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[Qemu-devel] [PATCH v6 27/42] commit: Deal with filters
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH v6 27/42] commit: Deal with filters |
Date: |
Fri, 9 Aug 2019 18:13:52 +0200 |
This includes some permission limiting (for example, we only need to
take the RESIZE permission if the base is smaller than the top).
Signed-off-by: Max Reitz <address@hidden>
---
block/block-backend.c | 16 +++++---
block/commit.c | 96 +++++++++++++++++++++++++++++++------------
blockdev.c | 6 ++-
3 files changed, 85 insertions(+), 33 deletions(-)
diff --git a/block/block-backend.c b/block/block-backend.c
index c13c5c83b0..0bc592d023 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -2180,11 +2180,17 @@ int blk_commit_all(void)
AioContext *aio_context = blk_get_aio_context(blk);
aio_context_acquire(aio_context);
- if (blk_is_inserted(blk) && blk->root->bs->backing) {
- int ret = bdrv_commit(blk->root->bs);
- if (ret < 0) {
- aio_context_release(aio_context);
- return ret;
+ if (blk_is_inserted(blk)) {
+ BlockDriverState *non_filter;
+
+ /* Legacy function, so skip implicit filters */
+ non_filter = bdrv_skip_implicit_filters(blk->root->bs);
+ if (bdrv_filtered_cow_child(non_filter)) {
+ int ret = bdrv_commit(non_filter);
+ if (ret < 0) {
+ aio_context_release(aio_context);
+ return ret;
+ }
}
}
aio_context_release(aio_context);
diff --git a/block/commit.c b/block/commit.c
index 5a7672c7c7..40d1c8eeac 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -37,6 +37,7 @@ typedef struct CommitBlockJob {
BlockBackend *top;
BlockBackend *base;
BlockDriverState *base_bs;
+ BlockDriverState *above_base;
BlockdevOnError on_error;
bool base_read_only;
bool chain_frozen;
@@ -110,7 +111,7 @@ static void commit_abort(Job *job)
* XXX Can (or should) we somehow keep 'consistent read' blocked even
* after the failed/cancelled commit job is gone? If we already wrote
* something to base, the intermediate images aren't valid any more. */
- bdrv_replace_node(s->commit_top_bs, backing_bs(s->commit_top_bs),
+ bdrv_replace_node(s->commit_top_bs, s->commit_top_bs->backing->bs,
&error_abort);
bdrv_unref(s->commit_top_bs);
@@ -174,7 +175,7 @@ static int coroutine_fn commit_run(Job *job, Error **errp)
break;
}
/* Copy if allocated above the base */
- ret = bdrv_is_allocated_above(blk_bs(s->top), blk_bs(s->base), false,
+ ret = bdrv_is_allocated_above(blk_bs(s->top), s->above_base, true,
offset, COMMIT_BUFFER_SIZE, &n);
copy = (ret == 1);
trace_commit_one_iteration(s, offset, n, ret);
@@ -267,15 +268,35 @@ void commit_start(const char *job_id, BlockDriverState
*bs,
CommitBlockJob *s;
BlockDriverState *iter;
BlockDriverState *commit_top_bs = NULL;
+ BlockDriverState *filtered_base;
Error *local_err = NULL;
+ int64_t base_size, top_size;
+ uint64_t perms, iter_shared_perms;
int ret;
assert(top != bs);
- if (top == base) {
+ if (bdrv_skip_rw_filters(top) == bdrv_skip_rw_filters(base)) {
error_setg(errp, "Invalid files for merge: top and base are the same");
return;
}
+ base_size = bdrv_getlength(base);
+ if (base_size < 0) {
+ error_setg_errno(errp, -base_size, "Could not inquire base image
size");
+ return;
+ }
+
+ top_size = bdrv_getlength(top);
+ if (top_size < 0) {
+ error_setg_errno(errp, -top_size, "Could not inquire top image size");
+ return;
+ }
+
+ perms = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE;
+ if (base_size < top_size) {
+ perms |= BLK_PERM_RESIZE;
+ }
+
s = block_job_create(job_id, &commit_job_driver, NULL, bs, 0, BLK_PERM_ALL,
speed, creation_flags, NULL, NULL, errp);
if (!s) {
@@ -315,17 +336,43 @@ void commit_start(const char *job_id, BlockDriverState
*bs,
s->commit_top_bs = commit_top_bs;
- /* Block all nodes between top and base, because they will
- * disappear from the chain after this operation. */
- assert(bdrv_chain_contains(top, base));
- for (iter = top; iter != base; iter = backing_bs(iter)) {
- /* XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves
- * at s->base (if writes are blocked for a node, they are also blocked
- * for its backing file). The other options would be a second filter
- * driver above s->base. */
+ /*
+ * Block all nodes between top and base, because they will
+ * disappear from the chain after this operation.
+ * Note that this assumes that the user is fine with removing all
+ * nodes (including R/W filters) between top and base. Assuring
+ * this is the responsibility of the interface (i.e. whoever calls
+ * commit_start()).
