[libvirt PATCH v2 0/2] storage_driver: add support for cluster_size QCOW2 option
Pavel Hrdina (2): storage: add support for QCOW2 cluster_size option storage_file: add support to probe cluster_size from QCOW2 images docs/formatstorage.html.in | 6 ++ docs/schemas/storagecommon.rng | 7 ++ docs/schemas/storagevol.rng | 3 + src/conf/storage_conf.c | 12 ++++ src/storage/storage_util.c | 8 +++ src/storage_file/storage_file_probe.c | 70 ++++++++++++++----- .../qcow2-clusterSize.argv | 6 ++ tests/storagevolxml2argvtest.c | 4 ++ .../vol-qcow2-clusterSize.xml | 17 +++++ .../vol-qcow2-clusterSize.xml | 17 +++++ tests/storagevolxml2xmltest.c | 1 + 11 files changed, 134 insertions(+), 17 deletions(-) create mode 100644 tests/storagevolxml2argvdata/qcow2-clusterSize.argv create mode 100644 tests/storagevolxml2xmlin/vol-qcow2-clusterSize.xml create mode 100644 tests/storagevolxml2xmlout/vol-qcow2-clusterSize.xml -- 2.31.1
The default value hard-coded in QEMU (64KiB) is not always the ideal. Having a possibility to set the cluster_size by user may in specific use-cases improve performance for QCOW2 images. QEMU internally has some limits, the value has to be between 512B and 2048KiB and must by power of two, except when the image has Extended L2 Entries the minimal value has to be 16KiB. Since qemu-img ensures the value is correct and the limit is not always the same libvirt will not duplicate any of these checks as the error message from qemu-img is good enough: Cluster size must be a power of two between 512 and 2048k Resolves: https://gitlab.com/libvirt/libvirt/-/issues/154 Signed-off-by: Pavel Hrdina <phrdina@redhat.com> --- Changes in v2: - Documentation now describes only what can be affected by changing cluster_size. docs/formatstorage.html.in | 6 ++++++ docs/schemas/storagecommon.rng | 7 +++++++ docs/schemas/storagevol.rng | 3 +++ src/conf/storage_conf.c | 12 ++++++++++++ src/storage/storage_util.c | 5 +++++ .../qcow2-clusterSize.argv | 6 ++++++ tests/storagevolxml2argvtest.c | 4 ++++ .../vol-qcow2-clusterSize.xml | 17 +++++++++++++++++ .../vol-qcow2-clusterSize.xml | 17 +++++++++++++++++ tests/storagevolxml2xmltest.c | 1 + 10 files changed, 78 insertions(+) create mode 100644 tests/storagevolxml2argvdata/qcow2-clusterSize.argv create mode 100644 tests/storagevolxml2xmlin/vol-qcow2-clusterSize.xml create mode 100644 tests/storagevolxml2xmlout/vol-qcow2-clusterSize.xml diff --git a/docs/formatstorage.html.in b/docs/formatstorage.html.in index cac44503da..9ee5b89ee6 100644 --- a/docs/formatstorage.html.in +++ b/docs/formatstorage.html.in @@ -791,6 +791,7 @@ </encryption> <compat>1.1</compat> <nocow/> + <clusterSize unit='KiB'>64</clusterSize> <features> <lazy_refcounts/> </features> @@ -867,6 +868,11 @@ the file image is used in VM. To create non-raw file images, it requires QEMU version since 2.1. <span class="since">Since 1.2.7</span> </dd> + <dt><code>clusterSize</code></dt> + <dd>Changes the qcow2 cluster size which can affect image file size + and performance. + <span class="since">Since 7.4.0</span> + </dd> <dt><code>features</code></dt> <dd>Format-specific features. Only used for <code>qcow2</code> now. Valid sub-elements are: diff --git a/docs/schemas/storagecommon.rng