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[Cluster-devel] [PATCH] 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.

Patch passed a simulated test program created for this issue yesterday - havn't really tried it out on installer yet. Will continue to installer test today. Pass it up for a quick eyeball examine.

-- Wendy
--- linux-2.6.18/fs/gfs2/inode.h	2006-11-27 15:34:45.000000000 -0500
+++ linux/fs/gfs2/inode.h	2006-12-15 02:45:16.000000000 -0500
@@ -34,6 +34,7 @@ int gfs2_inode_refresh(struct gfs2_inode
 
 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,
--- linux-2.6.18/fs/gfs2/inode.c	2006-11-27 15:34:45.000000000 -0500
+++ linux/fs/gfs2/inode.c	2006-12-15 02:59:54.000000000 -0500
@@ -300,16 +300,14 @@ out:
 }
 
 /**
- * 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;
@@ -338,6 +336,20 @@ int gfs2_change_nlink(struct gfs2_inode 
 	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_di.di_nlink == 0) {
 		struct gfs2_rgrpd *rgd;
 		struct gfs2_holder ri_gh, rg_gh;
--- linux-2.6.18/fs/gfs2/ops_inode.c	2006-11-27 15:34:45.000000000 -0500
+++ linux/fs/gfs2/ops_inode.c	2006-12-15 02:54:09.000000000 -0500
@@ -716,12 +716,12 @@ static int gfs2_rename(struct inode *odi
 		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;
 	}
@@ -735,7 +735,9 @@ static int gfs2_rename(struct inode *odi
 			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)
+				gfs2_unlink_di(&nip->i_inode);
 		}
 		if (error)
 			goto out_end_trans;

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