@@ -47,7 +47,7 @@ int coroutine_fn GRAPH_RDLOCK
bdrv_co_common_block_status_above(BlockDriverState *bs,
BlockDriverState *base,
bool include_base,
- bool want_zero,
+ unsigned int mode,
int64_t offset,
int64_t bytes,
int64_t *pnum,
@@ -78,7 +78,7 @@ int co_wrapper_mixed_bdrv_rdlock
bdrv_common_block_status_above(BlockDriverState *bs,
BlockDriverState *base,
bool include_base,
- bool want_zero,
+ unsigned int mode,
int64_t offset,
int64_t bytes,
int64_t *pnum,
@@ -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 {
@@ -608,15 +608,16 @@ 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.
@@ -628,8 +629,8 @@ 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);
/*
@@ -653,8 +654,8 @@ 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);
@@ -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);
@@ -2364,10 +2364,8 @@ int bdrv_flush_all(void)
* Drivers not implementing the functionality are assumed to not support
* backing files, hence all their sectors are reported as allocated.
*
- * If 'want_zero' is true, the caller is querying for mapping
- * purposes, with a focus on valid BDRV_BLOCK_OFFSET_VALID, _DATA, and
- * _ZERO where possible; otherwise, the result favors larger 'pnum',
- * with a focus on accurate BDRV_BLOCK_ALLOCATED.
+ * 'mode' serves as a hint as to which results are favored; see enum
+ * BlockStatusMode for details of the supported modes.
*
* If 'offset' is beyond the end of the disk image the return value is
* BDRV_BLOCK_EOF and 'pnum' is set to 0.
@@ -2387,7 +2385,7 @@ int bdrv_flush_all(void)
* set to the host mapping and BDS corresponding to the guest offset.
*/
static int coroutine_fn GRAPH_RDLOCK
-bdrv_co_do_block_status(BlockDriverState *bs, bool want_zero,
+bdrv_co_do_block_status(BlockDriverState *bs, unsigned int mode,
int64_t offset, int64_t bytes,
int64_t *pnum, int64_t *map, BlockDriverState **file)
{
@@ -2476,7 +2474,7 @@ bdrv_co_do_block_status(BlockDriverState *bs, bool want_zero,
local_file = bs;
local_map = aligned_offset;
} else {
- ret = bs->drv->bdrv_co_block_status(bs, want_zero, aligned_offset,
+ ret = bs->drv->bdrv_co_block_status(bs, mode, aligned_offset,
aligned_bytes, pnum, &local_map,
&local_file);
@@ -2488,10 +2486,10 @@ bdrv_co_do_block_status(BlockDriverState *bs, bool want_zero,
* the cache requires an RCU update, so double check here to avoid
* such an update if possible.
*
- * Check want_zero, because we only want to update the cache when we
+ * Check mode, because we only want to update the cache when we
* have accurate information about what is zero and what is data.
*/
- if (want_zero &&
+ if (mode == BDRV_WANT_PRECISE &&
ret == (BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID) &&
QLIST_EMPTY(&bs->children))
{
@@ -2548,7 +2546,7 @@ bdrv_co_do_block_status(BlockDriverState *bs, bool want_zero,
if (ret & BDRV_BLOCK_RAW) {
assert(ret & BDRV_BLOCK_OFFSET_VALID && local_file);
- ret = bdrv_co_do_block_status(local_file, want_zero, local_map,
+ ret = bdrv_co_do_block_status(local_file, mode, local_map,
*pnum, pnum, &local_map, &local_file);
goto out;
}
@@ -2560,7 +2558,7 @@ bdrv_co_do_block_status(BlockDriverState *bs, bool want_zero,
if (!cow_bs) {
ret |= BDRV_BLOCK_ZERO;
- } else if (want_zero) {
+ } else if (mode == BDRV_WANT_PRECISE) {
int64_t size2 = bdrv_co_getlength(cow_bs);
if (size2 >= 0 && offset >= size2) {
@@ -2569,14 +2567,14 @@ bdrv_co_do_block_status(BlockDriverState *bs, bool want_zero,
}
}
- if (want_zero && ret & BDRV_BLOCK_RECURSE &&
+ if (mode == BDRV_WANT_PRECISE && ret & BDRV_BLOCK_RECURSE &&
local_file && local_file != bs &&
(ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
(ret & BDRV_BLOCK_OFFSET_VALID)) {
int64_t file_pnum;
int ret2;
- ret2 = bdrv_co_do_block_status(local_file, want_zero, local_map,
+ ret2 = bdrv_co_do_block_status(local_file, mode, local_map,
*pnum, &file_pnum, NULL, NULL);
if (ret2 >= 0) {
/* Ignore errors. This is just providing extra information, it
