This patch converts dm-multipath target to request-based from bio-based.
Basically, the patch just converts the I/O unit from struct bio
to struct request.
In the course of the conversion, it also changes the I/O queueing
mechanism. The change in the I/O queueing is described in details
as follows.
I/O queueing mechanism change
-----------------------------
In I/O submission, map_io(), there is no mechanism change from
bio-based, since the clone request is ready for retry as it is.
However, in I/O complition, do_end_io(), there is a mechanism change
from bio-based, since the clone request is not ready for retry.
In do_end_io() of bio-based, the clone bio has all needed memory
for resubmission. So the target driver can queue it and resubmit
it later without memory allocations.
The mechanism has almost no overhead.
On the other hand, in do_end_io() of request-based, the clone request
doesn't have clone bios, so the target driver can't resubmit it
as it is. To resubmit the clone request, memory allocation for
clone bios is needed, and it takes some overheads.
To avoid the overheads just for queueing, the target driver doesn't
queue the clone request inside itself.
Instead, the target driver asks dm core for queueing and remapping
the original request of the clone request, since the overhead for
queueing is just a freeing memory for the clone request.
As a result, the target driver doesn't need to record/restore
the information of the original request for resubmitting
the clone request. So dm_bio_details in dm_mpath_io is removed.
multipath_busy()
---------------------
The target driver returns "busy", only when the following case:
o The target driver will map I/Os, if map() function is called
and
o The mapped I/Os will wait on underlying device's queue due to
their congestions, if map() function is called now.
In other cases, the target driver doesn't return "busy".
Otherwise, dm core will keep the I/Os and the target driver can't
do what it wants.
(e.g. the target driver can't map I/Os now, so wants to kill I/Os.)
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Acked-by: Hannes Reinecke <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
Request-based dm doesn't have barrier support yet.
So we need to set QUEUE_ORDERED_DRAIN only for bio-based dm.
Since the device type is decided at the first table loading time,
the flag set is deferred until then.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Acked-by: Hannes Reinecke <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
This patch adds core functions for request-based dm.
When struct mapped device (md) is initialized, md->queue has
an I/O scheduler and the following functions are used for
request-based dm as the queue functions:
make_request_fn: dm_make_request()
pref_fn: dm_prep_fn()
request_fn: dm_request_fn()
softirq_done_fn: dm_softirq_done()
lld_busy_fn: dm_lld_busy()
Actual initializations are done in another patch (PATCH 2).
Below is a brief summary of how request-based dm behaves, including:
- making request from bio
- cloning, mapping and dispatching request
- completing request and bio
- suspending md
- resuming md
bio to request
==============
md->queue->make_request_fn() (dm_make_request()) calls __make_request()
for a bio submitted to the md.
Then, the bio is kept in the queue as a new request or merged into
another request in the queue if possible.
Cloning and Mapping
===================
Cloning and mapping are done in md->queue->request_fn() (dm_request_fn()),
when requests are dispatched after they are sorted by the I/O scheduler.
dm_request_fn() checks busy state of underlying devices using
target's busy() function and stops dispatching requests to keep them
on the dm device's queue if busy.
It helps better I/O merging, since no merge is done for a request
once it is dispatched to underlying devices.
Actual cloning and mapping are done in dm_prep_fn() and map_request()
called from dm_request_fn().
dm_prep_fn() clones not only request but also bios of the request
so that dm can hold bio completion in error cases and prevent
the bio submitter from noticing the error.
(See the "Completion" section below for details.)
After the cloning, the clone is mapped by target's map_rq() function
and inserted to underlying device's queue using
blk_insert_cloned_request().
Completion
==========
Request completion can be hooked by rq->end_io(), but then, all bios
in the request will have been completed even error cases, and the bio
submitter will have noticed the error.
To prevent the bio completion in error cases, request-based dm clones
both bio and request and hooks both bio->bi_end_io() and rq->end_io():
bio->bi_end_io(): end_clone_bio()
rq->end_io(): end_clone_request()
Summary of the request completion flow is below:
blk_end_request() for a clone request
=> blk_update_request()
=> bio->bi_end_io() == end_clone_bio() for each clone bio
=> Free the clone bio
=> Success: Complete the original bio (blk_update_request())
Error: Don't complete the original bio
=> blk_finish_request()
=> rq->end_io() == end_clone_request()
=> blk_complete_request()
=> dm_softirq_done()
=> Free the clone request
=> Success: Complete the original request (blk_end_request())
Error: Requeue the original request
end_clone_bio() completes the original request on the size of
the original bio in successful cases.
Even if all bios in the original request are completed by that
completion, the original request must not be completed yet to keep
the ordering of request completion for the stacking.
So end_clone_bio() uses blk_update_request() instead of
blk_end_request().
