[GFS2] Fix change nlink deadlock

Bugzilla 215088

Fix deadlock in gfs2_change_nlink() while installing RHEL5 into GFS2
partition. The gfs2_rename() apparently needs block allocation for the
new name (into the directory) where it requires rg locks. At the same
time, while updating the nlink count for the replaced file,
gfs2_change_nlink() tries to return the inode meta-data back to resource
group where it needs rg locks too. Our logic doesn't allow process to
acquire these locks recursively by the same process  (RHEL installer)
that results a BUG call. This only happens within rename code path and
only if the destination file exists before the rename operation.
Signed-off-by: NS. Wendy Cheng <wcheng@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

fs/gfs2/inode.c

@@ -281,16 +281,14 @@ int gfs2_dinode_dealloc(struct gfs2_inode *ip)
 }
 
 /**
- * gfs2_change_nlink - Change nlink count on inode
+ * gfs2_change_nlink_i - Change nlink count on inode
  * @ip: The GFS2 inode
  * @diff: The change in the nlink count required
  *
  * Returns: errno
  */
-
-int gfs2_change_nlink(struct gfs2_inode *ip, int diff)
+int gfs2_change_nlink_i(struct gfs2_inode *ip, int diff)
 {
-	struct gfs2_sbd *sdp = ip->i_inode.i_sb->s_fs_info;
 	struct buffer_head *dibh;
 	u32 nlink;
 	int error;
@@ -322,6 +320,20 @@ int gfs2_change_nlink(struct gfs2_inode *ip, int diff)
 	brelse(dibh);
 	mark_inode_dirty(&ip->i_inode);
 
+	return error;
+}
+
+int gfs2_change_nlink(struct gfs2_inode *ip, int diff)
+{
+	struct gfs2_sbd *sdp = ip->i_inode.i_sb->s_fs_info;
+	int error;
+
+	/* update the nlink */
+	error = gfs2_change_nlink_i(ip, diff);
+	if (error)
+		return error;
+
+	/* return meta data block back to rg */
 	if (ip->i_inode.i_nlink == 0) {
 		struct gfs2_rgrpd *rgd;
 		struct gfs2_holder ri_gh, rg_gh;

fs/gfs2/inode.h

@@ -40,6 +40,7 @@ int gfs2_inode_refresh(struct gfs2_inode *ip);
 
 int gfs2_dinode_dealloc(struct gfs2_inode *inode);
 int gfs2_change_nlink(struct gfs2_inode *ip, int diff);
+int gfs2_change_nlink_i(struct gfs2_inode *ip, int diff);
 struct inode *gfs2_lookupi(struct inode *dir, const struct qstr *name,
 			   int is_root, struct nameidata *nd);
 struct inode *gfs2_createi(struct gfs2_holder *ghs, const struct qstr *name,

fs/gfs2/ops_inode.c

@@ -553,6 +553,7 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
 	int alloc_required;
 	unsigned int x;
 	int error;
+	struct gfs2_rgrpd *rgd;
 
 	if (ndentry->d_inode) {
 		nip = GFS2_I(ndentry->d_inode);
@@ -684,12 +685,12 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
 		error = gfs2_trans_begin(sdp, sdp->sd_max_dirres +
 					 al->al_rgd->rd_ri.ri_length +
 					 4 * RES_DINODE + 4 * RES_LEAF +
-					 RES_STATFS + RES_QUOTA, 0);
+					 RES_STATFS + RES_QUOTA + 1, 0);
 		if (error)
 			goto out_ipreserv;
 	} else {
 		error = gfs2_trans_begin(sdp, 4 * RES_DINODE +
-					 5 * RES_LEAF, 0);
+					 5 * RES_LEAF + 1, 0);
 		if (error)
 			goto out_gunlock;
 	}
@@ -703,7 +704,25 @@ static int gfs2_rename(struct inode *odir, struct dentry *odentry,
 			error = gfs2_dir_del(ndip, &ndentry->d_name);
 			if (error)
 				goto out_end_trans;
-			error = gfs2_change_nlink(nip, -1);
+			error = gfs2_change_nlink_i(nip, -1);
+			if ((!error) && (nip->i_inode.i_nlink == 0)) {
+				error = -EIO;
+				rgd = gfs2_blk2rgrpd(sdp, nip->i_num.no_addr);
+				if (rgd) {
+					struct gfs2_holder nlink_rg_gh;
+					if (rgd != nip->i_alloc.al_rgd)
+						error = gfs2_glock_nq_init(
+						rgd->rd_gl, LM_ST_EXCLUSIVE,
+						0, &nlink_rg_gh);
+					else
+						error = 0;
+                			if (!error) {
+						gfs2_unlink_di(&nip->i_inode);
+						if (rgd != nip->i_alloc.al_rgd)
+							gfs2_glock_dq_uninit(&nlink_rg_gh);
+					}
+				}
+			}
 		}
 		if (error)
 			goto out_end_trans;