From: Paolo Bonzini <pbonzini@redhat.com>
To: qemu-devel@nongnu.org
Cc: kwolf@redhat.com, qemu-block@nongnu.org
Subject: [PATCH v3 2/7] scsi-generic: pass max_segments via max_iov field in BlockLimits
Date: Thu, 3 Jun 2021 15:37:17 +0200 [thread overview]
Message-ID: <20210603133722.218465-3-pbonzini@redhat.com> (raw)
In-Reply-To: <20210603133722.218465-1-pbonzini@redhat.com>
I/O to a disk via read/write is not limited by the number of segments allowed
by the host adapter; the kernel can split requests if needed, and the limit
imposed by the host adapter can be very low (256k or so) to avoid that SG_IO
returns EINVAL if memory is heavily fragmented.
Since this value is only interesting for SG_IO-based I/O, do not include
it in the max_transfer and only take it into account when patching the
block limits VPD page in the scsi-generic device.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
block/file-posix.c | 3 +--
hw/scsi/scsi-generic.c | 6 ++++--
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/block/file-posix.c b/block/file-posix.c
index 58db526cc2..e3241a0dd3 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1239,8 +1239,7 @@ static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
ret = sg_get_max_segments(s->fd);
if (ret > 0) {
- bs->bl.max_transfer = MIN(bs->bl.max_transfer,
- ret * qemu_real_host_page_size);
+ bs->bl.max_iov = ret;
}
}
diff --git a/hw/scsi/scsi-generic.c b/hw/scsi/scsi-generic.c
index 98c30c5d5c..82e1e2ee79 100644
--- a/hw/scsi/scsi-generic.c
+++ b/hw/scsi/scsi-generic.c
@@ -179,10 +179,12 @@ static void scsi_handle_inquiry_reply(SCSIGenericReq *r, SCSIDevice *s)
(r->req.cmd.buf[1] & 0x01)) {
page = r->req.cmd.buf[2];
if (page == 0xb0) {
- uint32_t max_transfer =
- blk_get_max_transfer(s->conf.blk) / s->blocksize;
+ uint32_t max_transfer = blk_get_max_transfer(s->conf.blk);
+ uint32_t max_iov = blk_get_max_iov(s->conf.blk);
assert(max_transfer);
+ max_transfer = MIN_NON_ZERO(max_transfer, max_iov * qemu_real_host_page_size)
+ / s->blocksize;
stl_be_p(&r->buf[8], max_transfer);
/* Also take care of the opt xfer len. */
stl_be_p(&r->buf[12],
--
2.31.1
next prev parent reply other threads:[~2021-06-03 13:38 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-03 13:37 [PATCH v3 0/7] block: file-posix queue Paolo Bonzini
2021-06-03 13:37 ` [PATCH v3 1/7] file-posix: fix max_iov for /dev/sg devices Paolo Bonzini
2021-06-07 5:39 ` Vladimir Sementsov-Ogievskiy
2021-06-07 6:16 ` Vladimir Sementsov-Ogievskiy
2021-06-07 7:23 ` Vladimir Sementsov-Ogievskiy
2021-06-15 15:58 ` Max Reitz
2021-06-03 13:37 ` Paolo Bonzini [this message]
2021-06-15 16:06 ` [PATCH v3 2/7] scsi-generic: pass max_segments via max_iov field in BlockLimits Max Reitz
2021-06-15 16:20 ` Max Reitz
2021-06-15 17:41 ` Paolo Bonzini
2021-06-03 13:37 ` [PATCH v3 3/7] block: add max_hw_transfer to BlockLimits Paolo Bonzini
2021-06-03 17:33 ` Eric Blake
2021-06-04 7:21 ` Paolo Bonzini
2021-06-15 16:18 ` Max Reitz
2021-06-16 13:18 ` Paolo Bonzini
2021-06-16 13:46 ` Max Reitz
2021-06-17 9:59 ` Paolo Bonzini
2021-06-03 13:37 ` [PATCH v3 4/7] file-posix: try BLKSECTGET on block devices too, do not round to power of 2 Paolo Bonzini
2021-06-15 16:32 ` Max Reitz
2021-06-03 13:37 ` [PATCH v3 5/7] block: feature detection for host block support Paolo Bonzini
2021-06-15 16:40 ` Max Reitz
2021-06-03 13:37 ` [PATCH v3 6/7] block: check for sys/disk.h Paolo Bonzini
2021-06-15 16:42 ` Max Reitz
2021-06-03 13:37 ` [PATCH v3 7/7] block: detect DKIOCGETBLOCKCOUNT/SIZE before use Paolo Bonzini
2021-06-15 16:50 ` Max Reitz
2021-06-15 16:57 ` Daniel P. Berrangé
2021-06-07 13:52 ` [PATCH v3 0/7] block: file-posix queue Maxim Levitsky
2021-06-10 13:40 ` Paolo Bonzini
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