From 1aa16aaa360e6d5aa0bc32f0c9942ba2e90a5f28 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 23 Jun 2010 14:52:20 -0300 Subject: [PATCH 08/11] block: Add bdrv_(p)write_sync RH-Author: Kevin Wolf Message-id: <1277304741-19012-2-git-send-email-kwolf@redhat.com> Patchwork-id: 10132 O-Subject: [RHEL-6 qemu-kvm PATCH 1/2] block: Add bdrv_(p)write_sync Bugzilla: 607200 RH-Acked-by: Amit Shah RH-Acked-by: Jes Sorensen RH-Acked-by: Christoph Hellwig Bugzilla: 607200 Add new functions that write and flush the written data to disk immediately. This is what needs to be used for image format metadata to maintain integrity for cache=... modes that don't use O_DSYNC. (Actually, we only need barriers, and therefore the functions are defined as such, but flushes is what is implemented in this patch - we can try to change that later) Signed-off-by: Kevin Wolf (cherry picked from commit f08145fe16470aca09304099888f68cfbc5d1de7) --- block.c | 37 +++++++++++++++++++++++++++++++++++++ block.h | 4 ++++ 2 files changed, 41 insertions(+), 0 deletions(-) Signed-off-by: Eduardo Habkost --- block.c | 37 +++++++++++++++++++++++++++++++++++++ block.h | 4 ++++ 2 files changed, 41 insertions(+), 0 deletions(-) diff --git a/block.c b/block.c index 0aa3ce7..976145b 100644 --- a/block.c +++ b/block.c @@ -951,6 +951,43 @@ int bdrv_pwrite(BlockDriverState *bs, int64_t offset, return count1; } +/* + * Writes to the file and ensures that no writes are reordered across this + * request (acts as a barrier) + * + * Returns 0 on success, -errno in error cases. + */ +int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset, + const void *buf, int count) +{ + int ret; + + ret = bdrv_pwrite(bs, offset, buf, count); + if (ret < 0) { + return ret; + } + + /* No flush needed for cache=writethrough, it uses O_DSYNC */ + if ((bs->open_flags & BDRV_O_CACHE_MASK) != 0) { + bdrv_flush(bs); + } + + return 0; +} + +/* + * Writes to the file and ensures that no writes are reordered across this + * request (acts as a barrier) + * + * Returns 0 on success, -errno in error cases. + */ +int bdrv_write_sync(BlockDriverState *bs, int64_t sector_num, + const uint8_t *buf, int nb_sectors) +{ + return bdrv_pwrite_sync(bs, BDRV_SECTOR_SIZE * sector_num, + buf, BDRV_SECTOR_SIZE * nb_sectors); +} + /** * Truncate file to 'offset' bytes (needed only for file protocols) */ diff --git a/block.h b/block.h index f8bd98a..a394e2a 100644 --- a/block.h +++ b/block.h @@ -78,6 +78,10 @@ int bdrv_pread(BlockDriverState *bs, int64_t offset, void *buf, int count); int bdrv_pwrite(BlockDriverState *bs, int64_t offset, const void *buf, int count); +int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset, + const void *buf, int count); +int bdrv_write_sync(BlockDriverState *bs, int64_t sector_num, + const uint8_t *buf, int nb_sectors); int bdrv_truncate(BlockDriverState *bs, int64_t offset); int64_t bdrv_getlength(BlockDriverState *bs); void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr); -- 1.7.0.3