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[Qemu-devel] [PATCH 3/3] update_refcount: Write complete sectors
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 3/3] update_refcount: Write complete sectors |
Date: |
Tue, 16 Jun 2009 11:31:30 +0200 |
When updating the refcount blocks in update_refcount(), write complete sectors
instead of updating single entries.
Signed-off-by: Kevin Wolf <address@hidden>
---
block/qcow2-refcount.c | 34 ++++++++++++++++++++++++++--------
1 files changed, 26 insertions(+), 8 deletions(-)
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index b38390c..dd6e293 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -209,6 +209,27 @@ static int64_t alloc_refcount_block(BlockDriverState *bs,
int64_t cluster_index)
return refcount_block_offset;
}
+#define REFCOUNTS_PER_SECTOR (512 >> REFCOUNT_SHIFT)
+static int write_refcount_block_entries(BDRVQcowState *s,
+ int64_t refcount_block_offset, int first_index, int last_index)
+{
+ size_t size;
+
+ first_index &= ~(REFCOUNTS_PER_SECTOR - 1);
+ last_index = (last_index + REFCOUNTS_PER_SECTOR)
+ & ~(REFCOUNTS_PER_SECTOR - 1);
+
+ size = (last_index - first_index) << REFCOUNT_SHIFT;
+ if (bdrv_pwrite(s->hd,
+ refcount_block_offset + (first_index << REFCOUNT_SHIFT),
+ &s->refcount_block_cache[first_index], size) != size)
+ {
+ return -EIO;
+ }
+
+ return 0;
+}
+
/* XXX: cache several refcount block clusters ? */
static int update_refcount(BlockDriverState *bs,
int64_t offset, int64_t length,
@@ -238,10 +259,9 @@ static int update_refcount(BlockDriverState *bs,
old_table_index = table_index;
table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
if ((old_table_index >= 0) && (table_index != old_table_index)) {
- size_t size = (last_index - first_index + 1) << REFCOUNT_SHIFT;
- if (bdrv_pwrite(s->hd,
- refcount_block_offset + (first_index << REFCOUNT_SHIFT),
- &s->refcount_block_cache[first_index], size) != size)
+
+ if (write_refcount_block_entries(s, refcount_block_offset,
+ first_index, last_index) < 0)
{
return -EIO;
}
@@ -278,10 +298,8 @@ static int update_refcount(BlockDriverState *bs,
/* Write last changed block to disk */
if (refcount_block_offset != 0) {
- size_t size = (last_index - first_index + 1) << REFCOUNT_SHIFT;
- if (bdrv_pwrite(s->hd,
- refcount_block_offset + (first_index << REFCOUNT_SHIFT),
- &s->refcount_block_cache[first_index], size) != size)
+ if (write_refcount_block_entries(s, refcount_block_offset,
+ first_index, last_index) < 0)
{
return -EIO;
}
--
1.6.0.6