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authorTejun Heo <tj@kernel.org>2015-06-08 14:57:31 +0900
committerJens Axboe <axboe@fb.com>2015-06-08 09:05:06 -0600
commit412a19b64ad17f7650ff778fd2cb9032938cf71f (patch)
treedfee77d911dc3814dd3b453977ee3e8183bcb50e /fs/9p/vfs_super.c
parent5857cd637bc0d60dc7e37af396b01324f199d89b (diff)
v9fs: fix error handling in v9fs_session_init()
On failure, v9fs_session_init() returns with the v9fs_session_info struct partially initialized and expects the caller to invoke v9fs_session_close() to clean it up; however, it doesn't track whether the bdi is initialized or not and curiously invokes bdi_destroy() in both vfs_session_init() failure path too. A. If v9fs_session_init() fails before the bdi is initialized, the follow-up v9fs_session_close() will invoke bdi_destroy() on an uninitialized bdi. B. If v9fs_session_init() fails after the bdi is initialized, bdi_destroy() will be called twice on the same bdi - once in the failure path of v9fs_session_init() and then by v9fs_session_close(). A is broken no matter what. B used to be okay because bdi_destroy() allowed being invoked multiple times on the same bdi, which BTW was broken in its own way - if bdi_destroy() was invoked on an initialiezd but !registered bdi, it'd fail to free percpu counters. Since f0054bb1e1f3 ("writeback: move backing_dev_info->wb_lock and ->worklist into bdi_writeback"), this no longer work - bdi_destroy() on an initialized but not registered bdi works correctly but multiple invocations of bdi_destroy() is no longer allowed. The obvious culprit here is v9fs_session_init()'s odd and broken error behavior. It should simply clean up after itself on failures. This patch makes the following updates to v9fs_session_init(). * @rc -> @retval error return propagation removed. It didn't serve any purpose. Just use @rc. * Move addition to v9fs_sessionlist to the end of the function so that incomplete sessions are not put on the list or iterated and error path doesn't have to worry about it. * Update error handling so that it cleans up after itself. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs/9p/vfs_super.c')
-rw-r--r--fs/9p/vfs_super.c8
1 files changed, 2 insertions, 6 deletions
diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index e99a338a4638..bf495cedec26 100644
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -130,11 +130,7 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
fid = v9fs_session_init(v9ses, dev_name, data);
if (IS_ERR(fid)) {
retval = PTR_ERR(fid);
- /*
- * we need to call session_close to tear down some
- * of the data structure setup by session_init
- */
- goto close_session;
+ goto free_session;
}
sb = sget(fs_type, NULL, v9fs_set_super, flags, v9ses);
@@ -195,8 +191,8 @@ static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
clunk_fid:
p9_client_clunk(fid);
-close_session:
v9fs_session_close(v9ses);
+free_session:
kfree(v9ses);
return ERR_PTR(retval);