ocfs2: Fix NULL pointer deref when writing local dquot

commit_dqblk() can write quota info to global file. That is actually a bad
thing to do because if we are just modifying local quota file, we are not
prepared (do not hold proper locks, do not have transaction credits) to do
a modification of the global quota file. So do not use commit_dqblk() and
instead call our writing function directly.

Acked-by: Joel Becker <Joel.Becker@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>

3 files changed, 12 insertions, 12 deletions

diff --git a/fs/ocfs2/quota.h b/fs/ocfs2/quota.h
index 903ffa933d53..196fcb52d95d 100644
--- a/fs/ocfs2/quota.h
+++ b/fs/ocfs2/quota.h
@@ -109,6 +109,7 @@ int ocfs2_read_quota_phys_block(struct inode *inode, u64 p_block,
                                 struct buffer_head **bh);
 int ocfs2_create_local_dquot(struct dquot *dquot);
 int ocfs2_local_release_dquot(handle_t *handle, struct dquot *dquot);
+int ocfs2_local_write_dquot(struct dquot *dquot);
 
 extern const struct dquot_operations ocfs2_quota_operations;
 extern struct quota_format_type ocfs2_quota_format;
diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index 734995823740..2bb35fe00511 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -612,14 +612,13 @@ static int ocfs2_sync_dquot_helper(struct dquot *dquot, unsigned long type)
         }
         mutex_lock(&sb_dqopt(sb)->dqio_mutex);
         status = ocfs2_sync_dquot(dquot);
-        mutex_unlock(&sb_dqopt(sb)->dqio_mutex);
         if (status < 0)
                 mlog_errno(status);
         /* We have to write local structure as well... */
-        dquot_mark_dquot_dirty(dquot);
-        status = dquot_commit(dquot);
+        status = ocfs2_local_write_dquot(dquot);
         if (status < 0)
                 mlog_errno(status);
+        mutex_unlock(&sb_dqopt(sb)->dqio_mutex);
         ocfs2_commit_trans(osb, handle);
 out_ilock:
         ocfs2_unlock_global_qf(oinfo, 1);
@@ -658,7 +657,9 @@ static int ocfs2_write_dquot(struct dquot *dquot)
                 mlog_errno(status);
                 goto out;
         }
-        status = dquot_commit(dquot);
+        mutex_lock(&sb_dqopt(dquot->dq_sb)->dqio_mutex);
+        status = ocfs2_local_write_dquot(dquot);
+        mutex_unlock(&sb_dqopt(dquot->dq_sb)->dqio_mutex);
         ocfs2_commit_trans(osb, handle);
 out:
         mlog_exit(status);
@@ -831,7 +832,6 @@ static int ocfs2_mark_dquot_dirty(struct dquot *dquot)
         struct ocfs2_super *osb = OCFS2_SB(sb);
 
         mlog_entry("id=%u, type=%d", dquot->dq_id, type);
-        dquot_mark_dquot_dirty(dquot);
 
         /* In case user set some limits, sync dquot immediately to global
          * quota file so that information propagates quicker */
@@ -856,14 +856,14 @@ static int ocfs2_mark_dquot_dirty(struct dquot *dquot)
         }
         mutex_lock(&sb_dqopt(sb)->dqio_mutex);
         status = ocfs2_sync_dquot(dquot);
-        mutex_unlock(&sb_dqopt(sb)->dqio_mutex);
         if (status < 0) {
                 mlog_errno(status);
-                goto out_trans;
+                goto out_dlock;
         }
         /* Now write updated local dquot structure */
-        status = dquot_commit(dquot);
-out_trans:
+        status = ocfs2_local_write_dquot(dquot);
+out_dlock:
+        mutex_unlock(&sb_dqopt(sb)->dqio_mutex);
         ocfs2_commit_trans(osb, handle);
 out_ilock:
         ocfs2_unlock_global_qf(oinfo, 1);
@@ -915,7 +915,7 @@ static void ocfs2_destroy_dquot(struct dquot *dquot)
 }
 
 const struct dquot_operations ocfs2_quota_operations = {
-        .write_dquot    = ocfs2_write_dquot,
+        /* We never make dquot dirty so .write_dquot is never called */
         .acquire_dquot  = ocfs2_acquire_dquot,
         .release_dquot  = ocfs2_release_dquot,
         .mark_dirty     = ocfs2_mark_dquot_dirty,
diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
index 778947f0e951..551a6bff9f2c 100644
--- a/fs/ocfs2/quota_local.c
+++ b/fs/ocfs2/quota_local.c
@@ -892,7 +892,7 @@ static void olq_set_dquot(struct buffer_head *bh, void *private)
 }
 
 /* Write dquot to local quota file */
-static int ocfs2_local_write_dquot(struct dquot *dquot)
+int ocfs2_local_write_dquot(struct dquot *dquot)
 {
         struct super_block *sb = dquot->dq_sb;
         struct ocfs2_dquot *od = OCFS2_DQUOT(dquot);
@@ -1309,7 +1309,6 @@ static const struct quota_format_ops ocfs2_format_ops = {
         .read_file_info         = ocfs2_local_read_info,
         .write_file_info        = ocfs2_global_write_info,
         .free_file_info         = ocfs2_local_free_info,
-        .commit_dqblk           = ocfs2_local_write_dquot,
 };
 
 struct quota_format_type ocfs2_quota_format = {