In error cases, end_clone_bio() doesn't complete the original bio.
It just frees the cloned bio and gives over the error handling to
end_clone_request().
end_clone_request(), which is called with queue lock held, completes
the clone request and the original request in a softirq context
(dm_softirq_done()), which has no queue lock, to avoid a deadlock
issue on submission of another request during the completion:
- The submitted request may be mapped to the same device
- Request submission requires queue lock, but the queue lock
has been held by itself and it doesn't know that
The clone request has no clone bio when dm_softirq_done() is called.
So target drivers can't resubmit it again even error cases.
Instead, they can ask dm core for requeueing and remapping
the original request in that cases.
suspend
=======
Request-based dm uses stopping md->queue as suspend of the md.
For noflush suspend, just stops md->queue.
For flush suspend, inserts a marker request to the tail of md->queue.
And dispatches all requests in md->queue until the marker comes to
the front of md->queue. Then, stops dispatching request and waits
for the all dispatched requests to complete.
After that, completes the marker request, stops md->queue and
wake up the waiter on the suspend queue, md->wait.
resume
======
Starts md->queue.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
This patch adds a service time oriented dynamic load balancer,
dm-service-time, which selects the path with the shortest estimated
service time for the incoming I/O.
The service time is estimated by dividing the in-flight I/O size
by a performance value of each path.
The performance value can be given as a table argument at the table
loading time. If no performance value is given, all paths are
considered equal.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
This patch makes two additions to the dm path selector interface for
dynamic load balancers:
o a new hook, start_io()
o a new parameter 'nr_bytes' to select_path()/start_io()/end_io()
to pass the size of the I/O
start_io() is called when a target driver actually submits I/O
to the selected path.
Path selectors can use it to start accounting of the I/O.
(e.g. counting the number of in-flight I/Os.)
The start_io hook is based on the patch posted by Stefan Bader:
https://www.redhat.com/archives/dm-devel/2005-October/msg00050.html
nr_bytes, the size of the I/O, is so path selectors can take the
size of the I/O into account when deciding which path to use.
dm-service-time uses it to estimate service time, for example.
(Added the nr_bytes member to dm_mpath_io instead of using existing
details.bi_size, since request-based dm patch deletes it.)
Signed-off-by: Stefan Bader <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
This patch adds the following 2 interfaces for request-stacking drivers:
- blk_rq_prep_clone(struct request *clone, struct request *orig,
struct bio_set *bs, gfp_t gfp_mask,
int (*bio_ctr)(struct bio *, struct bio*, void *),
void *data)
* Clones bios in the original request to the clone request
(bio_ctr is called for each cloned bios.)
* Copies attributes of the original request to the clone request.
The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not
copied.
- blk_rq_unprep_clone(struct request *clone)
* Frees cloned bios from the clone request.
Request stacking drivers (e.g. request-based dm) need to make a clone
request for a submitted request and dispatch it to other devices.
To allocate request for the clone, request stacking drivers may not
be able to use blk_get_request() because the allocation may be done
in an irq-disabled context.
So blk_rq_prep_clone() takes a request allocated by the caller
as an argument.
For each clone bio in the clone request, request stacking drivers
should be able to set up their own completion handler.
So blk_rq_prep_clone() takes a callback function which is called
for each clone bio, and a pointer for private data which is passed
to the callback.
NOTE:
blk_rq_prep_clone() doesn't copy any actual data of the original
request. Pages are shared between original bios and cloned bios.
So caller must not complete the original request before the clone
request.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Cc: Boaz Harrosh <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
I found one more mis-conversion to the 'request is always dequeued
when completing' model in elv_abort_queue() during code inspection.
Although I haven't hit any problem caused by this mis-conversion yet
and just done compile/boot test, please apply if you have no problem.
Request must be dequeued when it completes.
However, elv_abort_queue() completes requests without dequeueing.
This will cause oops in the __blk_end_request_all().
This patch fixes the oops.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
The commit below in 2.6-block/for-2.6.31 causes no diskstat problem
because the blk_discard_rq() check was added with '&&'.
It should be 'blk_fs_request() || blk_discard_rq()'.
This patch does it and fixes the no diskstat problem.
Please review and apply.
------ /proc/diskstat without this patch -------------------------------------
8 0 sda 0 0 0 0 0 0 0 0 0 0 0
------------------------------------------------------------------------------
----- /proc/diskstat with this patch applied ---------------------------------
8 0 sda 4186 303 373621 61600 9578 3859 107468 169479 2 89755 231059
------------------------------------------------------------------------------
--------------------------------------------------------------------------
commit c69d48540c
Author: Jens Axboe <[email protected]>
Date: Fri Apr 24 08:12:19 2009 +0200
block: include discard requests in IO accounting
We currently don't do merging on discard requests, but we potentially
could. If we do, then we need to include discard requests in the IO
accounting, or merging would end up decrementing in_flight IO counters
for an IO which never incremented them.
