qcow2: Add falloc and full preallocation option

preallocation=falloc allocates disk space by posix_fallocate(),
preallocation=full allocates disk space by writing zeros to disk.
Both modes imply preallocation=metadata.

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

4 files changed, 90 insertions, 43 deletions

diff --git a/block/qcow2.c b/block/qcow2.c
index 2d68b51f14..0daf25cb58 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 || prealloc == PREALLOC_MODE_FALLOC) {
+        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 == PREALLOC_MODE_METADATA) {
+    if (prealloc != PREALLOC_MODE_OFF) {
         BDRVQcowState *s = bs->opaque;
         qemu_co_mutex_lock(&s->lock);
         ret = preallocate(bs);
@@ -1958,14 +2008,6 @@ static int qcow2_create(const char *filename, QemuOpts *opts, Error **errp)
         flags |= BLOCK_FLAG_LAZY_REFCOUNTS;
     }
 
-    if (prealloc != PREALLOC_MODE_OFF &&
-        prealloc != PREALLOC_MODE_METADATA) {
-        ret = -EINVAL;
-        error_setg(errp, "Unsupported preallocate mode: %s",
-                   PreallocMode_lookup[prealloc]);
-        goto finish;
-    }
-
     if (backing_file && prealloc != PREALLOC_MODE_OFF) {
         error_setg(errp, "Backing file and preallocation cannot be used at "
                    "the same time");
@@ -2526,7 +2568,8 @@ 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, "
+                    "falloc, full)"
         },
         {
             .name = BLOCK_OPT_LAZY_REFCOUNTS,
diff --git a/qemu-doc.texi b/qemu-doc.texi
index 1f289d6a08..ef3be72ae2 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -584,9 +584,11 @@ 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{falloc},
+@code{full}). An image with preallocated metadata is initially larger but can
+improve performance when the image needs to grow. @code{falloc} and @code{full}
+preallocations are like the same options 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 d64d05edda..50d2cca7a0 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -476,9 +476,11 @@ 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{falloc},
+@code{full}). An image with preallocated metadata is initially larger but can
+improve performance when the image needs to grow. @code{falloc} and @code{full}
+preallocations are like the same options 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 413e7ef391..90c21c893b 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, 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, falloc, full)
 lazy_refcounts   Postpone refcount updates
 
 Testing: convert -o help