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[Qemu-devel] [PATCH V9 3/4] raw-posix: Add full image preallocation opti
From: |
Chen Fan |
Subject: |
[Qemu-devel] [PATCH V9 3/4] raw-posix: Add full image preallocation option |
Date: |
Tue, 27 May 2014 16:22:57 +0800 |
From: Hu Tao <address@hidden>
This patch adds a new option preallocation for raw format, and implements
full preallocation by writing zeros to disk.
The metadata option is changed to use posix_fallocate() to ensure
subsquent writes to image file won't fail because of lack of disk space.
The purpose is to ensure disk space for image file. In cases
posix_fallocate() is supported, metadata option can be used, otherwise
(posix_fallocate() is not supported by filesystem, or in case of thin
provisioning), full option has to be used. User has to choose the proper
way to use.
Signed-off-by: Hu Tao <address@hidden>
---
block/raw-posix.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 54 insertions(+), 7 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 710ea9b..07e2088 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1246,6 +1246,7 @@ 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);
@@ -1254,6 +1255,18 @@ static int raw_create(const char *filename,
QEMUOptionParameter *options,
if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
total_size = (options->value.n + BDRV_SECTOR_SIZE) &
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, "metadata")) {
+ prealloc = PREALLOC_MODE_METADATA;
+ } 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++;
}
@@ -1263,16 +1276,45 @@ 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;
}
+ 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;
}
@@ -1447,6 +1489,11 @@ 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 }
};
--
1.9.3
[Qemu-devel] [PATCH V9 2/4] raw, qcow2: don't convert file size to sector size, Chen Fan, 2014/05/27
[Qemu-devel] [PATCH V9 4/4] qcow2: Add full image preallocation option, Chen Fan, 2014/05/27