The iser connection teardown flow isn't over until the underlying
Connection Manager (e.g the IB CM) delivers a disconnected or timeout
event through the RDMA-CM. When the remote (target) side isn't
reachable, e.g when some HW e.g port/hca/switch isn't functioning or
taken down administratively, the CM timeout flow is used and the event
may be generated only after relatively long time -- on the order of
tens of seconds.
The current iser code exposes this possibly long delay to higher
layers, specifically to the iscsid daemon and iscsi kernel stack. As a
result, the iscsi stack doesn't respond well: this low-level CM delay
is added to the fail-over time under HA schemes such as the one
provided by DM multipath through the multipathd(8) service.
This patch enhances the reference counting scheme on iser's IB
connections so that the disconnect flow initiated by iscsid from user
space (ep_disconnect) doesn't wait for the CM to deliver the
disconnect/timeout event. (The connection teardown isn't done from
iser's view point until the event is delivered)
The iser ib (rdma) connection object is destroyed when its reference
count reaches zero. When this happens on the RDMA-CM callback
context, extra care is taken so that the RDMA-CM does the actual
destroying of the associated ID, since doing it in the callback is
prohibited.
The reference count of iser ib connection normally reaches three,
where the <ref, deref> relations are
1. conn <init, terminate>
2. conn <bind, stop/destroy>
3. cma id <create, disconnect/error/timeout callbacks>
With this patch, multipath fail-over time is about 30 seconds, while
without this patch, multipath fail-over time is about 130 seconds.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Add handler to handle events such as port up and down. This is useful
when testing high-availability schemes such as multi-pathing.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Remove unnecessary checks for the IB connection state and for QP
overflow, as conn state changes are reported by iSER to libiscsi and
handled there. QP overflow is theoretically possible only when
unsolicited data-outs are used; anyway it's being checked and handled
by HW drivers.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Simplify and shrink the logic/code used for the send descriptors.
Changes include removing struct iser_dto (an unnecessary abstraction),
using struct iser_regd_buf only for handling SCSI commands, using
dma_sync instead of dma_map/unmap, etc.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Use a different CQ for send completions, where send completions are
polled by the interrupt-driven receive completion handler. Therefore,
interrupts aren't used for the send CQ.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Now that both the posting and reaping of receive buffers is done in
the completion path, the counter of outstanding buffers not be atomic.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Currently, the recv buffer posting logic is based on the transactional
nature of iSER which allows for posting a buffer before sending a PDU.
Change this to post only when the number of outstanding recv buffers
is below a water mark and in a batched manner, thus simplifying and
optimizing the data path. Use a pre-allocated ring of recv buffers
instead of allocating from kmem cache. A special treatment is given
to the login response buffer whose size must be 8K unlike the size of
buffers used for any other purpose which is 128 bytes.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
We will make a major change in the recv buffer posting logic, after
which the problem commit bba7ebb "avoid recv buffer exhaustion caused
by unexpected PDUs" comes to solve doesn't exist any more, so revert it.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
There is no need to cap the queue depth in the modules. We set
this in userspace and can do that there. For performance testing
with ram based targets, this is helpful since we can have very
high queue depths.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
iSCSI/iSER targets may send PDUs without a prior request from the
initiator. RFC 5046 refers to these PDUs as "unexpected". NOP-In PDUs
with itt=RESERVED and Asynchronous Message PDUs occupy this category.
The amount of active "unexpected" PDU's an iSER target may have at any
time is governed by the MaxOutstandingUnexpectedPDUs key, which is not
yet supported.
Currently when an iSER target sends an "unexpected" PDU, the
initiators recv buffer consumed by the PDU is not replaced. If over
initial_post_recv_bufs_num "unexpected" PDUs are received then the
receive queue will run out of receive work requests entirely.
This patch ensures recv buffers consumed by "unexpected" PDUs are
replaced in the next iser_post_receive_control() call.
Signed-off-by: David Disseldorp <ddiss@sgi.com>
Signed-off-by: Ken Sandars <ksandars@sgi.com>
Acked-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
* git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6: (102 commits)
[SCSI] scsi_dh: fix kconfig related build errors
[SCSI] sym53c8xx: Fix bogus sym_que_entry re-implementation of container_of
[SCSI] scsi_cmnd.h: remove double inclusion of linux/blkdev.h
[SCSI] make struct scsi_{host,target}_type static
[SCSI] fix locking in host use of blk_plug_device()
[SCSI] zfcp: Cleanup external header file
[SCSI] zfcp: Cleanup code in zfcp_erp.c
[SCSI] zfcp: zfcp_fsf cleanup.
[SCSI] zfcp: consolidate sysfs things into one file.
[SCSI] zfcp: Cleanup of code in zfcp_aux.c
[SCSI] zfcp: Cleanup of code in zfcp_scsi.c
[SCSI] zfcp: Move status accessors from zfcp to SCSI include file.
