2 files changed, 51 insertions, 9 deletions

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 8dbfca01c7ea..5b767cf1f780 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -902,6 +902,27 @@ static struct ceph_msg *create_session_msg(u32 op, u64 seq)
         return msg;
 }
 
+static void encode_supported_features(void **p, void *end)
+{
+        static const unsigned char bits[] = CEPHFS_FEATURES_CLIENT_SUPPORTED;
+        static const size_t count = ARRAY_SIZE(bits);
+
+        if (count > 0) {
+                size_t i;
+                size_t size = ((size_t)bits[count - 1] + 64) / 64 * 8;
+
+                BUG_ON(*p + 4 + size > end);
+                ceph_encode_32(p, size);
+                memset(*p, 0, size);
+                for (i = 0; i < count; i++)
+                        ((unsigned char*)(*p))[i / 8] |= 1 << (bits[i] % 8);
+                *p += size;
+        } else {
+                BUG_ON(*p + 4 > end);
+                ceph_encode_32(p, 0);
+        }
+}
+
 /*
  * session message, specialization for CEPH_SESSION_REQUEST_OPEN
  * to include additional client metadata fields.
@@ -911,11 +932,11 @@ static struct ceph_msg *create_session_open_msg(struct ceph_mds_client *mdsc, u6
         struct ceph_msg *msg;
         struct ceph_mds_session_head *h;
         int i = -1;
-        int metadata_bytes = 0;
+        int extra_bytes = 0;
         int metadata_key_count = 0;
         struct ceph_options *opt = mdsc->fsc->client->options;
         struct ceph_mount_options *fsopt = mdsc->fsc->mount_options;
-        void *p;
+        void *p, *end;
 
         const char* metadata[][2] = {
                 {"hostname", mdsc->nodename},
@@ -926,21 +947,26 @@ static struct ceph_msg *create_session_open_msg(struct ceph_mds_client *mdsc, u6
         };
 
         /* Calculate serialized length of metadata */
-        metadata_bytes = 4;  /* map length */
+        extra_bytes = 4;  /* map length */
         for (i = 0; metadata[i][0]; ++i) {
-                metadata_bytes += 8 + strlen(metadata[i][0]) +
+                extra_bytes += 8 + strlen(metadata[i][0]) +
                         strlen(metadata[i][1]);
                 metadata_key_count++;
         }
+        /* supported feature */
+        extra_bytes += 4 + 8;
 
         /* Allocate the message */
-        msg = ceph_msg_new(CEPH_MSG_CLIENT_SESSION, sizeof(*h) + metadata_bytes,
+        msg = ceph_msg_new(CEPH_MSG_CLIENT_SESSION, sizeof(*h) + extra_bytes,
                            GFP_NOFS, false);
         if (!msg) {
                 pr_err("create_session_msg ENOMEM creating msg\n");
                 return NULL;
         }
-        h = msg->front.iov_base;
+        p = msg->front.iov_base;
+        end = p + msg->front.iov_len;
+
+        h = p;
         h->op = cpu_to_le32(CEPH_SESSION_REQUEST_OPEN);
         h->seq = cpu_to_le64(seq);
 
@@ -950,11 +976,11 @@ static struct ceph_msg *create_session_open_msg(struct ceph_mds_client *mdsc, u6
          *
          * ClientSession messages with metadata are v2
          */
-        msg->hdr.version = cpu_to_le16(2);
+        msg->hdr.version = cpu_to_le16(3);
         msg->hdr.compat_version = cpu_to_le16(1);
 
         /* The write pointer, following the session_head structure */
-        p = msg->front.iov_base + sizeof(*h);
+        p += sizeof(*h);
 
         /* Number of entries in the map */
         ceph_encode_32(&p, metadata_key_count);
@@ -972,6 +998,10 @@ static struct ceph_msg *create_session_open_msg(struct ceph_mds_client *mdsc, u6
                 p += val_len;
         }
 
+        encode_supported_features(&p, end);
+        msg->front.iov_len = p - msg->front.iov_base;
+        msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
+
         return msg;
 }
 
@@ -2749,7 +2779,7 @@ static void handle_session(struct ceph_mds_session *session,
         int wake = 0;
 
         /* decode */
-        if (msg->front.iov_len != sizeof(*h))
+        if (msg->front.iov_len < sizeof(*h))
                 goto bad;
         op = le32_to_cpu(h->op);
         seq = le64_to_cpu(h->seq);
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index 80a7523e1523..32fcce0d4d3c 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -16,6 +16,18 @@
 #include <linux/ceph/mdsmap.h>
 #include <linux/ceph/auth.h>
 
+/* The first 8 bits are reserved for old ceph releases */
+#define CEPHFS_FEATURE_MIMIC    8
+
+#define CEPHFS_FEATURES_ALL {           \
+  0, 1, 2, 3, 4, 5, 6, 7,               \
+  CEPHFS_FEATURE_MIMIC,                 \
+}
+
+#define CEPHFS_FEATURES_CLIENT_SUPPORTED CEPHFS_FEATURES_ALL
+#define CEPHFS_FEATURES_CLIENT_REQUIRED {}
+
+
 /*
  * Some lock dependencies:
  *