b/docs/schemas/storagecommon.rng index e3d08a8410..9ebb27700d 100644 --- a/docs/schemas/storagecommon.rng +++ b/docs/schemas/storagecommon.rng @@ -110,6 +110,13 @@ </data> </element> </define> + + <define name="clusterSize"> + <element name="clusterSize"> + <ref name="scaledInteger"/> + </element> + </define> + <define name="fileFormatFeatures"> <element name="features"> <interleave> diff --git a/docs/schemas/storagevol.rng b/docs/schemas/storagevol.rng index 22ce5eaa8d..3e0f482007 100644 --- a/docs/schemas/storagevol.rng +++ b/docs/schemas/storagevol.rng @@ -124,6 +124,9 @@ <empty/> </element> </optional> + <optional> + <ref name="clusterSize"/> + </optional> <optional> <ref name="fileFormatFeatures"/> </optional> diff --git a/src/conf/storage_conf.c b/src/conf/storage_conf.c index e481cac75c..0ecdb0969a 100644 --- a/src/conf/storage_conf.c +++ b/src/conf/storage_conf.c @@ -1416,6 +1416,13 @@ virStorageVolDefParseXML(virStoragePoolDef *pool, if (virXPathNode("./target/nocow", ctxt)) def->target.nocow = true; + if (virParseScaledValue("./target/clusterSize", + "./target/clusterSize/@unit", + ctxt, &def->target.clusterSize, + 1, ULLONG_MAX, false) < 0) { + return NULL; + } + if (virXPathNode("./target/features", ctxt)) { if ((n = virXPathNodeSet("./target/features/*", ctxt, &nodes)) < 0) return NULL; @@ -1580,6 +1587,11 @@ virStorageVolTargetDefFormat(virStorageVolOptions *options, virBufferEscapeString(buf, "<compat>%s</compat>\n", def->compat); + if (def->clusterSize > 0) { + virBufferAsprintf(buf, "<clusterSize unit='B'>%llu</clusterSize>\n", + def->clusterSize); + } + if (def->features) { size_t i; bool empty = virBitmapIsAllClear(def->features); diff --git a/src/storage/storage_util.c b/src/storage/storage_util.c index 2b0d08c65d..c8299852a3 100644 --- a/src/storage/storage_util.c +++ b/src/storage/storage_util.c @@ -664,6 +664,7 @@ struct _virStorageBackendQemuImgInfo { const char *path; unsigned long long size_arg; unsigned long long allocation; + unsigned long long clusterSize; bool encryption; bool preallocate; const char *compat; @@ -780,6 +781,9 @@ storageBackendCreateQemuImgOpts(virStorageEncryptionInfoDef *encinfo, else if (info->format == VIR_STORAGE_FILE_QCOW2) virBufferAddLit(&buf, "compat=0.10,"); + if (info->clusterSize > 0) + virBufferAsprintf(&buf, "cluster_size=%llu,", info->clusterSize); + if (info->features && info->format == VIR_STORAGE_FILE_QCOW2) { if (virBitmapIsBitSet(info->features, VIR_STORAGE_FILE_FEATURE_LAZY_REFCOUNTS)) { @@ -1130,6 +1134,7 @@ virStorageBackendCreateQemuImgCmdFromVol(virStoragePoolObj *pool, .compat = vol->target.compat, .features = vol->target.features, .nocow = vol->target.nocow, + .clusterSize = vol->target.clusterSize, .secretAlias = NULL, }; virStorageEncryption *enc = vol->target.encryption; diff --git a/tests/storagevolxml2argvdata/qcow2-clusterSize.argv b/tests/storagevolxml2argvdata/qcow2-clusterSize.argv new file mode 100644 index 0000000000..8878a26818 --- /dev/null +++ b/tests/storagevolxml2argvdata/qcow2-clusterSize.argv @@ -0,0 +1,6 @@ +qemu-img \ +create \ +-f qcow2 \ +-o compat=0.10,cluster_size=131072 \ +/var/lib/libvirt/images/OtherDemo.img \ +5242880K diff --git a/tests/storagevolxml2argvtest.c b/tests/storagevolxml2argvtest.c