This patch explicitly disables TX completion interrupt coalescing logic
in isert_put_response() and isert_put_datain() that was originally added
as an efficiency optimization in commit 95b60f07.

It has been reported that this change can trigger ABORT_TASK timeouts
under certain small block workloads, where disabling coalescing was
required for stability.  According to Sagi, this doesn't impact
overall performance, so go ahead and disable it for now.
Reported-by: NMoussa Ba <moussaba@micron.com>
Reported-by: NSagi Grimberg <sagig@dev.mellanox.co.il>
Cc: <stable@vger.kernel.org> # 3.13+
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

This patch adds a force_pr_aptpl device attribute used to force SPC-3 PR
Activate Persistence across Target Power Loss (APTPL) operation.  This
makes PR metadata write-out occur during state change regardless if new
PERSISTENT_RESERVE_OUT CDBs have their APTPL feature bit set.

This is useful during H/A failover in active/passive setups where all PR
state is being re-created on a different node, driven by configfs backend
device + export layout and pre-loaded $DEV/pr/res_aptpl_metadata.

Cc: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

This patch fixes a bug in handling of SPC-3 PR Activate Persistence
across Target Power Loss (APTPL) logic where re-creation of state for
MappedLUNs from dynamically generated NodeACLs did not occur during
I_T Nexus establishment.

It adds the missing core_scsi3_check_aptpl_registration() call during
core_tpg_check_initiator_node_acl() -> core_tpg_add_node_to_devs() in
order to replay any pre-loaded APTPL metadata state associated with
the newly connected SCSI Initiator Port.

Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: <stable@vger.kernel.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

The code is currently riddled with "drop the hardware_lock to avoid a
deadlock" bugs that expose races.  One of those races seems to expose a
valid warning in tcm_qla2xxx_clear_nacl_from_fcport_map.  Add some
bandaid to it.
Signed-off-by: NJoern Engel <joern@logfs.org>
Cc: <stable@vger.kernel.org> # v3.5+
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

If more than one thread is waiting for command ring space that includes
a PAD, then if the first one finishes (inserts a PAD and a CMD at the
start of the cmd ring) then the second one will incorrectly think it still
needs to insert a PAD (i.e. cmdr_space_needed is now wrong.) This will
lead to it asking for more space than it actually needs, and then inserting
a PAD somewhere else than at the end -- not what we want.

This patch moves the pad calculation inside is_ring_space_available() so
in the above scenario the second thread would then ask for space not
including a PAD. The patch also inserts a PAD op based upon an up-to-date
cmd_head, instead of the potentially stale value.
Signed-off-by: NAndy Grover <agrover@redhat.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

The SCSI command tag is set to the tag assigned from the block
layer, not the SCSI-II tag message. So we need to convert
it into the correct SCSI-II tag message based on the
device flags, not the tag value itself.
Signed-off-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NSagi Grimberg <sagig@mellanox.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Unused return value from down_interruptible
Reported-by: NOr Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: NSagi Grimberg <sagig@mellanox.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

This patch fixes up the following unused return smatch warnings:

  drivers/target/target_core_user.c:778 tcmu_netlink_event warn: unused return: ret = nla_put_string()
  drivers/target/target_core_user.c:780 tcmu_netlink_event warn: unused `return: ret = nla_put_u32()

(Fix up missing semicolon: grover)
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

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 returning scsi command status and optional sense
data.

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.

(Add kconfig depends NET - Randy)
Signed-off-by: NAndy Grover <agrover@redhat.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

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

Thanks to Richard W. M. Jones for review, and supplementing this doc
with the first two paragraphs.
Signed-off-by: NAndy Grover <agrover@redhat.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

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: NAndy Grover <agrover@redhat.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

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: NAndy Grover <agrover@redhat.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

During temporary resource starvation at lower transport layer, command
is placed on queue full retry path, which expose this problem.  The TCM
queue full handling of SCF_TRANSPORT_TASK_SENSE currently sends the same
cmd twice to lower layer.  The 1st time led to cmd normal free path.
The 2nd time cause Null pointer access.

This regression bug was originally introduced v3.1-rc code in the
following commit:

commit e057f533
Author: Christoph Hellwig <hch@infradead.org>
Date:   Mon Oct 17 13:56:41 2011 -0400

    target: remove the transport_qf_callback se_cmd callback
Signed-off-by: NQuinn Tran <quinn.tran@qlogic.com>
Signed-off-by: NSaurav Kashyap <saurav.kashyap@qlogic.com>
Cc: <stable@vger.kernel.org> # v3.1+
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

On most (non-x86) 64bit platforms this will remove 8 padding bytes
from the structure.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Remove the inline attribute.  Modern compilers ignore it and the
function has grown beyond where inline made sense anyway.
Remove the BUG_ON(!cmd->sg_mapped), and instead return if sg_mapped is
not set.  Every caller is doing this check, so we might as well have it
in one place instead of four.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Also removes the declarations from the header - including two
declarations without function definitions or callers.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

list_for_each_entry_safe is necessary if list objects are deleted from
the list while traversing it.  Not the case here, so we can use the base
list_for_each_entry variant.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

The target code has a rather generous helping of smp_mb__after_atomic()
throughout the code base.  Most atomic operations were followed by one
and none were preceded by smp_mb__before_atomic(), nor accompanied by a
comment explaining the need for a barrier.

