[Cluster-devel] [GFS2 PATCH] GFS2: Temporarily zero i_no_addr when creating a dinode

[Cluster-devel] [GFS2 PATCH] GFS2: Temporarily zero i_no_addr when creating a dinode

[Bob Peterson]

Hi,

Before this patch i_no_addr was not initialized until after the
return from allocating its block. That meant the i_no_addr was
temporarily uninitialized storage. Ordinarily that's not a concern,
but if inplace_reserve can't find space, it can call try_rgrp_unlink
which references i_no_addr as a block to avoid. That can result in
unpredictable behavior. More importantly, the trace point in
gfs2_alloc_blocks references ip->i_no_addr before it is set, which
is misleading when reading the kernel traces. This patch makes it
look like the new dinode block was assigned in the name of inode 0
rather than a random inode that's completely unrelated.

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

diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
index e279c3c..4f405d4 100644
--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -667,6 +667,7 @@ static int gfs2_create_inode(struct inode *dir, struct dentry *dentry,
 	ip->i_height = 0;
 	ip->i_depth = 0;
 	ip->i_entries = 0;
+	ip->i_no_addr = 0; /* Temporarily zero until real addr is assigned */
 
 	switch(mode & S_IFMT) {
 	case S_IFREG: