There are many [__]blk_end_request() call sites which call it with
full request length and expect full completion. Many of them ensure
that the request actually completes by doing BUG_ON() the return
value, which is awkward and error-prone.
This patch adds [__]blk_end_request_all() which takes @rq and @error
and fully completes the request. BUG_ON() is added to to ensure that
this actually happens.
Most conversions are simple but there are a few noteworthy ones.
* cdrom/viocd: viocd_end_request() replaced with direct calls to
__blk_end_request_all().
* s390/block/dasd: dasd_end_request() replaced with direct calls to
__blk_end_request_all().
* s390/char/tape_block: tapeblock_end_request() replaced with direct
calls to blk_end_request_all().
[ Impact: cleanup ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Mike Miller <mike.miller@hp.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
rq->start_time was initialized in init_request_from_bio() so special
requests didn't have start_time set. This has been okay as start_time
has been used only for fs requests; however, there is no indication of
this actually is the case or not. Set rq->start_time in blk_rq_init()
and guarantee that all initialized rq's have its start_time set. This
improves consistency at virtually no cost and future changes will make
use of the timestamp for !bio requests.
[ Impact: rq->start_time is valid for all requests ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Request completion has gone through several changes and became a bit
messy over the time. Clean it up.
1. end_that_request_data() is a thin wrapper around
end_that_request_data_first() which checks whether bio is NULL
before doing anything and handles bidi completion.
blk_update_request() is a thin wrapper around
end_that_request_data() which clears nr_sectors on the last
iteration but doesn't use the bidi completion.
Clean it up by moving the initial bio NULL check and nr_sectors
clearing on the last iteration into end_that_request_data() and
renaming it to blk_update_request(), which makes blk_end_io() the
only user of end_that_request_data(). Collapse
end_that_request_data() into blk_end_io().
2. There are four visible completion variants - blk_end_request(),
__blk_end_request(), blk_end_bidi_request() and end_request().
blk_end_request() and blk_end_bidi_request() uses blk_end_request()
as the backend but __blk_end_request() and end_request() use
separate implementation in __blk_end_request() due to different
locking rules.
blk_end_bidi_request() is identical to blk_end_io(). Collapse
blk_end_io() into blk_end_bidi_request(), separate out request
update into internal helper blk_update_bidi_request() and add
__blk_end_bidi_request(). Redefine [__]blk_end_request() as thin
inline wrappers around [__]blk_end_bidi_request().
3. As the whole request issue/completion usages are about to be
modified and audited, it's a good chance to convert completion
functions return bool which better indicates the intended meaning
of return values.
4. The function name end_that_request_last() is from the days when it
was a public interface and slighly confusing. Give it a proper
internal name - blk_finish_request().
5. Add description explaning that blk_end_bidi_request() can be safely
used for uni requests as suggested by Boaz Harrosh.
The only visible behavior change is from #1. nr_sectors counts are
cleared after the final iteration no matter which function is used to
complete the request. I couldn't find any place where the code
assumes those nr_sectors counters contain the values for the last
segment and this change is good as it makes the API much more
consistent as the end result is now same whether a request is
completed using [__]blk_end_request() alone or in combination with
blk_update_request().
API further cleaned up per Christoph's suggestion.
[ Impact: cleanup, rq->*nr_sectors always updated after req completion ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Boaz Harrosh <bharrosh@panasas.com>
Cc: Christoph Hellwig <hch@infradead.org>
With recent IDE updates, blk_end_request_callback() doesn't have any
user now. Kill it.
[ Impact: removal of unused convoluted interface ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Impact: code reorganization
elv_next_request() and elv_dequeue_request() are public block layer
interface than actual elevator implementation. They mostly deal with
how requests interact with block layer and low level drivers at the
beginning of rqeuest processing whereas __elv_next_request() is the
actual eleveator request fetching interface.
Move the two functions to blk-core.c. This prepares for further
interface cleanup.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reorder request completion functions such that
* All request completion functions are located together.
* Functions which are used by only one caller is put right above the
caller.
* end_request() is put after other completion functions but before
blk_update_request().
This change is for completion function cleanup which will follow.
[ Impact: cleanup, code reorganization ]
Signed-off-by: Tejun Heo <tj@kernel.org>
blk_insert_request() doesn't need to worry about REQ_SOFTBARRIER.
Don't set it. Combined with recent ide updates, REQ_SOFTBARRIER is
now only used in elevator proper and for discard requests.
[ Impact: cleanup ]
Signed-off-by: Tejun Heo <tj@kernel.org>
RQ_NOMERGE_FLAGS already clears defines which REQ flags aren't
mergeable. There is no reason to specify it superflously. It only
adds to confusion. Don't set REQ_NOMERGE for barriers and requests
with specific queueing directive. REQ_NOMERGE is now exclusively used
by the merging code.
[ Impact: cleanup ]
Signed-off-by: Tejun Heo <tj@kernel.org>
blk_start_queueing() is identical to __blk_run_queue() except that it
doesn't check for recursion. None of the current users depends on
blk_start_queueing() running request_fn directly. Replace usages of
blk_start_queueing() with [__]blk_run_queue() and kill it.
[ Impact: removal of mostly duplicate interface function ]
Signed-off-by: Tejun Heo <tj@kernel.org>
__blk_run_queue wraps blk_invoke_request_fn() such that it
additionally removes plug and bails out early if the queue is empty.
Both extra operations have their own pending mechanisms and don't
cause any harm correctness-wise when they are done superflously.
The only user of blk_invoke_request_fn() being blk_start_queue(),
there isn't much reason to keep both functions around. Merge
blk_invoke_request_fn() into __blk_run_queue() and make
blk_start_queue() use __blk_run_queue() instead.
[ Impact: merge two subtly different internal functions ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Impact: subtle behavior change
For fs requests, rq is only carrier of bios and rq error status as a
whole doesn't mean much. This is the reason why rq->errors is being
cleared on each partial completion of a request as on each partial
completion the error status is transferred to the respective bios.
For pc requests, rq->errors is used to carry error status to the
issuer and thus __end_that_request_first() doesn't clear it on such
cases.
The condition was fine till now as only fs and pc requests have used
bio and thus the bio completion path. However, future changes will
unify data accesses to bio and all non fs users care about rq error
status. Clear rq->errors on bio completion only for fs requests.
In general, the implicit clearing is a bit too subtle especially as
the meaning of rq->errors is completely dependent on low level
drivers. Unifying / cleaning up rq->errors usage and letting llds
manage it would be better. TODO comment added.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
This simplifies I/O stat accounting switching code and separates it
completely from I/O scheduler switch code.
Requests are accounted according to the state of their request queue
at the time of the request allocation. There is no need anymore to
flush the request queue when switching I/O accounting state.
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
branch tracer, intel-iommu: fix build with CONFIG_BRANCH_TRACER=y
branch tracer: Fix for enabling branch profiling makes sparse unusable
ftrace: Correct a text align for event format output
Update /debug/tracing/README
tracing/ftrace: alloc the started cpumask for the trace file
tracing, x86: remove duplicated #include
ftrace: Add check of sched_stopped for probe_sched_wakeup
function-graph: add proper initialization for init task
tracing/ftrace: fix missing include string.h
tracing: fix incorrect return type of ns2usecs()
tracing: remove CALLER_ADDR2 from wakeup tracer
blktrace: fix pdu_len when tracing packet command requests
blktrace: small cleanup in blk_msg_write()
blktrace: NUL-terminate user space messages
tracing: move scripts/trace/power.pl to scripts/tracing/power.pl
The request inherits the unplug flag from the bio, but it isn't actually
used. The bio flag stops at __make_request(), which tells it to unplug
after submission. Passing it on to the request doesn't make any sense.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This forces in_flight to be zero when turning off or on the I/O stat
accounting and stops updating I/O stats in attempt_merge() when
accounting is turned off.
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
By default, CFQ will anticipate more IO from a given io context if the
previously completed IO was sync. This used to be fine, since the only
sync IO was reads and O_DIRECT writes. But with more "normal" sync writes
being used now, we don't want to anticipate for those.
Add a bio/request flag that informs the IO scheduler that this is a sync
request that we should not idle for. Introduce WRITE_ODIRECT specifically
for O_DIRECT writes, and make sure that the other sync writes set this
flag.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For the older SSD devices that don't do command queuing, we do want to
enable plugging to get better merging.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This makes sure that we never wait on async IO for sync requests, instead
of doing the split on writes vs reads.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Put a WARN_ON in __blk_put_request if it is about to
leak bio(s). This is a serious bug that can happen in error
handling code paths.
For this to work I have fixed a couple of places in block/ where
request->bio != NULL ownership was not honored. And a small cleanup
at sg_io() while at it.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Some initial probe requests don't have disk->queue mapped yet, so we
can't rely on a non-NULL queue in blk_queue_io_stat(). Wrap it in
blk_do_io_stat().
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This allows us to turn off disk stat accounting completely, for the cases
where the 0.5-1% reduction in system time is important.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This fixes a "regression" from 2.6.28, where the barrier probes that file
systems may do would trigger additional end request warnings in dmesg.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Tejun Heo
Jerome Marchand
Linus Torvalds
Jens Axboe
Li Zefan
Boaz Harrosh