This patch adds a new option preallocation for raw format, and implements
full preallocation.
Signed-off-by: Hu Tao <address@hidden>
---
block/raw-posix.c | 92 +++++++++++++++++++++++++++++++++++++++++++------------
qemu-doc.texi | 8 +++++
qemu-img.texi | 8 +++++
3 files changed, 88 insertions(+), 20 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index abe0759..25f66f2 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>
@@ -1365,6 +1366,9 @@ static int raw_create(const char *filename, QemuOpts
*opts, Error **errp)
int result = 0;
int64_t total_size = 0;
bool nocow = false;
+ PreallocMode prealloc = PREALLOC_MODE_OFF;
+ char *buf = NULL;
+ Error *local_err = NULL;
strstart(filename, "file:", &filename);
@@ -1372,37 +1376,80 @@ static int raw_create(const char *filename, QemuOpts *opts, Error **errp)
total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
BDRV_SECTOR_SIZE);
nocow = qemu_opt_get_bool(opts, BLOCK_OPT_NOCOW, false);
+ buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
+ prealloc = qapi_enum_parse(PreallocMode_lookup, buf,
+ PREALLOC_MODE_MAX, PREALLOC_MODE_OFF,
+ &local_err);
+ g_free(buf);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ result = -EINVAL;
+ goto out;
+ }
fd = qemu_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
0644);
if (fd < 0) {
result = -errno;
error_setg_errno(errp, -result, "Could not create file");
- } else {
- if (nocow) {
+ goto out;
+ }
+
+ if (nocow) {
#ifdef __linux__
- /* Set NOCOW flag to solve performance issue on fs like btrfs.
- * This is an optimisation. The FS_IOC_SETFLAGS ioctl return value
- * will be ignored since any failure of this operation should not
- * block the left work.
- */
- int attr;
- if (ioctl(fd, FS_IOC_GETFLAGS, &attr) == 0) {
- attr |= FS_NOCOW_FL;
- ioctl(fd, FS_IOC_SETFLAGS, &attr);
- }
-#endif
+ /* Set NOCOW flag to solve performance issue on fs like btrfs.
+ * This is an optimisation. The FS_IOC_SETFLAGS ioctl return value
+ * will be ignored since any failure of this operation should not
+ * block the left work.
+ */
+ int attr;
+ if (ioctl(fd, FS_IOC_GETFLAGS, &attr) == 0) {
+ attr |= FS_NOCOW_FL;
+ ioctl(fd, FS_IOC_SETFLAGS, &attr);
}
+#endif
+ }
- if (ftruncate(fd, total_size) != 0) {
- result = -errno;
- error_setg_errno(errp, -result, "Could not resize file");
- }
- if (qemu_close(fd) != 0) {
- result = -errno;
- error_setg_errno(errp, -result, "Could not close the new file");
+ if (ftruncate(fd, total_size) != 0) {
+ result = -errno;
+ error_setg_errno(errp, -result, "Could not resize file");
+ goto out_close;
+ }
+
+ if (prealloc == PREALLOC_MODE_FULL) {
+ /* posix_fallocate() doesn't set errno. */
+ result = -posix_fallocate(fd, 0, total_size);
+ if (result != 0) {
+ 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);
}
+ } else if (prealloc != PREALLOC_MODE_OFF) {
+ result = -1;
+ error_setg(errp, "Unsupported preallocation mode: %s",
+ PreallocMode_lookup[prealloc]);
+ }
+
+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;
}
@@ -1585,6 +1632,11 @@ static QemuOptsList raw_create_opts = {
.type = QEMU_OPT_BOOL,
.help = "Turn off copy-on-write (valid only on btrfs)"
},
+ {
+ .name = BLOCK_OPT_PREALLOC,
+ .type = QEMU_OPT_STRING,
+ .help = "Preallocation mode (allowed values: off, full)"
+ },
{ /* end of list */ }
}
};
diff --git a/qemu-doc.texi b/qemu-doc.texi
index 2b232ae..2637765 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -527,6 +527,14 @@ Linux or NTFS on Windows), then only the written sectors
will reserve
space. Use @code{qemu-img info} to know the real size used by the
image or @code{ls -ls} on Unix/Linux.
+Supported options:
address@hidden @code
address@hidden preallocation
+Preallocation mode(allowed values: @code{off}, @code{full}). An image is
+writing zeros to underlying storage.
address@hidden table
+
@item qcow2
QEMU image format, the most versatile format. Use it to have smaller
images (useful if your filesystem does not supports holes, for example
diff --git a/qemu-img.texi b/qemu-img.texi
index cb68948..063ec61 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -418,6 +418,14 @@ Linux or NTFS on Windows), then only the written sectors
will reserve
space. Use @code{qemu-img info} to know the real size used by the
image or @code{ls -ls} on Unix/Linux.
+Supported options:
address@hidden @code
address@hidden preallocation
+Preallocation mode(allowed values: @code{off}, @code{full}). An image is
+fully preallocated by calling posix_fallocate() if it's available, or by
+writing zeros to underlying storage.
address@hidden table
+