From cd7fca952ce8456955f7f4e11df9ced14204c2f1 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 6 Jul 2016 11:22:39 +0200 Subject: nbd-server: Use a separate BlockBackend The builtin NBD server uses its own BlockBackend now instead of reusing the monitor/guest device one. This means that it has its own writethrough setting now. The builtin NBD server always uses writeback caching now regardless of whether the guest device has WCE enabled. qemu-nbd respects the cache mode given on the command line. We still need to keep a reference to the monitor BB because we put an eject notifier on it, but we don't use it for any I/O. Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake Reviewed-by: Max Reitz --- nbd/server.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) (limited to 'nbd') diff --git a/nbd/server.c b/nbd/server.c index 80fbb4da1d..472f584c32 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -69,6 +69,7 @@ struct NBDExport { AioContext *ctx; + BlockBackend *eject_notifier_blk; Notifier eject_notifier; }; @@ -807,11 +808,18 @@ static void nbd_eject_notifier(Notifier *n, void *data) nbd_export_close(exp); } -NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size, +NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset, off_t size, uint16_t nbdflags, void (*close)(NBDExport *), + bool writethrough, BlockBackend *on_eject_blk, Error **errp) { + BlockBackend *blk; NBDExport *exp = g_malloc0(sizeof(NBDExport)); + + blk = blk_new(); + blk_insert_bs(blk, bs); + blk_set_enable_write_cache(blk, !writethrough); + exp->refcount = 1; QTAILQ_INIT(&exp->clients); exp->blk = blk; @@ -827,11 +835,14 @@ NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size, exp->close = close; exp->ctx = blk_get_aio_context(blk); - blk_ref(blk); blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp); - exp->eject_notifier.notify = nbd_eject_notifier; - blk_add_remove_bs_notifier(blk, &exp->eject_notifier); + if (on_eject_blk) { + blk_ref(on_eject_blk); + exp->eject_notifier_blk = on_eject_blk; + exp->eject_notifier.notify = nbd_eject_notifier; + blk_add_remove_bs_notifier(on_eject_blk, &exp->eject_notifier); + } /* * NBD exports are used for non-shared storage migration. Make sure @@ -844,6 +855,7 @@ NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size, return exp; fail: + blk_unref(blk); g_free(exp); return NULL; } @@ -914,7 +926,10 @@ void nbd_export_put(NBDExport *exp) } if (exp->blk) { - notifier_remove(&exp->eject_notifier); + if (exp->eject_notifier_blk) { + notifier_remove(&exp->eject_notifier); + blk_unref(exp->eject_notifier_blk); + } blk_remove_aio_context_notifier(exp->blk, blk_aio_attached, blk_aio_detach, exp); blk_unref(exp->blk); -- cgit v1.2.1