Rework table reference counting.

The existing code uses a reference counter. When the last reference is
dropped and the counter reaches zero, the table destructor is called.
Table reference counters are acquired/released from upcalls from other
kernel code (dm_any_congested, dm_merge_bvec, dm_unplug_all).
If the reference counter reaches zero in one of the upcalls, the table
destructor is called from almost random kernel code.

This leads to various problems:
* dm_any_congested being called under a spinlock, which calls the
  destructor, which calls some sleeping function.
* the destructor attempting to take a lock that is already taken by the
  same process.
* stale reference from some other kernel code keeps the table
  constructed, which keeps some devices open, even after successful
  return from "dmsetup remove". This can confuse lvm and prevent closing
  of underlying devices or reusing device minor numbers.

The patch changes reference counting so that the table destructor can be
called only at predetermined places.

The table has always exactly one reference from either mapped_device->map
or hash_cell->new_map. After this patch, this reference is not counted
in table->holders.  A pair of dm_create_table/dm_destroy_table functions
is used for table creation/destruction.

Temporary references from the other code increase table->holders. A pair
of dm_table_get/dm_table_put functions is used to manipulate it.

When the table is about to be destroyed, we wait for table->holders to
reach 0. Then, we call the table destructor.  We use active waiting with
msleep(1), because the situation happens rarely (to one user in 5 years)
and removing the device isn't performance-critical task: the user doesn't
care if it takes one tick more or not.

This way, the destructor is called only at specific points
(dm_table_destroy function) and the above problems associated with lazy
destruction can't happen.

Finally remove the temporary protection added to dm_any_congested().
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

Implement barrier support for single device DM devices

This patch implements barrier support in DM for the common case of dm linear
just remapping a single underlying device. In this case we can safely
pass the barrier through because there can be no reordering between
devices.

 NB. Any DM device might cease to support barriers if it gets
     reconfigured so code must continue to allow for a possible
     -EOPNOTSUPP on every barrier bio submitted.  - agk
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

This patch prepares some kmem_caches for request-based dm.
Signed-off-by: NKiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

Allow NULL buffer in dm_copy_name_and_uuid if you only want to return one of
the fields.

(Required by a following patch that adds these fields to sysfs.)
Signed-off-by: NMilan Broz <mbroz@redhat.com>
Reviewed-by: NAlasdair G Kergon <agk@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

Check that the log bitmap will fit within the log device.
Signed-off-by: NMilan Broz <mbroz@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

Move log size validation from mirror target to log constructor.

Removed PAGE_SIZE restriction we no longer think necessary.
Signed-off-by: NMilan Broz <mbroz@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

rw_header function updates three members of io_req data every time
when I/O is processed. bi_rw and notify.fn are never modified once
they get initialized, and so they can be set in advance.

header_to_disk() can also be pulled out of write_header() since only one
caller needs it and write_header() can be replaced by rw_header()
directly.
Signed-off-by: NTakahiro Yasui <tyasui@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

Change dm_unregister_target to return void and use BUG() for error
reporting.

dm_unregister_target can only fail because of programming bug in the
target driver. It can't fail because of user's behavior or disk errors.

This patch changes unregister_target to return void and use BUG if
someone tries to unregister non-registered target or unregister target
that is in use.

This patch removes code duplication (testing of error codes in all dm
targets) and reports bugs in just one place, in dm_unregister_target. In
some target drivers, these return codes were ignored, which could lead
to a situation where bugs could be missed.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

Always increase the error count when I/O on a leg of a mirror fails.

The error count is used to decide whether to select an alternative
mirror leg.  If the target doesn't use the "handle_errors" feature, the
error count is not updated and the bio can get requeued forever by the
read callback.

Fix it by increasing error_count before the handle_errors feature
checking.

Cc: stable@kernel.org
Signed-off-by: NMilan Broz <mbroz@redhat.com>
Signed-off-by: NJonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

In create_log_context function, dm_io_client_destroy function needs
to be called, when memory allocation of disk_header, sync_bits and
recovering_bits failed, but dm_io_client_destroy is not called.

