Merge branch 'for-linus' of ../linux-2.6-block into block-for-2.6.39/core
This merge creates two set of conflicts. One is simple context
conflicts caused by removal of throtl_scheduled_delayed_work() in
for-linus and removal of throtl_shutdown_timer_wq() in
for-2.6.39/core.
The other is caused by commit 255bb490c8 (block: blk-flush shouldn't
call directly into q->request_fn() __blk_run_queue()) in for-linus
crashing with FLUSH reimplementation in for-2.6.39/core. The conflict
isn't trivial but the resolution is straight-forward.
* __blk_run_queue() calls in flush_end_io() and flush_data_end_io()
should be called with @force_kblockd set to %true.
* elv_insert() in blk_kick_flush() should use
%ELEVATOR_INSERT_REQUEUE.
Both changes are to avoid invoking ->request_fn() directly from
request completion path and closely match the changes in the commit
255bb490c8.
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
index 4ed7b5c..d915c16 100644
--- a/Documentation/cgroups/blkio-controller.txt
+++ b/Documentation/cgroups/blkio-controller.txt
@@ -343,34 +343,6 @@
CFQ sysfs tunable
=================
-/sys/block/<disk>/queue/iosched/group_isolation
------------------------------------------------
-
-If group_isolation=1, it provides stronger isolation between groups at the
-expense of throughput. By default group_isolation is 0. In general that
-means that if group_isolation=0, expect fairness for sequential workload
-only. Set group_isolation=1 to see fairness for random IO workload also.
-
-Generally CFQ will put random seeky workload in sync-noidle category. CFQ
-will disable idling on these queues and it does a collective idling on group
-of such queues. Generally these are slow moving queues and if there is a
-sync-noidle service tree in each group, that group gets exclusive access to
-disk for certain period. That means it will bring the throughput down if
-group does not have enough IO to drive deeper queue depths and utilize disk
-capacity to the fullest in the slice allocated to it. But the flip side is
-that even a random reader should get better latencies and overall throughput
-if there are lots of sequential readers/sync-idle workload running in the
-system.
-
-If group_isolation=0, then CFQ automatically moves all the random seeky queues
-in the root group. That means there will be no service differentiation for
-that kind of workload. This leads to better throughput as we do collective
-idling on root sync-noidle tree.
-
-By default one should run with group_isolation=0. If that is not sufficient
-and one wants stronger isolation between groups, then set group_isolation=1
-but this will come at cost of reduced throughput.
-
/sys/block/<disk>/queue/iosched/slice_idle
------------------------------------------
On a faster hardware CFQ can be slow, especially with sequential workload.
diff --git a/block/blk-core.c b/block/blk-core.c
index 518dd42..74d496c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -149,39 +149,29 @@
static void req_bio_endio(struct request *rq, struct bio *bio,
unsigned int nbytes, int error)
{
- struct request_queue *q = rq->q;
+ if (error)
+ clear_bit(BIO_UPTODATE, &bio->bi_flags);
+ else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
+ error = -EIO;
- if (&q->flush_rq != rq) {
- if (error)
- clear_bit(BIO_UPTODATE, &bio->bi_flags);
- else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
- error = -EIO;
-
- if (unlikely(nbytes > bio->bi_size)) {
- printk(KERN_ERR "%s: want %u bytes done, %u left\n",
- __func__, nbytes, bio->bi_size);
- nbytes = bio->bi_size;
- }
-
- if (unlikely(rq->cmd_flags & REQ_QUIET))
- set_bit(BIO_QUIET, &bio->bi_flags);
-
- bio->bi_size -= nbytes;
- bio->bi_sector += (nbytes >> 9);
-
- if (bio_integrity(bio))
- bio_integrity_advance(bio, nbytes);
-
- if (bio->bi_size == 0)
- bio_endio(bio, error);
- } else {
- /*
- * Okay, this is the sequenced flush request in
- * progress, just record the error;
- */
- if (error && !q->flush_err)
- q->flush_err = error;
+ if (unlikely(nbytes > bio->bi_size)) {
+ printk(KERN_ERR "%s: want %u bytes done, %u left\n",
+ __func__, nbytes, bio->bi_size);
+ nbytes = bio->bi_size;
}
+
+ if (unlikely(rq->cmd_flags & REQ_QUIET))
+ set_bit(BIO_QUIET, &bio->bi_flags);
+
+ bio->bi_size -= nbytes;
+ bio->bi_sector += (nbytes >> 9);
+
+ if (bio_integrity(bio))
+ bio_integrity_advance(bio, nbytes);
+
+ /* don't actually finish bio if it's part of flush sequence */
+ if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
+ bio_endio(bio, error);
}
void blk_dump_rq_flags(struct request *rq, char *msg)
@@ -390,13 +380,16 @@
* that its ->make_request_fn will not re-add plugging prior to calling
* this function.
