iSER uses the DMA mapping api to map the page holding the
SCSI command data to the HCA DMA address space. When the
command data is not aligned for RDMA, the data is copied
to/from an allocated buffer which in turn is used for
executing this command. The pages associated with the
command must be unmapped before being touched.
Signed-off-by: Erez Zilber <erezz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Fast Memory Registration (fmr) is used to register for rdma an sg whose
elements are not linearly sequential after dma mapping.
The IB verbs layer provides an "all dma memory MR (memory region)" which
can be used for RDMA-ing a dma linearly sequential buffer.
Change the code to use the dma mr instead of doing fmr when dma mapping
produces a single dma entry sg.
Signed-off-by: Erez Zilber <erezz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
fix and add some debug prints related to iser
handling of memory for rdma.
Signed-off-by: Erez Zilber <erezz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
As iser is able to use at most one rdma operation for the
execution of a scsi command, and registration of the sg
associated with scsi command has its restrictions, the code
checks if an sg is "aligned for rdma".
Alignment for rdma is measured in "fmr page" units whose
possible resolutions are different between HCAs and can be
smaller, equal or bigger to the system page size.
When the system page size is bigger than 4KB (eg the default
with ia64 kernels) there a bigger chance that an sg would be
aligned for rdma if the fmr page size is 4KB.
Change the code to create FMR whose pages are of size 4KB
and to take that into account when processing the sg.
Signed-off-by: Erez Zilber <erezz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
dma mapping may include a "compaction" of the sg associated with scsi command.
Hence, the size of the maximal prefix of the SG which is aligned for rdma must be
compared against the length of the dma mapped sg (mem->dma_nents) and not against
the size of it before it was mapped (mem->size).
Signed-off-by: Erez Zilber <erezz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This file contains the processing carried over an SG list associated with
a SCSI command such that it can be registered with the IB verbs. The
registration produces a network virtual address (VA) and a remote access
key (RKEY or STAG in iSER spec notation) which are used by the target for
its RDMA operation.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