+ */
+ s->above_base = bdrv_find_overlay(top, base);
+ assert(s->above_base);
+
+ /*
+ * The topmost node with
+ * bdrv_skip_rw_filters(filtered_base) == bdrv_skip_rw_filters(base)
+ */
+ filtered_base = bdrv_filtered_cow_bs(s->above_base);
+ assert(bdrv_skip_rw_filters(filtered_base) == bdrv_skip_rw_filters(base));
+
+ /*
+ * XXX BLK_PERM_WRITE needs to be allowed so we don't block ourselves
+ * at s->base (if writes are blocked for a node, they are also blocked
+ * for its backing file). The other options would be a second filter
+ * driver above s->base.
+ */
+ iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE;
+
+ for (iter = top; iter != base; iter = bdrv_filtered_bs(iter)) {
+ if (iter == filtered_base) {
+ /*
+ * From here on, all nodes are filters on the base. This
+ * allows us to share BLK_PERM_CONSISTENT_READ.
+ */
+ iter_shared_perms |= BLK_PERM_CONSISTENT_READ;
+ }
+
ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
- BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE,
- errp);
+ iter_shared_perms, errp);
if (ret < 0) {
goto fail;
}
@@ -342,9 +389,7 @@ void commit_start(const char *job_id, BlockDriverState *bs,
}
s->base = blk_new(s->common.job.aio_context,
- BLK_PERM_CONSISTENT_READ
- | BLK_PERM_WRITE
- | BLK_PERM_RESIZE,
+ perms,
BLK_PERM_CONSISTENT_READ
| BLK_PERM_GRAPH_MOD
| BLK_PERM_WRITE_UNCHANGED);
@@ -412,19 +457,22 @@ int bdrv_commit(BlockDriverState *bs)
if (!drv)
return -ENOMEDIUM;
- if (!bs->backing) {
+ backing_file_bs = bdrv_filtered_cow_bs(bs);
+
+ if (!backing_file_bs) {
return -ENOTSUP;
}
if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_COMMIT_SOURCE, NULL) ||
- bdrv_op_is_blocked(bs->backing->bs, BLOCK_OP_TYPE_COMMIT_TARGET,
NULL)) {
+ bdrv_op_is_blocked(backing_file_bs, BLOCK_OP_TYPE_COMMIT_TARGET, NULL))
+ {
return -EBUSY;
}
- ro = bs->backing->bs->read_only;
+ ro = backing_file_bs->read_only;
if (ro) {
- if (bdrv_reopen_set_read_only(bs->backing->bs, false, NULL)) {
+ if (bdrv_reopen_set_read_only(backing_file_bs, false, NULL)) {
return -EACCES;
}
}
@@ -440,8 +488,6 @@ int bdrv_commit(BlockDriverState *bs)
}
/* Insert commit_top block node above backing, so we can write to it */
- backing_file_bs = backing_bs(bs);
-
commit_top_bs = bdrv_new_open_driver(&bdrv_commit_top, NULL, BDRV_O_RDWR,
&local_err);
if (commit_top_bs == NULL) {
@@ -526,15 +572,13 @@ ro_cleanup:
qemu_vfree(buf);
blk_unref(backing);
- if (backing_file_bs) {
- bdrv_set_backing_hd(bs, backing_file_bs, &error_abort);
- }
+ bdrv_set_backing_hd(bs, backing_file_bs, &error_abort);
bdrv_unref(commit_top_bs);
blk_unref(src);
if (ro) {
/* ignoring error return here */
- bdrv_reopen_set_read_only(bs->backing->bs, true, NULL);
+ bdrv_reopen_set_read_only(backing_file_bs, true, NULL);
}
return ret;
diff --git a/blockdev.c b/blockdev.c
index c6f79b4e0e..7bef41c0b0 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1094,7 +1094,7 @@ void hmp_commit(Monitor *mon, const QDict *qdict)
return;
}
- bs = blk_bs(blk);
+ bs = bdrv_skip_implicit_filters(blk_bs(blk));
aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
@@ -3454,7 +3454,9 @@ void qmp_block_commit(bool has_job_id, const char
*job_id, const char *device,
assert(bdrv_get_aio_context(base_bs) == aio_context);
- for (iter = top_bs; iter != backing_bs(base_bs); iter = backing_bs(iter)) {
+ for (iter = top_bs; iter != bdrv_filtered_bs(base_bs);
+ iter = bdrv_filtered_bs(iter))
+ {
if (bdrv_op_is_blocked(iter, BLOCK_OP_TYPE_COMMIT_TARGET, errp)) {
goto out;
}
--
2.21.0
- Re: [Qemu-devel] [PATCH v6 22/42] block: Fix bdrv_get_allocated_file_size's fallback, (continued)
- [Qemu-devel] [PATCH v6 23/42] blockdev: Use CAF in external_snapshot_prepare(), Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 24/42] block: Use child access functions for QAPI queries, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 26/42] backup: Deal with filters, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 25/42] mirror: Deal with filters, Max Reitz, 2019/08/09
- Re: [Qemu-devel] [PATCH v6 25/42] mirror: Deal with filters, Vladimir Sementsov-Ogievskiy, 2019/08/31
- [Qemu-devel] [PATCH v6 27/42] commit: Deal with filters,
Max Reitz <=
- [Qemu-devel] [PATCH v6 28/42] stream: Deal with filters, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 29/42] nbd: Use CAF when looking for dirty bitmap, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 30/42] qemu-img: Use child access functions, Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 31/42] block: Drop backing_bs(), Max Reitz, 2019/08/09
- [Qemu-devel] [PATCH v6 32/42] block: Make bdrv_get_cumulative_perm() public, Max Reitz, 2019/08/09