[Cluster-devel] [PATCH 2/4] GFS2: Set gl_object in inode lookup only after block type check

[Bob Peterson <rpeterso@redhat.com>]

Before this patch, the inode glock's gl_object was set after a
reference was acquired, but before the block type was verified.
In cases where the block was unlinked, then freed and reused on
another node, a residule delete callback (delete_work) would try
to look up the inode, eventually failing the block check, but
only after it overwrites gl_object with a pointer to the wrong
inode. This patch moves the assignment of gl_object after the
block check so it won't be improperly overwritten.

Likewise, at the end of the function, gfs2_inode_lookup was
clearing gl_object, even in cases where it wasn't set, such as
when the block type check fails. The patch only clears it if
actually set it.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
 fs/gfs2/inode.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index 608e4bf60754..69f66e83920a 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -145,7 +145,6 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 		if (unlikely(error))
 			goto fail;
 		flush_delayed_work(&ip->i_gl->gl_work);
-		glock_set_object(ip->i_gl, ip);
 
 		error = gfs2_glock_get(sdp, no_addr, &gfs2_iopen_glops, CREATE, &io_gl);
 		if (unlikely(error))
@@ -170,6 +169,7 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 			}
 		}
 
+		glock_set_object(ip->i_gl, ip);
 		set_bit(GIF_INVALID, &ip->i_flags);
 		error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT, &ip->i_iopen_gh);
 		if (unlikely(error))
@@ -207,9 +207,10 @@ struct inode *gfs2_inode_lookup(struct super_block *sb, unsigned int type,
 fail_put:
 	if (io_gl)
 		gfs2_glock_put(io_gl);
-	if (gfs2_holder_initialized(&i_gh))
+	if (gfs2_holder_initialized(&i_gh)) {
+		glock_clear_object(ip->i_gl, ip);
 		gfs2_glock_dq_uninit(&i_gh);
-	glock_clear_object(ip->i_gl, ip);
+	}
 fail:
 	iget_failed(inode);
 	return ERR_PTR(error);
-- 
2.13.3