From e058bf5e47af745997f99aa21c003e40f50bddcc Mon Sep 17 00:00:00 2001

From: John Snow <jsnow@redhat.com>

Date: Wed, 18 Jul 2018 22:55:03 +0200

Subject: [PATCH 245/268] nbd/server: implement dirty bitmap export

RH-Author: John Snow <jsnow@redhat.com>

Message-id: <20180718225511.14878-28-jsnow@redhat.com>

Patchwork-id: 81412

O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH 27/35] nbd/server: implement dirty bitmap export

Bugzilla: 1207657

RH-Acked-by: Eric Blake <eblake@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Fam Zheng <famz@redhat.com>

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Handle a new NBD meta namespace: "qemu", and corresponding queries:

"qemu:dirty-bitmap:<export bitmap name>".

With the new metadata context negotiated, BLOCK_STATUS query will reply

with dirty-bitmap data, converted to extents. The new public function

nbd_export_bitmap selects which bitmap to export. For now, only one bitmap

may be exported.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Message-Id: <20180609151758.17343-5-vsementsov@virtuozzo.com>

Reviewed-by: Eric Blake <eblake@redhat.com>

[eblake: wording tweaks, minor cleanups, additional tracing]

Signed-off-by: Eric Blake <eblake@redhat.com>

(cherry picked from commit 3d068aff16d6dbf066328977c5152847a62f2a0a)

Signed-off-by: John Snow <jsnow@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 include/block/nbd.h |   8 +-

 nbd/server.c        | 278 +++++++++++++++++++++++++++++++++++++++++++++++-----

 nbd/trace-events    |   1 +

 3 files changed, 262 insertions(+), 25 deletions(-)

diff --git a/include/block/nbd.h b/include/block/nbd.h

index fcdcd54..8bb9606 100644

--- a/include/block/nbd.h

+++ b/include/block/nbd.h

@@ -229,11 +229,13 @@ enum {

 #define NBD_REPLY_TYPE_ERROR         NBD_REPLY_ERR(1)

 #define NBD_REPLY_TYPE_ERROR_OFFSET  NBD_REPLY_ERR(2)

-/* Flags for extents (NBDExtent.flags) of NBD_REPLY_TYPE_BLOCK_STATUS,

- * for base:allocation meta context */

+/* Extent flags for base:allocation in NBD_REPLY_TYPE_BLOCK_STATUS */

 #define NBD_STATE_HOLE (1 << 0)

 #define NBD_STATE_ZERO (1 << 1)

+/* Extent flags for qemu:dirty-bitmap in NBD_REPLY_TYPE_BLOCK_STATUS */

+#define NBD_STATE_DIRTY (1 << 0)

+

 static inline bool nbd_reply_type_is_error(int type)

 {

     return type & (1 << 15);

@@ -315,6 +317,8 @@ void nbd_client_put(NBDClient *client);

 void nbd_server_start(SocketAddress *addr, const char *tls_creds,

                       Error **errp);

+void nbd_export_bitmap(NBDExport *exp, const char *bitmap,

+                       const char *bitmap_export_name, Error **errp);

 /* nbd_read

  * Reads @size bytes from @ioc. Returns 0 on success.

diff --git a/nbd/server.c b/nbd/server.c

index 9171cd4..2c2d62c 100644

--- a/nbd/server.c

+++ b/nbd/server.c

@@ -23,6 +23,13 @@

 #include "nbd-internal.h"

 #define NBD_META_ID_BASE_ALLOCATION 0

+#define NBD_META_ID_DIRTY_BITMAP 1

+

+/* NBD_MAX_BITMAP_EXTENTS: 1 mb of extents data. An empirical

+ * constant. If an increase is needed, note that the NBD protocol

+ * recommends no larger than 32 mb, so that the client won't consider

+ * the reply as a denial of service attack. */

+#define NBD_MAX_BITMAP_EXTENTS (0x100000 / 8)

 static int system_errno_to_nbd_errno(int err)

 {

@@ -80,6 +87,9 @@ struct NBDExport {

     BlockBackend *eject_notifier_blk;

     Notifier eject_notifier;

+

+    BdrvDirtyBitmap *export_bitmap;

+    char *export_bitmap_context;

 };

 static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);

@@ -92,6 +102,7 @@ typedef struct NBDExportMetaContexts {

     bool valid; /* means that negotiation of the option finished without

                    errors */

     bool base_allocation; /* export base:allocation context (block status) */

+    bool bitmap; /* export qemu:dirty-bitmap:<export bitmap name> */

 } NBDExportMetaContexts;

 struct NBDClient {

@@ -814,6 +825,56 @@ static int nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *meta,

                                      &meta->base_allocation, errp);

 }

+/* nbd_meta_bitmap_query

+ *

+ * Handle query to 'qemu:' namespace.

+ * @len is the amount of text remaining to be read from the current name, after

+ * the 'qemu:' portion has been stripped.

+ *

+ * Return -errno on I/O error, 0 if option was completely handled by

+ * sending a reply about inconsistent lengths, or 1 on success. */

+static int nbd_meta_qemu_query(NBDClient *client, NBDExportMetaContexts *meta,

+                               uint32_t len, Error **errp)

+{

+    bool dirty_bitmap = false;

+    size_t dirty_bitmap_len = strlen("dirty-bitmap:");

+    int ret;

+

+    if (!meta->exp->export_bitmap) {

+        trace_nbd_negotiate_meta_query_skip("no dirty-bitmap exported");

+        return nbd_opt_skip(client, len, errp);

+    }

+

+    if (len == 0) {

+        if (client->opt == NBD_OPT_LIST_META_CONTEXT) {

+            meta->bitmap = true;

+        }

+        trace_nbd_negotiate_meta_query_parse("empty");

+        return 1;

+    }

+

+    if (len < dirty_bitmap_len) {

+        trace_nbd_negotiate_meta_query_skip("not dirty-bitmap:");

+        return nbd_opt_skip(client, len, errp);

+    }

+

+    len -= dirty_bitmap_len;

+    ret = nbd_meta_pattern(client, "dirty-bitmap:", &dirty_bitmap, errp);

+    if (ret <= 0) {

+        return ret;

+    }

+    if (!dirty_bitmap) {

+        trace_nbd_negotiate_meta_query_skip("not dirty-bitmap:");

+        return nbd_opt_skip(client, len, errp);

+    }

+

+    trace_nbd_negotiate_meta_query_parse("dirty-bitmap:");

+

+    return nbd_meta_empty_or_pattern(

+            client, meta->exp->export_bitmap_context +

+            strlen("qemu:dirty_bitmap:"), len, &meta->bitmap, errp);

+}

+

 /* nbd_negotiate_meta_query

  *

  * Parse namespace name and call corresponding function to parse body of the

@@ -829,9 +890,14 @@ static int nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *meta,

 static int nbd_negotiate_meta_query(NBDClient *client,

                                     NBDExportMetaContexts *meta, Error **errp)

 {

+    /*

+     * Both 'qemu' and 'base' namespaces have length = 5 including a

+     * colon. If another length namespace is later introduced, this

+     * should certainly be refactored.

+     */

     int ret;

-    char query[sizeof("base:") - 1];

-    size_t baselen = strlen("base:");

+    size_t ns_len = 5;

+    char ns[5];

     uint32_t len;

     ret = nbd_opt_read(client, &len, sizeof(len), errp);

@@ -840,25 +906,27 @@ static int nbd_negotiate_meta_query(NBDClient *client,

     }

     cpu_to_be32s(&len;;

-    /* The only supported namespace for now is 'base'. So query should start

-     * with 'base:'. Otherwise, we can ignore it and skip the remainder. */

-    if (len < baselen) {

+    if (len < ns_len) {

         trace_nbd_negotiate_meta_query_skip("length too short");

         return nbd_opt_skip(client, len, errp);

     }

-    len -= baselen;

-    ret = nbd_opt_read(client, query, baselen, errp);

+    len -= ns_len;

+    ret = nbd_opt_read(client, ns, ns_len, errp);

     if (ret <= 0) {

         return ret;

