Blame SOURCES/kvm-raw-posix-Add-falloc-and-full-preallocation-option.patch

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From 61a3061760caaaaa4f025f5712dcd8f84f2f5d70 Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Mon, 10 Nov 2014 09:14:06 +0100
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Subject: [PATCH 29/41] raw-posix: Add falloc and full preallocation option
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Message-id: <1415610847-15383-4-git-send-email-mreitz@redhat.com>
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Patchwork-id: 62239
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O-Subject: [RHEL-7.1 qemu-kvm PATCH v2 3/4] raw-posix: Add falloc and full preallocation option
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Bugzilla: 1087724
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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From: Hu Tao <hutao@cn.fujitsu.com>
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This patch adds a new option preallocation for raw format, and implements
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falloc and full preallocation.
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Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
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Reviewed-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 06247428be8037b3739280f82cb29efe8397695f)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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Conflicts:
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	block/raw-posix.c
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QEMUOptionParameter has not been replaced with QemuOpts downstream
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(upstream 6f482f742dd841b45297fb0e5f3d2c81779253be) and no "nocow"
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downstream.
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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---
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 block/raw-posix.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++------
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 qemu-doc.texi     |  9 ++++++++
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 qemu-img.texi     |  9 ++++++++
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 3 files changed, 78 insertions(+), 7 deletions(-)
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diff --git a/block/raw-posix.c b/block/raw-posix.c
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index 9ee5b8e..cfe7452 100644
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--- a/block/raw-posix.c
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+++ b/block/raw-posix.c
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@@ -30,6 +30,7 @@
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 #include "block/thread-pool.h"
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 #include "qemu/iov.h"
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 #include "raw-aio.h"
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+#include "qapi/util.h"
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 #if defined(__APPLE__) && (__MACH__)
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 #include <paths.h>
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@@ -1230,11 +1231,23 @@ static int raw_create(const char *filename, QEMUOptionParameter *options,
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     int fd;
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     int result = 0;
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     int64_t total_size = 0;
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+    PreallocMode prealloc = PREALLOC_MODE_OFF;
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+    char *buf = NULL;
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+    Error *local_err = NULL;
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     /* Read out options */
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     while (options && options->name) {
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         if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
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             total_size = options->value.n / BDRV_SECTOR_SIZE;
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+        } else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) {
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+            prealloc = qapi_enum_parse(PreallocMode_lookup, options->value.s,
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+                                       PREALLOC_MODE_MAX, PREALLOC_MODE_OFF,
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+                                       &local_err);
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+            if (local_err) {
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+                error_propagate(errp, local_err);
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+                result = -EINVAL;
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+                goto out;
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+            }
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         }
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         options++;
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     }
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@@ -1244,16 +1257,51 @@ static int raw_create(const char *filename, QEMUOptionParameter *options,
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     if (fd < 0) {
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         result = -errno;
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         error_setg_errno(errp, -result, "Could not create file");
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-    } else {
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-        if (ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) {
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-            result = -errno;
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-            error_setg_errno(errp, -result, "Could not resize file");
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+        goto out;
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+    }
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+
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+    if (ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) {
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+        result = -errno;
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+        error_setg_errno(errp, -result, "Could not resize file");
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+        goto out_close;
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+    }
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+
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+    if (prealloc == PREALLOC_MODE_FALLOC) {
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+        /* posix_fallocate() doesn't set errno. */
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+        result = -posix_fallocate(fd, 0, total_size * BDRV_SECTOR_SIZE);
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+        if (result != 0) {
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+            error_setg_errno(errp, -result,
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+                             "Could not preallocate data for the new file");
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         }
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-        if (qemu_close(fd) != 0) {
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-            result = -errno;
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-            error_setg_errno(errp, -result, "Could not close the new file");
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+    } else if (prealloc == PREALLOC_MODE_FULL) {
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+        buf = g_malloc0(65536);
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+        int64_t num = 0, left = total_size * BDRV_SECTOR_SIZE;
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+
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+        while (left > 0) {
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+            num = MIN(left, 65536);
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+            result = write(fd, buf, num);
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+            if (result < 0) {
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+                result = -errno;
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+                error_setg_errno(errp, -result,
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+                                 "Could not write to the new file");
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+                break;
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+            }
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+            left -= num;
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         }
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+        fsync(fd);
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+        g_free(buf);
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+    } else if (prealloc != PREALLOC_MODE_OFF) {
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+        result = -EINVAL;
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+        error_setg(errp, "Unsupported preallocation mode: %s",
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+                   PreallocMode_lookup[prealloc]);
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+    }
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+
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+out_close:
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+    if (qemu_close(fd) != 0 && result == 0) {
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+        result = -errno;
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+        error_setg_errno(errp, -result, "Could not close the new file");
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     }
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+out:
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     return result;
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 }
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@@ -1404,6 +1452,11 @@ static QEMUOptionParameter raw_create_options[] = {
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         .type = OPT_SIZE,
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         .help = "Virtual disk size"
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     },
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+    {
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+        .name = BLOCK_OPT_PREALLOC,
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+        .type = OPT_STRING,
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+        .help = "Preallocation mode (allowed values: off, falloc, full)"
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+    },
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     { NULL }
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 };
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diff --git a/qemu-doc.texi b/qemu-doc.texi
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index 54ab3c5..dc5b49e 100644
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--- a/qemu-doc.texi
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+++ b/qemu-doc.texi
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@@ -527,6 +527,15 @@ Linux or NTFS on Windows), then only the written sectors will reserve
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 space. Use @code{qemu-img info} to know the real size used by the
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 image or @code{ls -ls} on Unix/Linux.
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+Supported options:
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+@table @code
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+@item preallocation
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+Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).
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+@code{falloc} mode preallocates space for image by calling posix_fallocate().
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+@code{full} mode preallocates space for image by writing zeros to underlying
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+storage.
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+@end table
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+
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 @item qcow2
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 QEMU image format, the most versatile format. Use it to have smaller
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 images (useful if your filesystem does not supports holes, for example
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diff --git a/qemu-img.texi b/qemu-img.texi
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index 5f99ebb..80d3261 100644
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--- a/qemu-img.texi
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+++ b/qemu-img.texi
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@@ -392,6 +392,15 @@ Linux or NTFS on Windows), then only the written sectors will reserve
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 space. Use @code{qemu-img info} to know the real size used by the
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 image or @code{ls -ls} on Unix/Linux.
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+Supported options:
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+@table @code
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+@item preallocation
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+Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).
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+@code{falloc} mode preallocates space for image by calling posix_fallocate().
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+@code{full} mode preallocates space for image by writing zeros to underlying
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+storage.
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+@end table
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+
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 @item qcow2
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 QEMU image format, the most versatile format. Use it to have smaller
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 images (useful if your filesystem does not supports holes, for example
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-- 
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1.8.3.1
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