*
+ * This function does not cancel any asynchronous activity arising
+ * out of elevator or throttling code. That would require elevaotor_exit()
+ * and blk_throtl_exit() to be called with queue lock initialized.
+ *
*/
void blk_sync_queue(struct request_queue *q)
{
del_timer_sync(&q->unplug_timer);
del_timer_sync(&q->timeout);
cancel_work_sync(&q->unplug_work);
- throtl_shutdown_timer_wq(q);
}
EXPORT_SYMBOL(blk_sync_queue);
@@ -457,6 +450,11 @@
kobject_put(&q->kobj);
}
+/*
+ * Note: If a driver supplied the queue lock, it should not zap that lock
+ * unexpectedly as some queue cleanup components like elevator_exit() and
+ * blk_throtl_exit() need queue lock.
+ */
void blk_cleanup_queue(struct request_queue *q)
{
/*
@@ -475,6 +473,8 @@
if (q->elevator)
elevator_exit(q->elevator);
+ blk_throtl_exit(q);
+
blk_put_queue(q);
}
EXPORT_SYMBOL(blk_cleanup_queue);
@@ -541,7 +541,9 @@
init_timer(&q->unplug_timer);
setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
INIT_LIST_HEAD(&q->timeout_list);
- INIT_LIST_HEAD(&q->pending_flushes);
+ INIT_LIST_HEAD(&q->flush_queue[0]);
+ INIT_LIST_HEAD(&q->flush_queue[1]);
+ INIT_LIST_HEAD(&q->flush_data_in_flight);
INIT_WORK(&q->unplug_work, blk_unplug_work);
kobject_init(&q->kobj, &blk_queue_ktype);
@@ -549,6 +551,12 @@
mutex_init(&q->sysfs_lock);
spin_lock_init(&q->__queue_lock);
+ /*
+ * By default initialize queue_lock to internal lock and driver can
+ * override it later if need be.
+ */
+ q->queue_lock = &q->__queue_lock;
+
return q;
}
EXPORT_SYMBOL(blk_alloc_queue_node);
@@ -633,7 +641,10 @@
q->unprep_rq_fn = NULL;
q->unplug_fn = generic_unplug_device;
q->queue_flags = QUEUE_FLAG_DEFAULT;
- q->queue_lock = lock;
+
+ /* Override internal queue lock with supplied lock pointer */
+ if (lock)
+ q->queue_lock = lock;
/*
* This also sets hw/phys segments, boundary and size
@@ -762,6 +773,25 @@
}
/*
+ * Determine if elevator data should be initialized when allocating the
+ * request associated with @bio.
+ */
+static bool blk_rq_should_init_elevator(struct bio *bio)
+{
+ if (!bio)
+ return true;
+
+ /*
+ * Flush requests do not use the elevator so skip initialization.
+ * This allows a request to share the flush and elevator data.
+ */
+ if (bio->bi_rw & (REQ_FLUSH | REQ_FUA))
+ return false;
+
+ return true;
+}
+
+/*
* Get a free request, queue_lock must be held.
* Returns NULL on failure, with queue_lock held.
* Returns !NULL on success, with queue_lock *not held*.
@@ -773,7 +803,7 @@
struct request_list *rl = &q->rq;
struct io_context *ioc = NULL;
const bool is_sync = rw_is_sync(rw_flags) != 0;
- int may_queue, priv;
+ int may_queue, priv = 0;
may_queue = elv_may_queue(q, rw_flags);
if (may_queue == ELV_MQUEUE_NO)
@@ -817,9 +847,11 @@
rl->count[is_sync]++;
rl->starved[is_sync] = 0;
- priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
- if (priv)
- rl->elvpriv++;
+ if (blk_rq_should_init_elevator(bio)) {
+ priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
+ if (priv)
+ rl->elvpriv++;
+ }
if (blk_queue_io_stat(q))
rw_flags |= REQ_IO_STAT;
@@ -1220,7 +1252,7 @@
spin_lock_irq(q->queue_lock);
if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
- where = ELEVATOR_INSERT_FRONT;
+ where = ELEVATOR_INSERT_FLUSH;
goto get_rq;
}
@@ -1805,7 +1837,7 @@
* normal IO on queueing nor completion. Accounting the
* containing request is enough.
