Target/iser: Get isert_conn reference once got to connected_handler

In case the connection didn't reach connected state, disconnected
handler will never be invoked thus the second kref_put on
isert_conn will be missing.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Target/iser: Don't put isert_conn inside disconnected handler

disconnected_handler is invoked on several CM events (such
as DISCONNECTED, DEVICE_REMOVAL, TIMEWAIT_EXIT...). Since
multiple  events can occur while before isert_free_conn is
invoked, we might put all isert_conn references and free
the connection too early.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Target/iser: Avoid calling rdma_disconnect twice

rdma_disconnect may be called in 2 code flows:
- isert_wait_conn: disconnect initiated be the target
- disconnected_handler: disconnect invoked by the initiator

In case isert_conn->disconnect is true then rdma_disconnect
was called in disconnected handler, no need to call it again
from isert_wait_conn.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
target/configfs: Remove unnecessary null test

This patch removes the null test on lun_cg. lun_cg is initialized
at the beginning of the function to &lun->lun_group. Since lun_cg is
dereferenced prior to the null test, it must be a valid pointer.

The following Coccinelle script is used for detecting the change:

@r@
expression e,f;
identifier g,y;
statement S1,S2;
@@

*e = &f->g
<+...
 f->y
 ...+>
*if (e != NULL || ...)
 S1 else S2

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Target/iser: Fix initiator_depth and responder_resources

The iser target is the RDMA requester and the iser initiator is the
RDMA responder. In order to determine the max inflight RDMA READ requests
to set on the QP (initiator_depth), it should take the min between the
initiator published initiator_depth and the max inflight rdma read
requests its local HCA support (max_qp_init_rd_atom).

The target will never handle incoming RDMA READ requests so no need to
set responder_resources.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
iscsi-target: Ignore ICF_GOT_LAST_DATAOUT during Data-Out ITT lookup

This patch adds a explicit check in iscsit_find_cmd_from_itt_or_dump()
to ignore commands with ICF_GOT_LAST_DATAOUT set.  This is done to
address the case where an ITT is being reused for DataOUT, but the
previous command with the same ITT has not yet been acknowledged by
ExpStatSN and removed from the per connection command list.

This issue was originally manifesting itself by referencing the
previous command during ITT lookup, and subsequently hitting the
check in iscsit_check_dataout_hdr() for ICF_GOT_LAST_DATAOUT, that
resulted in the DataOUT PDU + associated payload being silently
dumped.

Reported-by: Arshad Hussain <arshad.hussain@calsoftinc.com>
Tested-by: Arshad Hussain <arshad.hussain@calsoftinc.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
target: Remove unneeded check in sbc_parse_cdb

The check of SCF_SCSI_DATA_CDB seems to be a remnant from before hch's
refactoring of this function. There are no places where that flag is set
that cmd->execute_cmd isn't also set.

Signed-off-by: Andy Grover <agrover@redhat.com>
uio: Export definition of struct uio_device

In order to prevent a O(n) search of the filesystem to link up its uio
node with its target configuration, TCMU needs to know the minor number
that UIO assigned. Expose the definition of this struct so TCMU can
access this field.

Signed-off-by: Andy Grover <agrover@redhat.com>
target: Add a user-passthrough backstore

Add a LIO storage engine that presents commands to userspace for execution.
This would allow more complex backstores to be implemented out-of-kernel,
and also make experimentation a-la FUSE (but at the SCSI level -- "SUSE"?)
possible.

It uses a mmap()able UIO device per LUN to share a command ring and data
area. The commands are raw SCSI CDBs and iovs for in/out data. The command
ring is also reused for scsi command status and sense data, if present.

This implementation is based on Shaohua Li's earlier version but heavily
modified. Differences include:

* Shared memory allocated by kernel, not locked-down user pages
* Single ring for command request and response
* Offsets instead of embedded pointers
* Generic SCSI CDB passthrough instead of per-cmd specialization in ring
  format.
* Uses UIO device instead of anon_file passed in mailbox.
* Optional in-kernel handling of some commands.

The main reason for these differences is to permit greater resiliency
if the user process dies or hangs.

Things not yet implemented (on purpose):

* Zero copy. The data area is flexible enough to allow page flipping or
  backend-allocated pages to be used by fabrics, but it's not clear these
  are performance wins. Can come later.
* Out-of-order command completion by userspace. Possible to add by just
  allowing userspace to change cmd_id in rsp cmd entries, but currently
  not supported.
* No locks between kernel cmd submission and completion routines. Sounds
  like it's possible, but this can come later.
* Sparse allocation of mmaped area. Current code vmallocs the whole thing.
  If the mapped area was larger and not fully mapped then the driver would
  have more freedom to change cmd and data area sizes based on demand.

Current code open issues:

* The use of idrs may be overkill -- we maybe can replace them with a
  simple counter to generate cmd_ids, and a hash table to get a cmd_id's
  associated pointer.
* Use of a free-running counter for cmd ring instead of explicit modulo
  math. This would require power-of-2 cmd ring size.
* Random printks in code, still.

Signed-off-by: Andy Grover <agrover@redhat.com>
target: Add documentation on the target userspace pass-through driver

Describes the driver and its interface to make it possible for user
programs to back a LIO-exported LUN.

Signed-off-by: Andy Grover <agrover@redhat.com>