reiserfs: Fix lock ordering during remount

When remounting reiserfs dquot_suspend() or dquot_resume() can be called.
These functions take dqonoff_mutex which ranks above write lock so we have
to drop it before calling into quota code.

CC: stable@vger.kernel.org # >= 3.0
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 20 insertions, 7 deletions

diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 1078ae179993..5372980ec458 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -1335,7 +1335,7 @@ static int reiserfs_remount(struct super_block *s, int *mount_flags, char *arg)
                                 kfree(qf_names[i]);
 #endif
                 err = -EINVAL;
-                goto out_err;
+                goto out_unlock;
         }
 #ifdef CONFIG_QUOTA
         handle_quota_files(s, qf_names, &qfmt);
@@ -1379,7 +1379,7 @@ static int reiserfs_remount(struct super_block *s, int *mount_flags, char *arg)
         if (blocks) {
                 err = reiserfs_resize(s, blocks);
                 if (err != 0)
-                        goto out_err;
+                        goto out_unlock;
         }
 
         if (*mount_flags & MS_RDONLY) {
@@ -1389,9 +1389,15 @@ static int reiserfs_remount(struct super_block *s, int *mount_flags, char *arg)
                         /* it is read-only already */
                         goto out_ok;
 
+                /*
+                 * Drop write lock. Quota will retake it when needed and lock
+                 * ordering requires calling dquot_suspend() without it.
+                 */
+                reiserfs_write_unlock(s);
                 err = dquot_suspend(s, -1);
                 if (err < 0)
                         goto out_err;
+                reiserfs_write_lock(s);
 
                 /* try to remount file system with read-only permissions */
                 if (sb_umount_state(rs) == REISERFS_VALID_FS
@@ -1401,7 +1407,7 @@ static int reiserfs_remount(struct super_block *s, int *mount_flags, char *arg)
 
                 err = journal_begin(&th, s, 10);
                 if (err)
-                        goto out_err;
+                        goto out_unlock;
 
                 /* Mounting a rw partition read-only. */
                 reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s), 1);
@@ -1416,7 +1422,7 @@ static int reiserfs_remount(struct super_block *s, int *mount_flags, char *arg)
 
                 if (reiserfs_is_journal_aborted(journal)) {
                         err = journal->j_errno;
-                        goto out_err;
+                        goto out_unlock;
                 }
 
                 handle_data_mode(s, mount_options);
@@ -1425,7 +1431,7 @@ static int reiserfs_remount(struct super_block *s, int *mount_flags, char *arg)
                 s->s_flags &= ~MS_RDONLY;       /* now it is safe to call journal_begin */
                 err = journal_begin(&th, s, 10);
                 if (err)
-                        goto out_err;
+                        goto out_unlock;
 
                 /* Mount a partition which is read-only, read-write */
                 reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s), 1);
@@ -1442,10 +1448,16 @@ static int reiserfs_remount(struct super_block *s, int *mount_flags, char *arg)
         SB_JOURNAL(s)->j_must_wait = 1;
         err = journal_end(&th, s, 10);
         if (err)
-                goto out_err;
+                goto out_unlock;
 
         if (!(*mount_flags & MS_RDONLY)) {
+                /*
+                 * Drop write lock. Quota will retake it when needed and lock
+                 * ordering requires calling dquot_resume() without it.
+                 */
+                reiserfs_write_unlock(s);
                 dquot_resume(s, -1);
+                reiserfs_write_lock(s);
                 finish_unfinished(s);
                 reiserfs_xattr_init(s, *mount_flags);
         }
@@ -1455,9 +1467,10 @@ out_ok:
         reiserfs_write_unlock(s);
         return 0;
 
+out_unlock:
+        reiserfs_write_unlock(s);
 out_err:
         kfree(new_opts);
-        reiserfs_write_unlock(s);
         return err;
 }