*/
- if (blk_do_io_stat(req) && req != &req->q->flush_rq) {
+ if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) {
unsigned long duration = jiffies - req->start_time;
const int rw = rq_data_dir(req);
struct hd_struct *part;
diff --git a/block/blk-flush.c b/block/blk-flush.c
index b27d020..0bd8c9c 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -1,6 +1,69 @@
/*
* Functions to sequence FLUSH and FUA writes.
+ *
+ * Copyright (C) 2011 Max Planck Institute for Gravitational Physics
+ * Copyright (C) 2011 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ *
+ * REQ_{FLUSH|FUA} requests are decomposed to sequences consisted of three
+ * optional steps - PREFLUSH, DATA and POSTFLUSH - according to the request
+ * properties and hardware capability.
+ *
+ * If a request doesn't have data, only REQ_FLUSH makes sense, which
+ * indicates a simple flush request. If there is data, REQ_FLUSH indicates
+ * that the device cache should be flushed before the data is executed, and
+ * REQ_FUA means that the data must be on non-volatile media on request
+ * completion.
+ *
+ * If the device doesn't have writeback cache, FLUSH and FUA don't make any
+ * difference. The requests are either completed immediately if there's no
+ * data or executed as normal requests otherwise.
+ *
+ * If the device has writeback cache and supports FUA, REQ_FLUSH is
+ * translated to PREFLUSH but REQ_FUA is passed down directly with DATA.
+ *
+ * If the device has writeback cache and doesn't support FUA, REQ_FLUSH is
+ * translated to PREFLUSH and REQ_FUA to POSTFLUSH.
+ *
+ * The actual execution of flush is double buffered. Whenever a request
+ * needs to execute PRE or POSTFLUSH, it queues at
+ * q->flush_queue[q->flush_pending_idx]. Once certain criteria are met, a
+ * flush is issued and the pending_idx is toggled. When the flush
+ * completes, all the requests which were pending are proceeded to the next
+ * step. This allows arbitrary merging of different types of FLUSH/FUA
+ * requests.
+ *
+ * Currently, the following conditions are used to determine when to issue
+ * flush.
+ *
+ * C1. At any given time, only one flush shall be in progress. This makes
+ * double buffering sufficient.
+ *
+ * C2. Flush is deferred if any request is executing DATA of its sequence.
+ * This avoids issuing separate POSTFLUSHes for requests which shared
+ * PREFLUSH.
+ *
+ * C3. The second condition is ignored if there is a request which has
+ * waited longer than FLUSH_PENDING_TIMEOUT. This is to avoid
+ * starvation in the unlikely case where there are continuous stream of
+ * FUA (without FLUSH) requests.
+ *
+ * For devices which support FUA, it isn't clear whether C2 (and thus C3)
+ * is beneficial.
+ *
+ * Note that a sequenced FLUSH/FUA request with DATA is completed twice.
+ * Once while executing DATA and again after the whole sequence is
+ * complete. The first completion updates the contained bio but doesn't
+ * finish it so that the bio submitter is notified only after the whole
+ * sequence is complete. This is implemented by testing REQ_FLUSH_SEQ in
+ * req_bio_endio().
+ *
+ * The above peculiarity requires that each FLUSH/FUA request has only one
+ * bio attached to it, which is guaranteed as they aren't allowed to be
+ * merged in the usual way.
*/
+
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/bio.h>
@@ -11,58 +74,143 @@
/* FLUSH/FUA sequences */
enum {
- QUEUE_FSEQ_STARTED = (1 << 0), /* flushing in progress */
- QUEUE_FSEQ_PREFLUSH = (1 << 1), /* pre-flushing in progress */
- QUEUE_FSEQ_DATA = (1 << 2), /* data write in progress */
- QUEUE_FSEQ_POSTFLUSH = (1 << 3), /* post-flushing in progress */
- QUEUE_FSEQ_DONE = (1 << 4),
+ REQ_FSEQ_PREFLUSH = (1 << 0), /* pre-flushing in progress */
+ REQ_FSEQ_DATA = (1 << 1), /* data write in progress */
+ REQ_FSEQ_POSTFLUSH = (1 << 2), /* post-flushing in progress */
+ REQ_FSEQ_DONE = (1 << 3),
+
+ REQ_FSEQ_ACTIONS = REQ_FSEQ_PREFLUSH | REQ_FSEQ_DATA |
+ REQ_FSEQ_POSTFLUSH,
+
+ /*
+ * If flush has been pending longer than the following timeout,
+ * it's issued even if flush_data requests are still in flight.
