Merge tag 'pull-nbd-2025-05-14' of https://repo.or.cz/qemu/ericb into staging

NBD patches for 2025-05-14

- Eric Blake: fix blockdev-mirror to no longer inflate sparse destination
  that already reads as zero

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# gpg: Signature made Wed 14 May 2025 22:28:13 EDT
# gpg:                using RSA key 71C2CC22B1C4602927D2F3AAA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>" [full]
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>" [full]
# gpg:                 aka "[jpeg image of size 6874]" [full]
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A

* tag 'pull-nbd-2025-05-14' of https://repo.or.cz/qemu/ericb:
  mirror: Reduce I/O when destination is detect-zeroes:unmap
  tests: Add iotest mirror-sparse for recent patches
  iotests/common.rc: add disk_usage function
  mirror: Skip writing zeroes when target is already zero
  mirror: Skip pre-zeroing destination if it is already zero
  mirror: Drop redundant zero_target parameter
  mirror: Allow QMP override to declare target already zero
  mirror: Pass full sync mode rather than bool to internals
  mirror: Minor refactoring
  iotests: Improve iotest 194 to mirror data
  block: Add new bdrv_co_is_all_zeroes() function
  block: Let bdrv_co_is_zero_fast consolidate adjacent extents
  file-posix, gluster: Handle zero block status hint better
  block: Expand block status mode from bool to flags

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

5 files changed, 31 insertions, 17 deletions

diff --git a/include/block/block-common.h b/include/block/block-common.h
index 0b831ef87b..c8c626daea 100644
--- a/include/block/block-common.h
+++ b/include/block/block-common.h
@@ -333,6 +333,17 @@ typedef enum {
 #define BDRV_BLOCK_RECURSE      0x40
 #define BDRV_BLOCK_COMPRESSED   0x80
 
+/*
+ * Block status hints: the bitwise-or of these flags emphasize what
+ * the caller hopes to learn, and some drivers may be able to give
+ * faster answers by doing less work when the hint permits.
+ */
+#define BDRV_WANT_ZERO          BDRV_BLOCK_ZERO
+#define BDRV_WANT_OFFSET_VALID  BDRV_BLOCK_OFFSET_VALID
+#define BDRV_WANT_ALLOCATED     BDRV_BLOCK_ALLOCATED
+#define BDRV_WANT_PRECISE       (BDRV_WANT_ZERO | BDRV_WANT_OFFSET_VALID | \
+                                 BDRV_WANT_OFFSET_VALID)
+
 typedef QTAILQ_HEAD(BlockReopenQueue, BlockReopenQueueEntry) BlockReopenQueue;
 
 typedef struct BDRVReopenState {
diff --git a/include/block/block-io.h b/include/block/block-io.h
index b49e0537dd..b99cc98d26 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -161,6 +161,8 @@ bdrv_is_allocated_above(BlockDriverState *bs, BlockDriverState *base,
 
 int coroutine_fn GRAPH_RDLOCK
 bdrv_co_is_zero_fast(BlockDriverState *bs, int64_t offset, int64_t bytes);
+int coroutine_fn GRAPH_RDLOCK
+bdrv_co_is_all_zeroes(BlockDriverState *bs);
 
