ext4: simplify some code in read_mmp_block()

My static check complains because we have:

	if (!*bh)
		return -ENOMEM;
	if (*bh) {

The second check is unnecessary.

I've simplified this code by moving the "if (!*bh)" checks around.  Also
Andreas Dilger says we should probably print a warning if sb_getblk()
fails.

[ Restructured the code so that we print a warning message as well if
  the mmp block doesn't check out, and to print the error code to
  disambiguate between the error cases.  - TYT ]

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 25 insertions, 21 deletions

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 8313ca3324ec..048c52af2fb6 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -69,6 +69,7 @@ static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
                           ext4_fsblk_t mmp_block)
 {
         struct mmp_struct *mmp;
+        int ret;
 
         if (*bh)
                 clear_buffer_uptodate(*bh);
@@ -76,33 +77,36 @@ static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
         /* This would be sb_bread(sb, mmp_block), except we need to be sure
          * that the MD RAID device cache has been bypassed, and that the read
          * is not blocked in the elevator. */
-        if (!*bh)
+        if (!*bh) {
                 *bh = sb_getblk(sb, mmp_block);
-        if (!*bh)
-                return -ENOMEM;
-        if (*bh) {
-                get_bh(*bh);
-                lock_buffer(*bh);
-                (*bh)->b_end_io = end_buffer_read_sync;
-                submit_bh(READ_SYNC | REQ_META | REQ_PRIO, *bh);
-                wait_on_buffer(*bh);
-                if (!buffer_uptodate(*bh)) {
-                        brelse(*bh);
-                        *bh = NULL;
+                if (!*bh) {
+                        ret = -ENOMEM;
+                        goto warn_exit;
                 }
         }
-        if (unlikely(!*bh)) {
-                ext4_warning(sb, "Error while reading MMP block %llu",
-                             mmp_block);
-                return -EIO;
+
+        get_bh(*bh);
+        lock_buffer(*bh);
+        (*bh)->b_end_io = end_buffer_read_sync;
+        submit_bh(READ_SYNC | REQ_META | REQ_PRIO, *bh);
+        wait_on_buffer(*bh);
+        if (!buffer_uptodate(*bh)) {
+                brelse(*bh);
+                *bh = NULL;
+                ret = -EIO;
+                goto warn_exit;
         }
 
         mmp = (struct mmp_struct *)((*bh)->b_data);
-        if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC ||
-            !ext4_mmp_csum_verify(sb, mmp))
-                return -EINVAL;
-
-        return 0;
+        if (le32_to_cpu(mmp->mmp_magic) == EXT4_MMP_MAGIC &&
+            ext4_mmp_csum_verify(sb, mmp))
+                return 0;
+        ret = -EINVAL;
+
+warn_exit:
+        ext4_warning(sb, "Error %d while reading MMP block %llu",
+                     ret, mmp_block);
+        return ret;
 }
 
 /*