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[Qemu-block] [PATCH v2 3/5] block: Allow NULL file for bdrv_get_block_st
From: |
Eric Blake |
Subject: |
[Qemu-block] [PATCH v2 3/5] block: Allow NULL file for bdrv_get_block_status() |
Date: |
Wed, 24 May 2017 15:28:40 -0500 |
Not all callers care about which BDS owns the mapping for a given
range of the file. This patch merely simplifies the callers by
consolidating the logic in the common call point, while guaranteeing
a non-NULL file to all the driver callbacks, for no semantic change.
However, this will also set the stage for a future cleanup: when a
caller does not care about which BDS owns an offset, it would be
nice to allow the driver to optimize things to not have to return
BDRV_BLOCK_OFFSET_VALID in the first place. In the case of fragmented
allocation (for example, it's fairly easy to create a qcow2 image
where consecutive guest addresses are not at consecutive host
addresses), the current contract requires bdrv_get_block_status()
to clamp *pnum to the limit where host addresses are no longer
consecutive, but allowing a NULL file means that *pnum could be
set to the full length of known-allocated data.
Signed-off-by: Eric Blake <address@hidden>
---
v2: new patch
---
block/io.c | 15 +++++++++------
block/mirror.c | 3 +--
block/qcow2.c | 4 +---
qemu-img.c | 10 ++++------
4 files changed, 15 insertions(+), 17 deletions(-)
diff --git a/block/io.c b/block/io.c
index 8e6c3fe..eea74cb 100644
--- a/block/io.c
+++ b/block/io.c
@@ -706,7 +706,6 @@ int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags)
{
int64_t target_sectors, ret, nb_sectors, sector_num = 0;
BlockDriverState *bs = child->bs;
- BlockDriverState *file;
int n;
target_sectors = bdrv_nb_sectors(bs);
@@ -719,7 +718,7 @@ int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags)
if (nb_sectors <= 0) {
return 0;
}
- ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n, &file);
+ ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n, NULL);
if (ret < 0) {
error_report("error getting block status at sector %" PRId64 ":
%s",
sector_num, strerror(-ret));
@@ -1737,8 +1736,9 @@ typedef struct BdrvCoGetBlockStatusData {
* 'nb_sectors' is the max value 'pnum' should be set to. If nb_sectors goes
* beyond the end of the disk image it will be clamped.
*
- * If returned value is positive and BDRV_BLOCK_OFFSET_VALID bit is set, 'file'
- * points to the BDS which the sector range is allocated in.
+ * If returned value is positive, BDRV_BLOCK_OFFSET_VALID bit is set, and
+ * 'file' is non-NULL, then '*file' points to the BDS which the sector range
+ * is allocated in.
*/
static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
int64_t sector_num,
@@ -1748,7 +1748,11 @@ static int64_t coroutine_fn
bdrv_co_get_block_status(BlockDriverState *bs,
int64_t total_sectors;
int64_t n;
int64_t ret, ret2;
+ BlockDriverState *tmpfile;
+ if (!file) {
+ file = &tmpfile;
+ }
*file = NULL;
total_sectors = bdrv_nb_sectors(bs);
if (total_sectors < 0) {
@@ -1916,9 +1920,8 @@ int64_t bdrv_get_block_status(BlockDriverState *bs,
int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
{
- BlockDriverState *file;
int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum,
- &file);
+ NULL);
if (ret < 0) {
return ret;
}
diff --git a/block/mirror.c b/block/mirror.c