So enable accounting for discard requests.
<snip>
static inline int blk_do_io_stat(struct request *rq)
{
- return rq->rq_disk && blk_rq_io_stat(rq) && blk_fs_request(rq);
+ return rq->rq_disk && blk_rq_io_stat(rq) && blk_fs_request(rq) &&
+ blk_discard_rq(rq);
}
--------------------------------------------------------------------------
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch adds the following target interfaces for request-based dm.
map_rq : for mapping a request
rq_end_io : for finishing a request
busy : for avoiding performance regression from bio-based dm.
Target can tell dm core not to map requests now, and
that may help requests in the block layer queue to be
bigger by I/O merging.
In bio-based dm, this behavior is done by device
drivers managing the block layer queue.
But in request-based dm, dm core has to do that
since dm core manages the block layer queue.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
This patch implements q->lld_busy_fn() for scsi mid layer to export
its busy state for request stacking drivers.
For efficiency, no lock is taken to check the busy state of
shost/starget/sdev, since the returned value is not guaranteed and
may be changed after request stacking drivers call the function,
regardless of taking lock or not.
When scsi can't dispatch I/Os anymore and needs to kill I/Os
(e.g. !sdev), scsi needs to return 'not busy'.
Otherwise, request stacking drivers may hold requests forever.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: James Bottomley <[email protected]>
This patch refactors the busy checking codes of scsi_device,
Scsi_Host and scsi_target. There should be no functional change.
This is a preparation for another patch which exports scsi's busy
state to the block layer for request stacking drivers.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: James Bottomley <[email protected]>
This patch removes the DM_WQ_FLUSH_ALL state that is unnecessary.
The dm_queue_flush(md, DM_WQ_FLUSH_ALL, NULL) in dm_suspend()
is never invoked because:
- 'goto flush_and_out' is the same as 'goto out' because
the 'goto flush_and_out' is called only when '!noflush'
- If r is non-zero, then the code above will invoke 'goto out'
and skip this code.
No functional change.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Milan Broz <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
This patch moves 'is_active' from struct dm_path to struct pgpath
as it does not need exporting.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
This patch removes end_queued_request() and end_dequeued_request(),
which are no longer used.
As a results, users of __end_request() became only end_request().
So the actual code in __end_request() is moved to end_request()
and __end_request() is removed.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts elevator to use __blk_end_request() directly
so that end_{queued|dequeued}_request() can be removed.
Related 'uptodate' arguments is converted to 'error'.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts gdrom to use __blk_end_request() directly
so that end_{queued|dequeued}_request() can be removed.
gd.transfer is '1' in error cases and '0' in non-error cases,
so gdrom hasn't been propagating any error code to the block layer.
We can just convert error cases to '-EIO'.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Cc: Adrian McMenamin <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts memstick to use __blk_end_request() directly
so that end_{queued|dequeued}_request() can be removed.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Cc: Alex Dubov <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts virtio_blk to use __blk_end_request() directly
so that end_{queued|dequeued}_request() can be removed.
Related 'uptodate' argument is converted to 'error'.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Cc: Rusty Russell <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch adds an new interface, blk_lld_busy(), to check lld's
busy state from the block layer.
blk_lld_busy() calls down into low-level drivers for the checking
if the drivers set q->lld_busy_fn() using blk_queue_lld_busy().
This resolves a performance problem on request stacking devices below.
Some drivers like scsi mid layer stop dispatching request when
they detect busy state on its low-level device like host/target/device.
It allows other requests to stay in the I/O scheduler's queue
for a chance of merging.
Request stacking drivers like request-based dm should follow
the same logic.
However, there is no generic interface for the stacked device
to check if the underlying device(s) are busy.
If the request stacking driver dispatches and submits requests to
the busy underlying device, the requests will stay in
the underlying device's queue without a chance of merging.
This causes performance problem on burst I/O load.
With this patch, busy state of the underlying device is exported
via q->lld_busy_fn(). So the request stacking driver can check it
and stop dispatching requests if busy.
The underlying device driver must return the busy state appropriately:
1: when the device driver can't process requests immediately.
0: when the device driver can process requests immediately,
including abnormal situations where the device driver needs
to kill all requests.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Cc: Andrew Morton <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch adds a queue flag to indicate the block device can be
used for request stacking.
Request stacking drivers need to stack their devices on top of
only devices of which q->request_fn is functional.
Since bio stacking drivers (e.g. md, loop) basically initialize
their queue using blk_alloc_queue() and don't set q->request_fn,
the check of (q->request_fn == NULL) looks enough for that purpose.
