Block layer patches

- rbd: fix handling of holes in .bdrv_co_block_status
 - Fix potential crash in bdrv_set_backing_hd()
 - vhost-user-blk export: Fix shutdown with requests in flight
 - FUSE export: Fix build failure on FreeBSD
 - Documentation improvements
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Merge remote-tracking branch 'remotes/kwolf-gitlab/tags/for-upstream' into staging

Block layer patches

- rbd: fix handling of holes in .bdrv_co_block_status
- Fix potential crash in bdrv_set_backing_hd()
- vhost-user-blk export: Fix shutdown with requests in flight
- FUSE export: Fix build failure on FreeBSD
- Documentation improvements

# gpg: Signature made Tue 01 Feb 2022 15:14:24 GMT
# gpg:                using RSA key DC3DEB159A9AF95D3D7456FE7F09B272C88F2FD6
# gpg:                issuer "kwolf@redhat.com"
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" [full]
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kwolf-gitlab/tags/for-upstream:
  block/rbd: workaround for ceph issue #53784
  block/rbd: fix handling of holes in .bdrv_co_block_status
  qemu-img: Unify [-b [-F]] documentation
  qsd: Document fuse's allow-other option
  block.h: remove outdated comment
  block/export/fuse: Fix build failure on FreeBSD
  block/export/fuse: Rearrange if-else-if ladder in fuse_fallocate()
  block/export: Fix vhost-user-blk shutdown with requests in flight
  block: bdrv_set_backing_hd(): use drained section
  qemu-storage-daemon: Fix typo in vhost-user-blk help

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

block.c

@@ -3341,6 +3341,8 @@ int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
     int ret;
     Transaction *tran = tran_new();
 
+    bdrv_drained_begin(bs);
+
     ret = bdrv_set_backing_noperm(bs, backing_hd, tran, errp);
     if (ret < 0) {
         goto out;
@@ -3350,6 +3352,8 @@ int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
 out:
     tran_finalize(tran, ret);
 
+    bdrv_drained_end(bs);
+
     return ret;
 }
 

block/export/fuse.c

@@ -625,11 +625,33 @@ static void fuse_fallocate(fuse_req_t req, fuse_ino_t inode, int mode,
         return;
     }
 
+#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
     if (mode & FALLOC_FL_KEEP_SIZE) {
         length = MIN(length, blk_len - offset);
     }
+#endif /* CONFIG_FALLOCATE_PUNCH_HOLE */
 
-    if (mode & FALLOC_FL_PUNCH_HOLE) {
+    if (!mode) {
+        /* We can only fallocate at the EOF with a truncate */
+        if (offset < blk_len) {
+            fuse_reply_err(req, EOPNOTSUPP);
+            return;
+        }
+
+        if (offset > blk_len) {
+            /* No preallocation needed here */
+            ret = fuse_do_truncate(exp, offset, true, PREALLOC_MODE_OFF);
+            if (ret < 0) {
+                fuse_reply_err(req, -ret);
+                return;
+            }
+        }
+
+        ret = fuse_do_truncate(exp, offset + length, true,
+                               PREALLOC_MODE_FALLOC);
+    }
+#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
+    else if (mode & FALLOC_FL_PUNCH_HOLE) {
         if (!(mode & FALLOC_FL_KEEP_SIZE)) {
             fuse_reply_err(req, EINVAL);
             return;
@@ -643,6 +665,7 @@ static void fuse_fallocate(fuse_req_t req, fuse_ino_t inode, int mode,
             length -= size;
         } while (ret == 0 && length > 0);
     }
+#endif /* CONFIG_FALLOCATE_PUNCH_HOLE */
 #ifdef CONFIG_FALLOCATE_ZERO_RANGE
     else if (mode & FALLOC_FL_ZERO_RANGE) {
         if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + length > blk_len) {
@@ -665,25 +688,7 @@ static void fuse_fallocate(fuse_req_t req, fuse_ino_t inode, int mode,
         } while (ret == 0 && length > 0);
     }
 #endif /* CONFIG_FALLOCATE_ZERO_RANGE */
-    else if (!mode) {
+    else {
-        /* We can only fallocate at the EOF with a truncate */
-        if (offset < blk_len) {
-            fuse_reply_err(req, EOPNOTSUPP);
-            return;
-        }
-
-        if (offset > blk_len) {
-            /* No preallocation needed here */
-            ret = fuse_do_truncate(exp, offset, true, PREALLOC_MODE_OFF);
-            if (ret < 0) {
-                fuse_reply_err(req, -ret);
-                return;
-            }
-        }
-
-        ret = fuse_do_truncate(exp, offset + length, true,
-                               PREALLOC_MODE_FALLOC);
-    } else {
         ret = -EOPNOTSUPP;
     }
 

block/export/vhost-user-blk-server.c

@@ -172,6 +172,7 @@ vu_blk_discard_write_zeroes(VuBlkExport *vexp, struct iovec *iov,
     return VIRTIO_BLK_S_IOERR;
 }
 
