ocfs2: Fix possible deadlock in ocfs2_write_dquot()

It could happen that some limit has been set via quotactl() and in parallel
->mark_dirty() is called from another thread doing e.g. dquot_alloc_space(). In
such case ocfs2_write_dquot() must not try to sync the dquot because that needs
global quota lock but that ranks above transaction start.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index f4efa89..1ed0f7c 100644 (file)
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -754,7 +754,9 @@ static int ocfs2_mark_dquot_dirty(struct dquot *dquot)
        if (dquot->dq_flags & mask)
                sync = 1;
        spin_unlock(&dq_data_lock);
-       if (!sync) {
+       /* This is a slight hack but we can't afford getting global quota
+        * lock if we already have a transaction started. */
+       if (!sync || journal_current_handle()) {
                status = ocfs2_write_dquot(dquot);
                goto out;
        }