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[Qemu-devel] [RFC PATCH v0 3/3] gluster: Add support for creating zero-f
From: |
Bharata B Rao |
Subject: |
[Qemu-devel] [RFC PATCH v0 3/3] gluster: Add support for creating zero-filled image |
Date: |
Fri, 22 Nov 2013 12:46:18 +0530 |
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 <address@hidden>
---
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;
+ }
}
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