[Libguestfs] [nbdkit PATCH v2 05/13] backend: Pass flags argument through

Although our plugin interface has to support older users that didn't take a flag parameter, we want to allow newer plugins that can honor flags, as well as insist that all filters take a flag argument. This will allow future expansion to conditionally honor any flags passed over the NBD protocol; with immediate plans to support NBD_CMD_FLAG_FUA. So, make the backend interface always pass flags for actions corresponding to NBD wire commands. The .zero interface is currently the only user of a flag; note that our NBDKIT_FLAG_MAY_TRIM preserves our old internal sense, which is intentionally opposite of the NBD protocol NBD_CMD_FLAG_NO_HOLE, and that our flag values are not the same as the on-the-wire flag values. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- src/connections.c | 18 ++++++++++-------- src/internal.h | 14 ++++++++------ src/plugins.c | 18 ++++++++++++------ 3 files changed, 30 insertions(+), 20 deletions(-) diff --git a/src/connections.c b/src/connections.c index aac1d05..8446691 100644 --- a/src/connections.c +++ b/src/connections.c @@ -1,5 +1,5 @@ /* nbdkit - * Copyright (C) 2013-2017 Red Hat Inc. + * Copyright (C) 2013-2018 Red Hat Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without @@ -871,6 +871,7 @@ handle_request (struct connection *conn, void *buf) { bool flush_after_command; + uint32_t f = 0; /* Flush after command performed? */ flush_after_command = (flags & NBD_CMD_FLAG_FUA) != 0; @@ -883,28 +884,29 @@ handle_request (struct connection *conn, switch (cmd) { case NBD_CMD_READ: - if (backend->pread (backend, conn, buf, count, offset) == -1) + if (backend->pread (backend, conn, buf, count, offset, 0) == -1) return get_error (conn); break; case NBD_CMD_WRITE: - if (backend->pwrite (backend, conn, buf, count, offset) == -1) + if (backend->pwrite (backend, conn, buf, count, offset, 0) == -1) return get_error (conn); break; case NBD_CMD_FLUSH: - if (backend->flush (backend, conn) == -1) + if (backend->flush (backend, conn, 0) == -1) return get_error (conn); break; case NBD_CMD_TRIM: - if (backend->trim (backend, conn, count, offset) == -1) + if (backend->trim (backend, conn, count, offset, 0) == -1) return get_error (conn); break; case NBD_CMD_WRITE_ZEROES: - if (backend->zero (backend, conn, count, offset, - !(flags & NBD_CMD_FLAG_NO_HOLE)) == -1) + if (!(flags & NBD_CMD_FLAG_NO_HOLE)) + f |= NBDKIT_FLAG_MAY_TRIM; + if (backend->zero (backend, conn, count, offset, f) == -1) return get_error (conn); break; @@ -912,7 +914,7 @@ handle_request (struct connection *conn, abort (); } - if (flush_after_command && backend->flush (backend, conn) == -1) + if (flush_after_command && backend->flush (backend, conn, 0) == -1) return get_error (conn); return 0; diff --git a/src/internal.h b/src/internal.h index c4ee51b..be1a0ca 100644 --- a/src/internal.h +++ b/src/internal.h @@ -1,5 +1,5 @@ /* nbdkit - * Copyright (C) 2013-2017 Red Hat Inc. + * Copyright (C) 2013-2018 Red Hat Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without @@ -97,6 +97,8 @@ (type *) ((char *) __mptr - offsetof(type, member)); \ }) +#define NBDKIT_FLAG_MAY_TRIM (1<<0) /* Maps to !NBD_CMD_FLAG_NO_HOLE */ + /* main.c */ extern const char *exportname; extern const char *ipaddr; @@ -167,11 +169,11 @@ struct backend { int (*can_flush) (struct backend *, struct connection *conn); int (*is_rotational) (struct backend *, struct connection *conn); int (*can_trim) (struct backend *, struct connection *conn); - int (*pread) (struct backend *, struct connection *conn, void *buf, uint32_t