+ */
+ FLUSH_PENDING_TIMEOUT = 5 * HZ,
};
-static struct request *queue_next_fseq(struct request_queue *q);
+static bool blk_kick_flush(struct request_queue *q);
-unsigned blk_flush_cur_seq(struct request_queue *q)
+static unsigned int blk_flush_policy(unsigned int fflags, struct request *rq)
{
- if (!q->flush_seq)
- return 0;
- return 1 << ffz(q->flush_seq);
-}
+ unsigned int policy = 0;
-static struct request *blk_flush_complete_seq(struct request_queue *q,
- unsigned seq, int error)
-{
- struct request *next_rq = NULL;
-
- if (error && !q->flush_err)
- q->flush_err = error;
-
- BUG_ON(q->flush_seq & seq);
- q->flush_seq |= seq;
-
- if (blk_flush_cur_seq(q) != QUEUE_FSEQ_DONE) {
- /* not complete yet, queue the next flush sequence */
- next_rq = queue_next_fseq(q);
- } else {
- /* complete this flush request */
- __blk_end_request_all(q->orig_flush_rq, q->flush_err);
- q->orig_flush_rq = NULL;
- q->flush_seq = 0;
-
- /* dispatch the next flush if there's one */
- if (!list_empty(&q->pending_flushes)) {
- next_rq = list_entry_rq(q->pending_flushes.next);
- list_move(&next_rq->queuelist, &q->queue_head);
- }
+ if (fflags & REQ_FLUSH) {
+ if (rq->cmd_flags & REQ_FLUSH)
+ policy |= REQ_FSEQ_PREFLUSH;
+ if (blk_rq_sectors(rq))
+ policy |= REQ_FSEQ_DATA;
+ if (!(fflags & REQ_FUA) && (rq->cmd_flags & REQ_FUA))
+ policy |= REQ_FSEQ_POSTFLUSH;
}
- return next_rq;
+ return policy;
}
-static void blk_flush_complete_seq_end_io(struct request_queue *q,
- unsigned seq, int error)
+static unsigned int blk_flush_cur_seq(struct request *rq)
{
- bool was_empty = elv_queue_empty(q);
- struct request *next_rq;
+ return 1 << ffz(rq->flush.seq);
+}
- next_rq = blk_flush_complete_seq(q, seq, error);
+static void blk_flush_restore_request(struct request *rq)
+{
+ /*
+ * After flush data completion, @rq->bio is %NULL but we need to
+ * complete the bio again. @rq->biotail is guaranteed to equal the
+ * original @rq->bio. Restore it.
+ */
+ rq->bio = rq->biotail;
+
+ /* make @rq a normal request */
+ rq->cmd_flags &= ~REQ_FLUSH_SEQ;
+ rq->end_io = NULL;
+}
+
+/**
+ * blk_flush_complete_seq - complete flush sequence
+ * @rq: FLUSH/FUA request being sequenced
+ * @seq: sequences to complete (mask of %REQ_FSEQ_*, can be zero)
+ * @error: whether an error occurred
+ *
+ * @rq just completed @seq part of its flush sequence, record the
+ * completion and trigger the next step.
+ *
+ * CONTEXT:
+ * spin_lock_irq(q->queue_lock)
+ *
+ * RETURNS:
+ * %true if requests were added to the dispatch queue, %false otherwise.
+ */
+static bool blk_flush_complete_seq(struct request *rq, unsigned int seq,
+ int error)
+{
+ struct request_queue *q = rq->q;
+ struct list_head *pending = &q->flush_queue[q->flush_pending_idx];
+ bool queued = false;
+
+ BUG_ON(rq->flush.seq & seq);
+ rq->flush.seq |= seq;
+
+ if (likely(!error))
+ seq = blk_flush_cur_seq(rq);
+ else
+ seq = REQ_FSEQ_DONE;
+
+ switch (seq) {
+ case REQ_FSEQ_PREFLUSH:
+ case REQ_FSEQ_POSTFLUSH:
+ /* queue for flush */
+ if (list_empty(pending))
+ q->flush_pending_since = jiffies;
+ list_move_tail(&rq->flush.list, pending);
+ break;
+
+ case REQ_FSEQ_DATA:
+ list_move_tail(&rq->flush.list, &q->flush_data_in_flight);
+ list_add(&rq->queuelist, &q->queue_head);
+ queued = true;
+ break;
+
+ case REQ_FSEQ_DONE:
+ /*
+ * @rq was previously adjusted by blk_flush_issue() for
+ * flush sequencing and may already have gone through the
+ * flush data request completion path. Restore @rq for
+ * normal completion and end it.