     }

-    if (strncmp(query, "base:", baselen) != 0) {

-        trace_nbd_negotiate_meta_query_skip("not for base: namespace");

-        return nbd_opt_skip(client, len, errp);

+

+    if (!strncmp(ns, "base:", ns_len)) {

+        trace_nbd_negotiate_meta_query_parse("base:");

+        return nbd_meta_base_query(client, meta, len, errp);

+    } else if (!strncmp(ns, "qemu:", ns_len)) {

+        trace_nbd_negotiate_meta_query_parse("qemu:");

+        return nbd_meta_qemu_query(client, meta, len, errp);

     }

-    trace_nbd_negotiate_meta_query_parse("base:");

-    return nbd_meta_base_query(client, meta, len, errp);

+    trace_nbd_negotiate_meta_query_skip("unknown namespace");

+    return nbd_opt_skip(client, len, errp);

 }

 /* nbd_negotiate_meta_queries

@@ -928,6 +996,16 @@ static int nbd_negotiate_meta_queries(NBDClient *client,

         }

     }

+    if (meta->bitmap) {

+        ret = nbd_negotiate_send_meta_context(client,

+                                              meta->exp->export_bitmap_context,

+                                              NBD_META_ID_DIRTY_BITMAP,

+                                              errp);

+        if (ret < 0) {

+            return ret;

+        }

+    }

+

     ret = nbd_negotiate_send_rep(client, NBD_REP_ACK, errp);

     if (ret == 0) {

         meta->valid = true;

@@ -1556,6 +1634,11 @@ void nbd_export_put(NBDExport *exp)

             exp->blk = NULL;

         }

+        if (exp->export_bitmap) {

+            bdrv_dirty_bitmap_set_qmp_locked(exp->export_bitmap, false);

+            g_free(exp->export_bitmap_context);

+        }

+

         g_free(exp);

     }

 }

@@ -1797,9 +1880,15 @@ static int blockstatus_to_extent_be(BlockDriverState *bs, uint64_t offset,

 }

 /* nbd_co_send_extents

- * @extents should be in big-endian */

+ *

+ * @length is only for tracing purposes (and may be smaller or larger

+ * than the client's original request). @last controls whether

+ * NBD_REPLY_FLAG_DONE is sent. @extents should already be in

+ * big-endian format.

+ */

 static int nbd_co_send_extents(NBDClient *client, uint64_t handle,

-                               NBDExtent *extents, unsigned nb_extents,

+                               NBDExtent *extents, unsigned int nb_extents,

+                               uint64_t length, bool last,

                                uint32_t context_id, Error **errp)

 {

     NBDStructuredMeta chunk;

@@ -1809,7 +1898,9 @@ static int nbd_co_send_extents(NBDClient *client, uint64_t handle,

         {.iov_base = extents, .iov_len = nb_extents * sizeof(extents[0])}

     };

-    set_be_chunk(&chunk.h, NBD_REPLY_FLAG_DONE, NBD_REPLY_TYPE_BLOCK_STATUS,

+    trace_nbd_co_send_extents(handle, nb_extents, context_id, length, last);

+    set_be_chunk(&chunk.h, last ? NBD_REPLY_FLAG_DONE : 0,

+                 NBD_REPLY_TYPE_BLOCK_STATUS,

                  handle, sizeof(chunk) - sizeof(chunk.h) + iov[1].iov_len);

     stl_be_p(&chunk.context_id, context_id);

@@ -1819,8 +1910,8 @@ static int nbd_co_send_extents(NBDClient *client, uint64_t handle,

 /* Get block status from the exported device and send it to the client */

 static int nbd_co_send_block_status(NBDClient *client, uint64_t handle,

                                     BlockDriverState *bs, uint64_t offset,

-                                    uint64_t length, uint32_t context_id,

-                                    Error **errp)

+                                    uint64_t length, bool last,

+                                    uint32_t context_id, Error **errp)

 {

     int ret;

     NBDExtent extent;

@@ -1831,7 +1922,84 @@ static int nbd_co_send_block_status(NBDClient *client, uint64_t handle,

                 client, handle, -ret, "can't get block status", errp);

     }

-    return nbd_co_send_extents(client, handle, &extent, 1, context_id, errp);

+    return nbd_co_send_extents(client, handle, &extent, 1, length, last,

+                               context_id, errp);

+}

+

+/*

+ * Populate @extents from a dirty bitmap. Unless @dont_fragment, the

+ * final extent may exceed the original @length. Store in @length the

+ * byte length encoded (which may be smaller or larger than the

+ * original), and return the number of extents used.

