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authorKevin Wolf <kwolf@redhat.com>2020-09-24 17:26:52 +0200
committerKevin Wolf <kwolf@redhat.com>2020-10-02 15:46:40 +0200
commitb57e4de079d90caca05fed5b45aeb642c6c29aa0 (patch)
treeb76720bec980669ca9e4ee67aa92382e9a00ea5e /qemu-nbd.c
parent060102ad655544501b9d0d9f3fc8b8675883b463 (diff)
qemu-nbd: Use raw block driver for --offset
Instead of implementing qemu-nbd --offset in the NBD code, just put a raw block node with the requested offset on top of the user image and rely on that doing the job. This does not only simplify the nbd_export_new() interface and bring it closer to the set of options that the nbd-server-add QMP command offers, but in fact it also eliminates a potential source for bugs in the NBD code which previously had to add the offset manually in all relevant places. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200924152717.287415-7-kwolf@redhat.com> Acked-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'qemu-nbd.c')
-rw-r--r--qemu-nbd.c27
1 files changed, 12 insertions, 15 deletions
diff --git a/qemu-nbd.c b/qemu-nbd.c
index e39d3b23c1..16473d809c 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -524,7 +524,6 @@ int main(int argc, char **argv)
const char *port = NULL;
char *sockpath = NULL;
char *device = NULL;
- int64_t fd_size;
QemuOpts *sn_opts = NULL;
const char *sn_id_or_name = NULL;
const char *sopt = "hVb:o:p:rsnc:dvk:e:f:tl:x:T:D:B:L";
@@ -1037,6 +1036,17 @@ int main(int argc, char **argv)
}
bs = blk_bs(blk);
+ if (dev_offset) {
+ QDict *raw_opts = qdict_new();
+ qdict_put_str(raw_opts, "driver", "raw");
+ qdict_put_str(raw_opts, "file", bs->node_name);
+ qdict_put_int(raw_opts, "offset", dev_offset);
+ bs = bdrv_open(NULL, NULL, raw_opts, flags, &error_fatal);
+ blk_remove_bs(blk);
+ blk_insert_bs(blk, bs, &error_fatal);
+ bdrv_unref(bs);
+ }
+
blk_set_enable_write_cache(blk, !writethrough);
if (sn_opts) {
@@ -1054,21 +1064,8 @@ int main(int argc, char **argv)
}
bs->detect_zeroes = detect_zeroes;
- fd_size = blk_getlength(blk);
- if (fd_size < 0) {
- error_report("Failed to determine the image length: %s",
- strerror(-fd_size));
- exit(EXIT_FAILURE);
- }
-
- if (dev_offset >= fd_size) {
- error_report("Offset (%" PRIu64 ") has to be smaller than the image "
- "size (%" PRId64 ")", dev_offset, fd_size);
- exit(EXIT_FAILURE);
- }
- fd_size -= dev_offset;
- export = nbd_export_new(bs, dev_offset, fd_size, export_name,
+ export = nbd_export_new(bs, export_name,
export_description, bitmap, readonly, shared > 1,
nbd_export_closed, writethrough, NULL,
&error_fatal);