On Fri, Nov 22, 2013 at 12:46:18PM +0530, Bharata B Rao wrote:
> GlusterFS supports creation of zero-filled file on GlusterFS volume
> by means of an API called glfs_zerofill(). Use this API from QEMU to
> create an image that is filled with zeroes by using the preallocation
> option of qemu-img.
>
> qemu-img create gluster://server/volume/image -o preallocation=full 10G
>
> The allowed values for preallocation are 'full' and 'off'. By default
> preallocation is off and image is not zero-filled.
>
> glfs_zerofill() offloads the writing of zeroes to the server and if
> the storage supports SCSI WRITESAME, GlusterFS server can issue
> BLKZEROOUT ioctl to achieve the zeroing.
>
> Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com>
> ---
> block/gluster.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 45 insertions(+)
>
> diff --git a/block/gluster.c b/block/gluster.c
> index 15f5dfb..2368997 100644
> --- a/block/gluster.c
> +++ b/block/gluster.c
> @@ -381,6 +381,29 @@ out:
> qemu_aio_release(acb);
> return ret;
> }
> +
> +static inline int gluster_supports_zerofill(void)
> +{
> + return 1;
> +}
> +
> +static inline int qemu_gluster_zerofill(struct glfs_fd *fd, int64_t offset,
> + int64_t size)
> +{
> + return glfs_zerofill(fd, offset, size);
> +}
> +
> +#else
> +static inline int gluster_supports_zerofill(void)
> +{
> + return 0;
> +}
> +
> +static inline int qemu_gluster_zerofill(struct glfs_fd *fd, int64_t offset,
> + int64_t size)
> +{
> + return 0;
> +}
> #endif
>
> static int qemu_gluster_create(const char *filename,
> @@ -389,6 +412,7 @@ static int qemu_gluster_create(const char *filename,
> struct glfs *glfs;
> struct glfs_fd *fd;
> int ret = 0;
> + int prealloc = 0;
> int64_t total_size = 0;
> GlusterConf *gconf = g_malloc0(sizeof(GlusterConf));
>
> @@ -401,6 +425,18 @@ static int qemu_gluster_create(const char *filename,
> while (options && options->name) {
> if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
> total_size = options->value.n / BDRV_SECTOR_SIZE;
> + } else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) {
> + if (!options->value.s || !strcmp(options->value.s, "off")) {
> + prealloc = 0;
> + } else if (!strcmp(options->value.s, "full") &&
> + gluster_supports_zerofill()) {
> + prealloc = 1;
> + } else {
> + error_setg(errp, "Invalid preallocation mode: '%s'"
> + " or GlusterFS doesn't support zerofill API",
> + options->value.s);
> + return -EINVAL;
This leaks gconf. While probably not a huge deal for a .bdrv_create()
implementation, you should still set ret, and perform a 'goto out' here.
> + }
> }
> options++;
> }
> @@ -413,6 +449,10 @@ static int qemu_gluster_create(const char *filename,
> if (glfs_ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) {
> ret = -errno;
> }
> + if (prealloc && qemu_gluster_zerofill(fd, 0,
> + total_size * BDRV_SECTOR_SIZE)) {
> + ret = -errno;
> + }
> if (glfs_close(fd) != 0) {
> ret = -errno;
> }
> @@ -595,6 +635,11 @@ static QEMUOptionParameter qemu_gluster_create_options[]
> = {
> .type = OPT_SIZE,
> .help = "Virtual disk size"
> },
> + {
> + .name = BLOCK_OPT_PREALLOC,
> + .type = OPT_STRING,
> + .help = "Preallocation mode (allowed values: off, on)"
> + },
> { NULL }
> };
>
> --
> 1.7.11.7
>
>
