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| author | Paolo Bonzini <pbonzini@redhat.com> | 2021-04-14 19:51:48 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-06-25 10:54:12 +0200 |
| commit | 01ef8185b809af9d287e1a03a3f9d8ea8231118a (patch) | |
| tree | 3310b456ff028325cfe6b5e7bb286ab1c57ecc68 | |
| parent | 8ad5ab6148dca8aad297c134c09c84b0b92d45ed (diff) | |
| download | qemu-01ef8185b809af9d287e1a03a3f9d8ea8231118a.zip qemu-01ef8185b809af9d287e1a03a3f9d8ea8231118a.tar.gz qemu-01ef8185b809af9d287e1a03a3f9d8ea8231118a.tar.bz2 | |
scsi-generic: pass max_segments via max_iov field in BlockLimits
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>
Reviewed-by: Max Reitz <mreitz@redhat.com>
| -rw-r--r-- | block/file-posix.c | 3 | ||||
| -rw-r--r-- | 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 b8dc19c..6db690b 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -1237,8 +1237,7 @@ 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 40e0398..b6c4143 100644 --- a/hw/scsi/scsi-generic.c +++ b/hw/scsi/scsi-generic.c @@ -179,10 +179,12 @@ static int scsi_handle_inquiry_reply(SCSIGenericReq *r, SCSIDevice *s, int len) (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], |