search for: plugin_pread

...cit -1 value return from the plugin would trigger returning an error code to the client; all other values (whether -2, 0, or positive, even though the documentation only mentioned 0 as valid) would treat things as success on the reply to the client. > +++ b/src/plugins.c > static int > plugin_pread (struct backend *b, struct connection *conn, > void *buf, uint32_t count, uint64_t offset, uint32_t flags) > { > struct backend_plugin *p = container_of (b, struct backend_plugin, backend); > + int r; > > assert (connection_get_handle (conn, 0)); > as...

The concern is a client is blocked while processing a request. The nbdkit server design requires a thread per request being processed regardless of the number of connections or clients. We want to run 1000's of requests in parallel without needing a thread at nbdkit layer per request in flight. Our plugin layer is built around boost asio and a few threads in a worker pool running an io

...cal_get_error (); - if (!ret && plugin_errno_is_preserved ()) + if (!ret && backend->errno_is_preserved (backend)) ret = errno; return ret ? ret : EIO; } @@ -881,28 +883,28 @@ handle_request (struct connection *conn, switch (cmd) { case NBD_CMD_READ: - if (plugin_pread (conn, buf, count, offset) == -1) + if (backend->pread (backend, conn, buf, count, offset) == -1) return get_error (conn); break; case NBD_CMD_WRITE: - if (plugin_pwrite (conn, buf, count, offset) == -1) + if (backend->pwrite (backend, conn, buf, count, offset) == -1...

...cal_get_error (); - if (!ret && plugin_errno_is_preserved ()) + if (!ret && backend->errno_is_preserved (backend)) ret = errno; return ret ? ret : EIO; } @@ -881,28 +883,28 @@ handle_request (struct connection *conn, switch (cmd) { case NBD_CMD_READ: - if (plugin_pread (conn, buf, count, offset) == -1) + if (backend->pread (backend, conn, buf, count, offset) == -1) return get_error (conn); break; case NBD_CMD_WRITE: - if (plugin_pwrite (conn, buf, count, offset) == -1) + if (backend->pwrite (backend, conn, buf, count, offset) == -1...

...cal_get_error (); - if (!ret && plugin_errno_is_preserved ()) + if (!ret && backend->errno_is_preserved (backend)) ret = errno; return ret ? ret : EIO; } @@ -881,28 +883,28 @@ handle_request (struct connection *conn, switch (cmd) { case NBD_CMD_READ: - if (plugin_pread (conn, buf, count, offset) == -1) + if (backend->pread (backend, conn, buf, count, offset) == -1) return get_error (conn); break; case NBD_CMD_WRITE: - if (plugin_pwrite (conn, buf, count, offset) == -1) + if (backend->pwrite (backend, conn, buf, count, offset) == -1...

v1 -> v2: - Fixed everything mentioned in the review. Rich.

Somewhat invasive but mostly mechanical change to how plugins are called. This patch is in preparation for adding a second backend subtype for filters. Rich.

...struct connection *conn, uint32_t count, uint64_t offset); int (*zero) (struct backend *, struct connection *conn, uint32_t count, uint64_t offset, int may_trim); diff --git a/src/plugins.c b/src/plugins.c index e81a3d3..dfa9bc5 100644 --- a/src/plugins.c +++ b/src/plugins.c @@ -357,7 +357,7 @@ plugin_pread (struct backend *b, struct connection *conn, static int plugin_pwrite (struct backend *b, struct connection *conn, - void *buf, uint32_t count, uint64_t offset) + const void *buf, uint32_t count, uint64_t offset) { struct backend_plugin *p = (struct backend_plugi...

Tested via: term1$ qemu-nbd -k $PWD/sock -t -f raw -x foo junk --trace=nbd_\* term2$ ./nbdkit -f -v -e bar nbd socket=$PWD/sock export=foo term3$ qemu-io -t none -f raw nbd://localhost:10809/bar --trace=nbd_\* and checking the traces to see that 'w 0 1' vs. 'w -f 0 1' was able to influence whether the FUA flag showed up at the server in term1. Still to go: figure out how to

...Object_CallFunction_SizeT (callable=<optimized out>, format=<optimized out>) at /usr/src/debug/python3.9-3.9.0~b3-1.fc33.x86_64/Objects/call.c:596 #13 0x00007fc4b9f7b840 in py_pread (handle=0x9ee9f20, buf=0x9f98ca0, count=512, offset=0, flags=0) at python.c:619 #14 0x0000000000410d89 in plugin_pread (b=0x9f07040, handle=0x9ee9f20, buf=0x9f98ca0, count=512, offset=0, flags=0, err=0x7fc4ab220a78) at plugins.c:524 #15 0x000000000040653f in backend_pread (b=0x9f07040, buf=0x9f98ca0, count=512, offset=0, flags=0, err=0x7fc4ab220a78) at backend.c:485 #16 0x0000000000411f7e in handle_request (cmd=0,...

...on_get_handle (conn, 0)); debug ("can_trim"); if (p->plugin.can_trim) - return p->plugin.can_trim (connection_get_handle (conn)); + return p->plugin.can_trim (connection_get_handle (conn, 0)); else return p->plugin.trim != NULL; } @@ -345,12 +345,12 @@ plugin_pread (struct backend *b, struct connection *conn, { struct backend_plugin *p = container_of (b, struct backend_plugin, backend); - assert (connection_get_handle (conn)); + assert (connection_get_handle (conn, 0)); assert (p->plugin.pread != NULL); debug ("pread count=%" PRIu...