Cc: stable@kernel.org
Signed-off-by: NTakahiro Yasui <tyasui@redhat.com>
Acked-by: NJonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

Change yield() to msleep(1). If the thread had realtime priority,
yield() doesn't really yield, so the yielding process would loop
indefinitely and cause machine lockup.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

Move one dm_table_put() so that the last reference in the thread
gets dropped in __unbind().

This is required for a following patch,
dm-table-rework-reference-counting.patch, which will change the logic in
such a way that table destructor is called only at specific points in
the code.
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

Add standard interfaces for alarm/update irqs enabling.  Drivers are no
more required to implement equivalent ioctl code as rtc-dev will provide
it.

UIE emulation should now be handled correctly and will work even for those
RTC drivers who cannot be configured to do both UIE and AIE.
Signed-off-by: NAlessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Cc: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The function viafb_cursor() uses 2 stack-variables of CURSOR_SIZE bits;
CURSOR_SIZE is defined as (8 * 1024).  Using up twice 1k on stack is too
much for 4k-stack (though it works with 8k-stacks).  Make those two
variables kzalloc'ed to preserve stack space.

Also merge the whole lot of local struct's in viafb_ioctl into a union so
the stack usage gets minimized here as well.  (struct's are only accessed
in their indicidual IOCTL case) This second part is only compile-tested as
I know of no userspace app using the IOCTLs.
Signed-off-by: NBruno Prémont <bonbons@linux-vserver.org>
Cc: <JosephChan@via.com.tw>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

those two functions only used in that C file
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

CONFIG_NR_CPUS will be defined for all arch's whether SMP or not, but
it may not have made it into all arches yet.
Signed-off-by: NMike Travis <travis@sgi.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: Reduce memory usage, use new API.

This is part of an effort to reduce structure sizes for machines
configured with large NR_CPUS.  cpumask_t gets replaced by
cpumask_var_t, which is either struct cpumask[1] (small NR_CPUS) or
struct cpumask * (large NR_CPUS).

(Changes to powernow-k* by <travis>.)
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NMike Travis <travis@sgi.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NMike Day <ncmike@ncultra.org>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

These two IOMMUs can implement the current version of this API. So
select the API if one or both of these IOMMU drivers is selected.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

This API can be used by KVM for accessing different types of IOMMUs to
do device passthrough to guests. Beside that this API can also be used
by device drivers to map non-linear host memory into dma-linear
addresses to prevent sgather-gather DMA. UIO may be another user for
this API.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>

When domain is related to multiple iommus, need to check if the minimum agaw is sufficient for the mapped memory
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

These APIs are used by KVM to use VT-d
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

vm_domid won't be set in context, find available domain id for a device from its iommu.

For a virtual machine domain, a default agaw will be set, and skip top levels of page tables for iommu which has less agaw than default.
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

virtual machine domain is different from native DMA-API domain, implement separate allocation and free functions for virtual machine domain.
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Because virtual machine domain may have multiple devices from different iommus, it cannot use __iommu_flush_cache.

In some common low level functions, use domain_flush_cache instead of __iommu_flush_cache. On the other hand, in some functions, iommu can is specified or domain cannot be got, still use __iommu_flush_cache
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Add iommu reference count in domain, and add a lock to protect iommu setting including iommu_bmp, iommu_count and iommu_coherency.

virtual machine domain may have multiple devices from different iommus, so it needs to do more things when add/remove domain device info. Thus implement separate these functions for virtual machine domain.
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Add this flag for VT-d used in virtual machine, like KVM.
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

In dmar_domain, more than one iommus may be included in iommu_bmp. Due to "Coherency" capability may be different across iommus, set this variable to indicate iommu access is coherent or not. Only when all related iommus in a dmar_domain are all coherent, iommu access of this domain is coherent.
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

"SAGAW" capability may be different across iommus. Use a default agaw, but if default agaw is not supported in some iommus, choose a less supported agaw.
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

In order to support assigning multiple devices from different iommus to a domain, iommu bitmap is used to keep all iommus the domain are related to.
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

deferred_flush[] uses the iommu seq_id to index, so its iommu is fixed and can get it from g_iommus.
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

It's random number after the domain is allocated by kmem_cache_alloc
Signed-off-by: NWeidong Han <weidong.han@intel.com>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>