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cc07162953
Linux limits the size of iovecs to 1024 (UIO_MAXIOV in the kernel
sources, IOV_MAX in POSIX). Because of this, on some host adapters
requests with many iovecs are rejected with -EINVAL by the
io_submit() or readv()/writev() system calls.
In fact, the same limit applies to SG_IO as well. To fix both the
EINVAL and the possible performance issues from using fewer iovecs
than allowed by Linux (some HBAs have max_segments as low as 128),
introduce a separate entry in BlockLimits to hold the max_segments
value from sysfs. This new limit is used only for SG_IO and clamped
to bs->bl.max_iov anyway, just like max_hw_transfer is clamped to
bs->bl.max_transfer.
Reported-by: Halil Pasic <pasic@linux.ibm.com>
Cc: Hanna Reitz <hreitz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-block@nongnu.org
Cc: qemu-stable@nongnu.org
Fixes:
|
||
|---|---|---|
| .. | ||
| emulation.c | ||
| esp-pci.c | ||
| esp.c | ||
| Kconfig | ||
| lsi53c895a.c | ||
| megasas.c | ||
| meson.build | ||
| mfi.h | ||
| mpi.h | ||
| mptconfig.c | ||
| mptendian.c | ||
| mptsas.c | ||
| mptsas.h | ||
| scsi-bus.c | ||
| scsi-disk.c | ||
| scsi-generic.c | ||
| spapr_vscsi.c | ||
| srp.h | ||
| trace-events | ||
| trace.h | ||
| vhost-scsi-common.c | ||
| vhost-scsi.c | ||
| vhost-user-scsi.c | ||
| viosrp.h | ||
| virtio-scsi-dataplane.c | ||
| virtio-scsi.c | ||
| vmw_pvscsi.c | ||
| vmw_pvscsi.h | ||