count, uint64_t offset); - int (*pwrite) (struct backend *, struct connection *conn, const void *buf, uint32_t count, uint64_t offset); - int (*flush) (struct backend *, struct connection *conn); - int (*trim) (struct backend *, 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); + int (*pread) (struct backend *, struct connection *conn, void *buf, uint32_t count, uint64_t offset, uint32_t flags); + int (*pwrite) (struct backend *, struct connection *conn, const void *buf, uint32_t count, uint64_t offset, uint32_t flags); + int (*flush) (struct backend *, struct connection *conn, uint32_t flags); + int (*trim) (struct backend *, struct connection *conn, uint32_t count, uint64_t offset, uint32_t flags); + int (*zero) (struct backend *, struct connection *conn, uint32_t count, uint64_t offset, uint32_t flags); }; extern struct backend *plugin_register (const char *_filename, void *_dl, struct nbdkit_plugin *(*plugin_init) (void)); diff --git a/src/plugins.c b/src/plugins.c index 6a2ef66..4c6c3a5 100644 --- a/src/plugins.c +++ b/src/plugins.c @@ -1,5 +1,5 @@ /* nbdkit - * Copyright (C) 2013 Red Hat Inc. + * Copyright (C) 2013-2018 Red Hat Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without @@ -341,12 +341,13 @@ plugin_can_trim (struct backend *b, struct connection *conn) static int plugin_pread (struct backend *b, struct connection *conn, - void *buf, uint32_t count, uint64_t offset) + void *buf, uint32_t count, uint64_t offset, uint32_t flags) { struct backend_plugin *p = container_of (b, struct backend_plugin, backend); assert (connection_get_handle (conn)); assert (p->plugin.pread != NULL); + assert (!flags); debug ("pread count=%" PRIu32 " offset=%" PRIu64, count, offset); @@ -355,11 +356,12 @@ plugin_pread (struct backend *b, struct connection *conn, static int plugin_pwrite (struct backend *b, struct connection *conn, - const void *buf, uint32_t count, uint64_t offset) + const void *buf, uint32_t count, uint64_t offset, uint32_t flags) { struct backend_plugin *p = container_of (b, struct backend_plugin, backend); assert (connection_get_handle (conn)); + assert (!flags); debug ("pwrite count=%" PRIu32 " offset=%" PRIu64, count, offset); @@ -372,11 +374,12 @@ plugin_pwrite (struct backend *b, struct connection *conn, } static int -plugin_flush (struct backend *b, struct connection *conn) +plugin_flush (struct backend *b, struct connection *conn, uint32_t flags) { struct backend_plugin *p = container_of (b, struct backend_plugin, backend); assert (connection_get_handle (conn)); + assert (!flags); debug ("flush"); @@ -390,11 +393,12 @@ plugin_flush (struct backend *b, struct connection *conn) static int plugin_trim (struct backend *b, struct connection *conn, - uint32_t count, uint64_t offset) + uint32_t count, uint64_t offset, uint32_t flags) { struct backend_plugin *p = container_of (b, struct backend_plugin, backend); assert (connection_get_handle (conn)); + assert (!flags); debug ("trim count=%" PRIu32 " offset=%" PRIu64, count, offset); @@ -408,15 +412,17 @@ plugin_trim (struct backend *b, struct connection *conn, static int plugin_zero (struct backend *b, struct connection *conn, - uint32_t count, uint64_t offset, int may_trim) + uint32_t count, uint64_t offset, uint32_t flags) { struct backend_plugin *p = container_of (b, struct backend_plugin, backend); char *buf; uint32_t limit; int result; int err = 0; + int may_trim = (flags & NBDKIT_FLAG_MAY_TRIM) != 0; assert (connection_get_handle (conn)); + assert (!(flags & ~NBDKIT_FLAG_MAY_TRIM)); debug ("zero count=%" PRIu32 " offset=%" PRIu64 " may_trim=%d", count, offset, may_trim); -- 2.14.3