since linux 4.9, block device supports fallocate. kernel issues
block device zereout request and invalidates page cache. So
ioctl(fd, FALLOC_FL_ZERO_RANGE...) is safer than ioctl(fd,
BLKZEROOUT...). try to call do_fallocate, if failing, fallback.
use new field "has_fallocate_zero_range" with default value as
true. if do_fallocate returns -ENOTSUP, it will be set false.
Signed-off-by: zhenwei.pi <zhenwei...@youruncloud.com>
---
block/file-posix.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
diff --git a/block/file-posix.c b/block/file-posix.c
index d7fb772..842e940 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -159,8 +159,9 @@ typedef struct BDRVRawState {
bool discard_zeroes:1;
bool use_linux_aio:1;
bool page_cache_inconsistent:1;
- bool has_fallocate;
- bool needs_alignment;
+ bool has_fallocate:1;
+ bool has_fallocate_zero_range:1;
+ bool needs_alignment:1;
PRManager *pr_mgr;
} BDRVRawState;
@@ -549,6 +550,7 @@ static int raw_open_common(BlockDriverState *bs, QDict
*options,
s->has_discard = true;
s->has_write_zeroes = true;
+ s->has_fallocate_zero_range = true;
if ((bs->open_flags & BDRV_O_NOCACHE) != 0) {
s->needs_alignment = true;
}
@@ -1365,10 +1367,6 @@ static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData
*aiocb)
int64_t len;
#endif
- if (aiocb->aio_type & QEMU_AIO_BLKDEV) {
- return handle_aiocb_write_zeroes_block(aiocb);
- }
-
#ifdef CONFIG_XFS
if (s->is_xfs) {
return xfs_write_zeroes(s, aiocb->aio_offset, aiocb->aio_nbytes);
@@ -1376,16 +1374,25 @@ static ssize_t
handle_aiocb_write_zeroes(RawPosixAIOData *aiocb)
#endif
#ifdef CONFIG_FALLOCATE_ZERO_RANGE
- if (s->has_write_zeroes) {
+ /* since linux 4.9, block device supports fallocate. kernel issues
+ * block device zereout request and invalidates page cache. So
+ * ioctl(fd, FALLOC_FL_ZERO_RANGE...) is safer than ioctl(fd,
+ * BLKZEROOUT...). try to call do_fallocate, if failing, fallback.
+ */
+ if (s->has_fallocate_zero_range) {
int ret = do_fallocate(s->fd, FALLOC_FL_ZERO_RANGE,
aiocb->aio_offset, aiocb->aio_nbytes);
- if (ret == 0 || ret != -ENOTSUP) {
+ if (ret == 0) {
return ret;
- }
- s->has_write_zeroes = false;
+ } else if (ret == -ENOTSUP)
+ s->has_fallocate_zero_range = false;
}
#endif
+ if (aiocb->aio_type & QEMU_AIO_BLKDEV) {
+ return handle_aiocb_write_zeroes_block(aiocb);
+ }
+
#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
if (s->has_discard && s->has_fallocate) {
int ret = do_fallocate(s->fd,
--
2.7.4
