Re: [Qemu-devel] [PATCH 2/3] nbd: Add exports listing support.

[Hani Benhabiles <kroosec@gmail.com>]

On Tue, Jun 03, 2014 at 01:36:35PM +0200, Paolo Bonzini wrote:
> Il 31/05/2014 23:39, Hani Benhabiles ha scritto:
> >This is added by handling the NBD_OPT_LIST and NBD_OPT_ABORT options.
> >
> >NBD_REP_ERR_UNSUP is also sent for unknown NBD option values.
> >
> >Signed-off-by: Hani Benhabiles <hani@linux.com>
> >---
> > include/block/nbd.h |   5 ++
> > nbd.c               | 197 +++++++++++++++++++++++++++++++++++++++++-----------
> > 2 files changed, 162 insertions(+), 40 deletions(-)
> >
> >diff --git a/include/block/nbd.h b/include/block/nbd.h
> >index 95d52ab..fd7e057 100644
> >--- a/include/block/nbd.h
> >+++ b/include/block/nbd.h
> >@@ -51,6 +51,11 @@ struct nbd_reply {
> > /* New-style client flags. */
> > #define NBD_FLAG_C_FIXED_NEWSTYLE   (1 << 0)    /* Fixed newstyle protocol. */
> >
> >+/* Reply types. */
> >+#define NBD_REP_ACK             (1)             /* Data sending finished. */
> >+#define NBD_REP_SERVER          (2)             /* Export description. */
> >+#define NBD_REP_ERR_UNSUP       ((1 << 31) | 1) /* Unknown option. */
> >+
> > #define NBD_CMD_MASK_COMMAND	0x0000ffff
> > #define NBD_CMD_FLAG_FUA	(1 << 16)
> >
> >diff --git a/nbd.c b/nbd.c
> >index aa2e552..012e5da 100644
> >--- a/nbd.c
> >+++ b/nbd.c
> >@@ -64,6 +64,7 @@
> > #define NBD_REPLY_MAGIC         0x67446698
> > #define NBD_OPTS_MAGIC          0x49484156454F5054LL
> > #define NBD_CLIENT_MAGIC        0x0000420281861253LL
> >+#define NBD_REP_MAGIC           0x3e889045565a9LL
> >
> > #define NBD_SET_SOCK            _IO(0xab, 0)
> > #define NBD_SET_BLKSIZE         _IO(0xab, 1)
> >@@ -77,7 +78,9 @@
> > #define NBD_SET_TIMEOUT         _IO(0xab, 9)
> > #define NBD_SET_FLAGS           _IO(0xab, 10)
> >
> >-#define NBD_OPT_EXPORT_NAME     (1 << 0)
> >+#define NBD_OPT_EXPORT_NAME     (1)
> >+#define NBD_OPT_ABORT           (2)
> >+#define NBD_OPT_LIST            (3)
> >
> > /* Definitions for opaque data types */
> >
> >@@ -215,54 +218,98 @@ static ssize_t write_sync(int fd, void *buffer, size_t size)
> >
> > */
> >
> >-static int nbd_receive_options(NBDClient *client)
> >+static int nbd_send_rep(int csock, uint32_t type, uint32_t opt)
> > {
> >-    int csock = client->sock;
> >-    char name[256];
> >-    uint32_t tmp, length;
> >     uint64_t magic;
> >-    int rc;
> >-
> >-    /* Client sends:
> >-        [ 0 ..   3]   client flags
> >-        [ 4 ..  11]   NBD_OPTS_MAGIC
> >-        [12 ..  15]   NBD_OPT_EXPORT_NAME
> >-        [16 ..  19]   length
> >-        [20 ..  xx]   export name (length bytes)
> >-     */
> >+    uint32_t len;
> >
> >-    rc = -EINVAL;
> >-    if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
> >-        LOG("read failed");
> >-        goto fail;
> >+    magic = cpu_to_be64(NBD_REP_MAGIC);
> >+    if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
> >+        LOG("write failed (rep magic)");
> >+        return -EINVAL;
> >     }
> >-    TRACE("Checking client flags");
> >-    tmp = be32_to_cpu(tmp);
> >-    if (tmp != 0 && tmp != NBD_FLAG_C_FIXED_NEWSTYLE) {
> >-        LOG("Bad client flags received");
> >-        goto fail;
> >+    opt = cpu_to_be32(opt);
> >+    if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
> >+        LOG("write failed (rep opt)");
> >+        return -EINVAL;
> >     }
> >-
> >-    if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
> >-        LOG("read failed");
> >-        goto fail;
> >+    type = cpu_to_be32(type);
> >+    if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) {
> >+        LOG("write failed (rep type)");
> >+        return -EINVAL;
> >     }
> >-    TRACE("Checking opts magic");
> >-    if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
> >-        LOG("Bad magic received");
> >-        goto fail;
> >+    len = cpu_to_be32(0);
> >+    if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
> >+        LOG("write failed (rep data length)");
> >+        return -EINVAL;
> >     }
> >+    return 0;
> >+}
> >
> >-    if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
> >-        LOG("read failed");
> >-        goto fail;
> >+static int nbd_send_rep_list(int csock, NBDExport *exp)
> >+{
> >+    uint64_t magic, name_len;
> >+    uint32_t opt, type, len;
> >+
> >+    name_len = strlen(exp->name);
> >+    magic = cpu_to_be64(NBD_REP_MAGIC);
