diff mbox

[v7,for,2.0,4/4] qcow2: Add full image preallocation option

Message ID 6eff2de18cc1e860f31a1ea9c1afc71b8ee12f48.1395035846.git.hutao@cn.fujitsu.com
State New
Headers show

Commit Message

Hu Tao March 17, 2014, 6:53 a.m. UTC 
This adds a preallocation=full mode to qcow2 image creation, which
creates a non-sparse image file.

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
---
 block/qcow2.c              | 75 ++++++++++++++++++++++++++++++++++++++++++++--
 tests/qemu-iotests/082.out | 54 ++++++++++++++++-----------------
 2 files changed, 99 insertions(+), 30 deletions(-)

Comments

Kevin Wolf March 20, 2014, 1:38 p.m. UTC | #1 
Am 17.03.2014 um 07:53 hat Hu Tao geschrieben:
> This adds a preallocation=full mode to qcow2 image creation, which
> creates a non-sparse image file.
> 
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>

I see that you changed the implementation from bdrv_preallocate() to
bdrv_create() options in v4 after Stefan had asked whether
bdrv_preallocate() was really necessary or just complicating things.

In hindsight, do you really think the new code is simpler? I certainly
think this one is rather adventurous and the formulas to precalculate
the image file size are easy to get wrong.

Kevin
Hu Tao May 7, 2014, 2:39 a.m. UTC | #2 
Hi,

On Thu, Mar 20, 2014 at 02:38:32PM +0100, Kevin Wolf wrote:
> Am 17.03.2014 um 07:53 hat Hu Tao geschrieben:
> > This adds a preallocation=full mode to qcow2 image creation, which
> > creates a non-sparse image file.
> > 
> > Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> 
> I see that you changed the implementation from bdrv_preallocate() to
> bdrv_create() options in v4 after Stefan had asked whether
> bdrv_preallocate() was really necessary or just complicating things.
> 
> In hindsight, do you really think the new code is simpler? I certainly
> think this one is rather adventurous and the formulas to precalculate
> the image file size are easy to get wrong.

When I tried to implement the bdrv_preallocate() way, I found that it
was inevitable to precalculate the size. For example, in
qcow2::bdrv_preallcate() we have to call low level
raw::bdrv_preallocate() first, but we have to pass in the actual image
file size which we have to precalculate before qcow2::bdrv_preallocate()
can create any metadata.

Another problem I don't understand about bdrv_preallocate() is that how
it ensures existing data not being corrupted for every call to
bdrv_preallocate().

Regards,
Hu Tao
diff mbox

Patch

diff --git a/block/qcow2.c b/block/qcow2.c
index 33ecb8a..c4bb9f5 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1459,6 +1459,7 @@  static int qcow2_create2(const char *filename, int64_t total_size,
                          QEMUOptionParameter *options, int version,
                          Error **errp)
 {
+    QEMUOptionParameter *alloc_options = NULL;
     /* Calculate cluster_bits */
     int cluster_bits;
     cluster_bits = ffs(cluster_size) - 1;
@@ -1488,10 +1489,74 @@  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;
+        unsigned nreftablee, nrefblocke, nl1e, nl2e;
+        BlockDriver *drv;
+
+        total_size = align_offset(total_size, cluster_size);
+
+        drv = bdrv_find_protocol(filename, true);
+        if (drv == NULL) {
+            error_setg(errp, "Could not find protocol for file '%s'", filename);
+            return -ENOENT;
+        }
+
+        alloc_options = append_option_parameters(alloc_options,
+                                                 drv->create_options);
+        alloc_options = append_option_parameters(alloc_options, options);
+
+        /* header: 1 cluster */
+        meta_size += cluster_size;
+
+        /* total size of L2 tables */
+        nl2e = 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 = (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);
+
+        set_option_parameter_int(alloc_options, BLOCK_OPT_SIZE,
+                                 total_size + meta_size);
+        set_option_parameter(alloc_options, BLOCK_OPT_PREALLOC, "full");
+
+        options = alloc_options;
+    }
+
     ret = bdrv_create_file(filename, options, &local_err);
     if (ret < 0) {
         error_propagate(errp, local_err);
-        return ret;
+        goto out_options;
     }
 
     bs = NULL;
@@ -1499,7 +1564,7 @@  static int qcow2_create2(const char *filename, int64_t total_size,
                     NULL, &local_err);
     if (ret < 0) {
         error_propagate(errp, local_err);
-        return ret;
+        goto out_options;
     }
 
