quota: fix infinite loop

If we fail to start a transaction when releasing dquot, we have to call
dquot_release() anyway to mark dquot structure as inactive.  Otherwise we
end in an infinite loop inside dqput().

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: xb <xavier.bru@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 1 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 4550b83ab1c9..3c1397fa83df 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2698,8 +2698,11 @@ static int ext4_release_dquot(struct dquot *dquot)
 
         handle = ext4_journal_start(dquot_to_inode(dquot),
                                         EXT4_QUOTA_DEL_BLOCKS(dquot->dq_sb));
-        if (IS_ERR(handle))
+        if (IS_ERR(handle)) {
+                /* Release dquot anyway to avoid endless cycle in dqput() */
+                dquot_release(dquot);
                 return PTR_ERR(handle);
+        }
         ret = dquot_release(dquot);
         err = ext4_journal_stop(handle);
         if (!ret)
@@ -2832,6 +2835,12 @@ static ssize_t ext4_quota_write(struct super_block *sb, int type,
         struct buffer_head *bh;
         handle_t *handle = journal_current_handle();
 
+        if (!handle) {
+                printk(KERN_WARNING "EXT4-fs: Quota write (off=%Lu, len=%Lu)"
+                        " cancelled because transaction is not started.\n",
+                        (unsigned long long)off, (unsigned long long)len);
+                return -EIO;
+        }
         mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
         while (towrite > 0) {
                 tocopy = sb->s_blocksize - offset < towrite ?