Instead of trying to prove for every case whether or not it is needed,
this patch introduces atomic_inc_mb() and atomic_dec_mb(), which
explicitly include the memory barriers before and after the atomic
operation.  For now they are defined in a target header, although they
could be of general use.

Most of the existing atomic/mb combinations were replaced by the new
helpers.  In a few cases the atomic was sandwiched in
spin_lock/spin_unlock and I simply removed the barrier.

I suspect that in most cases the correct conversion would have been to
drop the barrier.  I also suspect that a few cases exist where a) the
barrier was necessary and b) a second barrier before the atomic would
have been necessary and got added by this patch.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

atomic_inc_return() already does an implicit memory barrier and the
second case was moved from an atomic to a plain flag operation.  If a
barrier were needed in the second case, it would have to be smp_mb(),
not a variant optimized away for x86 and other architectures.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

And while at it, do minimal coding style fixes in the area.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Simple and just called from one place.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndy Grover <agrover@redhat.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Remove core_tpg_pre_dellun entirely, since we don't need to get/check
a pointer we already have.

Nothing else can return an error, so core_dev_del_lun can return void.

Rename core_tpg_post_dellun to remove_lun - a clearer name, now that
pre_dellun is gone.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndy Grover <agrover@redhat.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Nothing in it can raise an error.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndy Grover <agrover@redhat.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Clearly a right-shift was meant.  Effectively doesn't make a difference,
as add_len is hard-coded to 8 and the high byte will be zero no matter
which way you shift.  But I hate leaving bad examples for others to
copy.

Found by coverity.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

This patch correctly handles match_int() errors in FILEIO + PSCSI
backend parameter parsing, which can potentially fail due to a
memory allocation failure or invalid argument.

Found by coverity.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Old code in iscsi_parse_pr_out_transport_id() was obviously buggy
and effectively ignored the high byte.

Found by coverity.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Coverity complained that lun_cg has been dereferenced in all paths
leading to NULL check.  It didn't mention that only a single path could
lead there and the code can be simplified even further.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

This patch fixes a memory leak on error in target_fabric_make_mappedlun(),
where se_lun_acl memory does not get released on exit.

Found by coverity.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Each case of match_strdup could leak memory if the same argument was
present before.  I am not too concerned, as it would require a
non-sensical combination like "target_lun=foo target_lun=bar", done
with root privileges and even then leak just a few bytes per instance.

But arg_p is different, as it will always leak memory.  Let's plug that
one.  And while at it, replace some &args[0] with args.

Found by coverity.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

last_intr_fail_name is a fixed-size array and could theoretically
overflow.  In reality intrname->value doesn't seem to depend on
untrusted input or be anywhere near 224 characters, so the overflow is
pretty theoretical.  But strlcpy is cheap enough.

Found by coverity.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Found by coverity.  At this point sock is non-NULL, so the check
to unnecessary.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

This patch drops the now duplicate + unnecessary check for -ENODEV from
iscsi_transport->iscsit_accept_np() for jumping to out:, or immediately
returning 1 in __iscsi_target_login_thread() code.

Since commit 81a9c5e7 the jump to out: and returning 1 have the same
effect, and end up hitting the ISCSI_NP_THREAD_SHUTDOWN check regardless
at the top of __iscsi_target_login_thread() during next loop iteration.

So that said, it's safe to go ahead and remove this duplicate check.
Reported-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

The return statement cannot be reached without either recovery or dump
being set to 1.  Therefore the condition always evaluates to true and
recovery and dump are useless variables.

Found by Coverity.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Found by coverity.  InitiatorName and InitiatorAlias are static arrays
and therefore always non-NULL.  At some point in the past they may have
been dynamically allocated, but for current code the condition is
useless.  If the intent was to check InitiatorName[0] instead, I cannot
find a use for that either.  Let's get rid of it.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Last user of buf was removed with c6037cc5.  While at it,
free_cpumask_var() handles a NULL argument just fine, so remove the
conditionals.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

Clearly the file was meant to contain an include guard, but it was
missing the #define part.
Signed-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

The use of "rcu_assign_pointer()" is NULLing out the pointer.
According to RCU_INIT_POINTER()'s block comment:
"1.   This use of RCU_INIT_POINTER() is NULLing out the pointer"
it is better to use it instead of rcu_assign_pointer() because it has a
smaller overhead.

The following Coccinelle semantic patch was used:
@@
@@

- rcu_assign_pointer
+ RCU_INIT_POINTER
  (..., NULL)
Signed-off-by: NAndreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

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: NHimangi Saraogi <himangi774@gmail.com>
Acked-by: NJulia Lawall <julia.lawall@lip6.fr>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>