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block/parallels: read parallels image header and BAT into single buffer

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This metadata cache would allow to properly batch BAT updates to disk
in next patches. These updates will be properly aligned to avoid
read-modify-write transactions on block level.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Roman Kagan <rkagan@parallels.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Roman Kagan <rkagan@parallels.com>
Message-id: 1430207220-24458-18-git-send-email-den@openvz.org
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Denis V. Lunev 2015-04-28 10:46:50 +03:00 committed by Stefan Hajnoczi
parent dd97cdc064
commit 9eae9cca95
1 changed files with 17 additions and 7 deletions
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24
block/parallels.c
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@ -61,6 +61,8 @@ typedef struct BDRVParallelsState {
*/
CoMutex lock;
ParallelsHeader *header;
uint32_t header_size;
uint32_t *bat_bitmap;
unsigned int bat_size;
@ -91,7 +93,7 @@ static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
{
BDRVParallelsState *s = bs->opaque;
ParallelsHeader ph;
int ret;
int ret, size;
ret = bdrv_pread(bs->file, 0, &ph, sizeof(ph));
if (ret < 0) {
@ -130,17 +132,25 @@ static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
ret = -EFBIG;
goto fail;
}
s->bat_bitmap = g_try_new(uint32_t, s->bat_size);
if (s->bat_size && s->bat_bitmap == NULL) {
size = sizeof(ParallelsHeader) + sizeof(uint32_t) * s->bat_size;
s->header_size = ROUND_UP(size, bdrv_opt_mem_align(bs->file));
s->header = qemu_try_blockalign(bs->file, s->header_size);
if (s->header == NULL) {
ret = -ENOMEM;
goto fail;
}
if (le32_to_cpu(ph.data_off) < s->header_size) {
/* there is not enough unused space to fit to block align between BAT
and actual data. We can't avoid read-modify-write... */
s->header_size = size;
}
ret = bdrv_pread(bs->file, sizeof(ParallelsHeader),
s->bat_bitmap, s->bat_size * sizeof(uint32_t));
ret = bdrv_pread(bs->file, 0, s->header, s->header_size);
if (ret < 0) {
goto fail;
}
s->bat_bitmap = (uint32_t *)(s->header + 1);
s->has_truncate = bdrv_has_zero_init(bs->file) &&
bdrv_truncate(bs->file, bdrv_getlength(bs->file)) == 0;
@ -152,7 +162,7 @@ fail_format:
error_setg(errp, "Image not in Parallels format");
ret = -EINVAL;
fail:
g_free(s->bat_bitmap);
qemu_vfree(s->header);
return ret;
}
@ -400,7 +410,7 @@ exit:
static void parallels_close(BlockDriverState *bs)
{
BDRVParallelsState *s = bs->opaque;
g_free(s->bat_bitmap);
qemu_vfree(s->header);
}
static QemuOptsList parallels_create_opts = {