However, dm will become both types of stacking driver (bio-based and
request-based). And dm will always set q->request_fn even if the dm
device is bio-based of which q->request_fn is not functional actually.
So we need something else to distinguish the type of the device.
Adding a queue flag is a solution for that.
The reason why dm always sets q->request_fn is to keep
the compatibility of dm user-space tools.
Currently, all dm user-space tools are using bio-based dm without
specifying the type of the dm device they use.
To use request-based dm without changing such tools, the kernel
must decide the type of the dm device automatically.
The automatic type decision can't be done at the device creation time
and needs to be deferred until such tools load a mapping table,
since the actual type is decided by dm target type included in
the mapping table.
So a dm device has to be initialized using blk_init_queue()
so that we can load either type of table.
Then, all queue stuffs are set (e.g. q->request_fn) and we have
no element to distinguish that it is bio-based or request-based,
even after a table is loaded and the type of the device is decided.
By the way, some stuffs of the queue (e.g. request_list, elevator)
are needless when the dm device is used as bio-based.
But the memory size is not so large (about 20[KB] per queue on ia64),
so I hope the memory loss can be acceptable for bio-based dm users.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch adds blk_insert_cloned_request(), a generic request
submission interface for request stacking drivers.
Request-based dm will use it to submit their clones to underlying
devices.
blk_rq_check_limits() is also added because it is possible that
the lower queue has stronger limitations than the upper queue
if multiple drivers are stacking at request-level.
Not only for blk_insert_cloned_request()'s internal use, the function
will be used by request-based dm when the queue limitation is
modified (e.g. by replacing dm's table).
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch adds blk_update_request(), which updates struct request
with completing its data part, but doesn't complete the struct
request itself.
Though it looks like end_that_request_first() of older kernels,
blk_update_request() should be used only by request stacking drivers.
Request-based dm will use it in bio->bi_end_io callback to update
the original request when a data part of a cloned request completes.
Followings are additional background information of why request-based
dm needs this interface.
- Request stacking drivers can't use blk_end_request() directly from
the lower driver's completion context (bio->bi_end_io or rq->end_io),
because some device drivers (e.g. ide) may try to complete
their request with queue lock held, and it may cause deadlock.
See below for detailed description of possible deadlock:
<http://marc.info/?l=linux-kernel&m=120311479108569&w=2>
- To solve that, request-based dm offloads the completion of
cloned struct request to softirq context (i.e. using
blk_complete_request() from rq->end_io).
- Though it is possible to use the same solution from bio->bi_end_io,
it will delay the notification of bio completion to the original
submitter. Also, it will cause inefficient partial completion,
because the lower driver can't perform the cloned request anymore
and request-based dm needs to requeue and redispatch it to
the lower driver again later. That's not good.
- So request-based dm needs blk_update_request() to perform the bio
completion in the lower driver's completion context, which is more
efficient.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch fixes the missing residual count setting in DMA mode,
which was introduced during the conversion to blk-end-request.
The residual count could be used by the request submitter.
So if it isn't set correctly, some upper layers does not work.
(e.g. wodim for CD burning.)
The bug is in only DMA mode.
In PIO mode, we are setting the residual count correctly,
so no need to fix.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Reported-by: Andreas Schwab <[email protected]>
Tested-by: Andreas Schwab <[email protected]>
Tested-by: Laura Garcia <[email protected]>
Tested-by: Borislav Petkov <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Bartlomiej Zolnierkiewicz <[email protected]>
I have reviewed all blk-end-request patches again to confirm whether
there are any similar problems with the last week's ide-cd panic:
http://lkml.org/lkml/2008/1/29/140
And I found a possible similar bug in ide-io change:
ide_end_drive_cmd() could be called for blk_pc_request() which could
have bios. To complete such requests correctly, we need to pass
the actual size of the request.
Otherwise, __blk_end_request() returns 1 because the request still has
bios, and the system will BUG() unnecessarily.
The following patch fixes the bug and should be applied on top of
Linus' git.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Bartlomiej Zolnierkiewicz <[email protected]>
This patch converts xsysace to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
xsysace is a little bit different from "normal" drivers.
xsysace driver has a state machine in it.
It calls end_that_request_first() and end_that_request_last()
from different states. (ACE_FSM_STATE_REQ_TRANSFER and
ACE_FSM_STATE_REQ_COMPLETE, respectively.)
However, those states are consecutive and without any interruption
inbetween.
So we can just follow the standard conversion rule (b) mentioned in
the patch subject "[PATCH 01/30] blk_end_request: add new request
completion interface".
Cc: Grant Likely <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts ub to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
Cc: Pete Zaitcev <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch merges complete_request() into end_that_request_last()
for cleanup.
complete_request() was introduced by earlier part of this patch-set,
not to break the existing users of end_that_request_last().