@@ -2627,7 +2625,7 @@ int coroutine_fn
bdrv_co_common_block_status_above(BlockDriverState *bs,
BlockDriverState *base,
bool include_base,
- bool want_zero,
+ unsigned int mode,
int64_t offset,
int64_t bytes,
int64_t *pnum,
@@ -2654,7 +2652,7 @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
return 0;
}
- ret = bdrv_co_do_block_status(bs, want_zero, offset, bytes, pnum,
+ ret = bdrv_co_do_block_status(bs, mode, offset, bytes, pnum,
map, file);
++*depth;
if (ret < 0 || *pnum == 0 || ret & BDRV_BLOCK_ALLOCATED || bs == base) {
@@ -2671,7 +2669,7 @@ bdrv_co_common_block_status_above(BlockDriverState *bs,
for (p = bdrv_filter_or_cow_bs(bs); include_base || p != base;
p = bdrv_filter_or_cow_bs(p))
{
- ret = bdrv_co_do_block_status(p, want_zero, offset, bytes, pnum,
+ ret = bdrv_co_do_block_status(p, mode, offset, bytes, pnum,
map, file);
++*depth;
if (ret < 0) {
@@ -2734,7 +2732,8 @@ int coroutine_fn bdrv_co_block_status_above(BlockDriverState *bs,
BlockDriverState **file)
{
IO_CODE();
- return bdrv_co_common_block_status_above(bs, base, false, true, offset,
+ return bdrv_co_common_block_status_above(bs, base, false,
+ BDRV_WANT_PRECISE, offset,
bytes, pnum, map, file, NULL);
}
@@ -2765,8 +2764,9 @@ int coroutine_fn bdrv_co_is_zero_fast(BlockDriverState *bs, int64_t offset,
return 1;
}
- ret = bdrv_co_common_block_status_above(bs, NULL, false, false, offset,
- bytes, &pnum, NULL, NULL, NULL);
+ ret = bdrv_co_common_block_status_above(bs, NULL, false, BDRV_WANT_ZERO,
+ offset, bytes, &pnum, NULL, NULL,
+ NULL);
if (ret < 0) {
return ret;
@@ -2782,9 +2782,9 @@ int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs, int64_t offset,
int64_t dummy;
IO_CODE();
- ret = bdrv_co_common_block_status_above(bs, bs, true, false, offset,
- bytes, pnum ? pnum : &dummy, NULL,
- NULL, NULL);
+ ret = bdrv_co_common_block_status_above(bs, bs, true, BDRV_WANT_ALLOCATED,
+ offset, bytes, pnum ? pnum : &dummy,
+ NULL, NULL, NULL);
if (ret < 0) {
return ret;
}
@@ -2817,7 +2817,8 @@ int coroutine_fn bdrv_co_is_allocated_above(BlockDriverState *bs,
int ret;
IO_CODE();
- ret = bdrv_co_common_block_status_above(bs, base, include_base, false,
+ ret = bdrv_co_common_block_status_above(bs, base, include_base,
+ BDRV_WANT_ALLOCATED,
offset, bytes, pnum, NULL, NULL,
&depth);
if (ret < 0) {
@@ -3709,8 +3710,8 @@ bdrv_co_preadv_snapshot(BdrvChild *child, int64_t offset, int64_t bytes,
}
int coroutine_fn
-bdrv_co_snapshot_block_status(BlockDriverState *bs,
- bool want_zero, int64_t offset, int64_t bytes,
+bdrv_co_snapshot_block_status(BlockDriverState *bs, unsigned int mode,
+ int64_t offset, int64_t bytes,
int64_t *pnum, int64_t *map,
BlockDriverState **file)
{
@@ -3728,7 +3729,7 @@ bdrv_co_snapshot_block_status(BlockDriverState *bs,
}
bdrv_inc_in_flight(bs);
- ret = drv->bdrv_co_snapshot_block_status(bs, want_zero, offset, bytes,
+ ret = drv->bdrv_co_snapshot_block_status(bs, mode, offset, bytes,
pnum, map, file);
bdrv_dec_in_flight(bs);
@@ -751,9 +751,9 @@ blkdebug_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
}
static int coroutine_fn GRAPH_RDLOCK
-blkdebug_co_block_status(BlockDriverState *bs, bool want_zero, int64_t offset,
- int64_t bytes, int64_t *pnum, int64_t *map,
- BlockDriverState **file)
+blkdebug_co_block_status(BlockDriverState *bs, unsigned int mode,
+ int64_t offset, int64_t bytes, int64_t *pnum,
+ int64_t *map, BlockDriverState **file)
{
int err;
@@ -291,8 +291,8 @@ cbw_co_preadv_snapshot(BlockDriverState *bs, int64_t offset, int64_t bytes,
}
static int coroutine_fn GRAPH_RDLOCK
-cbw_co_snapshot_block_status(BlockDriverState *bs,
- bool want_zero, int64_t offset, int64_t bytes,
+cbw_co_snapshot_block_status(BlockDriverState *bs, unsigned int mode,
+ int64_t offset, int64_t bytes,
int64_t *pnum, int64_t *map,
BlockDriverState **file)
{
@@ -3201,7 +3201,7 @@ static int find_allocation(BlockDriverState *bs, off_t start,
* well exceed it.
