ext4: support freezing ext2 (nojournal) file systems

Through an oversight, when we added nojournal support to ext4, we
didn't add support to allow file system freezing.  This is relatively
easy to add, so let's do it.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reported-by: Dexuan Cui <decui@microsoft.com>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 4770c98bdb6115381314708893e8fd96a293a5ee..4db537b3a16262a6ab14d0c29bb0627785818ea6 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1131,6 +1131,8 @@ static const struct super_operations ext4_nojournal_sops = {
        .drop_inode     = ext4_drop_inode,
        .evict_inode    = ext4_evict_inode,
        .sync_fs        = ext4_sync_fs,
+       .freeze_fs      = ext4_freeze,
+       .unfreeze_fs    = ext4_unfreeze,
        .put_super      = ext4_put_super,
        .statfs         = ext4_statfs,
        .remount_fs     = ext4_remount,
@@ -4758,23 +4760,26 @@ static int ext4_freeze(struct super_block *sb)
 
        journal = EXT4_SB(sb)->s_journal;
 
-       /* Now we set up the journal barrier. */
-       jbd2_journal_lock_updates(journal);
+       if (journal) {
+               /* Now we set up the journal barrier. */
+               jbd2_journal_lock_updates(journal);
 
-       /*
-        * Don't clear the needs_recovery flag if we failed to flush
-        * the journal.
-        */
-       error = jbd2_journal_flush(journal);
-       if (error < 0)
-               goto out;
+               /*
+                * Don't clear the needs_recovery flag if we failed to
+                * flush the journal.
+                */
+               error = jbd2_journal_flush(journal);
+               if (error < 0)
+                       goto out;
+       }
 
        /* Journal blocked and flushed, clear needs_recovery flag. */
        EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
        error = ext4_commit_super(sb, 1);
 out:
-       /* we rely on upper layer to stop further updates */
-       jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
+       if (journal)
+               /* we rely on upper layer to stop further updates */
+               jbd2_journal_unlock_updates(journal);
        return error;
 }