     /* Write the header */
@@ -1620,6 +1685,8 @@  out:
     if (bs) {
         bdrv_unref(bs);
     }
+out_options:
+    free_option_parameters(alloc_options);
     return ret;
 }
 
@@ -1655,6 +1722,8 @@  static int qcow2_create(const char *filename, QEMUOptionParameter *options,
                 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);
@@ -2220,7 +2289,7 @@  static QEMUOptionParameter qcow2_create_options[] = {
     {
         .name = BLOCK_OPT_PREALLOC,
         .type = 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/tests/qemu-iotests/082.out b/tests/qemu-iotests/082.out
index 28309a0..5689802 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
 
 Testing: create -f qcow2 -o ? TEST_DIR/t.qcow2 128M
@@ -75,7 +75,7 @@  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 -f qcow2 -o cluster_size=4k,help TEST_DIR/t.qcow2 128M
@@ -86,7 +86,7 @@  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 -f qcow2 -o cluster_size=4k,? TEST_DIR/t.qcow2 128M
@@ -97,7 +97,7 @@  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 -f qcow2 -o help,cluster_size=4k TEST_DIR/t.qcow2 128M
@@ -108,7 +108,7 @@  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 -f qcow2 -o ?,cluster_size=4k TEST_DIR/t.qcow2 128M
@@ -119,7 +119,7 @@  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 -f qcow2 -o cluster_size=4k -o help TEST_DIR/t.qcow2 128M
@@ -130,7 +130,7 @@  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 -f qcow2 -o cluster_size=4k -o ? TEST_DIR/t.qcow2 128M
@@ -141,7 +141,7 @@  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 -f qcow2 -o backing_file=TEST_DIR/t.qcow2,,help TEST_DIR/t.qcow2 128M
@@ -167,7 +167,7 @@  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
@@ -245,7 +245,7 @@  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 qcow2 -o ? TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
@@ -256,7 +256,7 @@  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 qcow2 -o cluster_size=4k,help TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
@@ -267,7 +267,7 @@  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 qcow2 -o cluster_size=4k,? TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
@@ -278,7 +278,7 @@  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 qcow2 -o help,cluster_size=4k TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
@@ -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
 
 Testing: convert -O qcow2 -o ?,cluster_size=4k TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
@@ -300,7 +300,7 @@  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 qcow2 -o cluster_size=4k -o help TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
@@ -311,7 +311,7 @@  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 qcow2 -o cluster_size=4k -o ? TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
@@ -322,7 +322,7 @@  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 qcow2 -o backing_file=TEST_DIR/t.qcow2,,help TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.base
@@ -348,7 +348,7 @@  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
@@ -415,7 +415,7 @@  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: amend -f qcow2 -o ? TEST_DIR/t.qcow2
@@ -426,7 +426,7 @@  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: amend -f qcow2 -o cluster_size=4k,help TEST_DIR/t.qcow2
@@ -437,7 +437,7 @@  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: amend -f qcow2 -o cluster_size=4k,? TEST_DIR/t.qcow2
@@ -448,7 +448,7 @@  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: amend -f qcow2 -o help,cluster_size=4k TEST_DIR/t.qcow2
@@ -459,7 +459,7 @@  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: amend -f qcow2 -o ?,cluster_size=4k TEST_DIR/t.qcow2
@@ -470,7 +470,7 @@  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: amend -f qcow2 -o cluster_size=4k -o help TEST_DIR/t.qcow2
@@ -481,7 +481,7 @@  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: amend -f qcow2 -o cluster_size=4k -o ? TEST_DIR/t.qcow2
@@ -492,7 +492,7 @@  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: amend -f qcow2 -o backing_file=TEST_DIR/t.qcow2,,help TEST_DIR/t.qcow2
@@ -520,7 +520,7 @@  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