The rport timers must be stopped before the SRP initiator destroys the
resources associated with the SCSI host. This is necessary because
otherwise the callback functions invoked from the SRP transport layer
could trigger a use-after-free. Stopping the rport timers before
invoking scsi_remove_host() can trigger long delays in the SCSI error
handler if a transport layer failure occurs while scsi_remove_host()
is in progress. Hence move the code for stopping the rport timers from
srp_rport_release() into a new function and invoke that function after
scsi_remove_host() has finished. This patch fixes the following
sporadic kernel crash:
kernel BUG at include/asm-generic/dma-mapping-common.h:64!
invalid opcode: 0000 [#1] SMP
RIP: 0010:[<ffffffffa03b20b1>] [<ffffffffa03b20b1>] srp_unmap_data+0x121/0x130 [ib_srp]
Call Trace:
[<ffffffffa03b20fc>] srp_free_req+0x3c/0x80 [ib_srp]
[<ffffffffa03b2188>] srp_finish_req+0x48/0x70 [ib_srp]
[<ffffffffa03b21fb>] srp_terminate_io+0x4b/0x60 [ib_srp]
[<ffffffffa03a6fb5>] __rport_fail_io_fast+0x75/0x80 [scsi_transport_srp]
[<ffffffffa03a7438>] rport_fast_io_fail_timedout+0x88/0xc0 [scsi_transport_srp]
[<ffffffff8108b370>] worker_thread+0x170/0x2a0
[<ffffffff81090876>] kthread+0x96/0xa0
[<ffffffff8100c0ca>] child_rip+0xa/0x20
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
The IB spec does not guarantee that the opcode is available in error
completions. Hence do not rely on it. See also commit 948d1e889e
("IB/srp: Introduce srp_handle_qp_err()").
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: <stable@vger.kernel.org> # v3.8
Signed-off-by: Roland Dreier <roland@purestorage.com>
If SCSI commands are submitted with a SCSI request timeout that is
lower than the the IB RC timeout, it can happen that the SCSI error
handler has already started device recovery before transport layer
error handling starts. So it can happen that the SCSI error handler
tries to abort a SCSI command after it has been reset by
srp_rport_reconnect().
Tell the SCSI error handler that such commands have finished and that
it is not necessary to continue its recovery strategy for commands
that have been reset by srp_rport_reconnect().
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Remove an SRP target from the SRP target list before invoking the last
scsi_host_put() call. This change is necessary because that last put
frees the memory that holds the srp_target_port structure.
This patch prevents the following kernel oops:
RIP: 0010:[<ffffffff810b00d0>] __lock_acquire+0x500/0x1570
Call Trace:
[<ffffffff810b11e4>] lock_acquire+0xa4/0x120
[<ffffffff81531206>] _spin_lock+0x36/0x70
[<ffffffffa01b6d8f>] srp_remove_work+0xef/0x180 [ib_srp]
[<ffffffff8109125c>] worker_thread+0x21c/0x3d0
[<ffffffff81096e86>] kthread+0x96/0xa0
[<ffffffff8100c20a>] child_rip+0xa/0x20
Signed-off-by: Vu Pham <vuhuong@mellanox.com>
[ bvanassche - Modified path description and CC'ed stable. ]
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Currently, it's not possible to change queue depth for a device behind
SRP host. Sometimes, we need to adjust queue_depth for performance
reason (eg storage busy, we need lower queue_depth to avoid running
into SCSI error handler), so this patch add support for SRP driver.
Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
Tested-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Certain storage configurations, e.g. a sufficiently large array of
hard disks in a RAID configuration, need a queue depth above 64 to
achieve optimal performance. Hence make the queue depth configurable.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Tested-by: Jack Wang <xjtuwjp@gmail.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
This patch does not change any functionality.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Cc: Roland Dreier <roland@purestorage.com>
Cc: Vu Pham <vu@mellanox.com>
Cc: Sebastian Riemer <sebastian.riemer@profitbricks.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
On an initiator system with multiple IB ports it is not yet possible
to figure out what the originating port of an SRP connection is. Hence
make the source GID available in sysfs.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
After a transport layer occurred, periodically try to reconnect
to the target until the dev_loss timer expires. Protect the
callback functions that can be invoked from inside the SCSI EH
against concurrent invocation with srp_reconnect_rport() via the
rport mutex. Change the default dev_loss_tmo from 60s into 600s
to give the reconnect mechanism a chance to kick in.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Add support for periodically reconnecting to an SRP target until
the dev_loss timer expires. After the tenth reconnection attempt,
gradually slow down subsequent reconnect attempts.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Start the reconnect timer, fast_io_fail timer and dev_loss timers if a
transport layer error occurs.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Enable fast_io_fail_tmo and dev_loss_tmo functionality for the IB SRP
initiator. Add kernel module parameters that allow to specify default
values for these parameters.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Keep the rport data structure around after srp_remove_host() has
finished until cleanup of the IB transport layer has finished
completely. This is necessary because later patches use the rport
pointer inside the queuecommand callback. Without this patch
accessing the rport from inside a queuecommand callback is racy
because srp_remove_host() must be invoked before scsi_remove_host()
and because the queuecommand callback could get invoked after
srp_remove_host() has finished. In other words, without this patch
the queuecommand callback can get invoked after the rport data
structure has been freed.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Allow the InfiniBand RC retry count to be configured by the user as an
option in the target login string. Reducing this retry count allows to
reduce the path failover time.
Signed-off-by: Vu Pham <vu@mellanox.com>
[ bvanassche: Rewrote patch description / changed default retry count ]
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
If the transport layer is offline it is more appropriate to let
srp_abort() return FAST_IO_FAIL instead of SUCCESS.
Reported-by: Sebastian Riemer <sebastian.riemer@profitbricks.com>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Several InfiniBand HCAs allow configuring the completion vector per
CQ. This allows spreading the workload created by IB completion
interrupts over multiple MSI-X vectors and hence over multiple CPU
cores. In other words, configuring the completion vector properly not
only allows reducing latency on an initiator connected to multiple
SRP targets but also allows improving throughput.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
An SRP target is required to maintain a single connection between
initiator and target. This means that if the 'add_target' attribute
is used to create a second connection to a target, the first
connection will be logged out and that the SCSI error handler will
kick in. The SCSI error handler will cause the SRP initiator to
reconnect, which will cause I/O over the second connection to fail.
Avoid such ping-pong behavior by disabling relogins.
If reconnecting manually is necessary, that is possible by deleting
and recreating an rport via sysfs.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Sebastian Riemer <sebastian.riemer@profitbricks.com>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
If reconnecting failed we know that no command completion will
be received anymore. Hence let the SCSI error handler fail such
commands immediately.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
The SRP initiator implements host reset by reconnecting to the SRP
target. That means that communication with the target is possible as
soon as host reset finished. Hence skip the host settle delay.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Sebastian Riemer <sebastian.riemer@profitbricks.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
The SCSI error handler assumes that the transport layer is operational
if an eh_abort_handler() returns SUCCESS. Hence srp_abort() only
should return SUCCESS if sending the ABORT TASK task management
function succeeded. This patch avoids the SCSI error handler skipping
the srp_reset_host() call after a transport layer error.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
If the add_one callback fails during driver load no resources are
allocated so there isn't a need to release any resources. Trying
to clean the resource may lead to the following kernel panic:
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffffa0132331>] srp_remove_one+0x31/0x240 [ib_srp]
RIP: 0010:[<ffffffffa0132331>] [<ffffffffa0132331>] srp_remove_one+0x31/0x240 [ib_srp]
Process rmmod (pid: 4562, threadinfo ffff8800dd738000, task ffff8801167e60c0)
Call Trace:
[<ffffffffa024500e>] ib_unregister_client+0x4e/0x120 [ib_core]
[<ffffffffa01361bd>] srp_cleanup_module+0x15/0x71 [ib_srp]
[<ffffffff810ac6a4>] sys_delete_module+0x194/0x260
[<ffffffff8100b0f2>] system_call_fastpath+0x16/0x1b
Signed-off-by: Dotan Barak <dotanb@dev.mellanox.co.il>
Reviewed-by: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Sebastian Riemer <sebastian.riemer@profitbricks.com>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
If an SRP target is no longer reachable and srp_reset_host() fails to
reconnect then ib_srp will invoke scsi_remove_host(). That function
will invoke __scsi_remove_device() for each LUN. And that last
function will change the device state from SDEV_TRANSPORT_OFFLINE into
SDEV_CANCEL. Certain user space software, e.g. older versions of
multipathd, continue queueing I/O to SCSI devices that are in the
SDEV_CANCEL state.