+ */

+static unsigned int bitmap_to_extents(BdrvDirtyBitmap *bitmap, uint64_t offset,

+                                      uint64_t *length, NBDExtent *extents,

+                                      unsigned int nb_extents,

+                                      bool dont_fragment)

+{

+    uint64_t begin = offset, end;

+    uint64_t overall_end = offset + *length;

+    unsigned int i = 0;

+    BdrvDirtyBitmapIter *it;

+    bool dirty;

+

+    bdrv_dirty_bitmap_lock(bitmap);

+

+    it = bdrv_dirty_iter_new(bitmap);

+    dirty = bdrv_get_dirty_locked(NULL, bitmap, offset);

+

+    assert(begin < overall_end && nb_extents);

+    while (begin < overall_end && i < nb_extents) {

+        if (dirty) {

+            end = bdrv_dirty_bitmap_next_zero(bitmap, begin);

+        } else {

+            bdrv_set_dirty_iter(it, begin);

+            end = bdrv_dirty_iter_next(it);

+        }

+        if (end == -1 || end - begin > UINT32_MAX) {

+            /* Cap to an aligned value < 4G beyond begin. */

+            end = MIN(bdrv_dirty_bitmap_size(bitmap),

+                      begin + UINT32_MAX + 1 -

+                      bdrv_dirty_bitmap_granularity(bitmap));

+        }

+        if (dont_fragment && end > overall_end) {

+            end = overall_end;

+        }

+

+        extents[i].length = cpu_to_be32(end - begin);

+        extents[i].flags = cpu_to_be32(dirty ? NBD_STATE_DIRTY : 0);

+        i++;

+        begin = end;

+        dirty = !dirty;

+    }

+

+    bdrv_dirty_iter_free(it);

+

+    bdrv_dirty_bitmap_unlock(bitmap);

+

+    *length = end - offset;

+    return i;

+}

+

+static int nbd_co_send_bitmap(NBDClient *client, uint64_t handle,

+                              BdrvDirtyBitmap *bitmap, uint64_t offset,

+                              uint32_t length, bool dont_fragment, bool last,

+                              uint32_t context_id, Error **errp)

+{

+    int ret;

+    unsigned int nb_extents = dont_fragment ? 1 : NBD_MAX_BITMAP_EXTENTS;

+    NBDExtent *extents = g_new(NBDExtent, nb_extents);

+    uint64_t final_length = length;

+

+    nb_extents = bitmap_to_extents(bitmap, offset, &final_length, extents,

+                                   nb_extents, dont_fragment);

+

+    ret = nbd_co_send_extents(client, handle, extents, nb_extents,

+                              final_length, last, context_id, errp);

+

+    g_free(extents);

+

+    return ret;

 }

 /* nbd_co_receive_request

@@ -2051,11 +2219,34 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,

             return nbd_send_generic_reply(client, request->handle, -EINVAL,

                                           "need non-zero length", errp);

         }

-        if (client->export_meta.valid && client->export_meta.base_allocation) {

-            return nbd_co_send_block_status(client, request->handle,

-                                            blk_bs(exp->blk), request->from,

-                                            request->len,

-                                            NBD_META_ID_BASE_ALLOCATION, errp);

+        if (client->export_meta.valid &&

+            (client->export_meta.base_allocation ||

+             client->export_meta.bitmap))

+        {

+            if (client->export_meta.base_allocation) {

+                ret = nbd_co_send_block_status(client, request->handle,

+                                               blk_bs(exp->blk), request->from,

+                                               request->len,

+                                               !client->export_meta.bitmap,

+                                               NBD_META_ID_BASE_ALLOCATION,

+                                               errp);