+/* Called with server refcount increased, must decrease before returning */
 static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
 {
     VuBlkReq *req = opaque;
@@ -286,10 +287,12 @@ static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
     }
 
     vu_blk_req_complete(req);
+    vhost_user_server_unref(server);
     return;
 
 err:
     free(req);
+    vhost_user_server_unref(server);
 }
 
 static void vu_blk_process_vq(VuDev *vu_dev, int idx)
@@ -310,6 +313,8 @@ static void vu_blk_process_vq(VuDev *vu_dev, int idx)
 
         Coroutine *co =
             qemu_coroutine_create(vu_blk_virtio_process_req, req);
+
+        vhost_user_server_ref(server);
         qemu_coroutine_enter(co);
     }
 }

block/rbd.c

@@ -1279,11 +1279,11 @@ static int qemu_rbd_diff_iterate_cb(uint64_t offs, size_t len,
     RBDDiffIterateReq *req = opaque;
 
     assert(req->offs + req->bytes <= offs);
-    /*
+
-     * we do not diff against a snapshot so we should never receive a callback
+    /* treat a hole like an unallocated area and bail out */
-     * for a hole.
+    if (!exists) {
-     */
+        return 0;
-    assert(exists);
+    }
 
     if (!req->exists && offs > req->offs) {
         /*
@@ -1320,6 +1320,7 @@ static int coroutine_fn qemu_rbd_co_block_status(BlockDriverState *bs,
     int status, r;
     RBDDiffIterateReq req = { .offs = offset };
     uint64_t features, flags;
+    uint64_t head = 0;
 
     assert(offset + bytes <= s->image_size);
 
@@ -1347,7 +1348,43 @@ static int coroutine_fn qemu_rbd_co_block_status(BlockDriverState *bs,
         return status;
     }
 
-    r = rbd_diff_iterate2(s->image, NULL, offset, bytes, true, true,
+#if LIBRBD_VERSION_CODE < LIBRBD_VERSION(1, 17, 0)
+    /*
+     * librbd had a bug until early 2022 that affected all versions of ceph that
+     * supported fast-diff. This bug results in reporting of incorrect offsets
+     * if the offset parameter to rbd_diff_iterate2 is not object aligned.
+     * Work around this bug by rounding down the offset to object boundaries.
+     * This is OK because we call rbd_diff_iterate2 with whole_object = true.
+     * However, this workaround only works for non cloned images with default
+     * striping.
+     *
+     * See: https://tracker.ceph.com/issues/53784
+     */
+
+    /* check if RBD image has non-default striping enabled */
+    if (features & RBD_FEATURE_STRIPINGV2) {
+        return status;
+    }
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+    /*
+     * check if RBD image is a clone (= has a parent).
+     *
+     * rbd_get_parent_info is deprecated from Nautilus onwards, but the
+     * replacement rbd_get_parent is not present in Luminous and Mimic.
+     */
+    if (rbd_get_parent_info(s->image, NULL, 0, NULL, 0, NULL, 0) != -ENOENT) {
+        return status;
+    }
+#pragma GCC diagnostic pop
+
+    head = req.offs & (s->object_size - 1);
+    req.offs -= head;
+    bytes += head;
+#endif
+
+    r = rbd_diff_iterate2(s->image, NULL, req.offs, bytes, true, true,
                           qemu_rbd_diff_iterate_cb, &req);
     if (r < 0 && r != QEMU_RBD_EXIT_DIFF_ITERATE2) {
         return status;
@@ -1366,7 +1403,8 @@ static int coroutine_fn qemu_rbd_co_block_status(BlockDriverState *bs,
         status = BDRV_BLOCK_ZERO | BDRV_BLOCK_OFFSET_VALID;
     }
 
-    *pnum = req.bytes;
+    assert(req.bytes > head);
+    *pnum = req.bytes - head;
     return status;
 }
 

docs/tools/qemu-img.rst

@@ -463,7 +463,7 @@ Command description:
   ``--skip-broken-bitmaps`` is also specified to copy only the
   consistent bitmaps.
 
-.. option:: create [--object OBJECTDEF] [-q] [-f FMT] [-b BACKING_FILE] [-F BACKING_FMT] [-u] [-o OPTIONS] FILENAME [SIZE]
+.. option:: create [--object OBJECTDEF] [-q] [-f FMT] [-b BACKING_FILE [-F BACKING_FMT]] [-u] [-o OPTIONS] FILENAME [SIZE]
 
