[pbs-devel] [PATCH v3 qemu] PVE: Add PBS block driver to map backup archives into VMs

[Stefan Reiter <s.reiter@proxmox.com>]

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
[error cleanups, file_open implementation]
Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
---
 block/Makefile.objs  |   2 +
 block/pbs.c          | 271 +++++++++++++++++++++++++++++++++++++++++++
 configure            |  10 ++
 qapi/block-core.json |  14 ++-
 4 files changed, 296 insertions(+), 1 deletion(-)
 create mode 100644 block/pbs.c

diff --git a/block/Makefile.objs b/block/Makefile.objs
index 8af7073c83..9785e4431d 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -5,6 +5,7 @@ block-obj-$(CONFIG_CLOOP) += cloop.o
 block-obj-$(CONFIG_BOCHS) += bochs.o
 block-obj-$(CONFIG_VVFAT) += vvfat.o
 block-obj-$(CONFIG_DMG) += dmg.o
+block-obj-$(CONFIG_PBS_BDRV) += pbs.o
 
 block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o qcow2-bitmap.o qcow2-threads.o
 block-obj-$(CONFIG_QED) += qed.o qed-l2-cache.o qed-table.o qed-cluster.o
@@ -76,3 +77,4 @@ io_uring.o-cflags  := $(LINUX_IO_URING_CFLAGS)
 io_uring.o-libs    := $(LINUX_IO_URING_LIBS)
 parallels.o-cflags := $(LIBXML2_CFLAGS)
 parallels.o-libs   := $(LIBXML2_LIBS)
+pbs.o-libs         := -lproxmox_backup_qemu
diff --git a/block/pbs.c b/block/pbs.c
new file mode 100644
index 0000000000..1481a2bfd1
--- /dev/null
+++ b/block/pbs.c
@@ -0,0 +1,271 @@
+/*
+ * Proxmox Backup Server read-only block driver
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qstring.h"
+#include "qemu/module.h"
+#include "qemu/option.h"
+#include "qemu/cutils.h"
+#include "block/block_int.h"
+
+#include <proxmox-backup-qemu.h>
+
+#define PBS_OPT_REPOSITORY "repository"
+#define PBS_OPT_SNAPSHOT "snapshot"
+#define PBS_OPT_ARCHIVE "archive"
+#define PBS_OPT_KEYFILE "keyfile"
+#define PBS_OPT_PASSWORD "password"
+#define PBS_OPT_FINGERPRINT "fingerprint"
+#define PBS_OPT_ENCRYPTION_PASSWORD "key_password"
+
+typedef struct {
+    ProxmoxRestoreHandle *conn;
+    char aid;
+    int64_t length;
+
+    char *repository;
+    char *snapshot;
+    char *archive;
+} BDRVPBSState;
+
+static QemuOptsList runtime_opts = {
+    .name = "pbs",
+    .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
+    .desc = {
+        {
+            .name = PBS_OPT_REPOSITORY,
+            .type = QEMU_OPT_STRING,
+            .help = "The server address and repository to connect to.",
+        },
+        {
+            .name = PBS_OPT_SNAPSHOT,
+            .type = QEMU_OPT_STRING,
+            .help = "The snapshot to read.",
+        },
+        {
+            .name = PBS_OPT_ARCHIVE,
+            .type = QEMU_OPT_STRING,
+            .help = "Which archive within the snapshot should be accessed.",
+        },
+        {
+            .name = PBS_OPT_PASSWORD,
+            .type = QEMU_OPT_STRING,
+            .help = "Server password. Can be passed as env var 'PBS_PASSWORD'.",
+        },
+        {
+            .name = PBS_OPT_FINGERPRINT,
+            .type = QEMU_OPT_STRING,
+            .help = "Server fingerprint. Can be passed as env var 'PBS_FINGERPRINT'.",
+        },
+        {
