[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: S. Wendy Cheng <wcheng@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

3 files changed, 39 insertions, 7 deletions

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index d122074c45e1..6bc443644c3c 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -281,16 +281,14 @@ 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;
@@ -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;
diff --git a/fs/gfs2/inode.h b/fs/gfs2/inode.h
index b57f448b15bc..85c67cb568d1 100644
--- a/fs/gfs2/inode.h
+++ b/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,
diff --git a/fs/gfs2/ops_inode.c b/fs/gfs2/ops_inode.c
index 636dda4c7d38..919e8947e710 100644
--- a/fs/gfs2/ops_inode.c
+++ b/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;