*/
static int coroutine_fn raw_co_block_status(BlockDriverState *bs,
- bool want_zero,
+ unsigned int mode,
int64_t offset,
int64_t bytes, int64_t *pnum,
int64_t *map,
@@ -3217,7 +3217,7 @@ static int coroutine_fn raw_co_block_status(BlockDriverState *bs,
return ret;
}
- if (!want_zero) {
+ if (mode != BDRV_WANT_PRECISE) {
*pnum = bytes;
*map = offset;
*file = bs;
@@ -1465,7 +1465,7 @@ exit:
* (Based on raw_co_block_status() from file-posix.c.)
*/
static int coroutine_fn qemu_gluster_co_block_status(BlockDriverState *bs,
- bool want_zero,
+ unsigned int mode,
int64_t offset,
int64_t bytes,
int64_t *pnum,
@@ -1482,7 +1482,7 @@ static int coroutine_fn qemu_gluster_co_block_status(BlockDriverState *bs,
return ret;
}
- if (!want_zero) {
+ if (mode != BDRV_WANT_PRECISE) {
*pnum = bytes;
*map = offset;
*file = bs;
@@ -694,9 +694,9 @@ out_unlock:
static int coroutine_fn iscsi_co_block_status(BlockDriverState *bs,
- bool want_zero, int64_t offset,
- int64_t bytes, int64_t *pnum,
- int64_t *map,
+ unsigned int mode,
+ int64_t offset, int64_t bytes,
+ int64_t *pnum, int64_t *map,
BlockDriverState **file)
{
IscsiLun *iscsilun = bs->opaque;
@@ -1397,8 +1397,8 @@ nbd_client_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
}
static int coroutine_fn GRAPH_RDLOCK nbd_client_co_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 ret, request_ret;
NBDExtent64 extent = { 0 };
@@ -227,9 +227,9 @@ static int null_reopen_prepare(BDRVReopenState *reopen_state,
}
static int coroutine_fn null_co_block_status(BlockDriverState *bs,
- bool want_zero, int64_t offset,
- int64_t bytes, int64_t *pnum,
- int64_t *map,
+ unsigned int mode,
+ int64_t offset, int64_t bytes,
+ int64_t *pnum, int64_t *map,
BlockDriverState **file)
{
BDRVNullState *s = bs->opaque;
@@ -416,9 +416,9 @@ parallels_co_flush_to_os(BlockDriverState *bs)
}
static int coroutine_fn GRAPH_RDLOCK
-parallels_co_block_status(BlockDriverState *bs, bool want_zero, int64_t offset,
- int64_t bytes, int64_t *pnum, int64_t *map,
- BlockDriverState **file)
+parallels_co_block_status(BlockDriverState *bs, unsigned int mode,
+ int64_t offset, int64_t bytes, int64_t *pnum,
+ int64_t *map, BlockDriverState **file)
{
BDRVParallelsState *s = bs->opaque;
int count;
@@ -530,7 +530,7 @@ get_cluster_offset(BlockDriverState *bs, uint64_t offset, int allocate,
}
static int coroutine_fn GRAPH_RDLOCK
-qcow_co_block_status(BlockDriverState *bs, bool want_zero,
+qcow_co_block_status(BlockDriverState *bs, unsigned int mode,
int64_t offset, int64_t bytes, int64_t *pnum,
int64_t *map, BlockDriverState **file)
{
@@ -2141,9 +2141,9 @@ static void qcow2_join_options(QDict *options, QDict *old_options)
}
static int coroutine_fn GRAPH_RDLOCK
-qcow2_co_block_status(BlockDriverState *bs, bool want_zero, int64_t offset,
- int64_t count, int64_t *pnum, int64_t *map,
- BlockDriverState **file)
+qcow2_co_block_status(BlockDriverState *bs, unsigned int mode,
+ int64_t offset, int64_t count, int64_t *pnum,
+ int64_t *map, BlockDriverState **file)
{
BDRVQcow2State *s = bs->opaque;
uint64_t host_offset;
@@ -833,9 +833,9 @@ fail:
}