+                if (ret < 0) {

+                    return ret;

+                }

+            }

+

+            if (client->export_meta.bitmap) {

+                ret = nbd_co_send_bitmap(client, request->handle,

+                                         client->exp->export_bitmap,

+                                         request->from, request->len,

+                                         request->flags & NBD_CMD_FLAG_REQ_ONE,

+                                         true, NBD_META_ID_DIRTY_BITMAP, errp);

+                if (ret < 0) {

+                    return ret;

+                }

+            }

+

+            return ret;

         } else {

             return nbd_send_generic_reply(client, request->handle, -EINVAL,

                                           "CMD_BLOCK_STATUS not negotiated",

@@ -2207,3 +2398,44 @@ void nbd_client_new(NBDExport *exp,

     co = qemu_coroutine_create(nbd_co_client_start, client);

     qemu_coroutine_enter(co);

 }

+

+void nbd_export_bitmap(NBDExport *exp, const char *bitmap,

+                       const char *bitmap_export_name, Error **errp)

+{

+    BdrvDirtyBitmap *bm = NULL;

+    BlockDriverState *bs = blk_bs(exp->blk);

+

+    if (exp->export_bitmap) {

+        error_setg(errp, "Export bitmap is already set");

+        return;

+    }

+

+    while (true) {

+        bm = bdrv_find_dirty_bitmap(bs, bitmap);

+        if (bm != NULL || bs->backing == NULL) {

+            break;

+        }

+

+        bs = bs->backing->bs;

+    }

+

+    if (bm == NULL) {

+        error_setg(errp, "Bitmap '%s' is not found", bitmap);

+        return;

+    }

+

+    if (bdrv_dirty_bitmap_enabled(bm)) {

+        error_setg(errp, "Bitmap '%s' is enabled", bitmap);

+        return;

+    }

+

+    if (bdrv_dirty_bitmap_qmp_locked(bm)) {

+        error_setg(errp, "Bitmap '%s' is locked", bitmap);

+        return;

+    }

+

+    bdrv_dirty_bitmap_set_qmp_locked(bm, true);

+    exp->export_bitmap = bm;

+    exp->export_bitmap_context =

+            g_strdup_printf("qemu:dirty-bitmap:%s", bitmap_export_name);

+}

diff --git a/nbd/trace-events b/nbd/trace-events

index dee081e..5e1d4af 100644

--- a/nbd/trace-events

+++ b/nbd/trace-events

@@ -64,6 +64,7 @@ nbd_co_send_simple_reply(uint64_t handle, uint32_t error, const char *errname, i

 nbd_co_send_structured_done(uint64_t handle) "Send structured reply done: handle = %" PRIu64

 nbd_co_send_structured_read(uint64_t handle, uint64_t offset, void *data, size_t size) "Send structured read data reply: handle = %" PRIu64 ", offset = %" PRIu64 ", data = %p, len = %zu"

 nbd_co_send_structured_read_hole(uint64_t handle, uint64_t offset, size_t size) "Send structured read hole reply: handle = %" PRIu64 ", offset = %" PRIu64 ", len = %zu"

+nbd_co_send_extents(uint64_t handle, unsigned int extents, uint32_t id, uint64_t length, int last) "Send block status reply: handle = %" PRIu64 ", extents = %u, context = %d (extents cover %" PRIu64 " bytes, last chunk = %d)"

 nbd_co_send_structured_error(uint64_t handle, int err, const char *errname, const char *msg) "Send structured error reply: handle = %" PRIu64 ", error = %d (%s), msg = '%s'"

 nbd_co_receive_request_decode_type(uint64_t handle, uint16_t type, const char *name) "Decoding type: handle = %" PRIu64 ", type = %" PRIu16 " (%s)"

 nbd_co_receive_request_payload_received(uint64_t handle, uint32_t len) "Payload received: handle = %" PRIu64 ", len = %" PRIu32

-- 

1.8.3.1