From: Marc Mari Date: Fri, 12 Aug 2016 13:27:03 +0000 (-0400) Subject: blockdev: Add dynamic module loading for block drivers X-Git-Tag: v2.8.0-rc0~126^2~3 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=88d88798b7efeb0be15b1a60e58b1f8ba4c2f700;p=thirdparty%2Fqemu.git blockdev: Add dynamic module loading for block drivers Extend the current module interface to allow for block drivers to be loaded dynamically on request. The only block drivers that can be converted into modules are the drivers that don't perform any init operation except for registering themselves. In addition, only the protocol drivers are being modularized, as they are the only ones which see significant performance benefits. The format drivers do not generally link to external libraries, so modularizing them is of no benefit from a performance perspective. All the necessary module information is located in a new structure found in module_block.h This spoils the purpose of 5505e8b76f (block/dmg: make it modular). Before this patch, if module build is enabled, block-dmg.so is linked to libbz2, whereas the main binary is not. In downstream, theoretically, it means only the qemu-block-extra package depends on libbz2, while the main QEMU package needn't to. With this patch, we (temporarily) change the case so that the main QEMU depends on libbz2 again. Signed-off-by: Marc Marí Signed-off-by: Colin Lord Reviewed-by: Stefan Hajnoczi Message-id: 1471008424-16465-4-git-send-email-clord@redhat.com Reviewed-by: Max Reitz [mreitz: Do a signed comparison against the length of block_driver_modules[], so it will not cause a compile error when empty] Signed-off-by: Max Reitz --- diff --git a/Makefile b/Makefile index b7d1200c166..f10361675da 100644 --- a/Makefile +++ b/Makefile @@ -247,9 +247,6 @@ Makefile: $(version-obj-y) $(version-lobj-y) libqemustub.a: $(stub-obj-y) libqemuutil.a: $(util-obj-y) -block-modules = $(foreach o,$(block-obj-m),"$(basename $(subst /,-,$o))",) NULL -util/module.o-cflags = -D'CONFIG_BLOCK_MODULES=$(block-modules)' - ###################################################################### qemu-img.o: qemu-img-cmds.h diff --git a/block.c b/block.c index 66ed1c03219..afaff93423d 100644 --- a/block.c +++ b/block.c @@ -27,6 +27,7 @@ #include "block/blockjob.h" #include "block/nbd.h" #include "qemu/error-report.h" +#include "module_block.h" #include "qemu/module.h" #include "qapi/qmp/qerror.h" #include "qapi/qmp/qbool.h" @@ -242,17 +243,40 @@ BlockDriverState *bdrv_new(void) return bs; } -BlockDriver *bdrv_find_format(const char *format_name) +static BlockDriver *bdrv_do_find_format(const char *format_name) { BlockDriver *drv1; + QLIST_FOREACH(drv1, &bdrv_drivers, list) { if (!strcmp(drv1->format_name, format_name)) { return drv1; } } + return NULL; } +BlockDriver *bdrv_find_format(const char *format_name) +{ + BlockDriver *drv1; + int i; + + drv1 = bdrv_do_find_format(format_name); + if (drv1) { + return drv1; + } + + /* The driver isn't registered, maybe we need to load a module */ + for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { + if (!strcmp(block_driver_modules[i].format_name, format_name)) { + block_module_load_one(block_driver_modules[i].library_name); + break; + } + } + + return bdrv_do_find_format(format_name); +} + static int bdrv_is_whitelisted(BlockDriver *drv, bool read_only) { static const char *whitelist_rw[] = { @@ -461,6 +485,19 @@ static BlockDriver *find_hdev_driver(const char *filename) return drv; } +static BlockDriver *bdrv_do_find_protocol(const char *protocol) +{ + BlockDriver *drv1; + + QLIST_FOREACH(drv1, &bdrv_drivers, list) { + if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) { + return drv1; + } + } + + return NULL; +} + BlockDriver *bdrv_find_protocol(const char *filename, bool allow_protocol_prefix, Error **errp) @@ -469,6 +506,7 @@ BlockDriver *bdrv_find_protocol(const char *filename, char protocol[128]; int len; const char *p; + int i; /* TODO Drivers without bdrv_file_open must be specified explicitly */ @@ -495,15 +533,25 @@ BlockDriver *bdrv_find_protocol(const char *filename, len = sizeof(protocol) - 