+            .name = PBS_OPT_ENCRYPTION_PASSWORD,
+            .type = QEMU_OPT_STRING,
+            .help = "Optional: Key password. Can be passed as env var 'PBS_ENCRYPTION_PASSWORD'.",
+        },
+        {
+            .name = PBS_OPT_KEYFILE,
+            .type = QEMU_OPT_STRING,
+            .help = "Optional: The path to the keyfile to use.",
+        },
+        { /* end of list */ }
+    },
+};
+
+
+// filename format:
+// pbs:repository=<repo>,snapshot=<snap>,password=<pw>,key_password=<kpw>,fingerprint=<fp>,archive=<archive>
+static void pbs_parse_filename(const char *filename, QDict *options,
+                                     Error **errp)
+{
+
+    if (!strstart(filename, "pbs:", &filename)) {
+        if (errp) error_setg(errp, "pbs_parse_filename failed - missing 'pbs:' prefix");
+    }
+
+
+    QemuOpts *opts = qemu_opts_parse_noisily(&runtime_opts, filename, false);
+    if (!opts) {
+        if (errp) error_setg(errp, "pbs_parse_filename failed");
+        return;
+    }
+
+    qemu_opts_to_qdict(opts, options);
+
+    qemu_opts_del(opts);
+}
+
+static int pbs_open(BlockDriverState *bs, QDict *options, int flags,
+                    Error **errp)
+{
+    QemuOpts *opts;
+    BDRVPBSState *s = bs->opaque;
+    char *pbs_error = NULL;
+
+    opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
+    qemu_opts_absorb_qdict(opts, options, &error_abort);
+
+    s->repository = g_strdup(qemu_opt_get(opts, PBS_OPT_REPOSITORY));
+    s->snapshot = g_strdup(qemu_opt_get(opts, PBS_OPT_SNAPSHOT));
+    s->archive = g_strdup(qemu_opt_get(opts, PBS_OPT_ARCHIVE));
+    const char *keyfile = qemu_opt_get(opts, PBS_OPT_KEYFILE);
+    const char *password = qemu_opt_get(opts, PBS_OPT_PASSWORD);
+    const char *fingerprint = qemu_opt_get(opts, PBS_OPT_FINGERPRINT);
+    const char *key_password = qemu_opt_get(opts, PBS_OPT_ENCRYPTION_PASSWORD);
+
+    if (!password) {
+        password = getenv("PBS_PASSWORD");
+    }
+    if (!fingerprint) {
+        fingerprint = getenv("PBS_FINGERPRINT");
+    }
+    if (!key_password) {
+        key_password = getenv("PBS_ENCRYPTION_PASSWORD");
+    }
+
+    /* connect to PBS server in read mode */
+    s->conn = proxmox_restore_new(s->repository, s->snapshot, password,
+        keyfile, key_password, fingerprint, &pbs_error);
+
+    /* invalidates qemu_opt_get char pointers from above */
+    qemu_opts_del(opts);
+
+    if (!s->conn) {
+        if (pbs_error && errp) error_setg(errp, "PBS restore_new failed: %s", pbs_error);
+        if (pbs_error) proxmox_backup_free_error(pbs_error);
+        return -ENOMEM;
+    }
+
+    int ret = proxmox_restore_connect(s->conn, &pbs_error);
+    if (ret < 0) {
+        if (pbs_error && errp) error_setg(errp, "PBS connect failed: %s", pbs_error);
+        if (pbs_error) proxmox_backup_free_error(pbs_error);
+        return -ECONNREFUSED;
+    }
+
+    /* acquire handle and length */
+    s->aid = proxmox_restore_open_image(s->conn, s->archive, &pbs_error);
+    if (s->aid < 0) {
+        if (pbs_error && errp) error_setg(errp, "PBS open_image failed: %s", pbs_error);
+        if (pbs_error) proxmox_backup_free_error(pbs_error);
