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[PATCH v4 2/2] file-posix: add sg_get_max_segments that actually works w
From: |
Tom Yan |
Subject: |
[PATCH v4 2/2] file-posix: add sg_get_max_segments that actually works with sg |
Date: |
Fri, 4 Sep 2020 10:09:07 +0800 |
sg devices have different major/minor than their corresponding
block devices. Using sysfs to get max segments never really worked
for them.
Fortunately the sg driver provides an ioctl to get sg_tablesize,
which is apparently equivalent to max segments.
Signed-off-by: Tom Yan <tom.ty89@gmail.com>
---
block/file-posix.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/block/file-posix.c b/block/file-posix.c
index 411a23cf99..9e37594145 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1178,6 +1178,21 @@ static int sg_get_max_transfer_length(int fd)
#endif
}
+static int sg_get_max_segments(int fd)
+{
+#ifdef SG_GET_SG_TABLESIZE
+ long max_segments = 0;
+
+ if (ioctl(fd, SG_GET_SG_TABLESIZE, &max_segments) == 0) {
+ return max_segments;
+ } else {
+ return -errno;
+ }
+#else
+ return -ENOSYS;
+#endif
+}
+
static int get_max_transfer_length(int fd)
{
#if defined(BLKSECTGET) && defined(BLKSSZGET)
@@ -1268,7 +1283,7 @@ static void hdev_refresh_limits(BlockDriverState *bs,
Error **errp)
bs->bl.max_transfer = pow2floor(ret);
}
- ret = get_max_segments(s->fd);
+ ret = bs->sg ? sg_get_max_segments(s->fd) : get_max_segments(s->fd);
if (ret > 0) {
bs->bl.max_transfer = MIN_NON_ZERO(bs->bl.max_transfer,
ret * qemu_real_host_page_size);
--
2.28.0
- [PATCH v4 1/2] file-posix: split hdev_refresh_limits from raw_refresh_limits, Tom Yan, 2020/09/03
- [PATCH v4 2/2] file-posix: add sg_get_max_segments that actually works with sg,
Tom Yan <=
- Re: [PATCH v4 2/2] file-posix: add sg_get_max_segments that actually works with sg, Tom Yan, 2020/09/06
- Re: [PATCH v4 2/2] file-posix: add sg_get_max_segments that actually works with sg, Tom Yan, 2020/09/06
- Re: [PATCH v4 2/2] file-posix: add sg_get_max_segments that actually works with sg, Maxim Levitsky, 2020/09/06
- Re: [PATCH v4 2/2] file-posix: add sg_get_max_segments that actually works with sg, Tom Yan, 2020/09/06
- Re: [PATCH v4 2/2] file-posix: add sg_get_max_segments that actually works with sg, Maxim Levitsky, 2020/09/06
- RE: [PATCH v4 2/2] file-posix: add sg_get_max_segments that actually works with sg, Dmitry Fomichev, 2020/09/06
- Re: [PATCH v4 2/2] file-posix: add sg_get_max_segments that actually works with sg, Tom Yan, 2020/09/06