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From 61a3061760caaaaa4f025f5712dcd8f84f2f5d70 Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Mon, 10 Nov 2014 09:14:06 +0100
Subject: [PATCH 29/41] raw-posix: Add falloc and full preallocation option

Message-id: <1415610847-15383-4-git-send-email-mreitz@redhat.com>
Patchwork-id: 62239
O-Subject: [RHEL-7.1 qemu-kvm PATCH v2 3/4] raw-posix: Add falloc and full preallocation option
Bugzilla: 1087724
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

From: Hu Tao <hutao@cn.fujitsu.com>

This patch adds a new option preallocation for raw format, and implements
falloc and full preallocation.

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 06247428be8037b3739280f82cb29efe8397695f)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

Conflicts:
	block/raw-posix.c

QEMUOptionParameter has not been replaced with QemuOpts downstream
(upstream 6f482f742dd841b45297fb0e5f3d2c81779253be) and no "nocow"
downstream.

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/raw-posix.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++------
 qemu-doc.texi     |  9 ++++++++
 qemu-img.texi     |  9 ++++++++
 3 files changed, 78 insertions(+), 7 deletions(-)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index 9ee5b8e..cfe7452 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>
@@ -1230,11 +1231,23 @@ static int raw_create(const char *filename, QEMUOptionParameter *options,
     int fd;
     int result = 0;
     int64_t total_size = 0;
+    PreallocMode prealloc = PREALLOC_MODE_OFF;
+    char *buf = NULL;
+    Error *local_err = NULL;
 
     /* Read out options */
     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)) {
+            prealloc = qapi_enum_parse(PreallocMode_lookup, options->value.s,
+                                       PREALLOC_MODE_MAX, PREALLOC_MODE_OFF,
+                                       &local_err);
+            if (local_err) {
+                error_propagate(errp, local_err);
+                result = -EINVAL;
+                goto out;
+            }
         }
         options++;
     }
@@ -1244,16 +1257,51 @@ 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 * BDRV_SECTOR_SIZE) != 0) {
-            result = -errno;
-            error_setg_errno(errp, -result, "Could not resize file");
+        goto out;
+    }
+
+    if (ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) {
+        result = -errno;
+        error_setg_errno(errp, -result, "Could not resize file");
+        goto out_close;
+    }
+
+    if (prealloc == PREALLOC_MODE_FALLOC) {
+        /* posix_fallocate() doesn't set errno. */
+        result = -posix_fallocate(fd, 0, total_size * BDRV_SECTOR_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) {
+        buf = g_malloc0(65536);
+        int64_t num = 0, left = total_size * BDRV_SECTOR_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");
+                break;
+            }
+            left -= num;
         }
+        fsync(fd);
+        g_free(buf);
+    } else if (prealloc != PREALLOC_MODE_OFF) {
+        result = -EINVAL;
+        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;
 }
 
@@ -1404,6 +1452,11 @@ 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, falloc, full)"
+    },
     { NULL }
 };
 
diff --git a/qemu-doc.texi b/qemu-doc.texi
index 54ab3c5..dc5b49e 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -527,6 +527,15 @@ 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:
+@table @code
+@item preallocation
+Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).
+@code{falloc} mode preallocates space for image by calling posix_fallocate().
+@code{full} mode preallocates space for image by writing zeros to underlying
+storage.
+@end 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 5f99ebb..80d3261 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -392,6 +392,15 @@ 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:
+@table @code
+@item preallocation
+Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).
+@code{falloc} mode preallocates space for image by calling posix_fallocate().
+@code{full} mode preallocates space for image by writing zeros to underlying
+storage.
+@end 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
-- 
1.8.3.1