If these I/O requests are submitted as SG_IO that means that the
REQ_PREEMPT flag will be set and hence that these requests will be
passed to srp_queuecommand(). These requests will time out. If new
requests are queued fast enough from user space these active requests
will prevent __scsi_remove_device() to finish.
Avoid this by failing I/O requests in the SDEV_CANCEL state if the
transport is offline. Introduce a new variable to keep track of the
transport state instead of failing requests if (!target->connected ||
target->qp_in_error), so that the SCSI error handler has a chance to
retry commands after a transport layer failure occurred.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: <stable@vger.kernel.org> # 3.8
Signed-off-by: Roland Dreier <roland@purestorage.com>
If a SCSI command times out it is passed to the SCSI error
handler. The SCSI error handler will try to abort the commands that
timed out. If aborting fails, a device reset will be attempted. If
the device reset also fails a host reset will be attempted. If the
host reset also fails the whole procedure will be repeated.
srp_abort() and srp_reset_device() fail for a QP in the error state.
srp_reset_host() fails after host removal has started. Hence if the
SCSI error handler gets invoked after host removal has started and
with the QP in the error state an endless loop will be triggered.
Modify the SCSI error handling functions in ib_srp as follows:
- Abort SCSI commands properly even if the QP is in the error state.
- Make srp_reset_host() reset SCSI requests even after host removal
has already started or if reconnecting fails.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dave@thedillows.org>
Cc: <stable@vger.kernel.org> # 3.8
Signed-off-by: Roland Dreier <roland@purestorage.com>
Do not send a task management function if sending will fail anyway
because either there is no RDMA/RC connection or the QP is in the
error state.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dave@thedillows.org>
Cc: <stable@vger.kernel.org> # 3.8
Signed-off-by: Roland Dreier <roland@purestorage.com>
Remove an assignment that incorrectly overwrites the connection state
update by srp_connect_target().
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dave@thedillows.org>
Cc: <stable@vger.kernel.org> # 3.8
Signed-off-by: Roland Dreier <roland@purestorage.com>
Make it possible to disconnect the IB RC connection used by the SRP
protocol to communicate with a target.
Have the SRP transport layer create a sysfs "delete" attribute for
initiator drivers that support this functionality.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Now that SRP recreates the CM ID, QP, and CQ for each connection,
there is no need to wait for the timewait state to complete.
Signed-off-by: Vu Pham <vu@mellanox.com>
Signed-off-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
HW QP FATAL errors persist over a reset operation, but we can recover
from that by recreating the QP and associated CQs for each connection.
Creating a new QP/CQ also completely forecloses any possibility of
getting stale completions or packets on the new connection.
Signed-off-by: Ishai Rabinovitz <ishai@mellanox.co.il>
Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
[ updated to current code from OFED, cleaned up commit message ]
Signed-off-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Only queue removal work after having changed the target state
into SRP_TARGET_REMOVED and not if that state was already equal
to SRP_TARGET_REMOVED. That allows us to remove the state
SRP_TARGET_DEAD. Add a call to srp_disconnect_target() in
srp_remove_target() -- due to previous changes it is now safe to
invoke that function even if the IB connection has already
been disconnected. This change allows us to replace the target
removal code in srp_remove_one() by an (indirect) call to
srp_remove_target(). Rename srp_target_port.work into
srp_target_port.remove_work to reflect its usage.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Keep track of the connection state. Only report QP errors while
connected. Only invoke ib_send_cm_dreq() when connected so that
invoking srp_disconnect_target() after having received a DREQ does not
cause an error message to be printed.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
If the RDMA RC connection is closed, tell the SCSI mid-layer to
terminate all pending commands instead of only the first.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Introduce the function srp_handle_qp_err(), change the type of
qp_in_error from int into bool and move the initialization of that
variable from srp_reconnect_target() to srp_connect_target().
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Since scsi_remove_host() has been modified so that SCSI error handling
functions will no longer be invoked after scsi_remove_host() returns,
the test at the start of srp_send_tsk_mgmt() is now superfluous.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Some SCSI upper layer drivers, e.g. sd, issue SCSI commands from
inside scsi_remove_host() (see the sd_shutdown() call in sd_remove()).
