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authorKevin Wolf <kwolf@redhat.com>2017-02-09 13:34:18 +0100
committerKevin Wolf <kwolf@redhat.com>2017-02-28 20:47:50 +0100
commita170a91fd3eab6155da39e740381867e80bcc93e (patch)
tree2d89e721a563130bc7bc9e990654c64118cb753c /block
parent4ef85a9c233936d9ac1400d67b066353a6e9f32f (diff)
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stream: Use real permissions in streaming block job
The correct permissions are relatively obvious here (and explained in code comments). For intermediate streaming, we need to reopen the top node read-write before creating the job now because the permissions system catches attempts to get the BLK_PERM_WRITE_UNCHANGED permission on a read-only node. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Acked-by: Fam Zheng <famz@redhat.com>
Diffstat (limited to 'block')
-rw-r--r--block/stream.c39
1 files changed, 27 insertions, 12 deletions
diff --git a/block/stream.c b/block/stream.c
index ba8650f..b9c2f43 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -84,6 +84,8 @@ static void stream_complete(BlockJob *job, void *opaque)
/* Reopen the image back in read-only mode if necessary */
if (s->bs_flags != bdrv_get_flags(bs)) {
+ /* Give up write permissions before making it read-only */
+ blk_set_perm(job->blk, 0, BLK_PERM_ALL, &error_abort);
bdrv_reopen(bs, s->bs_flags, NULL);
}
@@ -229,28 +231,35 @@ void stream_start(const char *job_id, BlockDriverState *bs,
BlockDriverState *iter;
int orig_bs_flags;
- /* FIXME Use real permissions */
- s = block_job_create(job_id, &stream_job_driver, bs, 0, BLK_PERM_ALL,
- speed, BLOCK_JOB_DEFAULT, NULL, NULL, errp);
- if (!s) {
- return;
- }
-
/* Make sure that the image is opened in read-write mode */
orig_bs_flags = bdrv_get_flags(bs);
if (!(orig_bs_flags & BDRV_O_RDWR)) {
if (bdrv_reopen(bs, orig_bs_flags | BDRV_O_RDWR, errp) != 0) {
- block_job_unref(&s->common);
return;
}
}
- /* Block all intermediate nodes between bs and base, because they
- * will disappear from the chain after this operation */
+ /* Prevent concurrent jobs trying to modify the graph structure here, we
+ * already have our own plans. Also don't allow resize as the image size is
+ * queried only at the job start and then cached. */
+ s = block_job_create(job_id, &stream_job_driver, bs,
+ BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
+ BLK_PERM_GRAPH_MOD,
+ BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
+ BLK_PERM_WRITE,
+ speed, BLOCK_JOB_DEFAULT, NULL, NULL, errp);
+ if (!s) {
+ goto fail;
+ }
+
+ /* Block all intermediate nodes between bs and base, because they will
+ * disappear from the chain after this operation. The streaming job reads
+ * every block only once, assuming that it doesn't change, so block writes
+ * and resizes. */
for (iter = backing_bs(bs); iter && iter != base; iter = backing_bs(iter)) {
- /* FIXME Use real permissions */
block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
- BLK_PERM_ALL, &error_abort);
+ BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED,
+ &error_abort);
}
s->base = base;
@@ -260,4 +269,10 @@ void stream_start(const char *job_id, BlockDriverState *bs,
s->on_error = on_error;
trace_stream_start(bs, base, s);
block_job_start(&s->common);
+ return;
+
+fail:
+ if (orig_bs_flags != bdrv_get_flags(bs)) {
+ bdrv_reopen(bs, s->bs_flags, NULL);
+ }
}