index 6058d2b689..9597509f00 100644 --- a/tests/storagevolxml2argvtest.c +++ b/tests/storagevolxml2argvtest.c @@ -238,6 +238,10 @@ mymain(void) "pool-dir", "vol-qcow2-nocapacity-backing", NULL, NULL, "qcow2-nocapacity", 0); + DO_TEST("pool-dir", "vol-qcow2-clusterSize", + NULL, NULL, + "qcow2-clusterSize", 0); + DO_TEST("pool-dir", "vol-file-iso", NULL, NULL, "iso", 0); diff --git a/tests/storagevolxml2xmlin/vol-qcow2-clusterSize.xml b/tests/storagevolxml2xmlin/vol-qcow2-clusterSize.xml new file mode 100644 index 0000000000..22534982a1 --- /dev/null +++ b/tests/storagevolxml2xmlin/vol-qcow2-clusterSize.xml @@ -0,0 +1,17 @@ +<volume> + <name>OtherDemo.img</name> + <key>/var/lib/libvirt/images/OtherDemo.img</key> + <capacity unit="G">5</capacity> + <allocation>294912</allocation> + <target> + <path>/var/lib/libvirt/images/OtherDemo.img</path> + <format type='qcow2'/> + <permissions> + <mode>0644</mode> + <owner>0</owner> + <group>0</group> + <label>unconfined_u:object_r:virt_image_t:s0</label> + </permissions> + <clusterSize unit='KiB'>128</clusterSize> + </target> +</volume> diff --git a/tests/storagevolxml2xmlout/vol-qcow2-clusterSize.xml b/tests/storagevolxml2xmlout/vol-qcow2-clusterSize.xml new file mode 100644 index 0000000000..393a492536 --- /dev/null +++ b/tests/storagevolxml2xmlout/vol-qcow2-clusterSize.xml @@ -0,0 +1,17 @@ +<volume type='file'> + <name>OtherDemo.img</name> + <key>/var/lib/libvirt/images/OtherDemo.img</key> + <capacity unit='bytes'>5368709120</capacity> + <allocation unit='bytes'>294912</allocation> + <target> + <path>/var/lib/libvirt/images/OtherDemo.img</path> + <format type='qcow2'/> + <permissions> + <mode>0644</mode> + <owner>0</owner> + <group>0</group> + <label>unconfined_u:object_r:virt_image_t:s0</label> + </permissions> + <clusterSize unit='B'>131072</clusterSize> + </target> +</volume> diff --git a/tests/storagevolxml2xmltest.c b/tests/storagevolxml2xmltest.c index ed24d98426..be38f50a51 100644 --- a/tests/storagevolxml2xmltest.c +++ b/tests/storagevolxml2xmltest.c @@ -88,6 +88,7 @@ mymain(void) DO_TEST("pool-dir", "vol-qcow2-nobacking"); DO_TEST("pool-dir", "vol-qcow2-encryption"); DO_TEST("pool-dir", "vol-qcow2-luks"); + DO_TEST("pool-dir", "vol-qcow2-clusterSize"); DO_TEST("pool-dir", "vol-luks"); DO_TEST("pool-dir", "vol-luks-cipher"); DO_TEST("pool-disk", "vol-partition"); -- 2.31.1
On Thu, May 20, 2021 at 17:14:31 +0200, Pavel Hrdina wrote:
The default value hard-coded in QEMU (64KiB) is not always the ideal. Having a possibility to set the cluster_size by user may in specific use-cases improve performance for QCOW2 images.
QEMU internally has some limits, the value has to be between 512B and 2048KiB and must by power of two, except when the image has Extended L2 Entries the minimal value has to be 16KiB.
Since qemu-img ensures the value is correct and the limit is not always the same libvirt will not duplicate any of these checks as the error message from qemu-img is good enough:
Cluster size must be a power of two between 512 and 2048k
Resolves: https://gitlab.com/libvirt/libvirt/-/issues/154
Signed-off-by: Pavel Hrdina <phrdina@redhat.com> ---
Changes in v2: - Documentation now describes only what can be affected by changing cluster_size.
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
From QEMU docs/interop/qcow2.txt :
Byte 20 - 23: cluster_bits Number of bits that are used for addressing an offset within a cluster (1 << cluster_bits is the cluster size). With this patch libvirt will be able to report the current cluster_size for all existing storage volumes managed by storage driver. Signed-off-by: Pavel Hrdina <phrdina@redhat.com> --- Changes in v2: - Reworkded to use callback. src/storage/storage_util.c | 3 ++ src/storage_file/storage_file_probe.c | 70 ++++++++++++++++++++------- 2 files changed, 56 insertions(+), 17 deletions(-) diff --git a/src/storage/storage_util.c b/src/storage/storage_util.c index c8299852a3..a7c9355bf9 100644 --- a/src/storage/storage_util.c +++ b/src/storage/storage_util.c @@ -3483,6 +3483,9 @@ storageBackendProbeTarget(virStorageSource *target, if (meta->capacity) target->capacity = meta->capacity; + if (meta->clusterSize > 0) + target->clusterSize = meta->clusterSize; + if (encryption && meta->encryption) { if (meta->encryption->payload_offset != -1) target->capacity -= meta->encryption->payload_offset * 512; diff --git a/src/storage_file/storage_file_probe.c b/src/storage_file/storage_file_probe.c index afe64da02e..07b7448bdd 100644 --- a/src/storage_file/storage_file_probe.c +++ b/src/storage_file/storage_file_probe.c @@ -95,6 +95,9 @@ struct FileTypeInfo { * or NULL if there is no COW base image, to RES; * return BACKING_STORE_* */ const struct FileEncryptionInfo *cryptInfo; /* Encryption info */ + unsigned long long (*getClusterSize)(const char *buf, + size_t buf_size, + int endian); int (*getBackingStore)(char **res, int *format, const char *buf, size_t buf_size); int (*getFeatures)(virBitmap **features, int format, @@ -104,6 +107,10 @@ struct FileTypeInfo { static int cowGetBackingStore(char **, int *, const char *, size_t); +static unsigned long long +qcow2GetClusterSize(const char *buf, + size_t buf_size, + int endian); static int qcowXGetBackingStore(char **, int *, const char *, size_t); static int qcow2GetFeatures(virBitmap **features, int format, @@ -116,7 +123,8 @@ qedGetBackingStore(char **, int *, const char *, size_t); #define QCOWX_HDR_VERSION (4) #define QCOWX_HDR_BACKING_FILE_OFFSET (QCOWX_HDR_VERSION+4) #define QCOWX_HDR_BACKING_FILE_SIZE (QCOWX_HDR_BACKING_FILE_OFFSET+8) -#define QCOWX_HDR_IMAGE_SIZE (QCOWX_HDR_BACKING_FILE_SIZE+4+4) +#define QCOWX_HDR_CLUSTER_BITS_OFFSET (QCOWX_HDR_BACKING_FILE_SIZE+4) +#define QCOWX_HDR_IMAGE_SIZE (QCOWX_HDR_CLUSTER_BITS_OFFSET+4) #define QCOW1_HDR_CRYPT (QCOWX_HDR_IMAGE_SIZE+8+1+1+2) #define QCOW2_HDR_CRYPT (QCOWX_HDR_IMAGE_SIZE+8) @@ -238,18 +246,18 @@ static struct FileEncryptionInfo const qcow2EncryptionInfo[] = { static struct FileTypeInfo const fileTypeInfo[] = { [VIR_STORAGE_FILE_NONE] = { 0, NULL, LV_LITTLE_ENDIAN, - -1, 0, {0}, 0, 0, 0, NULL, NULL, NULL }, + -1, 0, {0}, 0, 0, 0, NULL, NULL, NULL, NULL }, [VIR_STORAGE_FILE_RAW] = { 0, NULL, LV_LITTLE_ENDIAN, -1, 0, {0}, 0, 0, 0, luksEncryptionInfo, - NULL, NULL }, + NULL, NULL, NULL }, [VIR_STORAGE_FILE_DIR] = { 0, NULL, LV_LITTLE_ENDIAN, - -1, 0, {0}, 0, 0, 0, NULL, NULL, NULL }, + -1, 0, {0}, 0, 0, 0, NULL, NULL, NULL, NULL }, [VIR_STORAGE_FILE_BOCHS] = { /*"Bochs Virtual HD Image", */ /* Untested */ 0, NULL, LV_LITTLE_ENDIAN, 64, 4, {0x20000}, - 32+16+16+4+4+4+4+4, 8, 1, NULL, NULL, NULL + 32+16+16+4+4+4+4+4, 8, 1, NULL, NULL, NULL, NULL }, [VIR_STORAGE_FILE_CLOOP] = { /* #!/bin/sh @@ -258,7 +266,7 @@ static struct FileTypeInfo const fileTypeInfo[] = { */ /* Untested */ 0, NULL, LV_LITTLE_ENDIAN, -1, 0, {0}, - -1, 0, 0, NULL, NULL, NULL + -1, 0, 0, NULL, NULL, NULL, NULL }, [VIR_STORAGE_FILE_DMG] = { /* XXX QEMU says there's no magic for dmg, @@ -266,51 +274,52 @@ static struct FileTypeInfo const fileTypeInfo[] = { * would have to match) but then disables that check. */ 0, NULL, 0, -1, 0, {0}, - -1, 0, 0, NULL, NULL, NULL + -1, 0, 0, NULL, NULL, NULL, NULL }, [VIR_STORAGE_FILE_ISO] = { 32769, "CD001", LV_LITTLE_ENDIAN, -2, 0, {0}, - -1, 0, 0, NULL, NULL, NULL + -1, 0, 0, NULL, NULL, NULL, NULL }, [VIR_STORAGE_FILE_VPC] = { 0, "conectix", LV_BIG_ENDIAN, 12, 4, {0x10000}, - 8 + 4 + 4 + 8 + 4 + 4 + 2 + 2 + 4, 8, 1, NULL, NULL, NULL + 8 + 4 + 4 + 8 + 4 + 4 + 2 + 2 + 4, 8, 1, NULL, NULL, NULL, NULL }, /* TODO: add getBackingStore function */ [VIR_STORAGE_FILE_VDI] = { 64, "\x7f\x10\xda\xbe", LV_LITTLE_ENDIAN, 68, 4, {0x00010001}, - 64 + 5 * 4 + 256 + 7 * 4, 8, 1, NULL, NULL, NULL}, + 64 + 5 * 4 + 256 + 7 * 4, 8, 1, NULL, NULL, NULL, NULL}, /* Not direct file formats, but used for various drivers */ [VIR_STORAGE_FILE_FAT] = { 0, NULL, LV_LITTLE_ENDIAN, - -1, 0, {0}, 0, 0, 0, NULL, NULL, NULL }, + -1, 0, {0}, 0, 0, 0, NULL, NULL, NULL, NULL }, [VIR_STORAGE_FILE_VHD] = { 0, NULL, LV_LITTLE_ENDIAN, - -1, 0, {0}, 0, 0, 0, NULL, NULL, NULL }, + -1, 0, {0}, 0, 0, 0, NULL, NULL, NULL, NULL }, [VIR_STORAGE_FILE_PLOOP] = { 0, "WithouFreSpacExt", LV_LITTLE_ENDIAN, -2, 0, {0}, PLOOP_IMAGE_SIZE_OFFSET, 0, - PLOOP_SIZE_MULTIPLIER, NULL, NULL, NULL }, + PLOOP_SIZE_MULTIPLIER, NULL, NULL, NULL, NULL }, /* All formats with a backing store probe below here */ [VIR_STORAGE_FILE_COW] = { 0, "OOOM", LV_BIG_ENDIAN, 4, 4, {2}, - 4+4+1024+4, 8, 1, NULL, cowGetBackingStore, NULL + 4+4+1024+4, 8, 1, NULL, NULL, cowGetBackingStore, NULL }, [VIR_STORAGE_FILE_QCOW] = { 0, "QFI", LV_BIG_ENDIAN, 4, 4, {1}, QCOWX_HDR_IMAGE_SIZE, 8, 1, qcow1EncryptionInfo, - qcowXGetBackingStore, NULL + NULL, qcowXGetBackingStore, NULL }, [VIR_STORAGE_FILE_QCOW2] = { 0, "QFI", LV_BIG_ENDIAN, 4, 4, {2, 3}, QCOWX_HDR_IMAGE_SIZE, 8, 1, qcow2EncryptionInfo, + qcow2GetClusterSize, qcowXGetBackingStore, qcow2GetFeatures }, @@ -318,12 +327,12 @@ static struct FileTypeInfo const fileTypeInfo[] = { /* https://wiki.qemu.org/Features/QED */ 0, "QED", LV_LITTLE_ENDIAN, -2, 0, {0}, - QED_HDR_IMAGE_SIZE, 8, 1, NULL, qedGetBackingStore, NULL + QED_HDR_IMAGE_SIZE, 8, 1, NULL, NULL, qedGetBackingStore, NULL }, [VIR_STORAGE_FILE_VMDK] = { 0, "KDMV", LV_LITTLE_ENDIAN, 4, 4, {1, 2, 3}, - 4+4+4, 8, 512, NULL, vmdk4GetBackingStore, NULL + 4+4+4, 8, 512, NULL, NULL, vmdk4GetBackingStore, NULL }, }; G_STATIC_ASSERT(G_N_ELEMENTS(fileTypeInfo) == VIR_STORAGE_FILE_LAST); @@ -468,6 +477,28 @@ qcow2GetExtensions(const char *buf, } +static unsigned long long +qcow2GetClusterSize(const char *buf, + size_t buf_size, + int endian) +{ + int clusterBits = 0; + + if ((QCOWX_HDR_CLUSTER_BITS_OFFSET + 4) > buf_size) + return 0; + + if (endian == LV_LITTLE_ENDIAN) + clusterBits = virReadBufInt32LE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); + else + clusterBits = virReadBufInt32BE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); + + if (clusterBits > 0) + return 1 << clusterBits; + + return 0; +} + + static int qcowXGetBackingStore(char **res, int *format, @@ -890,6 +921,11 @@ virStorageFileProbeGetMetadata(virStorageSource *meta, meta->capacity *= fileTypeInfo[meta->format].sizeMultiplier; } + if (fileTypeInfo[meta->format].getClusterSize != NULL) { + meta->clusterSize = fileTypeInfo[meta->format].getClusterSize(buf, len, + fileTypeInfo[meta->format].endian); + } + VIR_FREE(meta->backingStoreRaw); if (fileTypeInfo[meta->format].getBackingStore != NULL) { int store = fileTypeInfo[meta->format].getBackingStore(&meta->backingStoreRaw, -- 2.31.1
On Thu, May 20, 2021 at 17:14:32 +0200, Pavel Hrdina wrote:
From QEMU docs/interop/qcow2.txt :
Byte 20 - 23: cluster_bits Number of bits that are used for addressing an offset within a cluster (1 << cluster_bits is the cluster size).
With this patch libvirt will be able to report the current cluster_size for all existing storage volumes managed by storage driver.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com> ---
Changes in v2: - Reworkded to use callback.
src/storage/storage_util.c | 3 ++ src/storage_file/storage_file_probe.c | 70 ++++++++++++++++++++------- 2 files changed, 56 insertions(+), 17 deletions(-)
[...]
