[libvirt PATCH 2/2] storage_file: add support to probe cluster_size from QCOW2 images
Pavel Hrdina
phrdina at redhat.com
Thu May 13 11:23:05 UTC 2021
>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 at redhat.com>
---
src/storage/storage_util.c | 3 ++
src/storage_file/storage_file_probe.c | 55 +++++++++++++++++++--------
2 files changed, 42 insertions(+), 16 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..423597049f 100644
--- a/src/storage_file/storage_file_probe.c
+++ b/src/storage_file/storage_file_probe.c
@@ -94,6 +94,9 @@ struct FileTypeInfo {
/* Store a COW base image path (possibly relative),
* or NULL if there is no COW base image, to RES;
* return BACKING_STORE_* */
+ int clusterBitsOffset; /* Byte offset from start of file where we find
+ * number of cluster bits, -1 to skip. */
+ int clusterBitsSize; /* Number of bytes for cluster bits. */
const struct FileEncryptionInfo *cryptInfo; /* Encryption info */
int (*getBackingStore)(char **res, int *format,
const char *buf, size_t buf_size);
@@ -116,7 +119,8 @@ 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 +242,18 @@ 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, -1, 0, NULL, NULL, NULL },
[VIR_STORAGE_FILE_RAW] = { 0, NULL, LV_LITTLE_ENDIAN,
- -1, 0, {0}, 0, 0, 0,
+ -1, 0, {0}, 0, 0, 0, -1, 0,
luksEncryptionInfo,
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, -1, 0, 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, -1, 0, NULL, NULL, NULL
},
[VIR_STORAGE_FILE_CLOOP] = {
/* #!/bin/sh
@@ -258,7 +262,7 @@ static struct FileTypeInfo const fileTypeInfo[] = {
*/ /* Untested */
0, NULL,
LV_LITTLE_ENDIAN, -1, 0, {0},
- -1, 0, 0, NULL, NULL, NULL
+ -1, 0, 0, -1, 0, NULL, NULL, NULL
},
[VIR_STORAGE_FILE_DMG] = {
/* XXX QEMU says there's no magic for dmg,
@@ -266,43 +270,44 @@ 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, -1, 0, NULL, NULL, NULL
},
[VIR_STORAGE_FILE_ISO] = {
32769, "CD001",
LV_LITTLE_ENDIAN, -2, 0, {0},
- -1, 0, 0, NULL, NULL, NULL
+ -1, 0, 0, -1, 0, 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, -1, 0, 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, -1, 0, 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, -1, 0, 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, -1, 0, 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, -1, 0, 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, -1, 0, NULL, cowGetBackingStore, NULL
},
[VIR_STORAGE_FILE_QCOW] = {
0, "QFI",
LV_BIG_ENDIAN, 4, 4, {1},
QCOWX_HDR_IMAGE_SIZE, 8, 1,
+ -1, 0,
qcow1EncryptionInfo,
qcowXGetBackingStore, NULL
},
@@ -310,6 +315,7 @@ static struct FileTypeInfo const fileTypeInfo[] = {
0, "QFI",
LV_BIG_ENDIAN, 4, 4, {2, 3},
QCOWX_HDR_IMAGE_SIZE, 8, 1,
+ QCOWX_HDR_CLUSTER_BITS_OFFSET, 4,
qcow2EncryptionInfo,
qcowXGetBackingStore,
qcow2GetFeatures
@@ -318,12 +324,12 @@ 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, -1, 0, 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, -1, 0, NULL, vmdk4GetBackingStore, NULL
},
};
G_STATIC_ASSERT(G_N_ELEMENTS(fileTypeInfo) == VIR_STORAGE_FILE_LAST);
@@ -890,6 +896,23 @@ virStorageFileProbeGetMetadata(virStorageSource *meta,
meta->capacity *= fileTypeInfo[meta->format].sizeMultiplier;
}
+ if (fileTypeInfo[meta->format].clusterBitsOffset != -1) {
+ int clusterBits = 0;
+
+ if ((fileTypeInfo[meta->format].clusterBitsOffset + 4) > len)
+ return 0;
+
+ if (fileTypeInfo[meta->format].endian == LV_LITTLE_ENDIAN)
+ clusterBits = virReadBufInt32LE(buf +
+ fileTypeInfo[meta->format].clusterBitsOffset);
+ else
+ clusterBits = virReadBufInt32BE(buf +
+ fileTypeInfo[meta->format].clusterBitsOffset);
+
+ if (clusterBits > 0)
+ meta->clusterSize = 1 << clusterBits;
+ }
+
VIR_FREE(meta->backingStoreRaw);
if (fileTypeInfo[meta->format].getBackingStore != NULL) {
int store = fileTypeInfo[meta->format].getBackingStore(&meta->backingStoreRaw,
--
2.31.1
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