From: Peter Lieven <pl@kamp.de>
To: qemu-devel@nongnu.org
Cc: kwolf@redhat.com, ronniesahlberg@gmail.com,
Peter Lieven <pl@kamp.de>,
stefanha@redhat.com, anthony@codemonkey.ws, pbonzini@redhat.com
Subject: [Qemu-devel] [PATCHv6] block/get_block_status: avoid redundant callouts on raw devices
Date: Tue, 8 Oct 2013 14:43:14 +0200 [thread overview]
Message-ID: <1381236194-18953-1-git-send-email-pl@kamp.de> (raw)
if a raw device like an iscsi target or host device is used
the current implementation makes a second call out to get
the block status of bs->file.
Signed-off-by: Peter Lieven <pl@kamp.de>
---
v6: made the result of raw_co_get_block_status valid by
adding BDRV_BLOCK_DATA and setting *pnum to nb_sectors
and calling bdrv_get_block_status on bs->file with
the offset and *pnum returned in the first callout.
v5: add a generic get_lba_status function in the raw driver which
adds the BDRV_BLOCK_RAW flag. bdrv_co_get_block_status will
handle the callout to bs->file then.
v4: use a flag to detect the raw driver instead of the strncmp
hack
block.c | 6 ++++++
block/raw_bsd.c | 4 +++-
include/block/block.h | 4 ++++
3 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/block.c b/block.c
index 93e113a..826eff0 100644
--- a/block.c
+++ b/block.c
@@ -3147,6 +3147,12 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
return ret;
}
+ if (ret & BDRV_BLOCK_RAW) {
+ assert(ret & BDRV_BLOCK_OFFSET_VALID);
+ return bdrv_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
+ *pnum, pnum);
+ }
+
if (!(ret & BDRV_BLOCK_DATA)) {
if (bdrv_has_zero_init(bs)) {
ret |= BDRV_BLOCK_ZERO;
diff --git a/block/raw_bsd.c b/block/raw_bsd.c
index d4ace60..d61906b 100644
--- a/block/raw_bsd.c
+++ b/block/raw_bsd.c
@@ -62,7 +62,9 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, int *pnum)
{
- return bdrv_get_block_status(bs->file, sector_num, nb_sectors, pnum);
+ *pnum = nb_sectors;
+ return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID | BDRV_BLOCK_DATA |
+ (sector_num << BDRV_SECTOR_BITS);
}
static int coroutine_fn raw_co_write_zeroes(BlockDriverState *bs,
diff --git a/include/block/block.h b/include/block/block.h
index f808550..003699e 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -84,6 +84,9 @@ typedef struct BlockDevOps {
/* BDRV_BLOCK_DATA: data is read from bs->file or another file
* BDRV_BLOCK_ZERO: sectors read as zero
* BDRV_BLOCK_OFFSET_VALID: sector stored in bs->file as raw data
+ * BDRV_BLOCK_RAW: used internally to indicate that the request
+ * was answered by the raw driver and that one
+ * should look in bs->file directly.
*
* If BDRV_BLOCK_OFFSET_VALID is set, bits 9-62 represent the offset in
* bs->file where sector data can be read from as raw data.
@@ -105,6 +108,7 @@ typedef struct BlockDevOps {
#define BDRV_BLOCK_DATA 1
#define BDRV_BLOCK_ZERO 2
#define BDRV_BLOCK_OFFSET_VALID 4
+#define BDRV_BLOCK_RAW 8
#define BDRV_BLOCK_OFFSET_MASK BDRV_SECTOR_MASK
typedef enum {
--
1.7.9.5
next reply other threads:[~2013-10-08 12:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-08 12:43 Peter Lieven [this message]
2013-10-08 18:11 ` [Qemu-devel] [PATCHv6] block/get_block_status: avoid redundant callouts on raw devices Eric Blake
2013-10-09 9:57 ` Kevin Wolf
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