gfs2: Change inode qa_data to allow multiple users

Before this patch, multiple users called gfs2_qa_alloc which allocated
a qadata structure to the inode, if quotas are turned on. Later, in
file close or evict, the structure was deleted with gfs2_qa_delete.
But there can be several competing processes who need access to the
structure. There were races between file close (release) and the others.
Thus, a release could delete the structure out from under a process
that relied upon its existence. For example, chown.

This patch changes the management of the qadata structures to be
a get/put scheme. Function gfs2_qa_alloc has been changed to gfs2_qa_get
and if the structure is allocated, the count essentially starts out at
1. Function gfs2_qa_delete has been renamed to gfs2_qa_put, and the
last guy to decrement the count to 0 frees the memory.

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

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index a6bf8f1e083e..68d934fa0f9f 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1401,6 +1401,8 @@ out_unlock:
 		fs_warn(sdp, "gfs2_evict_inode: %d\n", error);
 out:
 	truncate_inode_pages_final(&inode->i_data);
+	if (ip->i_qadata)
+		gfs2_assert_warn(sdp, ip->i_qadata->qa_ref == 0);
 	gfs2_rsqa_delete(ip, NULL);
 	gfs2_ordered_del_inode(ip);
 	clear_inode(inode);