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[Qemu-devel] [RFC PATCH 1/3] block: add bdrv_get_alignment, use it
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [RFC PATCH 1/3] block: add bdrv_get_alignment, use it |
Date: |
Wed, 23 Nov 2011 17:51:25 +0100 |
We cannot simply use the guest logical block size on the host; we need
to ask the protocol driver about the minimum required alignment.
Signed-off-by: Paolo Bonzini <address@hidden>
---
block.c | 26 ++++++++++++++++++++++++--
block.h | 1 +
block/raw-posix.c | 3 ++-
block_int.h | 1 +
4 files changed, 28 insertions(+), 3 deletions(-)
diff --git a/block.c b/block.c
index d015887..aba92ad 100644
--- a/block.c
+++ b/block.c
@@ -476,7 +476,7 @@ static int bdrv_open_common(BlockDriverState *bs, const
char *filename,
bs->sg = 0;
bs->open_flags = flags;
bs->growable = 0;
- bs->buffer_alignment = 512;
+ bs->buffer_alignment = 0;
pstrcpy(bs->filename, sizeof(bs->filename), filename);
bs->backing_file[0] = '\0';
@@ -1361,6 +1361,27 @@ int64_t bdrv_get_allocated_file_size(BlockDriverState
*bs)
}
/**
+ * Required buffer alignment for a file or device. Return < 0 if error or
unknown.
+ */
+int bdrv_get_alignment(BlockDriverState *bs)
+{
+ BlockDriver *drv = bs->drv;
+ if (!drv) {
+ return -ENOMEDIUM;
+ }
+ if (bs->buffer_alignment == 0) {
+ if (drv->bdrv_get_alignment) {
+ bs->buffer_alignment = drv->bdrv_get_alignment(bs);
+ } else if (bs->file) {
+ bs->buffer_alignment = bdrv_get_alignment(bs->file);
+ } else {
+ bs->buffer_alignment = BDRV_SECTOR_SIZE;
+ }
+ }
+ return bs->buffer_alignment;
+}
+
+/**
* Length of a file in bytes. Return < 0 if error or unknown.
*/
int64_t bdrv_getlength(BlockDriverState *bs)
@@ -3025,7 +3046,8 @@ void bdrv_set_buffer_alignment(BlockDriverState *bs, int
align)
void *qemu_blockalign(BlockDriverState *bs, size_t size)
{
- return qemu_memalign((bs && bs->buffer_alignment) ? bs->buffer_alignment :
512, size);
+ int alignment = bs ? bdrv_get_alignment(bs) : 512;
+ return qemu_memalign(alignment, size);
}
void bdrv_set_dirty_tracking(BlockDriverState *bs, int enable)
diff --git a/block.h b/block.h
index a826059..5fa632c 100644
--- a/block.h
+++ b/block.h
@@ -294,6 +294,7 @@ int bdrv_img_create(const char *filename, const char *fmt,
const char *base_filename, const char *base_fmt,
char *options, uint64_t img_size, int flags);
+int bdrv_get_alignment(BlockDriverState *bs);
void bdrv_set_buffer_alignment(BlockDriverState *bs, int align);
void *qemu_blockalign(BlockDriverState *bs, size_t size);
diff --git a/block/raw-posix.c b/block/raw-posix.c
index a3de373..3482fc8 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -301,10 +301,11 @@ static int raw_open(BlockDriverState *bs, const char
*filename, int flags)
*/
static int qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov)
{
+ int alignment = bdrv_get_alignment(bs);
int i;
for (i = 0; i < qiov->niov; i++) {
- if ((uintptr_t) qiov->iov[i].iov_base % bs->buffer_alignment) {
+ if ((uintptr_t) qiov->iov[i].iov_base % alignment) {
return 0;
}
}
diff --git a/block_int.h b/block_int.h
index 77c0187..6caf063 100644
--- a/block_int.h
+++ b/block_int.h
@@ -113,6 +113,7 @@ struct BlockDriver {
const char *protocol_name;
int (*bdrv_truncate)(BlockDriverState *bs, int64_t offset);
+ int (*bdrv_get_alignment)(BlockDriverState *bs);
int64_t (*bdrv_getlength)(BlockDriverState *bs);
int64_t (*bdrv_get_allocated_file_size)(BlockDriverState *bs);
int (*bdrv_write_compressed)(BlockDriverState *bs, int64_t sector_num,
--
1.7.7.1