Make sure that these commands have a chance to reach the SCSI device.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Block the SCSI host while reconnecting instead of representing the
reconnection activity as a distinct SRP target state. This allows us
to eliminate the target state SRP_TARGET_CONNECTING.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Increase the block layer timeout for disks so that it is above the
InfiniBand transport layer timeout.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
We need to call scsi_done() for commands after we abort them.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Cc: <stable@vger.kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
srp_free_req() uses the scsi_cmnd structure contents to unmap
buffers, so we must invoke srp_free_req() before we release
ownership of that structure.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Cc: <stable@vger.kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Avoid a crash caused by the scmnd->scsi_done(scmnd) call in
srp_process_rsp() being invoked with scsi_done == NULL. This can
happen if a reply is received during or after a command abort.
Reported-by: Joseph Glanville <joseph.glanville@orionvm.com.au>
Reference: http://marc.info/?l=linux-rdma&m=134314367801595
Cc: <stable@vger.kernel.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Remove sysfs attributes before removing a target instead of testing
the target state in every sysfs attribute callback method. Note: it is
safe to invoke a sysfs attribute removal method like
device_remove_file() twice on the same attribute.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Use pr_fmt() and pr_xxx() instead of more verbose printk() equivalents.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: Arun Sharma <asharma@fb.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SCSI scanning of a channel🆔lun triplet in Linux works as follows
(function scsi_scan_target() in drivers/scsi/scsi_scan.c):
- If lun == SCAN_WILD_CARD, send a REPORT LUNS command to the target
and process the result.
- If lun != SCAN_WILD_CARD, send an INQUIRY command to the LUN
corresponding to the specified channel🆔lun triplet to verify
whether the LUN exists.
So a SCSI driver must either take the channel and target id values in
account in its quecommand() function or it should declare that it only
supports one channel and one target id.
Currently the ib_srp driver does neither. As a result scanning the
SCSI bus via e.g. rescan-scsi-bus.sh causes many duplicate SCSI
devices to be created. For each 0:0:L device, several duplicates are
created with the same LUN number and with (C:I) != (0:0). Fix this by
declaring that the ib_srp driver only supports one channel and one
target id.
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: <stable@kernel.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Fix
drivers/infiniband/ulp/srp/ib_srp.c: In function 'srp_handle_recv':
drivers/infiniband/ulp/srp/ib_srp.c:1150: warning: cast to pointer from integer of different size
drivers/infiniband/ulp/srp/ib_srp.c: In function 'srp_send_completion':
drivers/infiniband/ulp/srp/ib_srp.c🔢 warning: cast to pointer from integer of different size
by adding an intermediate cast to uintptr_t.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Acked-by: David Dillow <dillowda@ornl.gov>
Now that we can get larger SG lists, we can take advantage of HCAs that
allow us to use larger FMR sizes. In many cases, we can use up to 512
entries, so start there and work our way down.
Signed-off-by: David Dillow <dillowda@ornl.gov>
This allows us to guarantee the ability to submit up to 8 MB requests
based on the current value of SCSI_MAX_SG_CHAIN_SEGMENTS. While FMR will
usually condense the requests into 8 SG entries, it is imperative that
the target support external tables in case the FMR mapping fails or is
not supported.
We add a safety valve to allow targets without the needed support to
reap the benefits of the large tables, but fail in a manner that lets
the user know that the data didn't make it to the device. The user must
add "allow_ext_sg=1" to the target parameters to indicate that the
target has the needed support.
If indirect_sg_entries is not specified in the modules options, then
the sg_tablesize for the target will default to cmd_sg_entries unless
overridden by the target options.
Signed-off-by: David Dillow <dillowda@ornl.gov>
Instead of forcing all of the S/G entries to fit in one FMR, and falling
back to indirect descriptors if that fails, allow the use of as many
FMRs as needed to map the request. This lays the groundwork for allowing
indirect descriptor tables that are larger than can fit in the command
IU, but should marginally improve performance now by reducing the number
of indirect descriptors needed.
We increase the minimum page size for the FMR pool to 4K, as larger
pages help increase the coverage of each FMR, and it is rare that the
kernel would send down a request with scattered 512 byte fragments.
This patch also move some of the target initialization code afte the
parsing of options, to keep it together with the new code that needs to
allocate memory based on the options given.
Signed-off-by: David Dillow <dillowda@ornl.gov>
Different configurations of target software allow differing max sizes of
the command IU. Allowing this to be changed per-target allows all
targets on an initiator to get an optimal setting.
We deprecate srp_sg_tablesize and replace it with cmd_sg_entries in
preparation for allowing more indirect descriptors than can fit in the
IU.
Signed-off-by: David Dillow <dillowda@ornl.gov>
Bart Van Assche