GFS2: Check rs_free with rd_rsspin protection

Hi,

For the last process to close a file opened for write, function gfs2_rsqa_delete was deleting the file's inode's block reservation out of the rgrp reservations tree. Then it was checking to make sure rs_free was 0, but it was performing the check outside the protection of rd_rsspin spin_lock. The rd_rsspin spin_lock protection is needed to prevent a race between the process freeing the reservation and another who is allocating a new set of blocks inside the same rgrp for the same inode, thus changing its value.

Signed-off-by Bob Peterson <[email protected]>

Regards,

Bob Peterson
Red Hat File Systems
---

fs/gfs2/rgrp.c +2 -3

index fba38ca..86ccc015 100644
@@ -658,6 +658,7 @@ void gfs2_rs_deltree(struct gfs2_blkreserv *rs)
  	if (rgd) {
  		spin_lock(&rgd->rd_rsspin);
  		__rs_deltree(rs);
+		BUG_ON(rs->rs_free);
  		spin_unlock(&rgd->rd_rsspin);
  	}
  }

@@ -671,10 +672,8 @@ void gfs2_rs_deltree(struct gfs2_blkreserv *rs)
  void gfs2_rsqa_delete(struct gfs2_inode *ip, atomic_t *wcount)
  {
  	down_write(&ip->i_rw_mutex);
-	if ((wcount == NULL) || (atomic_read(wcount) <= 1)) {
+	if ((wcount == NULL) || (atomic_read(wcount) <= 1))
  		gfs2_rs_deltree(&ip->i_res);
-		BUG_ON(ip->i_res.rs_free);
-	}
  	up_write(&ip->i_rw_mutex);
  	gfs2_qa_delete(ip, wcount);
  }