+        return -ENODEV;
+    }
+    s->length = proxmox_restore_get_image_length(s->conn, s->aid, &pbs_error);
+    if (s->length < 0) {
+        if (pbs_error && errp) error_setg(errp, "PBS get_image_length failed: %s", pbs_error);
+        if (pbs_error) proxmox_backup_free_error(pbs_error);
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
+static int pbs_file_open(BlockDriverState *bs, QDict *options, int flags,
+                         Error **errp)
+{
+    return pbs_open(bs, options, flags, errp);
+}
+
+static void pbs_close(BlockDriverState *bs) {
+    BDRVPBSState *s = bs->opaque;
+    g_free(s->repository);
+    g_free(s->snapshot);
+    g_free(s->archive);
+    proxmox_restore_disconnect(s->conn);
+}
+
+static int64_t pbs_getlength(BlockDriverState *bs)
+{
+    BDRVPBSState *s = bs->opaque;
+    return s->length;
+}
+
+typedef struct ReadCallbackData {
+    Coroutine *co;
+    AioContext *ctx;
+} ReadCallbackData;
+
+static void read_callback(void *callback_data)
+{
+    ReadCallbackData *rcb = callback_data;
+    aio_co_schedule(rcb->ctx, rcb->co);
+}
+
+static coroutine_fn int pbs_co_preadv(BlockDriverState *bs,
+                                      uint64_t offset, uint64_t bytes,
+                                      QEMUIOVector *qiov, int flags)
+{
+    BDRVPBSState *s = bs->opaque;
+    int ret;
+    char *pbs_error = NULL;
+    uint8_t *buf = malloc(bytes);
+
+    ReadCallbackData rcb = {
+        .co = qemu_coroutine_self(),
+        .ctx = qemu_get_current_aio_context(),
+    };
+
+    proxmox_restore_read_image_at_async(s->conn, s->aid, buf, offset, bytes,
+                                        read_callback, (void *) &rcb, &ret, &pbs_error);
+
+    qemu_coroutine_yield();
+
+    if (ret < 0) {
+        fprintf(stderr, "error during PBS read: %s\n", pbs_error ? pbs_error : "unknown error");
+        if (pbs_error) proxmox_backup_free_error(pbs_error);
+        return -EIO;
+    }
+
+    qemu_iovec_from_buf(qiov, 0, buf, bytes);
+    free(buf);
+
+    return ret;
+}
+
+static coroutine_fn int pbs_co_pwritev(BlockDriverState *bs,
+                                       uint64_t offset, uint64_t bytes,
+                                       QEMUIOVector *qiov, int flags)
+{
+    fprintf(stderr, "pbs-bdrv: cannot write to backup file, make sure "
+           "any attached disk devices are set to read-only!\n");
+    return -EPERM;
+}
+
+static void pbs_refresh_filename(BlockDriverState *bs)
+{
+    BDRVPBSState *s = bs->opaque;
+    snprintf(bs->exact_filename, sizeof(bs->exact_filename), "%s/%s(%s)",
+             s->repository, s->snapshot, s->archive);
+}
+
+static const char *const pbs_strong_runtime_opts[] = {
+    NULL
+};
+
+static BlockDriver bdrv_pbs_co = {
+    .format_name            = "pbs",
+    .protocol_name          = "pbs",
+    .instance_size          = sizeof(BDRVPBSState),
+
+    .bdrv_parse_filename    = pbs_parse_filename,
+
+    .bdrv_file_open         = pbs_file_open,
+    .bdrv_open              = pbs_open,
+    .bdrv_close             = pbs_close,
+    .bdrv_getlength         = pbs_getlength,
+
+    .bdrv_co_preadv         = pbs_co_preadv,
+    .bdrv_co_pwritev        = pbs_co_pwritev,
