ext4: clean up error handling in the MMP support

There is memory leak as both caller function kmmpd() and callee
read_mmp_block() not releasing bh_check  (i.e buffer_head).
Given patch fixes this problem.

[ Additional changes suggested by Andreas Dilger -- TYT ]

Signed-off-by: Jadhav Vikram <vikramjadhavpucsd2007@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 17 insertions, 17 deletions

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 0a512aa81bf7..24445275d330 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -91,21 +91,22 @@ static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
         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)
+        if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC) {
                 ret = -EFSCORRUPTED;
-        else if (!ext4_mmp_csum_verify(sb, mmp))
+                goto warn_exit;
+        }
+        if (!ext4_mmp_csum_verify(sb, mmp)) {
                 ret = -EFSBADCRC;
-        else
-                return 0;
-
+                goto warn_exit;
+        }
+        return 0;
 warn_exit:
+        brelse(*bh);
+        *bh = NULL;
         ext4_warning(sb, "Error %d while reading MMP block %llu",
                      ret, mmp_block);
         return ret;
@@ -181,15 +182,13 @@ static int kmmpd(void *data)
                     EXT4_FEATURE_INCOMPAT_MMP)) {
                         ext4_warning(sb, "kmmpd being stopped since MMP feature"
                                      " has been disabled.");
-                        EXT4_SB(sb)->s_mmp_tsk = NULL;
-                        goto failed;
+                        goto exit_thread;
                 }
 
                 if (sb->s_flags & MS_RDONLY) {
                         ext4_warning(sb, "kmmpd being stopped since filesystem "
                                      "has been remounted as readonly.");
-                        EXT4_SB(sb)->s_mmp_tsk = NULL;
-                        goto failed;
+                        goto exit_thread;
                 }
 
                 diff = jiffies - last_update_time;
@@ -211,9 +210,7 @@ static int kmmpd(void *data)
                         if (retval) {
                                 ext4_error(sb, "error reading MMP data: %d",
                                            retval);
-
-                                EXT4_SB(sb)->s_mmp_tsk = NULL;
-                                goto failed;
+                                goto exit_thread;
                         }
 
                         mmp_check = (struct mmp_struct *)(bh_check->b_data);
@@ -225,7 +222,9 @@ static int kmmpd(void *data)
                                              "The filesystem seems to have been"
                                              " multiply mounted.");
                                 ext4_error(sb, "abort");
-                                goto failed;
+                                put_bh(bh_check);
+                                retval = -EBUSY;
+                                goto exit_thread;
                         }
                         put_bh(bh_check);
                 }
@@ -248,7 +247,8 @@ static int kmmpd(void *data)
 
         retval = write_mmp_block(sb, bh);
 
-failed:
+exit_thread:
+        EXT4_SB(sb)->s_mmp_tsk = NULL;
         kfree(data);
         brelse(bh);
         return retval;