> >+    if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
> >+        LOG("write failed (magic)");
> >+        return -EINVAL;
> >     }
> >-    TRACE("Checking option");
> >-    if (tmp != be32_to_cpu(NBD_OPT_EXPORT_NAME)) {
> >-        LOG("Bad option received");
> >-        goto fail;
> >+    opt = cpu_to_be32(NBD_OPT_LIST);
> >+    if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
> >+        LOG("write failed (opt)");
> >+        return -EINVAL;
> >+    }
> >+    type = cpu_to_be32(NBD_REP_SERVER);
> >+    if (write_sync(csock, &type, sizeof(type)) != sizeof(type)) {
> >+        LOG("write failed (reply type)");
> >+        return -EINVAL;
> >+    }
> >+    len = cpu_to_be32(name_len + sizeof(len));
> >+    if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
> >+        LOG("write failed (length)");
> >+        return -EINVAL;
> >+    }
> >+    len = cpu_to_be32(name_len);
> >+    if (write_sync(csock, &len, sizeof(len)) != sizeof(len)) {
> >+        LOG("write failed (length)");
> >+        return -EINVAL;
> >+    }
> >+    if (write_sync(csock, exp->name, name_len) != name_len) {
> >+        LOG("write failed (buffer)");
> >+        return -EINVAL;
> >+    }
> >+    return 0;
> >+}
> >+
> >+static int nbd_send_list(NBDClient *client)
> >+{
> >+    int csock;
> >+    NBDExport *exp;
> >+
> >+    csock = client->sock;
> >+    /* For each export, send a NBD_REP_SERVER reply. */
> >+    QTAILQ_FOREACH(exp, &exports, next) {
> >+        if (nbd_send_rep_list(csock, exp)) {
> >+            return -EINVAL;
> >+        }
> >     }
> >+    /* Finish with a NBD_REP_ACK. */
> >+    return nbd_send_rep(csock, NBD_REP_ACK, NBD_OPT_LIST);
> >+}
> >+
> >+static int nbd_handle_export_name(NBDClient *client)
> >+{
> >+    int rc = -EINVAL, csock = client->sock;
> >+    char name[256];
> >+    uint32_t length;
> >
> >+    /* Client sends:
> >+        [16 ..  19]   length
> >+        [20 ..  xx]   export name (length bytes)
> >+     */
> >     if (read_sync(csock, &length, sizeof(length)) != sizeof(length)) {
> >         LOG("read failed");
> >         goto fail;
> >@@ -287,8 +334,76 @@ static int nbd_receive_options(NBDClient *client)
> >
> >     QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
> >     nbd_export_get(client->exp);
> >+    rc = 0;
> >+fail:
> >+    return rc;
> >+}
> >+
> >+static int nbd_receive_options(NBDClient *client)
> >+{
> >+    int rc = -EINVAL;
> >
> >-    TRACE("Option negotiation succeeded.");
> >+    while (1) {
> >+        int csock = client->sock;
> >+        uint32_t tmp;
> >+        uint64_t magic;
> >+
> >+        /* Client sends:
> >+            [ 0 ..   3]   client flags
> >+            [ 4 ..  11]   NBD_OPTS_MAGIC
> >+            [12 ..  15]   NBD option
> >+            ...           Rest of request
> >+        */
> >+
> >+        if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
> >+            LOG("read failed");
> >+            goto fail;
> >+        }
> >+        TRACE("Checking client flags");
> >+        tmp = be32_to_cpu(tmp);
> >+        if (tmp != 0 && tmp != NBD_FLAG_C_FIXED_NEWSTYLE) {
> >+            LOG("Bad client flags received");
> >+            goto fail;
> >+        }
> >+
> >+        if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
> >+            LOG("read failed");
> >+            goto fail;
> >+        }
> >+        TRACE("Checking opts magic");
> >+        if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
> >+            LOG("Bad magic received");
> >+            goto fail;
> >+        }
> >+
> >+        if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
> >+            LOG("read failed");
> >+            goto fail;
> >+        }
> >+
> >+        TRACE("Checking option");
> >+        switch (be32_to_cpu(tmp)) {
> >+        case NBD_OPT_LIST:
> >+            if (nbd_send_list(client) < 0) {
> >+                return -EINVAL;
> >+            }
> >+            break;
> 
> You can just do "return nbd_send_list(client);" here.  You probably should
> also rename the function to nbd_handle_list.
> 

Ack.

> >+        case NBD_OPT_ABORT:
> >+            return 1;
> >+
> >+        case NBD_OPT_EXPORT_NAME:
> >+            return nbd_handle_export_name(client);
> 
> Part of this patch belongs in patch 1.  This one should only add
> nbd_send_rep_list, nbd_handle_list and the NBD_OPT_LIST case.
> 

Alright, I will resend, making the changes you and Stefan suggested.

Thanks.