static int coroutine_fn GRAPH_RDLOCK
-bdrv_qed_co_block_status(BlockDriverState *bs, bool want_zero, int64_t pos,
- int64_t bytes, int64_t *pnum, int64_t *map,
- BlockDriverState **file)
+bdrv_qed_co_block_status(BlockDriverState *bs, unsigned int mode,
+ int64_t pos, int64_t bytes, int64_t *pnum,
+ int64_t *map, BlockDriverState **file)
{
BDRVQEDState *s = bs->opaque;
size_t len = MIN(bytes, SIZE_MAX);
@@ -1226,7 +1226,7 @@ static void quorum_child_perm(BlockDriverState *bs, BdrvChild *c,
* region contains zeroes, and BDRV_BLOCK_DATA otherwise.
*/
static int coroutine_fn GRAPH_RDLOCK
-quorum_co_block_status(BlockDriverState *bs, bool want_zero,
+quorum_co_block_status(BlockDriverState *bs, unsigned int mode,
int64_t offset, int64_t count,
int64_t *pnum, int64_t *map, BlockDriverState **file)
{
@@ -1238,7 +1238,7 @@ quorum_co_block_status(BlockDriverState *bs, bool want_zero,
for (i = 0; i < s->num_children; i++) {
int64_t bytes;
ret = bdrv_co_common_block_status_above(s->children[i]->bs, NULL, false,
- want_zero, offset, count,
+ mode, offset, count,
&bytes, NULL, NULL, NULL);
if (ret < 0) {
quorum_report_bad(QUORUM_OP_TYPE_READ, offset, count,
@@ -283,8 +283,8 @@ fail:
}
static int coroutine_fn GRAPH_RDLOCK
-raw_co_block_status(BlockDriverState *bs, bool want_zero, int64_t offset,
- int64_t bytes, int64_t *pnum, int64_t *map,
+raw_co_block_status(BlockDriverState *bs, unsigned int mode,
+ int64_t offset, int64_t bytes, int64_t *pnum, int64_t *map,
BlockDriverState **file)
{
BDRVRawState *s = bs->opaque;
@@ -1504,9 +1504,9 @@ static int qemu_rbd_diff_iterate_cb(uint64_t offs, size_t len,
}
static int coroutine_fn qemu_rbd_co_block_status(BlockDriverState *bs,
- bool want_zero, int64_t offset,
- int64_t bytes, int64_t *pnum,
- int64_t *map,
+ unsigned int mode,
+ int64_t offset, int64_t bytes,
+ int64_t *pnum, int64_t *map,
BlockDriverState **file)
{
BDRVRBDState *s = bs->opaque;
@@ -41,11 +41,11 @@ snapshot_access_co_preadv_part(BlockDriverState *bs,
static int coroutine_fn GRAPH_RDLOCK
snapshot_access_co_block_status(BlockDriverState *bs,
- bool want_zero, int64_t offset,
+ unsigned int mode, int64_t offset,
int64_t bytes, int64_t *pnum,
int64_t *map, BlockDriverState **file)
{
- return bdrv_co_snapshot_block_status(bs->file->bs, want_zero, offset,
+ return bdrv_co_snapshot_block_status(bs->file->bs, mode, offset,
bytes, pnum, map, file);
}
@@ -523,8 +523,8 @@ static int vdi_reopen_prepare(BDRVReopenState *state,
}
static int coroutine_fn GRAPH_RDLOCK
-vdi_co_block_status(BlockDriverState *bs, bool want_zero, int64_t offset,
- int64_t bytes, int64_t *pnum, int64_t *map,
+vdi_co_block_status(BlockDriverState *bs, unsigned int mode,
+ int64_t offset, int64_t bytes, int64_t *pnum, int64_t *map,
BlockDriverState **file)
{
BDRVVdiState *s = (BDRVVdiState *)bs->opaque;
@@ -1777,7 +1777,7 @@ static inline uint64_t vmdk_find_offset_in_cluster(VmdkExtent *extent,
}
static int coroutine_fn GRAPH_RDLOCK
-vmdk_co_block_status(BlockDriverState *bs, bool want_zero,
+vmdk_co_block_status(BlockDriverState *bs, unsigned int mode,
int64_t offset, int64_t bytes, int64_t *pnum,
