ceph: use correct index when encoding client supported features

stable inclusion
from stable-v5.10.138
commit 97cea2cb7c861f9c2f7870c6068c1131f59311ae
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I60QFD

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=97cea2cb7c861f9c2f7870c6068c1131f59311ae

--------------------------------

commit fea013e0 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: 9ba1e224 ("ceph: allocate the correct amount of extra bytes for the session features")
Signed-off-by: NLuís Henriques <lhenriques@suse.de>
Reviewed-by: NJeff Layton <jlayton@kernel.org>
Signed-off-by: NXiubo Li <xiubli@redhat.com>
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>

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))

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 {}