On 12.06.2014 05:54, Hu Tao wrote:
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 | 59 ++++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 52 insertions(+), 7 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 35057f0..73b10cd 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -30,6 +30,7 @@
#include "block/thread-pool.h"
#include "qemu/iov.h"
#include "raw-aio.h"
+#include "qapi/util.h"
#if defined(__APPLE__) && (__MACH__)
#include <paths.h>
@@ -1279,6 +1280,8 @@ static int raw_create(const char *filename,
QEMUOptionParameter *options,
int fd;
int result = 0;
int64_t total_size = 0;
+ PreallocMode prealloc = PREALLOC_MODE_OFF;
+ Error *error = NULL;
strstart(filename, "file:", &filename);
@@ -1286,6 +1289,14 @@ static int raw_create(const char *filename, QEMUOptionParameter *options,
while (options && options->name) {
if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
total_size = ROUND_UP(options->value.n, BDRV_SECTOR_SIZE);
+ } else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) {
+ prealloc = qapi_enum_parse(PreallocMode_lookup, options->value.s,
+ PREALLOC_MODE_MAX, PREALLOC_MODE_OFF,
+ &error);
+ if (error) {
+ error_propagate(errp, error);
+ return -EINVAL;
Could be "result = -EINVAL; goto out;" instead, but definitely isn't
wrong this way.
+ }
}
options++;
}
@@ -1295,16 +1306,45 @@ 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");
+ 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_METADATA) {
+ /* 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");
}
- if (qemu_close(fd) != 0) {
- result = -errno;
- error_setg_errno(errp, -result, "Could not close the new file");
+ } else if (prealloc == PREALLOC_MODE_FULL) {
+ char *buf = g_malloc0(65536);
+ int64_t num = 0, left = total_size;
+
+ while (left > 0) {
+ num = MIN(left, 65536);
+ result = write(fd, buf, num);
+ if (result < 0) {
+ result = -errno;
+ error_setg_errno(errp, -result,
+ "Could not write to the new file");
+ g_free(buf);
+ goto out_close;
+ }
+ left -= num;
}
Technically, a raw file does not have any metadata, therefore
preallocation=metadata is a bit ambiguous. I'd accept both allocating
nothing and allocating everything; you chose the latter, which is fine.
However, why do you implement the preallocation differently for
preallocation=full, then? posix_fallocate() does not seem to change the
contents of the areas which were newly allocated; and the ftruncate()
before made sure they are read back as zeroes. Therefore, using
ftruncate() and then posix_fallocate() seems to be functionally
equivalent to writing zeroes.
Max
+ fsync(fd);
+ g_free(buf);
}
+out_close:
+ if (qemu_close(fd) != 0 && result == 0) {
+ result = -errno;
+ error_setg_errno(errp, -result, "Could not close the new file");
+ }
+out:
return result;
}
@@ -1479,6 +1519,11 @@ static QEMUOptionParameter raw_create_options[] = {
.type = OPT_SIZE,
.help = "Virtual disk size"
},
+ {
+ .name = BLOCK_OPT_PREALLOC,
+ .type = OPT_STRING,
+ .help = "Preallocation mode (allowed values: off, metadata, full)"
+ },
{ NULL }
};
