From 1cc25ea8f2e081a5d8b6c0e958a7ac491389ea84 Mon Sep 17 00:00:00 2001 Message-Id: <1cc25ea8f2e081a5d8b6c0e958a7ac491389ea84.1350493760.git.minovotn@redhat.com> In-Reply-To: References: From: Jeffrey Cody Date: Wed, 17 Oct 2012 05:59:17 +0200 Subject: [PATCH 04/35] qcow2: Keep unknown header extension when rewriting header RH-Author: Jeffrey Cody Message-id: <6a4d0b7b7463792b4a9596a0f2c0ee485c9d89a0.1350447475.git.jcody@redhat.com> Patchwork-id: 43267 O-Subject: [RHEL6.4 qemu-kvm PATCH v4 04/35] qcow2: Keep unknown header extension when rewriting header Bugzilla: 767233 RH-Acked-by: Paolo Bonzini RH-Acked-by: Eric Blake RH-Acked-by: Kevin Wolf From: Kevin Wolf 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 (cherry picked from commit 75bab85ca01876f912caf46f5fcb4ca8d9a50584) Conflicts: block/qcow2.h Signed-off-by: Jeff Cody --- block/qcow2.c | 44 ++++++++++++++++++++++++++++++++++++++++++-- block/qcow2.h | 9 +++++++++ 2 files changed, 51 insertions(+), 2 deletions(-) Signed-off-by: Michal Novotny --- block/qcow2.c | 44 ++++++++++++++++++++++++++++++++++++++++++-- block/qcow2.h | 9 +++++++++ 2 files changed, 51 insertions(+), 2 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index dc7c2f1..30c4966 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -79,8 +79,10 @@ 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); @@ -130,8 +132,22 @@ 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; } } @@ -139,6 +155,16 @@ 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) { @@ -287,6 +313,7 @@ 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); @@ -628,6 +655,7 @@ 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); g_free(s->cluster_data); qcow2_refcount_close(bs); @@ -669,6 +697,7 @@ 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); @@ -716,6 +745,17 @@ 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 5654e27..4f4fa78 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -88,6 +88,13 @@ 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; @@ -126,6 +133,8 @@ typedef struct BDRVQcowState { int snapshots_size; int nb_snapshots; QCowSnapshot *snapshots; + + QLIST_HEAD(, Qcow2UnknownHeaderExtension) unknown_header_ext; } BDRVQcowState; /* XXX: use std qcow open function ? */ -- 1.7.11.7