From c61d0004bc37182cae0f92a865ad2f0625762610 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Fri, 27 Jul 2012 09:05:19 +0100 Subject: [PATCH] qcow2: introduce dirty bit This patch adds an incompatible feature bit to mark images that have not been closed cleanly. When a dirty image file is opened a consistency check and repair is performed. Update qemu-iotests 031 and 036 since the extension header size changes when we add feature bit table entries. Signed-off-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block/qcow2.c | 50 +++++++++++++++++++++++++++++++++++++++++++--- block/qcow2.h | 8 ++++++++ tests/qemu-iotests/031.out | 20 +++++++++---------- tests/qemu-iotests/036.out | 4 ++-- 4 files changed, 67 insertions(+), 15 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index 870148d..7fe1567 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -214,6 +214,27 @@ static void report_unsupported_feature(BlockDriverState *bs, } } +/* + * Clears the dirty bit and flushes before if necessary. Only call this + * function when there are no pending requests, it does not guard against + * concurrent requests dirtying the image. + */ +static int qcow2_mark_clean(BlockDriverState *bs) +{ + BDRVQcowState *s = bs->opaque; + + if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) { + int ret = bdrv_flush(bs); + if (ret < 0) { + return ret; + } + + s->incompatible_features &= ~QCOW2_INCOMPAT_DIRTY; + return qcow2_update_header(bs); + } + return 0; +} + static int qcow2_open(BlockDriverState *bs, int flags) { BDRVQcowState *s = bs->opaque; @@ -287,12 +308,13 @@ static int qcow2_open(BlockDriverState *bs, int flags) s->compatible_features = header.compatible_features; s->autoclear_features = header.autoclear_features; - if (s->incompatible_features != 0) { + if (s->incompatible_features & ~QCOW2_INCOMPAT_MASK) { void *feature_table = NULL; qcow2_read_extensions(bs, header.header_length, ext_end, &feature_table); report_unsupported_feature(bs, feature_table, - s->incompatible_features); + s->incompatible_features & + ~QCOW2_INCOMPAT_MASK); ret = -ENOTSUP; goto fail; } @@ -412,6 +434,22 @@ static int qcow2_open(BlockDriverState *bs, int flags) /* Initialise locks */ qemu_co_mutex_init(&s->lock); + /* Repair image if dirty */ + if ((s->incompatible_features & QCOW2_INCOMPAT_DIRTY) && + !bs->read_only) { + BdrvCheckResult result = {0}; + + ret = qcow2_check_refcounts(bs, &result, BDRV_FIX_ERRORS); + if (ret < 0) { + goto fail; + } + + ret = qcow2_mark_clean(bs); + if (ret < 0) { + goto fail; + } + } + #ifdef DEBUG_ALLOC { BdrvCheckResult result = {0}; @@ -785,6 +823,8 @@ static void qcow2_close(BlockDriverState *bs) qcow2_cache_flush(bs, s->l2_table_cache); qcow2_cache_flush(bs, s->refcount_block_cache); + qcow2_mark_clean(bs); + qcow2_cache_destroy(bs, s->l2_table_cache); qcow2_cache_destroy(bs, s->refcount_block_cache); @@ -949,7 +989,11 @@ int qcow2_update_header(BlockDriverState *bs) /* Feature table */ Qcow2Feature features[] = { - /* no feature defined yet */ + { + .type = QCOW2_FEAT_TYPE_INCOMPATIBLE, + .bit = QCOW2_INCOMPAT_DIRTY_BITNR, + .name = "dirty bit", + }, }; ret = header_ext_add(buf, QCOW2_EXT_MAGIC_FEATURE_TABLE, diff --git a/block/qcow2.h b/block/qcow2.h index 455b6d7..b5fefc0 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -110,6 +110,14 @@ enum { QCOW2_FEAT_TYPE_AUTOCLEAR = 2, }; +/* Incompatible feature bits */ +enum { + QCOW2_INCOMPAT_DIRTY_BITNR = 0, + QCOW2_INCOMPAT_DIRTY = 1 << QCOW2_INCOMPAT_DIRTY_BITNR, + + QCOW2_INCOMPAT_MASK = QCOW2_INCOMPAT_DIRTY, +}; + typedef struct Qcow2Feature { uint8_t type; uint8_t bit; diff --git a/tests/qemu-iotests/031.out b/tests/qemu-iotests/031.out index d3cab30..297b458 100644 --- a/tests/qemu-iotests/031.out +++ b/tests/qemu-iotests/031.out @@ -54,8 +54,8 @@ header_length 72 Header extension: magic 0x6803f857 -length 0 -data '' +length 48 +data Header extension: magic 0x12345678 @@ -68,7 +68,7 @@ No errors were found on the image. magic 0x514649fb version 2 -backing_file_offset 0x98 +backing_file_offset 0xc8 backing_file_size 0x17 cluster_bits 16 size 67108864 @@ -92,8 +92,8 @@ data 'host_device' Header extension: magic 0x6803f857 -length 0 -data '' +length 48 +data Header extension: magic 0x12345678 @@ -155,8 +155,8 @@ header_length 104 Header extension: magic 0x6803f857 -length 0 -data '' +length 48 +data Header extension: magic 0x12345678 @@ -169,7 +169,7 @@ No errors were found on the image. magic 0x514649fb version 3 -backing_file_offset 0xb8 +backing_file_offset 0xe8 backing_file_size 0x17 cluster_bits 16 size 67108864 @@ -193,8 +193,8 @@ data 'host_device' Header extension: magic 0x6803f857 -length 0 -data '' +length 48 +data Header extension: magic 0x12345678 diff --git a/tests/qemu-iotests/036.out b/tests/qemu-iotests/036.out index 6953e37..ca0fda1 100644 --- a/tests/qemu-iotests/036.out +++ b/tests/qemu-iotests/036.out @@ -46,7 +46,7 @@ header_length 104 Header extension: magic 0x6803f857 -length 0 -data '' +length 48 +data *** done -- 2.7.4