[Libguestfs] [PATCH nbdkit v2 06/11] plugins: Return NBD_FLAG_CAN_MULTI_CONN from some readonly plugins.

It is safe to return NBD_FLAG_CAN_MULTI_CONN from almost all readonly plugins. However only do it where the plugin thread model is NBDKIT_THREAD_MODEL_PARALLEL and the plugin could plausibly be used in a high performance situation. --- plugins/floppy/floppy.c | 8 ++++++++ plugins/iso/iso.c | 8 ++++++++ plugins/pattern/pattern.c | 8 ++++++++ plugins/random/random.c | 8 ++++++++ 4 files changed, 32 insertions(+) diff --git a/plugins/floppy/floppy.c b/plugins/floppy/floppy.c index 5e23c88..0efb8dd 100644 --- a/plugins/floppy/floppy.c +++ b/plugins/floppy/floppy.c @@ -122,6 +122,13 @@ floppy_get_size (void *handle) return virtual_size (&floppy.regions); } +/* Serves the same data over multiple connections. */ +static int +floppy_can_multi_conn (void *handle) +{ + return 1; +} + /* Read data from the file. */ static int floppy_pread (void *handle, void *buf, uint32_t count, uint64_t offset) @@ -192,6 +199,7 @@ static struct nbdkit_plugin plugin = { .magic_config_key = "dir", .open = floppy_open, .get_size = floppy_get_size, + .can_multi_conn = floppy_can_multi_conn, .pread = floppy_pread, .errno_is_preserved = 1, }; diff --git a/plugins/iso/iso.c b/plugins/iso/iso.c index 7ed5e7a..7431b48 100644 --- a/plugins/iso/iso.c +++ b/plugins/iso/iso.c @@ -258,6 +258,13 @@ iso_get_size (void *handle) return statbuf.st_size; } +/* Serves the same data over multiple connections. */ +static int +iso_can_multi_conn (void *handle) +{ + return 1; +} + /* Read data from the file. */ static int iso_pread (void *handle, void *buf, uint32_t count, uint64_t offset) @@ -291,6 +298,7 @@ static struct nbdkit_plugin plugin = { .magic_config_key = "dir", .open = iso_open, .get_size = iso_get_size, + .can_multi_conn = iso_can_multi_conn, .pread = iso_pread, .errno_is_preserved = 1, }; diff --git a/plugins/pattern/pattern.c b/plugins/pattern/pattern.c index 32db381..23e9019 100644 --- a/plugins/pattern/pattern.c +++ b/plugins/pattern/pattern.c @@ -88,6 +88,13 @@ pattern_get_size (void *handle) return size; } +/* Serves the same data over multiple connections. */ +static int +pattern_can_multi_conn (void *handle) +{ + return 1; +} + /* Read data. */ static int pattern_pread (void *handle, void *buf, uint32_t count, uint64_t offset, @@ -118,6 +125,7 @@ static struct nbdkit_plugin plugin = { .config_help = pattern_config_help, .open = pattern_open, .get_size = pattern_get_size, + .can_multi_conn = pattern_can_multi_conn, .pread = pattern_pread, /* In this plugin, errno is preserved properly along error return * paths from failed system calls. diff --git a/plugins/random/random.c b/plugins/random/random.c index 9c805ab..ba51520 100644 --- a/plugins/random/random.c +++ b/plugins/random/random.c @@ -107,6 +107,13 @@ random_get_size (void *handle) return size; } +/* Serves the same data over multiple connections. */ +static int +random_can_multi_conn (void *handle) +{ + return 1; +} + /* Read data. */ static int random_pread (void *handle, void *buf, uint32_t count, uint64_t offset, @@ -148,6 +155,7 @@ static struct nbdkit_plugin plugin = { .config_help = random_config_help, .open = random_open, .get_size = random_get_size, + .can_multi_conn = random_can_multi_conn, .pread = random_pread, /* In this plugin, errno is preserved properly along error return * paths from failed system calls. -- 2.19.2