reiserfs: Fix lock ordering during remount

commit 3bb3e1fc47aca554e7e2cc4deeddc24750987ac2 upstream.

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.

Signed-off-by: Jan Kara <jack@suse.cz>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 5e3527be11468b9ea29cadc87ebba7a96e404310..ea5ffc64d7f65a515d170412d3731dae0616ec19 100644 (file)
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -1207,7 +1207,7 @@ 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);
@@ -1250,7 +1250,7 @@ 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) {
@@ -1260,9 +1260,15 @@ 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
@@ -1272,7 +1278,7 @@ 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);
@@ -1287,7 +1293,7 @@ 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);
@@ -1296,7 +1302,7 @@ 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);
@@ -1313,11 +1319,17 @@ 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;
        s->s_dirt = 0;
 
        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);
        }
@@ -1327,9 +1339,10 @@ 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;
 }