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gluster: Add support for creating zero-filled image

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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 <bharata@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Bharata B Rao 2013-12-21 14:51:26 +05:30 committed by Kevin Wolf
parent 7c815372f3
commit cf7f616b9d
1 changed files with 49 additions and 1 deletions
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50
block/gluster.c
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@ -354,6 +354,29 @@ out:
g_slice_free(GlusterAIOCB, acb);
return ret;
}
static inline bool 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 bool 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,
@ -362,6 +385,7 @@ 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));
@ -374,6 +398,19 @@ 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);
ret = -EINVAL;
goto out;
}
}
options++;
}
@ -383,9 +420,15 @@ static int qemu_gluster_create(const char *filename,
if (!fd) {
ret = -errno;
} else {
if (glfs_ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) {
if (!glfs_ftruncate(fd, total_size * BDRV_SECTOR_SIZE)) {
if (prealloc && qemu_gluster_zerofill(fd, 0,
total_size * BDRV_SECTOR_SIZE)) {
ret = -errno;
}
} else {
ret = -errno;
}
if (glfs_close(fd) != 0) {
ret = -errno;
}
@ -560,6 +603,11 @@ 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, full)"
},
{ NULL }
};