 int GRAPH_RDLOCK
 bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 0d8187f656..2982dd3118 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -604,15 +604,16 @@ struct BlockDriver {
      * according to the current layer, and should only need to set
      * BDRV_BLOCK_DATA, BDRV_BLOCK_ZERO, BDRV_BLOCK_OFFSET_VALID,
      * and/or BDRV_BLOCK_RAW; if the current layer defers to a backing
-     * layer, the result should be 0 (and not BDRV_BLOCK_ZERO).  See
-     * block.h for the overall meaning of the bits.  As a hint, the
-     * flag want_zero is true if the caller cares more about precise
-     * mappings (favor accurate _OFFSET_VALID/_ZERO) or false for
-     * overall allocation (favor larger *pnum, perhaps by reporting
-     * _DATA instead of _ZERO).  The block layer guarantees input
-     * clamped to bdrv_getlength() and aligned to request_alignment,
-     * as well as non-NULL pnum, map, and file; in turn, the driver
-     * must return an error or set pnum to an aligned non-zero value.
+     * layer, the result should be 0 (and not BDRV_BLOCK_ZERO).  The
+     * caller will synthesize BDRV_BLOCK_ALLOCATED based on the
+     * non-zero results.  See block.h for the overall meaning of the
+     * bits.  As a hint, the flags in @mode may include a bitwise-or
+     * of BDRV_WANT_ALLOCATED, BDRV_WANT_OFFSET_VALID, or
+     * BDRV_WANT_ZERO based on what the caller is looking for in the
+     * results.  The block layer guarantees input clamped to
+     * bdrv_getlength() and aligned to request_alignment, as well as
+     * non-NULL pnum, map, and file; in turn, the driver must return
+     * an error or set pnum to an aligned non-zero value.
      *
      * Note that @bytes is just a hint on how big of a region the
      * caller wants to inspect.  It is not a limit on *pnum.
@@ -624,8 +625,8 @@ struct BlockDriver {
      * to clamping *pnum for return to its caller.
      */
     int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_block_status)(
-        BlockDriverState *bs,
-        bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum,
+        BlockDriverState *bs, unsigned int mode,
+        int64_t offset, int64_t bytes, int64_t *pnum,
         int64_t *map, BlockDriverState **file);
 
     /*
@@ -649,8 +650,8 @@ struct BlockDriver {
         QEMUIOVector *qiov, size_t qiov_offset);
 
     int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_snapshot_block_status)(
-        BlockDriverState *bs, bool want_zero, int64_t offset, int64_t bytes,
-        int64_t *pnum, int64_t *map, BlockDriverState **file);
+        BlockDriverState *bs, unsigned int mode, int64_t offset,
+        int64_t bytes, int64_t *pnum, int64_t *map, BlockDriverState **file);
 
     int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pdiscard_snapshot)(
         BlockDriverState *bs, int64_t offset, int64_t bytes);
diff --git a/include/block/block_int-global-state.h b/include/block/block_int-global-state.h
index 0d93783763..e7c8f1a856 100644
--- a/include/block/block_int-global-state.h
+++ b/include/block/block_int-global-state.h
@@ -139,7 +139,7 @@ BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs,
  * @buf_size: The amount of data that can be in flight at one time.
  * @mode: Whether to collapse all images in the chain to the target.
  * @backing_mode: How to establish the target's backing chain after completion.
- * @zero_target: Whether the target should be explicitly zero-initialized
+ * @target_is_zero: Whether the target already is zero-initialized.
  * @on_source_error: The action to take upon error reading from the source.
  * @on_target_error: The action to take upon error writing to the target.
  * @unmap: Whether to unmap target where source sectors only contain zeroes.
@@ -159,7 +159,7 @@ void mirror_start(const char *job_id, BlockDriverState *bs,
                   int creation_flags, int64_t speed,
                   uint32_t granularity, int64_t buf_size,
                   MirrorSyncMode mode, BlockMirrorBackingMode backing_mode,
-                  bool zero_target,
+                  bool target_is_zero,
                   BlockdevOnError on_source_error,
                   BlockdevOnError on_target_error,
                   bool unmap, const char *filter_node_name,
diff --git a/include/block/block_int-io.h b/include/block/block_int-io.h
index 4a7cf2b4fd..4f94eb3c5a 100644
--- a/include/block/block_int-io.h
+++ b/include/block/block_int-io.h
@@ -38,8 +38,8 @@
 int coroutine_fn GRAPH_RDLOCK bdrv_co_preadv_snapshot(BdrvChild *child,
     int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset);
 int coroutine_fn GRAPH_RDLOCK bdrv_co_snapshot_block_status(
-    BlockDriverState *bs, bool want_zero, int64_t offset, int64_t bytes,
-    int64_t *pnum, int64_t *map, BlockDriverState **file);
+    BlockDriverState *bs, unsigned int mode, int64_t offset,
+    int64_t bytes, int64_t *pnum, int64_t *map, BlockDriverState **file);
 int coroutine_fn GRAPH_RDLOCK bdrv_co_pdiscard_snapshot(BlockDriverState *bs,
     int64_t offset, int64_t bytes);