[Cluster-devel] [GFS2 PATCH v2] GFS2: Check if iopen is held when deleting inode

[Bob Peterson <rpeterso@redhat.com>]

Hi,

On 18 December 2015, I posted this upstream GFS2 patch. Since that time,
I discovered a bug that warrants expanding the scope of the patch.
This is the revised patch.

Patch description:

GFS2: Check if iopen is held when deleting inode

This patch fixes an error condition in which an inode is partially
created in gfs2_create_inode() but then some error is discovered,
which causes it to fail and call iput() before the iopen glock is
created or held. In that case, gfs2_delete_inode would try to
unlock an iopen glock that doesn't yet exist. Therefore, we test
its holder (which must exist) for the HIF_HOLDER bit before trying
to dq it.

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

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 795c2f3..8dedece 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1015,6 +1015,7 @@ void gfs2_glock_dq(struct gfs2_holder *gh)
 		handle_callback(gl, LM_ST_UNLOCKED, 0, false);
 
 	list_del_init(&gh->gh_list);
+	clear_bit(HIF_HOLDER, &gh->gh_iflags);
 	if (find_first_holder(gl) == NULL) {
 		if (glops->go_unlock) {
 			GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 8f960a5..f8a0cd8 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1551,12 +1551,16 @@ static void gfs2_evict_inode(struct inode *inode)
 			goto out_truncate;
 	}
 
-	ip->i_iopen_gh.gh_flags |= GL_NOCACHE;
-	gfs2_glock_dq_wait(&ip->i_iopen_gh);
-	gfs2_holder_reinit(LM_ST_EXCLUSIVE, LM_FLAG_TRY_1CB | GL_NOCACHE, &ip->i_iopen_gh);
-	error = gfs2_glock_nq(&ip->i_iopen_gh);
-	if (error)
-		goto out_truncate;
+	if (ip->i_iopen_gh.gh_gl &&
+	    test_bit(HIF_HOLDER, &ip->i_iopen_gh.gh_iflags)) {
+		ip->i_iopen_gh.gh_flags |= GL_NOCACHE;
+		gfs2_glock_dq_wait(&ip->i_iopen_gh);
+		gfs2_holder_reinit(LM_ST_EXCLUSIVE, LM_FLAG_TRY_1CB | GL_NOCACHE,
+				   &ip->i_iopen_gh);
+		error = gfs2_glock_nq(&ip->i_iopen_gh);
+		if (error)
+			goto out_truncate;
+	}
 
 	/* Case 1 starts here */
 
@@ -1606,11 +1610,13 @@ out_unlock:
 	if (gfs2_rs_active(&ip->i_res))
 		gfs2_rs_deltree(&ip->i_res);
 
-	if (test_bit(HIF_HOLDER, &ip->i_iopen_gh.gh_iflags)) {
-		ip->i_iopen_gh.gh_flags |= GL_NOCACHE;
-		gfs2_glock_dq_wait(&ip->i_iopen_gh);
+	if (ip->i_iopen_gh.gh_gl) {
+		if (test_bit(HIF_HOLDER, &ip->i_iopen_gh.gh_iflags)) {
+			ip->i_iopen_gh.gh_flags |= GL_NOCACHE;
+			gfs2_glock_dq_wait(&ip->i_iopen_gh);
+		}
+		gfs2_holder_uninit(&ip->i_iopen_gh);
 	}
-	gfs2_holder_uninit(&ip->i_iopen_gh);
 	gfs2_glock_dq_uninit(&gh);
 	if (error && error != GLR_TRYFAILED && error != -EROFS)
 		fs_warn(sdp, "gfs2_evict_inode: %d\n", error);