Since all users are converted to blk_end_request interfaces and
end_that_request_last() is no longer exported, the code can be
merged to end_that_request_last().
Cc: Boaz Harrosh <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts 'uptodate' arguments of no longer exported
interfaces, end_that_request_first/last, to 'error', and removes
internal conversions for it in blk_end_request interfaces.
Also, this patch removes no longer needed end_io_error().
Cc: Boaz Harrosh <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch removes the following functions:
o end_that_request_first()
o end_that_request_chunk()
and stops exporting the functions below:
o end_that_request_last()
Cc: Boaz Harrosh <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts scsi mid-layer to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
As a result, the interface of internal function, scsi_end_request(),
is changed.
Cc: James Bottomley <[email protected]>
Cc: Boaz Harrosh <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch adds a variant of the interface, blk_end_bidi_request(),
which completes a bidi request.
Bidi request must be completed as a whole, both rq and rq->next_rq
at once. So the interface has 2 arguments for completion size.
As for ->end_io, only rq->end_io is called (rq->next_rq->end_io is not
called). So if special completion handling is needed, the handler
must be set to rq->end_io.
And the handler must take care of freeing next_rq too, since
the interface doesn't care of it if rq->end_io is not NULL.
Cc: Boaz Harrosh <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts ide-cd (cdrom_newpc_intr()) to use blk_end_request
interfaces. Related 'uptodate' arguments are converted to 'error'.
In PIO mode, ide-cd (cdrom_newpc_intr()) needs to defer
end_that_request_last() until the device clears DRQ_STAT and raises
an interrupt after end_that_request_first().
So blk_end_request() has to return without completing request
even if no leftover in the request.
ide-cd uses blk_end_request_callback() and a dummy callback function,
which just returns value '1', to tell blk_end_request_callback()
about that.
Cc: Bartlomiej Zolnierkiewicz <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch adds a variant of the interface, blk_end_request_callback(),
which has driver callback feature.
Drivers may need to do special works between end_that_request_first()
and end_that_request_last().
For such drivers, blk_end_request_callback() allows it to pass
a callback function which is called between end_that_request_first()
and end_that_request_last().
This interface is only for fallback of other blk_end_request interfaces.
Drivers should avoid their tricky behaviors and use other interfaces
as much as possible.
Currently, only one driver, ide-cd, needs this interface.
So this interface should/will be removed, after the driver removes
such tricky behaviors.
o ide-cd (cdrom_newpc_intr())
In PIO mode, cdrom_newpc_intr() needs to defer end_that_request_last()
until the device clears DRQ_STAT and raises an interrupt after
end_that_request_first().
So end_that_request_first() and end_that_request_last() are called
separately in cdrom_newpc_intr().
This means blk_end_request_callback() has to return without
completing request even if no leftover in the request.
To satisfy the requirement, callback function has return value
so that drivers can tell blk_end_request_callback() to return
without completing request.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts "normal" parts of ide to use blk_end_request
interfaces. Related 'uptodate' arguments are converted to 'error'.
The conversion of 'uptodate' to 'error' is done only for the internal
function, __ide_end_request().
ide_end_request() was not changed since it's exported and used
by many ide drivers.
With this patch, blkdev_dequeue_request() in __ide_end_request() is
moved to blk_end_request, since blk_end_request takes care of
dequeueing request like below:
if (!list_empty(&rq->queuelist))
blkdev_dequeue_request(rq);
In the case of ide,
o 'dequeue' variable of __ide_end_request() is 1 only when the request
is still linked to the queue (i.e. rq->queuelist is not empty)
o 'dequeue' variable of __ide_end_request() is 0 only when the request
has already been removed from the queue (i.e. rq->queuelist is empty)
So blk_end_request can handle it correctly although ide always run
thought the code above.
Cc: Bartlomiej Zolnierkiewicz <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts cpqarray to use blk_end_request interfaces.
Related 'ok' arguments are converted to 'error'.
cpqarray is a little bit different from "normal" drivers.
cpqarray directly calls bio_endio() and disk_stat_add()
when completing request. But those can be replaced with
__end_that_request_first().
After the replacement, request completion procedures of
those drivers become like the following:
o end_that_request_first()
o add_disk_randomness()
o end_that_request_last()
This can be converted to __blk_end_request() by following
the rule (b) mentioned in the patch subject
"[PATCH 01/30] blk_end_request: add new request completion interface".
Cc: Mike Miller <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts cciss to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
cciss is a little bit different from "normal" drivers.
cciss directly calls bio_endio() and disk_stat_add()
when completing request. But those can be replaced with
__end_that_request_first().
After the replacement, request completion procedures of
those drivers become like the following:
o end_that_request_first()
o add_disk_randomness()
o end_that_request_last()
This can be converted to blk_end_request() by following
the rule (a) mentioned in the patch subject
"[PATCH 01/30] blk_end_request: add new request completion interface".