[SCSI] zfcp: Small QDIO cleanups
[SCSI] zfcp: Adapter reopen for large number of unsolicited status
[SCSI] zfcp: Fix error checking for ELS ADISC requests
[SCSI] zfcp: wait until adapter is finished with ERP during auto-port
[SCSI] ibmvfc: IBM Power Virtual Fibre Channel Adapter Client Driver
[SCSI] sg: Add target reset support
[SCSI] lib: Add support for the T10 (SCSI) Data Integrity Field CRC
[SCSI] sd: Move scsi_disk() accessor function to sd.h
...
The recv lock was defined so the iscsi layer could block
the recv path from processing IO during recovery. It
turns out iser just set a lock to that pointer which was pointless.
We now disconnect the transport connection before doing recovery
so we do not need the recv lock. For iscsi_tcp we still stop
the recv path incase older tools are being used.
This patch also has iscsi_itt_to_ctask user grab the session lock
and has the caller access the task with the lock or get a ref
to it in case the target is broken and sends a tmf success response
then sends data or a response for the command that was supposed to
be affected bty the tmf.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
This hooks iser into the iscsi endpoint code. Previously it handled the
lookup and allocation. This has been made generic so bnx2i and iser can
share it. It also allows us to pass iser the leading conn's ep, so we
know the ib_deivce being used and can set it as the scsi_host's parent.
And that allows scsi-ml to set the dma_mask based on those values.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
This handles the iscsi_cmd_task rename and renames
the iser cmd task to iser task.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Convert ib_iser to support merged tasks.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
After the stop_conn callback has returned the LLD should not
touch the scsi cmds. iscsi_tcp and libiscsi use the
conn->recv_lock and suspend_rx field to halt recv path
processing, but iser does not have any protection.
This patch modifies iser so that userspace can just
call the ep_disconnect callback, which will halt
all recv IO, before calling the stop_conn callback so
we do not have to worry about the conn->recv_lock and
suspend rx field. iser just needs to stop the send side
from accessing the ib conn.
Fixup to handle when the ep poll fails and ep disconnect
is called from Erez.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
max_cmd_len and max_conn are not really used. max_cmd_len is
always 16 and can be set by the LLD. max_conn is always one
since we do not support MCS.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Make iser_conn_release() and iser_start_rdma_unaligned_sg() static,
since they are only used in the .c file where they are defined. In
addition to being a cleanup, this even shrinks the generated code by
allowing the single call of iser_start_rdma_unaligned_sg() to be
inlined into its callsite. On x86_64:
add/remove: 0/1 grow/shrink: 1/0 up/down: 466/-533 (-67)
function old new delta
iser_reg_rdma_mem 1518 1984 +466
iser_start_rdma_unaligned_sg 533 - -533
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This patch allows us to set can_queue and cmds_per_lun from userspace
when we create the session/host. From there we can set it on a per
target basis. The patch fully converts iscsi_tcp, but only hooks
up ib_iser for cmd_per_lun since it currently has a lots of preallocations
based on can_queue.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Cc: Roland Dreier <rdreier@cisco.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
When a connection is terminated asynchronously from the iSCSI layer's
perspective, iSER needs to notify the iSCSI layer that the connection
has failed. This is done using a workqueue (switched to from the iSER
tasklet context). Meanwhile, the connection object (that holds the
work struct) is released. If the workqueue function wasn't called
yet, it will be called later with a NULL pointer, which will crash the
kernel.
The context switch (tasklet to workqueue) is not required, and
everything can be done from the iSER tasklet. This eliminates the NULL
work struct bug (and simplifies the code).
Signed-off-by: Erez Zilber <erezz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Convert iSER to use the new verbs DMA mapping functions for kernel
verbs consumers.
Signed-off-by: Ralph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
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>
iSER uses a data transaction object (struct iser_dto) as part
of its IB data descriptors (struct iser_desc) management.
It also uses a hierarchy of connection structures pointing to
each other. A DTO may exist even after the iscsi_iser connection
pointed by it is destroyed (eg one that is bound to a post
receive buffer which was flushed by the IB HW). Hence DTOs need
point to the lowest connection, which is struct iser_conn.
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>
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>
iSCSI RFC states that the first burst length must be smaller than the
max burst length. We currently assume targets will be good, but that may
not be the case, so this patch adds a check.
This patch also moves the unsol data out offset to the lib so the LLDs
do not have to track it.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
iSER (iSCSI Extensions for RDMA) transport provider driver for the iSCSI
initiator, whose other parts (under drivers/scsi) are scsi_transport_iscsi
- the transport management module, iscsi_tcp - the TCP transport provider
module and libiscsi - a kernel library (module) implementing functionality
needed by both TCP and iSER transports. iSER is both a provider of the iSCSI
transport api and a SCSI low level driver.
This file contains internal data structures and non static service functions.
Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
