foundation.org: clean up error recovery flow]
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index d591903..5647d8f 100644 (file)
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -9,6 +9,7 @@
 
 #include <linux/kernel.h>
 #include <linux/string.h>
+#include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/wait.h>
 #include <linux/sched.h>
@@ -319,9 +320,10 @@ void zcomp_destroy(struct zcomp *comp)
 
 /*
  * search available compressors for requested algorithm.
- * allocate new zcomp and initialize it. return NULL
- * if requested algorithm is not supported or in case
- * of init error
+ * allocate new zcomp and initialize it. return compressing
+ * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
+ * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
+ * case of allocation error.
  */
 struct zcomp *zcomp_create(const char *compress, int max_strm)
 {
@@ -330,11 +332,11 @@ struct zcomp *zcomp_create(const char *compress, int max_strm)
 
        backend = find_backend(compress);
        if (!backend)
-               return NULL;
+               return ERR_PTR(-EINVAL);
 
        comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
        if (!comp)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
 
        comp->backend = backend;
        if (max_strm > 1)
@@ -343,7 +345,7 @@ struct zcomp *zcomp_create(const char *compress, int max_strm)
                zcomp_strm_single_create(comp);
        if (!comp->stream) {
                kfree(comp);
-               return NULL;
+               return ERR_PTR(-ENOMEM);
        }
        return comp;
 }

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index e4d536b..6b462d2 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -31,6 +31,7 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/vmalloc.h>
+#include <linux/err.h>
 
 #include "zram_drv.h"
 
@@ -583,7 +584,7 @@ static ssize_t disksize_store(struct device *dev,
        struct zcomp *comp;
        struct zram_meta *meta;
        struct zram *zram = dev_to_zram(dev);
-       int err = -EINVAL;
+       int err;
 
        disksize = memparse(buf, NULL);
        if (!disksize)
@@ -595,18 +596,18 @@ static ssize_t disksize_store(struct device *dev,
                return -ENOMEM;
 
        comp = zcomp_create(zram->compressor, zram->max_comp_streams);
-       if (!comp) {
+       if (IS_ERR(comp)) {
                pr_info("Cannot initialise %s compressing backend\n",
                                zram->compressor);
-               goto out_cleanup;
+               err = PTR_ERR(comp);
+               goto out_free_meta;
        }
 
        down_write(&zram->init_lock);
        if (init_done(zram)) {
-               up_write(&zram->init_lock);
                pr_info("Cannot change disksize for initialized device\n");
                err = -EBUSY;
-               goto out_cleanup;
+               goto out_destroy_comp;
        }
 
        zram->meta = meta;
@@ -614,12 +615,12 @@ static ssize_t disksize_store(struct device *dev,
        zram->disksize = disksize;
        set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
        up_write(&zram->init_lock);
-
        return len;
 
-out_cleanup:
-       if (comp)
-               zcomp_destroy(comp);
+out_destroy_comp:
+       up_write(&zram->init_lock);
+       zcomp_destroy(comp);
+out_free_meta:
        zram_meta_free(meta);
        return err;
 }