Cc: Mike Miller <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts s390 to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
As a result, the interfaces of internal functions below are changed:
o dasd_end_request
o tapeblock_end_request
Cc: Martin Schwidefsky <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: [email protected]
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts mmc to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
Cc: Pierre Ossman <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts i2o_block to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
As a result, the interface of internal function, i2o_block_end_request(),
is changed.
Cc: Markus Lidel <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts viocd to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
As a result, the interface of internal function, viocd_end_request(),
is changed.
Cc: Stephen Rothwell <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts xen-blkfront to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
Cc: Jeremy Fitzhardinge <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts viodasd to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
As a result, the interface of internal function, viodasd_end_request(),
is changed.
Cc: Stephen Rothwell <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts sx8 to use blk_end_request interfaces.
Related 'uptodate' and 'is_ok' arguments are converted to 'error'.
As a result, the interfaces of internal functions below are changed.
o carm_end_request_queued
o carm_end_rq
o carm_handle_array_info
o carm_handle_scan_chan
o carm_handle_generic
o carm_handle_rw
The 'is_ok' is set at only one place in carm_handle_resp() below:
int is_ok = (status == RMSG_OK);
And the value is propagated to all functions above, and no modification
in other places.
So the actual conversion of the 'is_ok' is done at only one place above.
Cc: Jeff Garzik <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts sunvdc to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
As a result, the interface of internal function, vdc_end_request(),
is changed.
Cc: David S. Miller <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts nbd to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
Cc: Paul Clements <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts floppy to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
As a result, the interface of internal function, floppy_end_request(),
is changed.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts DAC960 to use blk_end_request interfaces.
Related 'UpToDate' arguments are converted to 'Error'.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts um to use blk_end_request interfaces.
Related 'uptodate' arguments are converted to 'error'.
As a result, the interface of internal function, ubd_end_request(),
is changed.
Cc: Jeff Dike <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts arm's OMAP mailbox driver to use
blk_end_request interfaces.
If the original code was converted literally, blk_end_request would
be called with '-EIO' because end_that_request_last() were called
with '0' (i.e. failure).
But I think these '0's are bugs in the original code because it's
unlikely that all requests are treated as failure.
(The bugs should have no effect unless these requests have an end_io
callback.)
So I changed them to pass '0' (i.e. success) to blk_end_request.
Cc: Toshihiro Kobayashi <[email protected]>
Cc: Hiroshi DOYU <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch converts core parts of block layer to use blk_end_request
interfaces. Related 'uptodate' arguments are converted to 'error'.
'dequeue' argument was originally introduced for end_dequeued_request(),
where no attempt should be made to dequeue the request as it's already
dequeued.
However, it's not necessary as it can be checked with
list_empty(&rq->queuelist).
(Dequeued request has empty list and queued request doesn't.)
And it has been done in blk_end_request interfaces.
As a result of this patch, end_queued_request() and
end_dequeued_request() become identical. A future patch will merge
and rename them and change users of those functions.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch adds/exports functions to get the size of request in bytes.
They are useful because blk_end_request interfaces take bytes
as a completed I/O size instead of sectors.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This patch adds 2 new interfaces for request completion:
o blk_end_request() : called without queue lock
o __blk_end_request() : called with queue lock held
blk_end_request takes 'error' as an argument instead of 'uptodate',
which current end_that_request_* take.
The meanings of values are below and the value is used when bio is
completed.
0 : success
< 0 : error
Some device drivers call some generic functions below between
end_that_request_{first/chunk} and end_that_request_last().
o add_disk_randomness()
o blk_queue_end_tag()
o blkdev_dequeue_request()
These are called in the blk_end_request interfaces as a part of
generic request completion.
So all device drivers become to call above functions.
To decide whether to call blkdev_dequeue_request(), blk_end_request
uses list_empty(&rq->queuelist) (blk_queued_rq() macro is added for it).
So drivers must re-initialize it using list_init() or so before calling
blk_end_request if drivers use it for its specific purpose.
(Currently, there is no driver which completes request without
re-initializing the queuelist after used it. So rq->queuelist
can be used for the purpose above.)
"Normal" drivers can be converted to use blk_end_request()
in a standard way shown below.
a) end_that_request_{chunk/first}
spin_lock_irqsave()
(add_disk_randomness(), blk_queue_end_tag(), blkdev_dequeue_request())
end_that_request_last()
spin_unlock_irqrestore()
=> blk_end_request()
b) spin_lock_irqsave()
end_that_request_{chunk/first}
(add_disk_randomness(), blk_queue_end_tag(), blkdev_dequeue_request())
end_that_request_last()
spin_unlock_irqrestore()
=> spin_lock_irqsave()
__blk_end_request()
spin_unlock_irqsave()
c) spin_lock_irqsave()
(add_disk_randomness(), blk_queue_end_tag(), blkdev_dequeue_request())
end_that_request_last()
spin_unlock_irqrestore()
=> blk_end_request() or spin_lock_irqsave()
__blk_end_request()
spin_unlock_irqrestore()
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
Implement the pushback feature for the multipath target.