...nnection *conn, if (!conn->can_flush || conn->readonly) flush_after_command = false; + /* The plugin should call nbdkit_set_error() to request a particular + error, otherwise we fallback to errno or EIO. */ + tls_set_error (0); + switch (cmd) { case NBD_CMD_READ: r = plugin_pread (conn, buf, count, offset); if (r == -1) { - *error = errno ? errno : EIO; + *error = _get_error (); return 0; } break; @@ -640,7 +658,7 @@ _handle_request (struct connection *conn, case NBD_CMD_WRITE: r = plugin_pwrite (conn, buf, count, offset); if (r...

...tion_get_handle (conn, 0)); debug ("can_trim"); if (p->plugin.can_trim) - return p->plugin.can_trim (connection_get_handle (conn)); + return p->plugin.can_trim (connection_get_handle (conn, 0)); else return p->plugin.trim != NULL; } @@ -345,13 +345,13 @@ plugin_pread (struct backend *b, struct connection *conn, { struct backend_plugin *p = container_of (b, struct backend_plugin, backend); - assert (connection_get_handle (conn)); + assert (connection_get_handle (conn, 0)); assert (p->plugin.pread != NULL); assert (!flags); debug ("pread...

...return p->plugin.trim != NULL; } +/* Grab the appropriate error value. + */ +static int +get_error (struct backend_plugin *p) +{ + int ret = threadlocal_get_error (); + + if (!ret && p->plugin.errno_is_preserved) + ret = errno; + return ret ? ret : EIO; +} + static int plugin_pread (struct backend *b, struct connection *conn, void *buf, uint32_t count, uint64_t offset, uint32_t flags) { struct backend_plugin *p = container_of (b, struct backend_plugin, backend); + int r; assert (connection_get_handle (conn, 0)); assert (p->plugin.pread != NULL);...

...ters can call this to set the true errno, in cases * where !errno_is_preserved. */ @@ -656,6 +672,7 @@ static struct backend plugin_functions = { .can_trim = plugin_can_trim, .can_zero = plugin_can_zero, .can_fua = plugin_can_fua, + .can_multi_conn = plugin_can_multi_conn, .pread = plugin_pread, .pwrite = plugin_pwrite, .flush = plugin_flush, diff --git a/tests/test-layers-filter.c b/tests/test-layers-filter.c index c5a96e7..6da6ee6 100644 --- a/tests/test-layers-filter.c +++ b/tests/test-layers-filter.c @@ -167,6 +167,15 @@ test_layers_filter_can_fua (struct nbdkit_next_ops *next_o...

...); +} + +static int +plugin_can_fua (struct backend *b, struct connection *conn) +{ + debug ("can_fua"); + + // TODO - wire FUA flag support into plugins. Until then, this copies + // can_flush, since that's how we emulate FUA + return plugin_can_flush (b, conn); +} + static int plugin_pread (struct backend *b, struct connection *conn, void *buf, uint32_t count, uint64_t offset, uint32_t flags) @@ -535,6 +555,8 @@ static struct backend plugin_functions = { .flush = plugin_flush, .trim = plugin_trim, .zero = plugin_zero, + .can_zero = plugin_can_zero, + .can_fu...

...internal projects. I have uploaded the entire cbdkit source to our github at https://github.com/dev-cloudbd/cbdkit The relevant files are include/cbdkit-plugin.h src/connections.c src/plugins.c Specifically, the connections.c functions recv_request send_reply and the plugins.c functions plugin_pread plugin_pwrite cbdkit_async_reply cbdkit_async_reply_read cbdkit_async_reply_error On Fri, Jan 19, 2018 at 12:05 PM, Eric Blake <eblake@redhat.com> wrote: > On 01/19/2018 10:56 AM, Shaun McDowell wrote: > > > Limitation: The kernel will (with today's default settings) typ...

...unctions = { .free = plugin_free, .thread_model = plugin_thread_model, @@ -717,12 +749,14 @@ static struct backend plugin_functions = { .can_extents = plugin_can_extents, .can_fua = plugin_can_fua, .can_multi_conn = plugin_can_multi_conn, + .can_cache = plugin_can_cache, .pread = plugin_pread, .pwrite = plugin_pwrite, .flush = plugin_flush, .trim = plugin_trim, .zero = plugin_zero, .extents = plugin_extents, + .cache = plugin_cache, }; /* Register and load a plugin. */ diff --git a/server/protocol-handshake.c b/server/protocol-handshake.c index 03377a9..af1cd18 100644...

A combination of the work that both Rich and I have been doing lately, where filters use only the new API with flags on every command that the client can send over the wire (we can then add support for more flags in nbdkit without having to add new callbacks, as NBD adds more flags upstream). Eric Blake (4): protocol: Split flags from cmd field in requests backend: Pass flags argument through

...te errors, sets *error to errno (or EIO if errno is not - * set) and returns 0. + * On read/write errors, sets *error appropriately and returns 0. */ static int _handle_request (struct connection *conn, @@ -632,7 +646,7 @@ _handle_request (struct connection *conn, case NBD_CMD_READ: r = plugin_pread (conn, buf, count, offset); if (r == -1) { - *error = errno ? errno : EIO; + *error = get_error (conn); return 0; } break; @@ -640,7 +654,7 @@ _handle_request (struct connection *conn, case NBD_CMD_WRITE: r = plugin_pwrite (conn, buf, count, offset); if...