1; memcpy(protocol, filename, len); protocol[len] = '\0'; - QLIST_FOREACH(drv1, &bdrv_drivers, list) { - if (drv1->protocol_name && - !strcmp(drv1->protocol_name, protocol)) { - return drv1; + + drv1 = bdrv_do_find_protocol(protocol); + if (drv1) { + return drv1; + } + + for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { + if (block_driver_modules[i].protocol_name && + !strcmp(block_driver_modules[i].protocol_name, protocol)) { + block_module_load_one(block_driver_modules[i].library_name); + break; } } - error_setg(errp, "Unknown protocol '%s'", protocol); - return NULL; + drv1 = bdrv_do_find_protocol(protocol); + if (!drv1) { + error_setg(errp, "Unknown protocol '%s'", protocol); + } + return drv1; } /* diff --git a/block/Makefile.objs b/block/Makefile.objs index 55da6266fe4..3da471e3886 100644 --- a/block/Makefile.objs +++ b/block/Makefile.objs @@ -1,4 +1,4 @@ -block-obj-y += raw_bsd.o qcow.o vdi.o vmdk.o cloop.o bochs.o vpc.o vvfat.o +block-obj-y += raw_bsd.o qcow.o vdi.o vmdk.o cloop.o bochs.o vpc.o vvfat.o dmg.o block-obj-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o block-obj-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o block-obj-y += qed-check.o @@ -40,7 +40,6 @@ gluster.o-libs := $(GLUSTERFS_LIBS) ssh.o-cflags := $(LIBSSH2_CFLAGS) ssh.o-libs := $(LIBSSH2_LIBS) archipelago.o-libs := $(ARCHIPELAGO_LIBS) -block-obj-m += dmg.o dmg.o-libs := $(BZIP2_LIBS) qcow.o-libs := -lz linux-aio.o-libs := -laio diff --git a/include/qemu/module.h b/include/qemu/module.h index 2370708445a..dc2c9d4c4ee 100644 --- a/include/qemu/module.h +++ b/include/qemu/module.h @@ -52,9 +52,12 @@ typedef enum { #define qapi_init(function) module_init(function, MODULE_INIT_QAPI) #define type_init(function) module_init(function, MODULE_INIT_QOM) +#define block_module_load_one(lib) module_load_one("block-", lib) + void register_module_init(void (*fn)(void), module_init_type type); void register_dso_module_init(void (*fn)(void), module_init_type type); void module_call_init(module_init_type type); +void module_load_one(const char *prefix, const char *lib_name); #endif diff --git a/util/module.c b/util/module.c index 86e3f7aba00..a5f7fbd9413 100644 --- a/util/module.c +++ b/util/module.c @@ -87,14 +87,11 @@ void register_dso_module_init(void (*fn)(void), module_init_type type) QTAILQ_INSERT_TAIL(&dso_init_list, e, node); } -static void module_load(module_init_type type); - void module_call_init(module_init_type type) { ModuleTypeList *l; ModuleEntry *e; - module_load(type); l = find_type(type); QTAILQ_FOREACH(e, l, node) { @@ -145,6 +142,7 @@ static int module_load_file(const char *fname) ret = -EINVAL; } else { QTAILQ_FOREACH(e, &dso_init_list, node) { + e->init(); register_module_init(e->init, e->type); } ret = 0; @@ -159,14 +157,10 @@ out: } #endif -static void module_load(module_init_type type) +void module_load_one(const char *prefix, const char *lib_name) { #ifdef CONFIG_MODULES char *fname = NULL; - const char **mp; - static const char *block_modules[] = { - CONFIG_BLOCK_MODULES - }; char *exec_dir; char *dirs[3]; int i = 0; @@ -177,15 +171,6 @@ static void module_load(module_init_type type) return; } - switch (type) { - case MODULE_INIT_BLOCK: - mp = block_modules; - break; - default: - /* no other types have dynamic modules for now*/ - return; - } - exec_dir = qemu_get_exec_dir(); dirs[i++] = g_strdup_printf("%s", CONFIG_QEMU_MODDIR); dirs[i++] = g_strdup_printf("%s/..", exec_dir ? : ""); @@ -194,16 +179,15 @@ static void module_load(module_init_type type) g_free(exec_dir); exec_dir = NULL; - for ( ; *mp; mp++) { - for (i = 0; i < ARRAY_SIZE(dirs); i++) { - fname = g_strdup_printf("%s/%s%s", dirs[i], *mp, HOST_DSOSUF); - ret = module_load_file(fname); - g_free(fname); - fname = NULL; - /* Try loading until loaded a module file */ - if (!ret) { - break; - } + for (i = 0; i < ARRAY_SIZE(dirs); i++) { + fname = g_strdup_printf("%s/%s%s%s", + dirs[i], prefix, lib_name, HOST_DSOSUF); + ret = module_load_file(fname); + g_free(fname); + fname = NULL; + /* Try loading until loaded a module file */ + if (!ret) { + break; } }