ceph: use correct index when encoding client supported features

commit fea013e020e6ecc7be75bea0d61697b7e916b44d upstream.

Feature bits have to be encoded into the correct locations.  This hasn't
been an issue so far because the only hole in the feature bits was in bit
10 (CEPHFS_FEATURE_RECLAIM_CLIENT), which is located in the 2nd byte.  When
adding more bits that go beyond the this 2nd byte, the bug will show up.

[xiubli: remove incorrect comment for CEPHFS_FEATURES_CLIENT_SUPPORTED]

Fixes: 9ba1e224538a ("ceph: allocate the correct amount of extra bytes for the session features")
Signed-off-by: Luís Henriques <lhenriques@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 33f517d549ce521e8725a436ffde55be2e2e4788..0aded10375fdd79c0a42f9287b83d4c5d8bd1b22 100644 (file)
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1220,14 +1220,17 @@ static int encode_supported_features(void **p, void *end)
        if (count > 0) {
                size_t i;
                size_t size = FEATURE_BYTES(count);
+               unsigned long bit;
 
                if (WARN_ON_ONCE(*p + 4 + size > end))
                        return -ERANGE;
 
                ceph_encode_32(p, size);
                memset(*p, 0, size);
-               for (i = 0; i < count; i++)
-                       ((unsigned char*)(*p))[i / 8] |= BIT(feature_bits[i] % 8);
+               for (i = 0; i < count; i++) {
+                       bit = feature_bits[i];
+                       ((unsigned char *)(*p))[bit / 8] |= BIT(bit % 8);
+               }
                *p += size;
        } else {
                if (WARN_ON_ONCE(*p + 4 > end))

diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index 1140aecd82ce427ccefed070f479e24a527946ae..2a49e331987becb802a8018e3865306c4a2f19a1 100644 (file)
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -33,10 +33,6 @@ enum ceph_feature_type {
        CEPHFS_FEATURE_MAX = CEPHFS_FEATURE_METRIC_COLLECT,
 };
 
-/*
- * This will always have the highest feature bit value
- * as the last element of the array.
- */
 #define CEPHFS_FEATURES_CLIENT_SUPPORTED {     \
        0, 1, 2, 3, 4, 5, 6, 7,                 \
        CEPHFS_FEATURE_MIMIC,                   \
@@ -45,8 +41,6 @@ enum ceph_feature_type {
        CEPHFS_FEATURE_MULTI_RECONNECT,         \
        CEPHFS_FEATURE_DELEG_INO,               \
        CEPHFS_FEATURE_METRIC_COLLECT,          \
-                                               \
-       CEPHFS_FEATURE_MAX,                     \
 }
 #define CEPHFS_FEATURES_CLIENT_REQUIRED {}