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 981a915906314b6c259879210e6da65140934ff7..6859967df2b192cdb4864e058add3e38cda9dabe 100644 (file)
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1184,14 +1184,17 @@ 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 f5adbebcb38e5ca53508afd03f4622fb838ae55c..acf33d7192bb6e61267063fa54d7d8c4cb9219e1 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 {}