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

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 = {