index e86f8f8..4563ba7 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -392,7 +392,6 @@ static uint64_t coroutine_fn
mirror_iteration(MirrorBlockJob *s)
while (nb_chunks > 0 && sector_num < end) {
int64_t ret;
int io_sectors, io_sectors_acct;
- BlockDriverState *file;
enum MirrorMethod {
MIRROR_METHOD_COPY,
MIRROR_METHOD_ZERO,
@@ -402,7 +401,7 @@ static uint64_t coroutine_fn
mirror_iteration(MirrorBlockJob *s)
assert(!(sector_num % sectors_per_chunk));
ret = bdrv_get_block_status_above(source, NULL, sector_num,
nb_chunks * sectors_per_chunk,
- &io_sectors, &file);
+ &io_sectors, NULL);
if (ret < 0) {
io_sectors = MIN(nb_chunks * sectors_per_chunk, max_io_sectors);
} else if (ret & BDRV_BLOCK_DATA) {
diff --git a/block/qcow2.c b/block/qcow2.c
index b3ba5da..8e9e29b 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2448,7 +2448,6 @@ static bool is_zero_sectors(BlockDriverState *bs, int64_t
start,
uint32_t count)
{
int nr;
- BlockDriverState *file;
int64_t res;
if (start + count > bs->total_sectors) {
@@ -2458,8 +2457,7 @@ static bool is_zero_sectors(BlockDriverState *bs, int64_t
start,
if (!count) {
return true;
}
- res = bdrv_get_block_status_above(bs, NULL, start, count,
- &nr, &file);
+ res = bdrv_get_block_status_above(bs, NULL, start, count, &nr, NULL);
return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == count;
}
diff --git a/qemu-img.c b/qemu-img.c
index 5aef8ef..cb78696 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1398,7 +1398,6 @@ static int img_compare(int argc, char **argv)
for (;;) {
int64_t status1, status2;
- BlockDriverState *file;
nb_sectors = sectors_to_process(total_sectors, sector_num);
if (nb_sectors <= 0) {
@@ -1406,7 +1405,7 @@ static int img_compare(int argc, char **argv)
}
status1 = bdrv_get_block_status_above(bs1, NULL, sector_num,
total_sectors1 - sector_num,
- &pnum1, &file);
+ &pnum1, NULL);
if (status1 < 0) {
ret = 3;
error_report("Sector allocation test failed for %s", filename1);
@@ -1416,7 +1415,7 @@ static int img_compare(int argc, char **argv)
status2 = bdrv_get_block_status_above(bs2, NULL, sector_num,
total_sectors2 - sector_num,
- &pnum2, &file);
+ &pnum2, NULL);
if (status2 < 0) {
ret = 3;
error_report("Sector allocation test failed for %s", filename2);
@@ -1615,15 +1614,14 @@ static int convert_iteration_sectors(ImgConvertState
*s, int64_t sector_num)
n = MIN(s->total_sectors - sector_num, BDRV_REQUEST_MAX_SECTORS);
if (s->sector_next_status <= sector_num) {
- BlockDriverState *file;
if (s->target_has_backing) {
ret = bdrv_get_block_status(blk_bs(s->src[src_cur]),
sector_num - src_cur_offset,
- n, &n, &file);
+ n, &n, NULL);
} else {
ret = bdrv_get_block_status_above(blk_bs(s->src[src_cur]), NULL,
sector_num - src_cur_offset,
- n, &n, &file);
+ n, &n, NULL);
}
if (ret < 0) {
return ret;
--
2.9.4
- [Qemu-block] [PATCH v2 0/5] more blkdebug tweaks, Eric Blake, 2017/05/24
- [Qemu-block] [PATCH v2 2/5] block: Guarantee that *file is set on bdrv_get_block_status(), Eric Blake, 2017/05/24
- [Qemu-block] [PATCH v2 3/5] block: Allow NULL file for bdrv_get_block_status(),
Eric Blake <=
- [Qemu-block] [PATCH v2 4/5] block: Simplify use of BDRV_BLOCK_RAW, Eric Blake, 2017/05/24
- [Qemu-block] [PATCH v2 5/5] blkdebug: Support .bdrv_co_get_block_status, Eric Blake, 2017/05/24
- Re: [Qemu-block] [Qemu-devel] [PATCH v2 0/5] more blkdebug tweaks, Fam Zheng, 2017/05/25