diff mbox

[v13,6/6] qcow2: Add full preallocation option

Message ID 4b14d32b73bf4c0e234771e802a819df4a9e1bb1.1409299732.git.hutao@cn.fujitsu.com
State New
Headers show

Commit Message

Hu Tao Aug. 29, 2014, 8:33 a.m. UTC 
preallocation=full allocates disk space by fallocating the space if
posix_fallocate() is available, otherwise by writing zeros to disk to
ensure disk space in any cases.

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
---
 block/qcow2.c              | 61 +++++++++++++++++++++++++++++++++++++++-------
 qemu-doc.texi              |  7 +++---
 qemu-img.texi              |  7 +++---
 tests/qemu-iotests/082.out | 54 ++++++++++++++++++++--------------------
 4 files changed, 87 insertions(+), 42 deletions(-)

Comments

Max Reitz Sept. 2, 2014, 9:55 p.m. UTC | #1 
On 29.08.2014 10:33, Hu Tao wrote:
> preallocation=full allocates disk space by fallocating the space if
> posix_fallocate() is available, otherwise by writing zeros to disk to
> ensure disk space in any cases.
>
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> ---
>   block/qcow2.c              | 61 +++++++++++++++++++++++++++++++++++++++-------
>   qemu-doc.texi              |  7 +++---
>   qemu-img.texi              |  7 +++---
>   tests/qemu-iotests/082.out | 54 ++++++++++++++++++++--------------------
>   4 files changed, 87 insertions(+), 42 deletions(-)

Reviewed-by: Max Reitz <mreitz@redhat.com>
Kevin Wolf Sept. 4, 2014, 1:09 p.m. UTC | #2 
Am 29.08.2014 um 10:33 hat Hu Tao geschrieben:
> preallocation=full allocates disk space by fallocating the space if
> posix_fallocate() is available, otherwise by writing zeros to disk to
> ensure disk space in any cases.
> 
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> ---
>  block/qcow2.c              | 61 +++++++++++++++++++++++++++++++++++++++-------
>  qemu-doc.texi              |  7 +++---
>  qemu-img.texi              |  7 +++---
>  tests/qemu-iotests/082.out | 54 ++++++++++++++++++++--------------------
>  4 files changed, 87 insertions(+), 42 deletions(-)

> +        qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
> +                            aligned_total_size + meta_size);
> +        qemu_opt_set(opts, BLOCK_OPT_PREALLOC, PreallocMode_lookup[prealloc]);
> +    }

This means that if used with a protocol that doesn't have a
preallocation option, it gets silently ignored. I'm not completely
decided yet whether that's a bug or a feature. :-)

Kevin
Hu Tao Sept. 9, 2014, 3:23 a.m. UTC | #3 
On Thu, Sep 04, 2014 at 03:09:08PM +0200, Kevin Wolf wrote:
> Am 29.08.2014 um 10:33 hat Hu Tao geschrieben:
> > preallocation=full allocates disk space by fallocating the space if
> > posix_fallocate() is available, otherwise by writing zeros to disk to
> > ensure disk space in any cases.
> > 
> > Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> > ---
> >  block/qcow2.c              | 61 +++++++++++++++++++++++++++++++++++++++-------
> >  qemu-doc.texi              |  7 +++---
> >  qemu-img.texi              |  7 +++---
> >  tests/qemu-iotests/082.out | 54 ++++++++++++++++++++--------------------
> >  4 files changed, 87 insertions(+), 42 deletions(-)
> 
> > +        qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
> > +                            aligned_total_size + meta_size);
> > +        qemu_opt_set(opts, BLOCK_OPT_PREALLOC, PreallocMode_lookup[prealloc]);
> > +    }
> 
> This means that if used with a protocol that doesn't have a
> preallocation option, it gets silently ignored. I'm not completely
> decided yet whether that's a bug or a feature. :-)

We can add code to reject preallocation option if it is determined as a
bug later, but it seems not necessary currently.

Regards,
Hu
diff mbox

Patch

diff --git a/block/qcow2.c b/block/qcow2.c
index 95fb240..f222fff 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1772,6 +1772,56 @@  static int qcow2_create2(const char *filename, int64_t total_size,
     Error *local_err = NULL;
     int ret;
 
