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authorPaolo Bonzini <pbonzini@redhat.com>2012-10-18 16:49:18 +0200
committerKevin Wolf <kwolf@redhat.com>2012-10-24 10:26:19 +0200
commit1755da16e32c15b22a521e8a38539e4b5cf367f3 (patch)
tree5990c65a246cb189f0f44b2a7452e409fa646f56 /block.c
parent9156df12a4f3b3db63d1b292d081d814f02e311a (diff)
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block: introduce new dirty bitmap functionality
Assert that write_compressed is never used with the dirty bitmap. Setting the bits early is wrong, because a coroutine might concurrently examine them and copy incomplete data from the source. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block.c')
-rw-r--r--block.c51
1 files changed, 45 insertions, 6 deletions
diff --git a/block.c b/block.c
index e06d78f..2c3d3da 100644
--- a/block.c
+++ b/block.c
@@ -2391,7 +2391,7 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
}
if (bs->dirty_bitmap) {
- set_dirty_bitmap(bs, sector_num, nb_sectors, 1);
+ bdrv_set_dirty(bs, sector_num, nb_sectors);
}
if (bs->wr_highest_sector < sector_num + nb_sectors - 1) {
@@ -2960,9 +2960,7 @@ int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num,
if (bdrv_check_request(bs, sector_num, nb_sectors))
return -EIO;
- if (bs->dirty_bitmap) {
- set_dirty_bitmap(bs, sector_num, nb_sectors, 1);
- }
+ assert(!bs->dirty_bitmap);
return drv->bdrv_write_compressed(bs, sector_num, buf, nb_sectors);
}
@@ -4269,13 +4267,54 @@ int bdrv_get_dirty(BlockDriverState *bs, int64_t sector)
if (bs->dirty_bitmap &&
(sector << BDRV_SECTOR_BITS) < bdrv_getlength(bs)) {
- return !!(bs->dirty_bitmap[chunk / (sizeof(unsigned long) * 8)] &
- (1UL << (chunk % (sizeof(unsigned long) * 8))));
+ return !!(bs->dirty_bitmap[chunk / BITS_PER_LONG] &
+ (1UL << (chunk % BITS_PER_LONG)));
} else {
return 0;
}
}
+int64_t bdrv_get_next_dirty(BlockDriverState *bs, int64_t sector)
+{
+ int64_t chunk;
+ int bit, elem;
+
+ /* Avoid an infinite loop. */
+ assert(bs->dirty_count > 0);
+
+ sector = (sector | (BDRV_SECTORS_PER_DIRTY_CHUNK - 1)) + 1;
+ chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
+
+ QEMU_BUILD_BUG_ON(sizeof(bs->dirty_bitmap[0]) * 8 != BITS_PER_LONG);
+ elem = chunk / BITS_PER_LONG;
+ bit = chunk % BITS_PER_LONG;
+ for (;;) {
+ if (sector >= bs->total_sectors) {
+ sector = 0;
+ bit = elem = 0;
+ }
+ if (bit == 0 && bs->dirty_bitmap[elem] == 0) {
+ sector += BDRV_SECTORS_PER_DIRTY_CHUNK * BITS_PER_LONG;
+ elem++;
+ } else {
+ if (bs->dirty_bitmap[elem] & (1UL << bit)) {
+ return sector;
+ }
+ sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
+ if (++bit == BITS_PER_LONG) {
+ bit = 0;
+ elem++;
+ }
+ }
+ }
+}
+
+void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
+ int nr_sectors)
+{
+ set_dirty_bitmap(bs, cur_sector, nr_sectors, 1);
+}
+
void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
int nr_sectors)
{