The pushback request is used when:
1) there are no valid paths;
2) queue_if_no_path was set;
3) a suspend is being issued with the DMF_NOFLUSH_SUSPENDING flag.
Otherwise bios are returned to applications with -EIO.
To check whether queue_if_no_path is specified or not, you need to check
both queue_if_no_path and saved_queue_if_no_path, because presuspend saves
the original queue_if_no_path value to saved_queue_if_no_path.
The check for 1 already exists in both map_io() and do_end_io().
So this patch adds __must_push_back() to check 2 and 3.
Test results:
See the test results in the preceding patch.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
Cc: [email protected]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
In device-mapper I/O is sometimes queued within targets for later processing.
For example the multipath target can be configured to store I/O when no paths
are available instead of returning it -EIO.
This patch allows the device-mapper core to instruct a target to transfer the
contents of any such in-target queue back into the core. This frees up the
resources used by the target so the core can replace that target with an
alternative one and then resend the I/O to it. Without this patch the only
way to change the target in such circumstances involves returning the I/O with
an error back to the filesystem/application. In the multipath case, this
patch will let us add new paths for existing I/O to try after all the existing
paths have failed.
DMF_NOFLUSH_SUSPENDING
----------------------
If the DM_NOFLUSH_FLAG ioctl option is specified at suspend time, the
DMF_NOFLUSH_SUSPENDING flag is set in md->flags during dm_suspend(). It
is always cleared before dm_suspend() returns.
The flag must be visible while the target is flushing pending I/Os so it
is set before presuspend where the flush starts and unset after the wait
for md->pending where the flush ends.
Target drivers can check this flag by calling dm_noflush_suspending().
DM_MAPIO_REQUEUE / DM_ENDIO_REQUEUE
-----------------------------------
A target's map() function can now return DM_MAPIO_REQUEUE to request the
device mapper core queue the bio.
Similarly, a target's end_io() function can return DM_ENDIO_REQUEUE to request
the same. This has been labelled 'pushback'.
The __map_bio() and clone_endio() functions in the core treat these return
values as errors and call dec_pending() to end the I/O.
dec_pending
-----------
dec_pending() saves the pushback request in struct dm_io->error. Once all
the split clones have ended, dec_pending() will put the original bio on
the md->pushback list. Note that this supercedes any I/O errors.
It is possible for the suspend with DM_NOFLUSH_FLAG to be aborted while
in progress (e.g. by user interrupt). dec_pending() checks for this and
returns -EIO if it happened.
pushdback list and pushback_lock
--------------------------------
The bio is queued on md->pushback temporarily in dec_pending(), and after
all pending I/Os return, md->pushback is merged into md->deferred in
dm_suspend() for re-issuing at resume time.
md->pushback_lock protects md->pushback.
The lock should be held with irq disabled because dec_pending() can be
called from interrupt context.
Queueing bios to md->pushback in dec_pending() must be done atomically
with the check for DMF_NOFLUSH_SUSPENDING flag. So md->pushback_lock is
held when checking the flag. Otherwise dec_pending() may queue a bio to
md->pushback after the interrupted dm_suspend() flushes md->pushback.
Then the bio would be left in md->pushback.
Flag setting in dm_suspend() can be done without md->pushback_lock because
the flag is checked only after presuspend and the set value is already
made visible via the target's presuspend function.
The flag can be checked without md->pushback_lock (e.g. the first part of
the dec_pending() or target drivers), because the flag is checked again
with md->pushback_lock held when the bio is really queued to md->pushback
as described above. So even if the flag is cleared after the lockless
checkings, the bio isn't left in md->pushback but returned to applications
with -EIO.
Other notes on the current patch
--------------------------------
- md->pushback is added to the struct mapped_device instead of using
md->deferred directly because md->io_lock which protects md->deferred is
rw_semaphore and can't be used in interrupt context like dec_pending(),
and md->io_lock protects the DMF_BLOCK_IO flag of md->flags too.
- Don't issue lock_fs() in dm_suspend() if the DM_NOFLUSH_FLAG
ioctl option is specified, because I/Os generated by lock_fs() would be
pushed back and never return if there were no valid devices.
- If an error occurs in dm_suspend() after the DMF_NOFLUSH_SUSPENDING
flag is set, md->pushback must be flushed because I/Os may be queued to
the list already. (flush_and_out label in dm_suspend())
Test results
------------
I have tested using multipath target with the next patch.
