search for: backend_can_write

...bool using_tls; bool structured_replies; bool meta_context_base_allocation; diff --git a/server/backend.c b/server/backend.c index 374d8540..196b48e4 100644 --- a/server/backend.c +++ b/server/backend.c @@ -144,73 +144,130 @@ backend_get_size (struct backend *b, struct connection *conn) int backend_can_write (struct backend *b, struct connection *conn) { + struct b_conn_handle *h = &conn->handles[b->i]; + debug ("%s: can_write", b->name); - return b->can_write (b, conn); + if (h->can_write == -1) + h->can_write = b->can_write (b, conn); + return h->can_...

This is a subset of the last half of the larger 9-patch series. The uncontroversial first half of that series is pushed, but here, I tried to reduce the size of the patches by splitting out some of the more complex changes, so that the rest of the changes remaining in the series are more mechanical. In turn, it forced me to write timing tests, which let me spot another spot where we are wasting

...null__ (1))); -extern int backend_reopen (struct backend *b, struct connection *conn, - int readonly) - __attribute__((__nonnull__ (1, 2))); -extern int64_t backend_get_size (struct backend *b, struct connection *conn) - __attribute__((__nonnull__ (1, 2))); -extern int backend_can_write (struct backend *b, struct connection *conn) - __attribute__((__nonnull__ (1, 2))); -extern int backend_can_flush (struct backend *b, struct connection *conn) - __attribute__((__nonnull__ (1, 2))); -extern int backend_is_rotational (struct backend *b, struct connection *conn) - __attribute__((__...

v1 was here: https://www.redhat.com/archives/libguestfs/2020-February/msg00081.html v2 replaces struct connection *conn = GET_CONN; with GET_CONN; which sets conn implicitly and asserts that it is non-NULL. If we actually want to test if conn is non-NULL or behave differently, then you must use threadlocal_get_conn() instead, and some existing uses do that. Rich.

The third patch is a large but mechanical change which gets rid of passing around struct connection * entirely within the server, preferring instead to reference the connection through thread-local storage. I hope this is a gateway to simplifying other parts of the code. Rich.

...t, readonly); } static int64_t next_get_size (void *nxdata) { - struct b_h *b_h = nxdata; - return backend_get_size (b_h->b); + struct backend *b_next = nxdata; + return backend_get_size (b_next); } static int next_can_write (void *nxdata) { - struct b_h *b_h = nxdata; - return backend_can_write (b_h->b); + struct backend *b_next = nxdata; + return backend_can_write (b_next); } static int next_can_flush (void *nxdata) { - struct b_h *b_h = nxdata; - return backend_can_flush (b_h->b); + struct backend *b_next = nxdata; + return backend_can_flush (b_next); } static int...

Now instead of validating just the client's request, we are validating that all filters are passing valid requests on down. In protocol.c, we were able to assert that our computation of eflags populated all of the flags, and thus calls such as backend_can_write would not fail; however, with filters, keeping those assertions mean the burden is now on the filter to avoid calling into next_ops->FOO without first priming the cache of next_ops->can_FOO. An audit of existing filters did not find any more culprits. Signed-off-by: Eric Blake <eblake@re...

...end_get_size (top); if (size == -1) return -1; if (size < 0) { @@ -98,57 +98,57 @@ protocol_common_open (uint64_t *exportsize, uint16_t *flags) /* Check all flags even if they won't be advertised, to prime the * cache and make later request validation easier. */ - fl = backend_can_write (backend); + fl = backend_can_write (top); if (fl == -1) return -1; if (!fl) eflags |= NBD_FLAG_READ_ONLY; - fl = backend_can_zero (backend); + fl = backend_can_zero (top); if (fl == -1) return -1; if (fl) eflags |= NBD_FLAG_SEND_WRITE_ZEROES; - fl = backend_...

