In my testing, the second mount will fail after umounting successfully.
The reason is that we put refcount of trans_mod in the correct case
rather than the error case in parse_opts() at last. That will cause the
refcount decrease to -1, and when we try to get trans_mod again in
try_module_get(), we could only increase refcount to 0 which will cause
failure as follows:
parse_opts
v9fs_get_trans_by_name
try_module_get : return NULL to caller which cause error
So we should put refcount of trans_mod in error case.
Link: http://lkml.kernel.org/r/5B3F39A0.2030509@huawei.com
Fixes: 9421c3e64137ec ("net/9p/client.c: fix potential refcnt problem of trans module")
Signed-off-by: Jun Piao <piaojun@huawei.com>
Reviewed-by: Yiwen Jiang <jiangyiwen@huawei.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Dominique Martinet <dominique.martinet@cea.fr>
Tested-by: Dominique Martinet <dominique.martinet@cea.fr>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
c290fba8c4