4.9-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 594d1644cd59447f4fceb592448d5cd09eb09b5e ]
This patch removes the check from nfs_compare_mount_options to see if a `sec' option was passed for the current mount before comparing auth flavors and instead just always compares auth flavors.
Consider the following scenario:
You have a server with the address 192.168.1.1 and two exports /export/a and /export/b. The first export supports `sys' and `krb5' security, the second just `sys'.
Assume you start with no mounts from the server.
The following results in EIOs being returned as the kernel nfs client incorrectly thinks it can share the underlying `struct nfs_server's:
$ mkdir /tmp/{a,b} $ sudo mount -t nfs -o vers=3,sec=krb5 192.168.1.1:/export/a /tmp/a $ sudo mount -t nfs -o vers=3 192.168.1.1:/export/b /tmp/b $ df >/dev/null df: ‘/tmp/b’: Input/output error
Signed-off-by: Chris Perl cperl@janestreet.com Signed-off-by: Anna Schumaker Anna.Schumaker@Netapp.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfs/super.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/nfs/super.c b/fs/nfs/super.c index 2fdb8f5a7b69..35aef192a13f 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -2403,8 +2403,7 @@ static int nfs_compare_mount_options(const struct super_block *s, const struct n goto Ebusy; if (a->acdirmax != b->acdirmax) goto Ebusy; - if (b->auth_info.flavor_len > 0 && - clnt_a->cl_auth->au_flavor != clnt_b->cl_auth->au_flavor) + if (clnt_a->cl_auth->au_flavor != clnt_b->cl_auth->au_flavor) goto Ebusy; return 1; Ebusy: