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, 8 insertions, 4 deletions

diff --git a/fs/gfs2/xattr.c b/fs/gfs2/xattr.c
index c4fbb96e001f..9d7667bc4292 100644
--- a/fs/gfs2/xattr.c
+++ b/fs/gfs2/xattr.c
@@ -1222,7 +1222,7 @@ static int gfs2_xattr_set(const struct xattr_handler *handler,
 	struct gfs2_holder gh;
 	int ret;
 
-	ret = gfs2_qa_alloc(ip);
+	ret = gfs2_qa_get(ip);
 	if (ret)
 		return ret;
 
@@ -1231,15 +1231,19 @@ static int gfs2_xattr_set(const struct xattr_handler *handler,
 	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;
 	} else {
-		if (WARN_ON_ONCE(ip->i_gl->gl_state != LM_ST_EXCLUSIVE))
-			return -EIO;
+		if (WARN_ON_ONCE(ip->i_gl->gl_state != LM_ST_EXCLUSIVE)) {
+			ret = -EIO;
+			goto out;
+		}
 		gfs2_holder_mark_uninitialized(&gh);
 	}
 	ret = __gfs2_xattr_set(inode, name, value, size, flags, handler->flags);
 	if (gfs2_holder_initialized(&gh))
 		gfs2_glock_dq_uninit(&gh);
+out:
+	gfs2_qa_put(ip);
 	return ret;
 }