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authorKevin Wolf <kwolf@redhat.com>2010-06-16 16:38:15 +0200
committerDoug Goldstein <cardoe@gentoo.org>2010-07-20 17:41:09 -0500
commit193ad843cd3579eea4705493d1878360fa624428 (patch)
tree793c656dce66dc9a75a453ed22f5a513b331f65f
parentqcow2: Restore L1 entry on l2_allocate failure (diff)
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block: Add bdrv_(p)write_sync
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 <kwolf@redhat.com> (cherry picked from commit f08145fe16470aca09304099888f68cfbc5d1de7)
-rw-r--r--block.c39
-rw-r--r--block.h4
-rw-r--r--block_int.h1
3 files changed, 44 insertions, 0 deletions
diff --git a/block.c b/block.c
index 298414c92..e3b3a5504 100644
--- a/block.c
+++ b/block.c
@@ -452,6 +452,8 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags,
(flags & (BDRV_O_CACHE_MASK|BDRV_O_NATIVE_AIO));
else
open_flags = flags & ~(BDRV_O_FILE | BDRV_O_SNAPSHOT);
+
+ bs->open_flags = open_flags;
if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv))
ret = -ENOTSUP;
else
@@ -779,6 +781,43 @@ 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 fa51ddf15..762d88a5c 100644
--- a/block.h
+++ b/block.h
@@ -77,6 +77,10 @@ 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);
diff --git a/block_int.h b/block_int.h
index 9a3b2e09d..631e8c56d 100644
--- a/block_int.h
+++ b/block_int.h
@@ -127,6 +127,7 @@ struct BlockDriverState {
int64_t total_sectors; /* if we are reading a disk image, give its
size in sectors */
int read_only; /* if true, the media is read only */
+ int open_flags; /* flags used to open the file, re-used for re-open */
int removable; /* if true, the media can be removed */
int locked; /* if true, the media cannot temporarily be ejected */
int encrypted; /* if true, the media is encrypted */