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authorKevin Wolf <kwolf@redhat.com>2016-07-06 11:22:39 +0200
committerKevin Wolf <kwolf@redhat.com>2016-09-05 19:06:47 +0200
commitcd7fca952ce8456955f7f4e11df9ced14204c2f1 (patch)
tree2d58a11ca8c6f967356c111e5750f9f8c924dd5a /nbd/server.c
parent0524e93a3fd7bff5bb4a584c372f2632ab7c0e0f (diff)
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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 <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'nbd/server.c')
-rw-r--r--nbd/server.c25
1 files changed, 20 insertions, 5 deletions
diff --git a/nbd/server.c b/nbd/server.c
index 80fbb4d..472f584 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);