Am 17.03.2014 um 07:53 hat Hu Tao geschrieben:
> This patch adds a new option preallocation for raw format, and implements
> full preallocation.
>
> Signed-off-by: Hu Tao <hu...@cn.fujitsu.com>
> ---
> block/raw-posix.c | 43 +++++++++++++++++++++++++++++++++++--------
> 1 file changed, 35 insertions(+), 8 deletions(-)
>
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index a363b71..e004ff8 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -1240,6 +1240,7 @@ static int raw_create(const char *filename,
> QEMUOptionParameter *options,
> int fd;
> int result = 0;
> int64_t total_size = 0;
> + PreallocMode prealloc = PREALLOC_MODE_OFF;
>
> strstart(filename, "file:", &filename);
>
> @@ -1247,6 +1248,16 @@ static int raw_create(const char *filename,
> QEMUOptionParameter *options,
> while (options && options->name) {
> if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
> total_size = options->value.n & BDRV_SECTOR_MASK;
> + } else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) {
> + if (!options->value.s || !strcmp(options->value.s, "off")) {
> + prealloc = PREALLOC_MODE_OFF;
> + } else if (!strcmp(options->value.s, "full")) {
> + prealloc = PREALLOC_MODE_FULL;
> + } else {
> + error_setg(errp, "Invalid preallocation mode: '%s'",
> + options->value.s);
> + return -EINVAL;
> + }
> }
> options++;
> }
> @@ -1256,16 +1267,27 @@ static int raw_create(const char *filename,
> QEMUOptionParameter *options,
> if (fd < 0) {
> result = -errno;
> error_setg_errno(errp, -result, "Could not create file");
> - } else {
> - if (ftruncate(fd, total_size) != 0) {
> - result = -errno;
> - error_setg_errno(errp, -result, "Could not resize file");
> - }
> - if (qemu_close(fd) != 0) {
> - result = -errno;
> - error_setg_errno(errp, -result, "Could not close the new file");
> + goto out;
> + }
> + if (ftruncate(fd, total_size) != 0) {
> + result = -errno;
> + error_setg_errno(errp, -result, "Could not resize file");
> + goto out_close;
> + }
> + if (prealloc == PREALLOC_MODE_FULL) {
> + /* posix_fallocate() doesn't set errno. */
> + result = -posix_fallocate(fd, 0, total_size);
> + if (result != 0) {
> + error_setg_errno(errp, -result,
> + "Could not preallocate data for the new file");
> }
Can you please make that PREALLOC_MODE_METADATA?
You're really only preallocating metadata on a filesystem level here. If
the backing block device were thin provisioned, we wouldn't make any
attempt to preallocate that (e.g. with a loop writing zeroes or
bdrv_write_zeroes() without BDRV_REQ_MAY_UNMAP), so I'd hardly call it
"full" preallocation.
Kevin