+
+    .bdrv_refresh_filename  = pbs_refresh_filename,
+    .strong_runtime_opts    = pbs_strong_runtime_opts,
+};
+
+static void bdrv_pbs_init(void)
+{
+    bdrv_register(&bdrv_pbs_co);
+}
+
+block_init(bdrv_pbs_init);
diff --git a/configure b/configure
index 23b5e93752..67054b5795 100755
--- a/configure
+++ b/configure
@@ -503,6 +503,7 @@ vvfat="yes"
 qed="yes"
 parallels="yes"
 sheepdog="yes"
+pbs_bdrv="yes"
 libxml2=""
 debug_mutex="no"
 libpmem=""
@@ -1553,6 +1554,10 @@ for opt do
   ;;
   --enable-sheepdog) sheepdog="yes"
   ;;
+  --disable-pbs-bdrv) pbs_bdrv="no"
+  ;;
+  --enable-pbs-bdrv) pbs_bdrv="yes"
+  ;;
   --disable-vhost-user) vhost_user="no"
   ;;
   --enable-vhost-user) vhost_user="yes"
@@ -1889,6 +1894,7 @@ disabled with --disable-FEATURE, default is enabled if available:
   qed             qed image format support
   parallels       parallels image format support
   sheepdog        sheepdog block driver support
+  pbs-bdrv        Proxmox backup server read-only block driver support
   crypto-afalg    Linux AF_ALG crypto backend driver
   capstone        capstone disassembler support
   debug-mutex     mutex debugging support
@@ -6726,6 +6732,7 @@ echo "vvfat support     $vvfat"
 echo "qed support       $qed"
 echo "parallels support $parallels"
 echo "sheepdog support  $sheepdog"
+echo "pbs-bdrv support  $pbs_bdrv"
 echo "capstone          $capstone"
 echo "libpmem support   $libpmem"
 echo "libudev           $libudev"
@@ -7578,6 +7585,9 @@ fi
 if test "$sheepdog" = "yes" ; then
   echo "CONFIG_SHEEPDOG=y" >> $config_host_mak
 fi
+if test "$pbs_bdrv" = "yes" ; then
+  echo "CONFIG_PBS_BDRV=y" >> $config_host_mak
+fi
 if test "$fuzzing" = "yes" ; then
   if test "$have_fuzzer" = "yes"; then
     FUZZ_LDFLAGS=" -fsanitize=address,fuzzer"
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 4fe3d6f751..2c83734b04 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2936,7 +2936,7 @@
             'luks', 'nbd', 'nfs', 'null-aio', 'null-co', 'nvme', 'parallels',
             'qcow', 'qcow2', 'qed', 'quorum', 'raw', 'rbd',
             { 'name': 'replication', 'if': 'defined(CONFIG_REPLICATION)' },
-            'sheepdog',
+            'sheepdog', 'pbs',
             'ssh', 'throttle', 'vdi', 'vhdx', 'vmdk', 'vpc', 'vvfat', 'vxhs' ] }
 
 ##
@@ -3000,6 +3000,17 @@
 { 'struct': 'BlockdevOptionsNull',
   'data': { '*size': 'int', '*latency-ns': 'uint64', '*read-zeroes': 'bool' } }
 
+##
+# @BlockdevOptionsPbs:
+#
+# Driver specific block device options for the PBS backend.
+#
+##
+{ 'struct': 'BlockdevOptionsPbs',
+  'data': { 'repository': 'str', 'snapshot': 'str', 'archive': 'str',
+            '*keyfile': 'str', '*password': 'str', '*fingerprint': 'str',
+            '*key_password': 'str' } }
+
 ##
 # @BlockdevOptionsNVMe:
 #
@@ -4122,6 +4133,7 @@
       'nfs':        'BlockdevOptionsNfs',
       'null-aio':   'BlockdevOptionsNull',
       'null-co':    'BlockdevOptionsNull',
+      'pbs':        'BlockdevOptionsPbs',
       'nvme':       'BlockdevOptionsNVMe',
       'parallels':  'BlockdevOptionsGenericFormat',
       'qcow2':      'BlockdevOptionsQcow2',
-- 
2.20.1