@@ -468,6 +477,28 @@ qcow2GetExtensions(const char *buf, }
+static unsigned long long +qcow2GetClusterSize(const char *buf, + size_t buf_size, + int endian)
The 'endian' argument makes sense only for generic getters. You know that qcow2 has always LV_BIG_ENDIAN set.
+{ + int clusterBits = 0; + + if ((QCOWX_HDR_CLUSTER_BITS_OFFSET + 4) > buf_size) + return 0; + + if (endian == LV_LITTLE_ENDIAN) + clusterBits = virReadBufInt32LE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); + else + clusterBits = virReadBufInt32BE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); + + if (clusterBits > 0) + return 1 << clusterBits; + + return 0; +}
Drop the 'endian' argument with appropriate cleanup and: Reviewed-by: Peter Krempa <pkrempa@redhat.com>
On Fri, May 21, 2021 at 09:40:21AM +0200, Peter Krempa wrote:
On Thu, May 20, 2021 at 17:14:32 +0200, Pavel Hrdina wrote:
From QEMU docs/interop/qcow2.txt :
Byte 20 - 23: cluster_bits Number of bits that are used for addressing an offset within a cluster (1 << cluster_bits is the cluster size).
With this patch libvirt will be able to report the current cluster_size for all existing storage volumes managed by storage driver.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com> ---
Changes in v2: - Reworkded to use callback.
src/storage/storage_util.c | 3 ++ src/storage_file/storage_file_probe.c | 70 ++++++++++++++++++++------- 2 files changed, 56 insertions(+), 17 deletions(-)
[...]
@@ -468,6 +477,28 @@ qcow2GetExtensions(const char *buf, }
+static unsigned long long +qcow2GetClusterSize(const char *buf, + size_t buf_size, + int endian)
The 'endian' argument makes sense only for generic getters. You know that qcow2 has always LV_BIG_ENDIAN set.
+{ + int clusterBits = 0; + + if ((QCOWX_HDR_CLUSTER_BITS_OFFSET + 4) > buf_size) + return 0; + + if (endian == LV_LITTLE_ENDIAN) + clusterBits = virReadBufInt32LE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); + else + clusterBits = virReadBufInt32BE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); + + if (clusterBits > 0) + return 1 << clusterBits; + + return 0; +}
Drop the 'endian' argument with appropriate cleanup and:
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Fixed and pushed. Thanks for the review. Pavel
On 5/20/21 11:14 AM, Pavel Hrdina wrote:
From QEMU docs/interop/qcow2.txt :
Byte 20 - 23: cluster_bits Number of bits that are used for addressing an offset within a cluster (1 << cluster_bits is the cluster size).
With this patch libvirt will be able to report the current cluster_size for all existing storage volumes managed by storage driver.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com> ---
Changes in v2: - Reworkded to use callback.
src/storage/storage_util.c | 3 ++ src/storage_file/storage_file_probe.c | 70 ++++++++++++++++++++------- 2 files changed, 56 insertions(+), 17 deletions(-)
[...]
+static unsigned long long +qcow2GetClusterSize(const char *buf, + size_t buf_size, + int endian) +{ + int clusterBits = 0; + + if ((QCOWX_HDR_CLUSTER_BITS_OFFSET + 4) > buf_size) + return 0; + + if (endian == LV_LITTLE_ENDIAN) + clusterBits = virReadBufInt32LE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); + else + clusterBits = virReadBufInt32BE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); + + if (clusterBits > 0) + return 1 << clusterBits; +
Coverity showed me a new error today: OVERFLOW_BEFORE_WIDEN 1) Event overflow_before_widen: Potentially overflowing expression "1 << clusterBits" with type "int" (32 bits, signed) is evaluated using 32-bit arithmetic, and then used in a context that expects an expression of type "unsigned long long" (64 bits, unsigned). (2) Event remediation: To avoid overflow, cast "1" to type "unsigned long long". John
+ return 0; +} + +
[...]
participants (3)
-
John Ferlan -
Pavel Hrdina -
Peter Krempa