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[Qemu-devel] [PULL 06/38] block/parallels: provide _co_readv routine for
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL 06/38] block/parallels: provide _co_readv routine for parallels format driver |
Date: |
Fri, 22 May 2015 10:01:38 +0100 |
From: "Denis V. Lunev" <address@hidden>
Main approach is taken from qcow2_co_readv.
The patch drops coroutine lock for the duration of IO operation and
peforms normal scatter-gather IO using standard QEMU backend.
The patch also adds comment about locking considerations in the driver.
Signed-off-by: Denis V. Lunev <address@hidden>
Reviewed-by: Roman Kagan <address@hidden>
Signed-off-by: Roman Kagan <address@hidden>
Message-id: address@hidden
CC: Roman Kagan <address@hidden>
CC: Kevin Wolf <address@hidden>
CC: Stefan Hajnoczi <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block/parallels.c | 54 +++++++++++++++++++++++++++++++++---------------------
1 file changed, 33 insertions(+), 21 deletions(-)
diff --git a/block/parallels.c b/block/parallels.c
index b469984..f3ffece 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -49,6 +49,10 @@ typedef struct ParallelsHeader {
} QEMU_PACKED ParallelsHeader;
typedef struct BDRVParallelsState {
+ /** Locking is conservative, the lock protects
+ * - image file extending (truncate, fallocate)
+ * - any access to block allocation table
+ */
CoMutex lock;
uint32_t *catalog_bitmap;
@@ -186,37 +190,45 @@ static int64_t coroutine_fn
parallels_co_get_block_status(BlockDriverState *bs,
BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
}
-static int parallels_read(BlockDriverState *bs, int64_t sector_num,
- uint8_t *buf, int nb_sectors)
+static coroutine_fn int parallels_co_readv(BlockDriverState *bs,
+ int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
BDRVParallelsState *s = bs->opaque;
+ uint64_t bytes_done = 0;
+ QEMUIOVector hd_qiov;
+ int ret = 0;
+
+ qemu_iovec_init(&hd_qiov, qiov->niov);
while (nb_sectors > 0) {
- int64_t position = seek_to_sector(s, sector_num);
- int n = cluster_remainder(s, sector_num, nb_sectors);
- if (position >= 0) {
- int ret = bdrv_read(bs->file, position, buf, n);
+ int64_t position;
+ int n, nbytes;
+
+ qemu_co_mutex_lock(&s->lock);
+ position = seek_to_sector(s, sector_num);
+ qemu_co_mutex_unlock(&s->lock);
+
+ n = cluster_remainder(s, sector_num, nb_sectors);
+ nbytes = n << BDRV_SECTOR_BITS;
+
+ if (position < 0) {
+ qemu_iovec_memset(qiov, bytes_done, 0, nbytes);
+ } else {
+ qemu_iovec_reset(&hd_qiov);
+ qemu_iovec_concat(&hd_qiov, qiov, bytes_done, nbytes);
+
+ ret = bdrv_co_readv(bs->file, position, n, &hd_qiov);
if (ret < 0) {
- return ret;
+ break;
}
- } else {
- memset(buf, 0, n << BDRV_SECTOR_BITS);
}
+
nb_sectors -= n;
sector_num += n;
- buf += n << BDRV_SECTOR_BITS;
+ bytes_done += nbytes;
}
- return 0;
-}
-static coroutine_fn int parallels_co_read(BlockDriverState *bs, int64_t
sector_num,
- uint8_t *buf, int nb_sectors)
-{
- int ret;
- BDRVParallelsState *s = bs->opaque;
- qemu_co_mutex_lock(&s->lock);
- ret = parallels_read(bs, sector_num, buf, nb_sectors);
- qemu_co_mutex_unlock(&s->lock);
+ qemu_iovec_destroy(&hd_qiov);
return ret;
}
@@ -231,9 +243,9 @@ static BlockDriver bdrv_parallels = {
.instance_size = sizeof(BDRVParallelsState),
.bdrv_probe = parallels_probe,
.bdrv_open = parallels_open,
- .bdrv_read = parallels_co_read,
.bdrv_close = parallels_close,
.bdrv_co_get_block_status = parallels_co_get_block_status,
+ .bdrv_co_readv = parallels_co_readv,
};
static void bdrv_parallels_init(void)
--
2.1.0
- [Qemu-devel] [PULL 00/38] Block patches, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 02/38] block/parallels: rename parallels_header to ParallelsHeader, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 03/38] block/parallels: switch to bdrv_read, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 01/38] iotests, parallels: quote TEST_IMG in 076 test to be path-safe, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 05/38] block/parallels: add get_block_status, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 07/38] block/parallels: replace magic constants 4, 64 with proper sizeofs, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 08/38] block/parallels: mark parallels format driver as zero inited, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 06/38] block/parallels: provide _co_readv routine for parallels format driver,
Stefan Hajnoczi <=
- [Qemu-devel] [PULL 04/38] block/parallels: read up to cluster end in one go, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 09/38] block/parallels: _co_writev callback for Parallels format, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 11/38] block/parallels: support parallels image creation, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 10/38] iotests, parallels: test for write into Parallels image, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 12/38] iotests, parallels: test for newly created parallels image via qemu-img, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 13/38] parallels: change copyright information in the image header, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 14/38] block/parallels: rename catalog_ names to bat_, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 18/38] block/parallels: move parallels_open/probe to the very end of the file, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 16/38] block/parallels: keep BAT bitmap data in little endian in memory, Stefan Hajnoczi, 2015/05/22
- [Qemu-devel] [PULL 15/38] block/parallels: create bat2sect helper, Stefan Hajnoczi, 2015/05/22