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[PULL 26/26] scsi-generic: pass max_segments via max_iov field in BlockL
From: |
Paolo Bonzini |
Subject: |
[PULL 26/26] scsi-generic: pass max_segments via max_iov field in BlockLimits |
Date: |
Thu, 20 May 2021 10:22:57 +0200 |
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 10b71d9a13..59c889d5a7 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1228,8 +1228,7 @@ 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
- [PULL 18/26] KVM: Disable manual dirty log when dirty ring enabled, (continued)
- [PULL 18/26] KVM: Disable manual dirty log when dirty ring enabled, Paolo Bonzini, 2021/05/20
- [PULL 06/26] meson: bump submodule to 0.57.2, Paolo Bonzini, 2021/05/20
- [PULL 22/26] remove qemu-options* from root directory, Paolo Bonzini, 2021/05/20
- [PULL 16/26] KVM: Cache kvm slot dirty bitmap size, Paolo Bonzini, 2021/05/20
- [PULL 25/26] qemu-config: load modules when instantiating option groups, Paolo Bonzini, 2021/05/20
- [PULL 10/26] memory: Introduce log_sync_global() to memory listener, Paolo Bonzini, 2021/05/20
- [PULL 11/26] KVM: Use a big lock to replace per-kml slots_lock, Paolo Bonzini, 2021/05/20
- [PULL 17/26] KVM: Add dirty-ring-size property, Paolo Bonzini, 2021/05/20
- [PULL 13/26] KVM: Provide helper to get kvm dirty log, Paolo Bonzini, 2021/05/20
- [PULL 23/26] replication: move include out of root directory, Paolo Bonzini, 2021/05/20
- [PULL 26/26] scsi-generic: pass max_segments via max_iov field in BlockLimits,
Paolo Bonzini <=
- [PULL 24/26] vl: allow not specifying size in -m when using -M memory-backend, Paolo Bonzini, 2021/05/20
- Re: [PULL 00/26] Misc patches for 2021-05-20, no-reply, 2021/05/20
- Re: [PULL 00/26] Misc patches for 2021-05-20, Peter Maydell, 2021/05/20