It's easy to use the sh script to demonstrate that nbdkit is inefficiently calling into .get_size, .can_fua, and friends more than necessary. We've also commented on the list in the past that it would be nice to ensure that when filters call into next_ops, they are not violating constraints (as we've have to fix several bugs in the past where we did not have such checking to protect

I think this is my last round of patches for issues I identified with the retry filter. With this in place, it should be safe to interject another filter in between retry and the plugin. Eric Blake (5): retry: Don't call into closed plugin tests: Refactor test-retry-reopen-fail.sh tests: Enhance retry test to cover failed reopen server: Move prepare/finalize/close recursion to

...l__ (1, 2))); +extern int backend_reopen (struct backend *b, struct connection *conn, + int readonly) + __attribute__((__nonnull__ (1, 2))); extern int64_t backend_get_size (struct backend *b, struct connection *conn) __attribute__((__nonnull__ (1, 2))); extern int backend_can_write (struct backend *b, struct connection *conn) -- 2.23.0

...l__ (1, 2))); +extern int backend_reopen (struct backend *b, struct connection *conn, + int readonly) + __attribute__((__nonnull__ (1, 2))); extern int64_t backend_get_size (struct backend *b, struct connection *conn) __attribute__((__nonnull__ (1, 2))); extern int backend_can_write (struct backend *b, struct connection *conn) -- 2.23.0

...quot;, b->name, readonly); + + assert (h->handle == NULL); + assert (h->can_write == -1); + if (readonly) + h->can_write = 0; + return b->open (b, conn, readonly); +} + void backend_set_handle (struct backend *b, struct connection *conn, void *handle) { @@ -195,12 +209,8 @@ backend_can_write (struct backend *b, struct connection *conn) debug ("%s: can_write", b->name); - if (h->can_write == -1) { - /* Special case for outermost backend when -r is in effect. */ - if (readonly && b == backend) - return h->can_write = 0; + if (h->can_write =...

...ruct backend *b_next = nxdata; - return backend_reopen (b_next, readonly); -} - -static int64_t -next_get_size (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_get_size (b_next); -} - -static int -next_can_write (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_can_write (b_next); -} - -static int -next_can_flush (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_can_flush (b_next); -} - -static int -next_is_rotational (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_is_rotational (b_next); -} - -static int -next_can_trim...

...tsize && @@ -291,7 +291,7 @@ int64_t backend_get_size (struct backend *b) { GET_CONN; - struct b_conn_handle *h = &conn->handles[b->i]; + struct handle *h = get_handle (conn, b->i); controlpath_debug ("%s: get_size", b->name); @@ -305,7 +305,7 @@ int backend_can_write (struct backend *b) { GET_CONN; - struct b_conn_handle *h = &conn->handles[b->i]; + struct handle *h = get_handle (conn, b->i); controlpath_debug ("%s: can_write", b->name); @@ -319,7 +319,7 @@ int backend_can_flush (struct backend *b) { GET_CONN; - stru...

...nn *nxdata = handle; + assert (nxdata->b == b->next && nxdata->conn == conn); if (f->filter.can_write) - return f->filter.can_write (&next_ops, &nxdata, handle); + return f->filter.can_write (&next_ops, nxdata, nxdata->handle); else return backend_can_write (b->next, conn); } @@ -470,10 +494,11 @@ static int filter_can_flush (struct backend *b, struct connection *conn, void *handle) { struct backend_filter *f = container_of (b, struct backend_filter, backend); - struct b_conn nxdata = { .b = b->next, .conn = conn }; + struct b_conn *nxda...

...9a4 100644 --- a/server/filters.c +++ b/server/filters.c @@ -291,6 +291,7 @@ filter_close (struct backend *b, void *handle) static struct nbdkit_next_ops next_ops = { .reopen = backend_reopen, + .export_description = backend_export_description, .get_size = backend_get_size, .can_write = backend_can_write, .can_flush = backend_can_flush, @@ -334,6 +335,17 @@ filter_finalize (struct backend *b, void *handle) return 0; } +static const char * +filter_export_description (struct backend *b, void *handle) +{ + struct backend_filter *f = container_of (b, struct backend_filter, backend); + + if (f...

This is a retry filter implementation as outlined here: https://www.redhat.com/archives/libguestfs/2019-September/msg00167.html It is only lightly tested. One way to test it is to try an SSH copy (see the commit message for patch 2/2), and in the middle of the copy kill the per-connection sshd on the remote machine. You will see that the copy recovers after a few seconds. Add the nbdkit -v

v1 was here: https://www.redhat.com/archives/libguestfs/2019-September/msg00199.html v2: - Adds a fairly simple yet comprehensive test using sh plugin. - Rebase and retest. Patch 1 is a misc patch not really related to the series. Rich.

The immediate reason for this patch is to reduce the amount of debugging in virt-v2v with using the virt-v2v -v option (because this implies running nbdkit in verbose mode too). Most of the messages are datapath ones about pread/pwrite requests, and in fact as we've added more filters on top of nbdkit these messages have got more and more verbose. However they are not particularly