gfs2: Switch lock order of inode and iopen glock

This patch tries to fix the continual ABBA deadlocks we keep having
between the iopen and inode glocks. This switches the lock order in
gfs2_inode_lookup and gfs2_create_inode so the iopen glock is always
locked first.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

Author: Andreas Gruenbacher

fs/gfs2/inode.c

@@ -131,7 +131,21 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 		struct gfs2_sbd *sdp = GFS2_SB(inode);
 		struct gfs2_glock *io_gl;
 
-		error = gfs2_glock_get(sdp, no_addr, &gfs2_inode_glops, CREATE, &ip->i_gl);
+		error = gfs2_glock_get(sdp, no_addr, &gfs2_inode_glops, CREATE,
+				       &ip->i_gl);
+		if (unlikely(error))
+			goto fail;
+
+		error = gfs2_glock_get(sdp, no_addr, &gfs2_iopen_glops, CREATE,
+				       &io_gl);
+		if (unlikely(error))
+			goto fail;
+
+		if (blktype != GFS2_BLKST_UNLINKED)
+			gfs2_cancel_delete_work(io_gl);
+		error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT,
+					   &ip->i_iopen_gh);
+		gfs2_glock_put(io_gl);
 		if (unlikely(error))
 			goto fail;
 
@@ -161,16 +175,6 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 
 		set_bit(GLF_INSTANTIATE_NEEDED, &ip->i_gl->gl_flags);
 
-		error = gfs2_glock_get(sdp, no_addr, &gfs2_iopen_glops, CREATE, &io_gl);
-		if (unlikely(error))
-			goto fail;
-		if (blktype != GFS2_BLKST_UNLINKED)
-			gfs2_cancel_delete_work(io_gl);
-		error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT, &ip->i_iopen_gh);
-		gfs2_glock_put(io_gl);
-		if (unlikely(error))
-			goto fail;
-
 		/* Lowest possible timestamp; will be overwritten in gfs2_dinode_in. */
 		inode->i_atime.tv_sec = 1LL << (8 * sizeof(inode->i_atime.tv_sec) - 1);
 		inode->i_atime.tv_nsec = 0;
@@ -716,13 +720,17 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	error = insert_inode_locked4(inode, ip->i_no_addr, iget_test, &ip->i_no_addr);
 	BUG_ON(error);
 
-	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_SKIP, ghs + 1);
+	error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT, &ip->i_iopen_gh);
 	if (error)
 		goto fail_gunlock2;
 
+	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_SKIP, ghs + 1);
+	if (error)
+		goto fail_gunlock3;
+
 	error = gfs2_trans_begin(sdp, blocks, 0);
 	if (error)
-		goto fail_gunlock2;
+		goto fail_gunlock3;
 
 	if (blocks > 1) {
 		ip->i_eattr = ip->i_no_addr + 1;
@@ -731,10 +739,6 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	init_dinode(dip, ip, symname);
 	gfs2_trans_end(sdp);
 
-	error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT, &ip->i_iopen_gh);
-	if (error)
-		goto fail_gunlock2;
-
 	glock_set_object(ip->i_gl, ip);
 	glock_set_object(io_gl, ip);
 	gfs2_set_iop(inode);
@@ -745,26 +749,26 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	if (default_acl) {
 		error = __gfs2_set_acl(inode, default_acl, ACL_TYPE_DEFAULT);
 		if (error)
-			goto fail_gunlock3;
+			goto fail_gunlock4;
 		posix_acl_release(default_acl);
 		default_acl = NULL;
 	}
 	if (acl) {
 		error = __gfs2_set_acl(inode, acl, ACL_TYPE_ACCESS);
 		if (error)
-			goto fail_gunlock3;
+			goto fail_gunlock4;
 		posix_acl_release(acl);
 		acl = NULL;
 	}
 
 	error = security_inode_init_security(&ip->i_inode, &dip->i_inode, name,
 					     &gfs2_initxattrs, NULL);
 	if (error)
-		goto fail_gunlock3;
+		goto fail_gunlock4;
 
 	error = link_dinode(dip, name, ip, &da);
 	if (error)
-		goto fail_gunlock3;
+		goto fail_gunlock4;
 
 	mark_inode_dirty(inode);
 	d_instantiate(dentry, inode);
@@ -782,9 +786,10 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	unlock_new_inode(inode);
 	return error;
 
-fail_gunlock3:
+fail_gunlock4:
 	glock_clear_object(ip->i_gl, ip);
 	glock_clear_object(io_gl, ip);
+fail_gunlock3:
 	gfs2_glock_dq_uninit(&ip->i_iopen_gh);
 fail_gunlock2:
 	gfs2_glock_put(io_gl);