+    if (prealloc == PREALLOC_MODE_FULL) {
+        int64_t meta_size = 0;
+        uint64_t nreftablee, nrefblocke, nl1e, nl2e;
+        int64_t aligned_total_size = align_offset(total_size, cluster_size);
+
+        /* header: 1 cluster */
+        meta_size += cluster_size;
+
+        /* total size of L2 tables */
+        nl2e = aligned_total_size / cluster_size;
+        nl2e = align_offset(nl2e, cluster_size / sizeof(uint64_t));
+        meta_size += nl2e * sizeof(uint64_t);
+
+        /* total size of L1 tables */
+        nl1e = nl2e * sizeof(uint64_t) / cluster_size;
+        nl1e = align_offset(nl1e, cluster_size / sizeof(uint64_t));
+        meta_size += nl1e * sizeof(uint64_t);
+
+        /* total size of refcount blocks
+         *
+         * note: every host cluster is reference-counted, including metadata
+         * (even refcount blocks are recursively included).
+         * Let:
+         *   a = total_size (this is the guest disk size)
+         *   m = meta size not including refcount blocks and refcount tables
+         *   c = cluster size
+         *   y1 = number of refcount blocks entries
+         *   y2 = meta size including everything
+         * then,
+         *   y1 = (y2 + a)/c
+         *   y2 = y1 * sizeof(u16) + y1 * sizeof(u16) * sizeof(u64) / c + m
+         * we can get y1:
+         *   y1 = (a + m) / (c - sizeof(u16) - sizeof(u16) * sizeof(u64) / c)
+         */
+        nrefblocke = (aligned_total_size + meta_size + cluster_size) /
+            (cluster_size - sizeof(uint16_t) -
+             1.0 * sizeof(uint16_t) * sizeof(uint64_t) / cluster_size);
+        nrefblocke = align_offset(nrefblocke, cluster_size / sizeof(uint16_t));
+        meta_size += nrefblocke * sizeof(uint16_t);
+
+        /* total size of refcount tables */
+        nreftablee = nrefblocke * sizeof(uint16_t) / cluster_size;
+        nreftablee = align_offset(nreftablee, cluster_size / sizeof(uint64_t));
+        meta_size += nreftablee * sizeof(uint64_t);
+
+        qemu_opt_set_number(opts, BLOCK_OPT_SIZE,
+                            aligned_total_size + meta_size);
+        qemu_opt_set(opts, BLOCK_OPT_PREALLOC, PreallocMode_lookup[prealloc]);
+    }
+
     ret = bdrv_create_file(filename, opts, &local_err);
     if (ret < 0) {
         error_propagate(errp, local_err);
@@ -1877,7 +1927,7 @@  static int qcow2_create2(const char *filename, int64_t total_size,
     }
 
     /* And if we're supposed to preallocate metadata, do that now */
-    if (prealloc) {
+    if (prealloc != PREALLOC_MODE_OFF) {
         BDRVQcowState *s = bs->opaque;
         qemu_co_mutex_lock(&s->lock);
         ret = preallocate(bs);
@@ -1958,13 +2008,6 @@  static int qcow2_create(const char *filename, QemuOpts *opts, Error **errp)
         flags |= BLOCK_FLAG_LAZY_REFCOUNTS;
     }
 
-    if (prealloc && prealloc != PREALLOC_MODE_METADATA) {
-        ret = -1;
-        error_setg(errp, "Unsupported preallocate mode: %s",
-                   PreallocMode_lookup[prealloc]);
-        goto finish;
-    }
-
     if (backing_file && prealloc) {
         error_setg(errp, "Backing file and preallocation cannot be used at "
                    "the same time");
@@ -2525,7 +2568,7 @@  static QemuOptsList qcow2_create_opts = {
         {
             .name = BLOCK_OPT_PREALLOC,
             .type = QEMU_OPT_STRING,
-            .help = "Preallocation mode (allowed values: off, metadata)"
+            .help = "Preallocation mode (allowed values: off, metadata, full)"
         },
         {
             .name = BLOCK_OPT_LAZY_REFCOUNTS,
diff --git a/qemu-doc.texi b/qemu-doc.texi
index 2637765..b72ff7c 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -583,9 +583,10 @@  sizes can improve the image file size whereas larger cluster sizes generally
 provide better performance.
 
 @item preallocation
-Preallocation mode (allowed values: off, metadata). An image with preallocated
-metadata is initially larger but can improve performance when the image needs
-to grow.
+Preallocation mode (allowed values: @code{off}, @code{metadata}, @code{full}).
+An image with preallocated metadata is initially larger but can improve
+performance when the image needs to grow. @code{full} preallocation is like
+the same option of @code{raw} format, but sets up metadata also.
 
 @item lazy_refcounts
 If this option is set to @code{on}, reference count updates are postponed with
diff --git a/qemu-img.texi b/qemu-img.texi
index 063ec61..7307331 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -474,9 +474,10 @@  sizes can improve the image file size whereas larger cluster sizes generally
 provide better performance.
 
 @item preallocation
-Preallocation mode (allowed values: off, metadata). An image with preallocated
-metadata is initially larger but can improve performance when the image needs
-to grow.
+Preallocation mode (allowed values: @code{off}, @code{metadata}, @code{full}).
+An image with preallocated metadata is initially larger but can improve
+performance when the image needs to grow. @code{full} preallocation is like
+the same option of @code{raw} format, but sets up metadata also.
 
 @item lazy_refcounts
 If this option is set to @code{on}, reference count updates are postponed with
diff --git a/tests/qemu-iotests/082.out b/tests/qemu-iotests/082.out
index 413e7ef..be6d3ca 100644
--- a/tests/qemu-iotests/082.out
+++ b/tests/qemu-iotests/082.out
@@ -64,7 +64,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -76,7 +76,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -88,7 +88,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -100,7 +100,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -112,7 +112,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -124,7 +124,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -136,7 +136,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -148,7 +148,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -175,7 +175,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 
 Testing: create -o help
@@ -253,7 +253,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -265,7 +265,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -277,7 +277,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -289,7 +289,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -301,7 +301,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -313,7 +313,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -325,7 +325,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -337,7 +337,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -364,7 +364,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 
 Testing: convert -o help
@@ -431,7 +431,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -443,7 +443,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -455,7 +455,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -467,7 +467,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -479,7 +479,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -491,7 +491,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -503,7 +503,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -515,7 +515,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 nocow            Turn off copy-on-write (valid only on btrfs)
 
@@ -544,7 +544,7 @@  backing_file     File name of a base image
 backing_fmt      Image format of the base image
 encryption       Encrypt the image
 cluster_size     qcow2 cluster size
-preallocation    Preallocation mode (allowed values: off, metadata)
+preallocation    Preallocation mode (allowed values: off, metadata, full)
 lazy_refcounts   Postpone refcount updates
 
 Testing: convert -o help