The following tests are for regression/compatibility:
- I/Os succeed when valid paths exist;
- I/Os fail when there are no valid paths and queue_if_no_path is not
set;
- I/Os are queued in the multipath target when there are no valid paths and
queue_if_no_path is set;
- The queued I/Os above fail when suspend is issued without the
DM_NOFLUSH_FLAG ioctl option. I/Os spanning 2 multipath targets also
fail.
The following tests are for the normal code path of new pushback feature:
- Queued I/Os in the multipath target are flushed from the target
but don't return when suspend is issued with the DM_NOFLUSH_FLAG
ioctl option;
- The I/Os above are queued in the multipath target again when
resume is issued without path recovery;
- The I/Os above succeed when resume is issued after path recovery
or table load;
- Queued I/Os in the multipath target succeed when resume is issued
with the DM_NOFLUSH_FLAG ioctl option after table load. I/Os
spanning 2 multipath targets also succeed.
The following tests are for the error paths of the new pushback feature:
- When the bdget_disk() fails in dm_suspend(), the
DMF_NOFLUSH_SUSPENDING flag is cleared and I/Os already queued to the
pushback list are flushed properly.
- When suspend with the DM_NOFLUSH_FLAG ioctl option is interrupted,
o I/Os which had already been queued to the pushback list
at the time don't return, and are re-issued at resume time;
o I/Os which hadn't been returned at the time return with EIO.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
Cc: [email protected]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Provide a dm ioctl option to request noflush suspending. (See next patch for
what this is for.) As the interface is extended, the version number is
incremented.
Other than accepting the new option through the interface, There is no change
to existing behaviour.
Test results:
Confirmed the option is given from user-space correctly.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
Cc: [email protected]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Update existing targets to use the new symbols for return values from target
map and end_io functions.
There is no effect on behaviour.
Test results:
Done build test without errors.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
Cc: [email protected]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Tighten the use of return values from the target map and end_io functions.
Values of 2 and above are now explictly reserved for future use. There are no
existing targets using such values.
The patch has no effect on existing behaviour.
o Reserve return values of 2 and above from target map functions.
Any positive value currently indicates "mapping complete", but all
existing drivers use the value 1. We now make that a requirement
so we can assign new meaning to higher values in future.
The new definition of return values from target map functions is:
< 0 : error
= 0 : The target will handle the io (DM_MAPIO_SUBMITTED).
= 1 : Mapping completed (DM_MAPIO_REMAPPED).
> 1 : Reserved (undefined). Previously this was the same as '= 1'.
o Reserve return values of 2 and above from target end_io functions
for similar reasons.
DM_ENDIO_INCOMPLETE is introduced for a return value of 1.
Test results:
I have tested by using the multipath target.
I/Os succeed when valid paths exist.
I/Os are queued in the multipath target when there are no valid paths and
queue_if_no_path is set.
I/Os fail when there are no valid paths and queue_if_no_path is not set.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
Cc: [email protected]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Change the interface of dm_suspend() so that we can pass several options
without increasing the number of parameters. The existing 'do_lockfs' integer
parameter is replaced by a flag DM_SUSPEND_LOCKFS_FLAG.
There is no functional change to the code.
Test results:
I have tested 'dmsetup suspend' command with/without the '--nolockfs'
option and confirmed the do_lockfs value is correctly set.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Alasdair G Kergon <[email protected]>
Cc: [email protected]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
An error path in table_load() forgets to release a table that won't now be
referenced.
Signed-off-by: Alasdair G Kergon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
When copying data from user-space to kernel-space by __copy_user(),
a page_not_present fault sometimes occurs at vmalloced kernel address
because of VHPT pre-fetching.
Ignore the page_not_present fault in ia64_do_page_fault() before
jumping into exception handlers.
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Signed-off-by: Tony Luck <[email protected]>
__cfq_get_queue(). __cfq_get_queue() finds an existing queue (struct
cfq_queue) of the current process for the device and returns it. If it's not
found, __cfq_get_queue() creates and returns a new one if __cfq_get_queue() is
called with __GFP_WAIT flag, or __cfq_get_queue() returns NULL (this means that
get_request() fails) if no __GFP_WAIT flag.
On the other hand, in __make_request(), get_request() is called without
__GFP_WAIT flag at the first time. Thus, the get_request() fails when there is
no existing queue, typically when it's called for the first I/O request of the
process to the device.
Though it will be followed by get_request_wait() for general case,
__make_request() will just end the I/O with an error (EWOULDBLOCK) when the
request was for read-ahead.
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Kiyoshi Ueda <[email protected]>
Signed-off-by: Jun'ichi Nomura <[email protected]>
Kiyoshi Ueda