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[Qemu-devel] [PATCH 11/15] qcow2: Keep unknown header extension when rew
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 11/15] qcow2: Keep unknown header extension when rewriting header |
Date: |
Fri, 10 Feb 2012 13:47:40 +0100 |
If we want header extensions to work as compatible extensions, we can't
destroy yet unknown header extensions when rewriting the header (e.g.
for changing the backing file). Save all unknown header extensions in a
list of blobs and include them in a new header.
Signed-off-by: Kevin Wolf <address@hidden>
---
block/qcow2.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
block/qcow2.h | 8 ++++++++
2 files changed, 50 insertions(+), 2 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index 9f8c2de..3692b45 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -77,8 +77,10 @@ static int qcow2_probe(const uint8_t *buf, int buf_size,
const char *filename)
static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset,
uint64_t end_offset)
{
+ BDRVQcowState *s = bs->opaque;
QCowExtension ext;
uint64_t offset;
+ int ret;
#ifdef DEBUG_EXT
printf("qcow2_read_extensions: start=%ld end=%ld\n", start_offset,
end_offset);
@@ -129,8 +131,22 @@ static int qcow2_read_extensions(BlockDriverState *bs,
uint64_t start_offset,
break;
default:
- /* unknown magic -- just skip it */
- offset = ((offset + ext.len + 7) & ~7);
+ /* unknown magic - save it in case we need to rewrite the header */
+ {
+ Qcow2UnknownHeaderExtension *uext;
+
+ uext = g_malloc0(sizeof(*uext) + ext.len);
+ uext->magic = ext.magic;
+ uext->len = ext.len;
+ QLIST_INSERT_HEAD(&s->unknown_header_ext, uext, next);
+
+ ret = bdrv_pread(bs->file, offset , uext->data, uext->len);
+ if (ret < 0) {
+ return ret;
+ }
+
+ offset = ((offset + ext.len + 7) & ~7);
+ }
break;
}
}
@@ -138,6 +154,16 @@ static int qcow2_read_extensions(BlockDriverState *bs,
uint64_t start_offset,
return 0;
}
+static void cleanup_unknown_header_ext(BlockDriverState *bs)
+{
+ BDRVQcowState *s = bs->opaque;
+ Qcow2UnknownHeaderExtension *uext, *next;
+
+ QLIST_FOREACH_SAFE(uext, &s->unknown_header_ext, next, next) {
+ QLIST_REMOVE(uext, next);
+ g_free(uext);
+ }
+}
static int qcow2_open(BlockDriverState *bs, int flags)
{
@@ -291,6 +317,7 @@ static int qcow2_open(BlockDriverState *bs, int flags)
return ret;
fail:
+ cleanup_unknown_header_ext(bs);
qcow2_free_snapshots(bs);
qcow2_refcount_close(bs);
g_free(s->l1_table);
@@ -632,6 +659,7 @@ static void qcow2_close(BlockDriverState *bs)
qcow2_cache_destroy(bs, s->l2_table_cache);
qcow2_cache_destroy(bs, s->refcount_block_cache);
+ cleanup_unknown_header_ext(bs);
g_free(s->cluster_cache);
qemu_vfree(s->cluster_data);
qcow2_refcount_close(bs);
@@ -705,6 +733,7 @@ int qcow2_update_header(BlockDriverState *bs)
int ret;
uint64_t total_size;
uint32_t refcount_table_clusters;
+ Qcow2UnknownHeaderExtension *uext;
buf = qemu_blockalign(bs, buflen);
memset(buf, 0, s->cluster_size);
@@ -752,6 +781,17 @@ int qcow2_update_header(BlockDriverState *bs)
buflen -= ret;
}
+ /* Keep unknown header extensions */
+ QLIST_FOREACH(uext, &s->unknown_header_ext, next) {
+ ret = header_ext_add(buf, uext->magic, uext->data, uext->len, buflen);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ buf += ret;
+ buflen -= ret;
+ }
+
/* End of header extensions */
ret = header_ext_add(buf, QCOW2_EXT_MAGIC_END, NULL, 0, buflen);
if (ret < 0) {
diff --git a/block/qcow2.h b/block/qcow2.h
index aae5f89..fc35838 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -87,6 +87,13 @@ typedef struct QCowSnapshot {
struct Qcow2Cache;
typedef struct Qcow2Cache Qcow2Cache;
+typedef struct Qcow2UnknownHeaderExtension {
+ uint32_t magic;
+ uint32_t len;
+ QLIST_ENTRY(Qcow2UnknownHeaderExtension) next;
+ uint8_t data[];
+} Qcow2UnknownHeaderExtension;
+
typedef struct BDRVQcowState {
int cluster_bits;
int cluster_size;
@@ -127,6 +134,7 @@ typedef struct BDRVQcowState {
QCowSnapshot *snapshots;
int flags;
+ QLIST_HEAD(, Qcow2UnknownHeaderExtension) unknown_header_ext;
} BDRVQcowState;
/* XXX: use std qcow open function ? */
--
1.7.6.5
- [Qemu-devel] [PULL 00/15] Block patches, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 01/15] cutils: extract buffer_is_zero() from qemu-img.c, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 02/15] block: add .bdrv_co_write_zeroes() interface, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 03/15] block: perform zero-detection during copy-on-read, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 04/15] qed: replace is_write with flags field, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 05/15] qed: add .bdrv_co_write_zeroes() support, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 06/15] qemu-io: add write -z option for bdrv_co_write_zeroes, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 14/15] sheepdog: fix co_recv coroutine context, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 15/15] AHCI: Masking of IRQs actually masks them, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 09/15] vpc: Round up image size during fixed image creation, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 11/15] qcow2: Keep unknown header extension when rewriting header,
Kevin Wolf <=
- [Qemu-devel] [PATCH 12/15] rewrite QEMU_BUILD_BUG_ON, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 10/15] qcow2: Update whole header at once, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 08/15] vpc: Add support for Fixed Disk type, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 13/15] AHCI: Fix port reset race, Kevin Wolf, 2012/02/10
- [Qemu-devel] [PATCH 07/15] iSCSI: add configuration variables for iSCSI, Kevin Wolf, 2012/02/10
- Re: [Qemu-devel] [PULL 00/15] Block patches, Kevin Wolf, 2012/02/15
- Re: [Qemu-devel] [PULL 00/15] Block patches, Anthony Liguori, 2012/02/15