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, 4 insertions, 2 deletions

diff --git a/fs/gfs2/acl.c b/fs/gfs2/acl.c
index cb09b85c5b10..2e939f5fe751 100644
--- a/fs/gfs2/acl.c
+++ b/fs/gfs2/acl.c
@@ -117,14 +117,14 @@ int gfs2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 	if (acl && acl->a_count > GFS2_ACL_MAX_ENTRIES(GFS2_SB(inode)))
 		return -E2BIG;
 
-	ret = gfs2_qa_alloc(ip);
+	ret = gfs2_qa_get(ip);
 	if (ret)
 		return ret;
 
 	if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
 		ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
 		if (ret)
-			return ret;
+			goto out;
 		need_unlock = true;
 	}
 
@@ -144,5 +144,7 @@ int gfs2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 unlock:
 	if (need_unlock)
 		gfs2_glock_dq_uninit(&gh);
+out:
+	gfs2_qa_put(ip);
 	return ret;
 }