linux-aio: properly bubble up errors from initialization
laio_init() can fail for a couple of reasons, which will lead to a NULL pointer dereference in laio_attach_aio_context(). To solve this, add a aio_setup_linux_aio() function which is called early in raw_open_common. If this fails, propagate the error up. The signature of aio_get_linux_aio() was not modified, because it seems preferable to return the actual errno from the possible failing initialization calls. Additionally, when the AioContext changes, we need to associate a LinuxAioState with the new AioContext. Use the bdrv_attach_aio_context callback and call the new aio_setup_linux_aio(), which will allocate a new AioContext if needed, and return errors on failures. If it fails for any reason, fallback to threaded AIO with an error message, as the device is already in-use by the guest. Add an assert that aio_get_linux_aio() cannot return NULL. Signed-off-by: Nishanth Aravamudan <naravamudan@digitalocean.com> Message-id: 20180622193700.6523-1-naravamudan@digitalocean.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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f18793b096
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@ -545,12 +545,18 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
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#ifdef CONFIG_LINUX_AIO
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/* Currently Linux does AIO only for files opened with O_DIRECT */
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if (s->use_linux_aio && !(s->open_flags & O_DIRECT)) {
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if (s->use_linux_aio) {
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if (!(s->open_flags & O_DIRECT)) {
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error_setg(errp, "aio=native was specified, but it requires "
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"cache.direct=on, which was not specified.");
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ret = -EINVAL;
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goto fail;
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}
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if (!aio_setup_linux_aio(bdrv_get_aio_context(bs), errp)) {
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error_prepend(errp, "Unable to use native AIO: ");
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goto fail;
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}
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}
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#else
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if (s->use_linux_aio) {
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error_setg(errp, "aio=native was specified, but is not supported "
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@ -1723,6 +1729,22 @@ static BlockAIOCB *raw_aio_flush(BlockDriverState *bs,
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return paio_submit(bs, s->fd, 0, NULL, 0, cb, opaque, QEMU_AIO_FLUSH);
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}
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static void raw_aio_attach_aio_context(BlockDriverState *bs,
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AioContext *new_context)
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{
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#ifdef CONFIG_LINUX_AIO
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BDRVRawState *s = bs->opaque;
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if (s->use_linux_aio) {
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Error *local_err;
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if (!aio_setup_linux_aio(new_context, &local_err)) {
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error_reportf_err(local_err, "Unable to use native AIO, "
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"falling back to thread pool: ");
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s->use_linux_aio = false;
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}
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}
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#endif
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}
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static void raw_close(BlockDriverState *bs)
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{
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BDRVRawState *s = bs->opaque;
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@ -2601,6 +2623,7 @@ BlockDriver bdrv_file = {
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.bdrv_refresh_limits = raw_refresh_limits,
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.bdrv_io_plug = raw_aio_plug,
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.bdrv_io_unplug = raw_aio_unplug,
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.bdrv_attach_aio_context = raw_aio_attach_aio_context,
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.bdrv_truncate = raw_truncate,
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.bdrv_getlength = raw_getlength,
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@ -15,6 +15,7 @@
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#include "block/raw-aio.h"
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#include "qemu/event_notifier.h"
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#include "qemu/coroutine.h"
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#include "qapi/error.h"
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#include <libaio.h>
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@ -470,16 +471,21 @@ void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context)
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qemu_laio_poll_cb);
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}
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LinuxAioState *laio_init(void)
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LinuxAioState *laio_init(Error **errp)
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{
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int rc;
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LinuxAioState *s;
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s = g_malloc0(sizeof(*s));
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if (event_notifier_init(&s->e, false) < 0) {
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rc = event_notifier_init(&s->e, false);
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if (rc < 0) {
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error_setg_errno(errp, -rc, "failed to to initialize event notifier");
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goto out_free_state;
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}
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if (io_setup(MAX_EVENTS, &s->ctx) != 0) {
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rc = io_setup(MAX_EVENTS, &s->ctx);
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if (rc < 0) {
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error_setg_errno(errp, -rc, "failed to create linux AIO context");
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goto out_close_efd;
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}
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@ -381,6 +381,9 @@ GSource *aio_get_g_source(AioContext *ctx);
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/* Return the ThreadPool bound to this AioContext */
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struct ThreadPool *aio_get_thread_pool(AioContext *ctx);
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/* Setup the LinuxAioState bound to this AioContext */
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struct LinuxAioState *aio_setup_linux_aio(AioContext *ctx, Error **errp);
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/* Return the LinuxAioState bound to this AioContext */
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struct LinuxAioState *aio_get_linux_aio(AioContext *ctx);
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@ -43,7 +43,7 @@
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/* linux-aio.c - Linux native implementation */
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#ifdef CONFIG_LINUX_AIO
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typedef struct LinuxAioState LinuxAioState;
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LinuxAioState *laio_init(void);
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LinuxAioState *laio_init(Error **errp);
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void laio_cleanup(LinuxAioState *s);
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int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
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uint64_t offset, QEMUIOVector *qiov, int type);
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@ -21,7 +21,7 @@ void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context)
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abort();
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}
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LinuxAioState *laio_init(void)
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LinuxAioState *laio_init(Error **errp)
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{
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abort();
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}
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12
util/async.c
12
util/async.c
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@ -323,12 +323,20 @@ ThreadPool *aio_get_thread_pool(AioContext *ctx)
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}
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#ifdef CONFIG_LINUX_AIO
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LinuxAioState *aio_get_linux_aio(AioContext *ctx)
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LinuxAioState *aio_setup_linux_aio(AioContext *ctx, Error **errp)
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{
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if (!ctx->linux_aio) {
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ctx->linux_aio = laio_init();
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ctx->linux_aio = laio_init(errp);
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if (ctx->linux_aio) {
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laio_attach_aio_context(ctx->linux_aio, ctx);
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}
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}
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return ctx->linux_aio;
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}
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LinuxAioState *aio_get_linux_aio(AioContext *ctx)
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{
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assert(ctx->linux_aio);
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return ctx->linux_aio;
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}
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#endif
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