int64_t *map, BlockDriverState **file)
{
@@ -726,7 +726,7 @@ fail:
}
static int coroutine_fn GRAPH_RDLOCK
-vpc_co_block_status(BlockDriverState *bs, bool want_zero,
+vpc_co_block_status(BlockDriverState *bs, unsigned int mode,
int64_t offset, int64_t bytes,
int64_t *pnum, int64_t *map,
BlockDriverState **file)
@@ -3134,9 +3134,9 @@ vvfat_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
}
static int coroutine_fn vvfat_co_block_status(BlockDriverState *bs,
- bool want_zero, int64_t offset,
- int64_t bytes, int64_t *n,
- int64_t *map,
+ unsigned int mode,
+ int64_t offset, int64_t bytes,
+ int64_t *n, int64_t *map,
BlockDriverState **file)
{
*n = bytes;
@@ -63,7 +63,7 @@ bdrv_test_co_truncate(BlockDriverState *bs, int64_t offset, bool exact,
}
static int coroutine_fn bdrv_test_co_block_status(BlockDriverState *bs,
- bool want_zero,
+ unsigned int mode,
int64_t offset, int64_t count,
int64_t *pnum, int64_t *map,
BlockDriverState **file)
This patch is purely mechanical, changing bool want_zero into an unsigned int for bitwise-or of flags. As of this patch, all implementations are unchanged (the old want_zero==true is now mode==BDRV_WANT_PRECISE which is a superset of BDRV_WANT_ZERO); but the callers in io.c that used to pass want_zero==false are now prepared for future driver changes that can now distinguish bewteen BDRV_WANT_ZERO vs. BDRV_WANT_ALLOCATED. The next patch will actually change the file-posix driver along those lines, now that we have more-specific hints. As for the background why this patch is useful: right now, the file-posix driver recognizes that if allocation is being queried, the entire image can be reported as allocated (there is no backing file to refer to) - but this throws away information on whether the entire image reads as zero (trivially true if lseek(SEEK_HOLE) at offset 0 returns -ENXIO, a bit more complicated to prove if the raw file was created with 'qemu-img create' since we intentionally allocate a small chunk of all-zero data to help with alignment probing). Later patches will add a generic algorithm for seeing if an entire file reads as zeroes. Signed-off-by: Eric Blake <eblake@redhat.com> --- In response to Stefan's ask for what it would look like as a bitmask of flags instead of an enum. Only the first two patches of the series change. block/coroutines.h | 4 +-- include/block/block-common.h | 11 +++++++ include/block/block_int-common.h | 27 +++++++++-------- include/block/block_int-io.h | 4 +-- block/io.c | 51 ++++++++++++++++---------------- block/blkdebug.c | 6 ++-- block/copy-before-write.c | 4 +-- block/file-posix.c | 4 +-- block/gluster.c | 4 +-- block/iscsi.c | 6 ++-- block/nbd.c | 4 +-- block/null.c | 6 ++-- block/parallels.c | 6 ++-- block/qcow.c | 2 +- block/qcow2.c | 6 ++-- block/qed.c | 6 ++-- block/quorum.c | 4 +-- block/raw-format.c | 4 +-- block/rbd.c | 6 ++-- block/snapshot-access.c | 4 +-- block/vdi.c | 4 +-- block/vmdk.c | 2 +- block/vpc.c | 2 +- block/vvfat.c | 6 ++-- tests/unit/test-block-iothread.c | 2 +- 25 files changed, 99 insertions(+), 86 deletions(-)