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>

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 0a512aa81bf7505ab8803cc90191249f91cb4a27..24445275d330e07cb38623e0d548989a2a7621c4 100644 (file)
--- 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;