   Create the new disk image *FILENAME* of size *SIZE* and format
   *FMT*. Depending on the file format, you can add one or more *OPTIONS*

docs/tools/qemu-storage-daemon.rst

@@ -76,7 +76,7 @@ Standard options:
 .. option:: --export [type=]nbd,id=<id>,node-name=<node-name>[,name=<export-name>][,writable=on|off][,bitmap=<name>]
   --export [type=]vhost-user-blk,id=<id>,node-name=<node-name>,addr.type=unix,addr.path=<socket-path>[,writable=on|off][,logical-block-size=<block-size>][,num-queues=<num-queues>]
   --export [type=]vhost-user-blk,id=<id>,node-name=<node-name>,addr.type=fd,addr.str=<fd>[,writable=on|off][,logical-block-size=<block-size>][,num-queues=<num-queues>]
-  --export [type=]fuse,id=<id>,node-name=<node-name>,mountpoint=<file>[,growable=on|off][,writable=on|off]
+  --export [type=]fuse,id=<id>,node-name=<node-name>,mountpoint=<file>[,growable=on|off][,writable=on|off][,allow-other=on|off|auto]
 
   is a block export definition. ``node-name`` is the block node that should be
   exported. ``writable`` determines whether or not the export allows write
@@ -103,7 +103,12 @@ Standard options:
   mounted). Consequently, applications that have opened the given file before
   the export became active will continue to see its original content. If
   ``growable`` is set, writes after the end of the exported file will grow the
-  block node to fit.
+  block node to fit.  The ``allow-other`` option controls whether users other
+  than the user running the process will be allowed to access the export.  Note
+  that enabling this option as a non-root user requires enabling the
+  user_allow_other option in the global fuse.conf configuration file.  Setting
+  ``allow-other`` to auto (the default) will try enabling this option, and on
+  error fall back to disabling it.
 
 .. option:: --monitor MONITORDEF
 

include/qemu/vhost-user-server.h

@@ -42,6 +42,8 @@ typedef struct {
     const VuDevIface *vu_iface;
 
     /* Protected by ctx lock */
+    unsigned int refcount;
+    bool wait_idle;
     VuDev vu_dev;
     QIOChannel *ioc; /* The I/O channel with the client */
     QIOChannelSocket *sioc; /* The underlying data channel with the client */
@@ -59,6 +61,9 @@ bool vhost_user_server_start(VuServer *server,
 
 void vhost_user_server_stop(VuServer *server);
 
+void vhost_user_server_ref(VuServer *server);
+void vhost_user_server_unref(VuServer *server);
+
 void vhost_user_server_attach_aio_context(VuServer *server, AioContext *ctx);
 void vhost_user_server_detach_aio_context(VuServer *server);
 

qemu-img-cmds.hx

@@ -52,9 +52,9 @@ SRST
 ERST
 
 DEF("create", img_create,
-    "create [--object objectdef] [-q] [-f fmt] [-b backing_file] [-F backing_fmt] [-u] [-o options] filename [size]")
+    "create [--object objectdef] [-q] [-f fmt] [-b backing_file [-F backing_fmt]] [-u] [-o options] filename [size]")
 SRST
-.. option:: create [--object OBJECTDEF] [-q] [-f FMT] [-b BACKING_FILE] [-F BACKING_FMT] [-u] [-o OPTIONS] FILENAME [SIZE]
+.. option:: create [--object OBJECTDEF] [-q] [-f FMT] [-b BACKING_FILE [-F BACKING_FMT]] [-u] [-o OPTIONS] FILENAME [SIZE]
 ERST
 
 DEF("dd", img_dd,

storage-daemon/qemu-storage-daemon.c

@@ -100,7 +100,7 @@ static void help(void)
 "\n"
 #ifdef CONFIG_FUSE
 "  --export [type=]fuse,id=<id>,node-name=<node-name>,mountpoint=<file>\n"
-"           [,growable=on|off][,writable=on|off]\n"
+"           [,growable=on|off][,writable=on|off][,allow-other=on|off|auto]\n"
 "                         export the specified block node over FUSE\n"
 "\n"
 #endif /* CONFIG_FUSE */
@@ -111,7 +111,7 @@ static void help(void)
 "                         export the specified block node as a\n"
 "                         vhost-user-blk device over UNIX domain socket\n"
 "  --export [type=]vhost-user-blk,id=<id>,node-name=<node-name>,\n"
-"           fd,addr.str=<fd>[,writable=on|off]\n"
+"           addr.type=fd,addr.str=<fd>[,writable=on|off]\n"
 "           [,logical-block-size=<block-size>][,num-queues=<num-queues>]\n"
 "                         export the specified block node as a\n"
 "                         vhost-user-blk device over file descriptor\n"

util/vhost-user-server.c

@@ -74,6 +74,20 @@ static void panic_cb(VuDev *vu_dev, const char *buf)
     error_report("vu_panic: %s", buf);
 }
 
+void vhost_user_server_ref(VuServer *server)
+{
+    assert(!server->wait_idle);
+    server->refcount++;
+}
+
+void vhost_user_server_unref(VuServer *server)
+{
+    server->refcount--;
+    if (server->wait_idle && !server->refcount) {
+        aio_co_wake(server->co_trip);
+    }
+}
+
 static bool coroutine_fn
 vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
 {
@@ -177,6 +191,14 @@ static coroutine_fn void vu_client_trip(void *opaque)
         /* Keep running */
     }
 
+    if (server->refcount) {
+        /* Wait for requests to complete before we can unmap the memory */
+        server->wait_idle = true;
+        qemu_coroutine_yield();
+        server->wait_idle = false;
+    }
+    assert(server->refcount == 0);
+
     vu_deinit(vu_dev);
 
     /* vu_deinit() should have called remove_watch() */