+ */
+ BUG_ON(!list_empty(&rq->queuelist));
+ list_del_init(&rq->flush.list);
+ blk_flush_restore_request(rq);
+ __blk_end_request_all(rq, error);
+ break;
+
+ default:
+ BUG();
+ }
+
+ return blk_kick_flush(q) | queued;
+}
+
+static void flush_end_io(struct request *flush_rq, int error)
+{
+ struct request_queue *q = flush_rq->q;
+ struct list_head *running = &q->flush_queue[q->flush_running_idx];
+ bool was_empty = elv_queue_empty(q);
+ bool queued = false;
+ struct request *rq, *n;
+
+ BUG_ON(q->flush_pending_idx == q->flush_running_idx);
+
+ /* account completion of the flush request */
+ q->flush_running_idx ^= 1;
+ elv_completed_request(q, flush_rq);
+
+ /* and push the waiting requests to the next stage */
+ list_for_each_entry_safe(rq, n, running, flush.list) {
+ unsigned int seq = blk_flush_cur_seq(rq);
+
+ BUG_ON(seq != REQ_FSEQ_PREFLUSH && seq != REQ_FSEQ_POSTFLUSH);
+ queued |= blk_flush_complete_seq(rq, seq, error);
+ }
/*
* Moving a request silently to empty queue_head may stall the
@@ -70,127 +218,154 @@
* from request completion path and calling directly into
* request_fn may confuse the driver. Always use kblockd.
*/
- if (was_empty && next_rq)
+ if (queued && was_empty)
__blk_run_queue(q, true);
}
-static void pre_flush_end_io(struct request *rq, int error)
+/**
+ * blk_kick_flush - consider issuing flush request
+ * @q: request_queue being kicked
+ *
+ * Flush related states of @q have changed, consider issuing flush request.
+ * Please read the comment at the top of this file for more info.
+ *
+ * CONTEXT:
+ * spin_lock_irq(q->queue_lock)
+ *
+ * RETURNS:
+ * %true if flush was issued, %false otherwise.
+ */
+static bool blk_kick_flush(struct request_queue *q)
{
- elv_completed_request(rq->q, rq);
- blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_PREFLUSH, error);
+ struct list_head *pending = &q->flush_queue[q->flush_pending_idx];
+ struct request *first_rq =
+ list_first_entry(pending, struct request, flush.list);
+
+ /* C1 described at the top of this file */
+ if (q->flush_pending_idx != q->flush_running_idx || list_empty(pending))
+ return false;
+
+ /* C2 and C3 */
+ if (!list_empty(&q->flush_data_in_flight) &&
+ time_before(jiffies,
+ q->flush_pending_since + FLUSH_PENDING_TIMEOUT))
+ return false;
+
+ /*
+ * Issue flush and toggle pending_idx. This makes pending_idx
+ * different from running_idx, which means flush is in flight.
+ */
+ blk_rq_init(q, &q->flush_rq);
+ q->flush_rq.cmd_type = REQ_TYPE_FS;
+ q->flush_rq.cmd_flags = WRITE_FLUSH | REQ_FLUSH_SEQ;
+ q->flush_rq.rq_disk = first_rq->rq_disk;
+ q->flush_rq.end_io = flush_end_io;
+
+ q->flush_pending_idx ^= 1;
+ elv_insert(q, &q->flush_rq, ELEVATOR_INSERT_REQUEUE);
+ return true;
}
static void flush_data_end_io(struct request *rq, int error)
{
- elv_completed_request(rq->q, rq);
- blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_DATA, error);
-}
-
-static void post_flush_end_io(struct request *rq, int error)
-{
- elv_completed_request(rq->q, rq);
- blk_flush_complete_seq_end_io(rq->q, QUEUE_FSEQ_POSTFLUSH, error);
-}
-
-static void init_flush_request(struct request *rq, struct gendisk *disk)
-{
- rq->cmd_type = REQ_TYPE_FS;
- rq->cmd_flags = WRITE_FLUSH;
- rq->rq_disk = disk;
-}
-
-static struct request *queue_next_fseq(struct request_queue *q)
-{
- struct request *orig_rq = q->orig_flush_rq;
- struct request *rq = &q->flush_rq;
-
- blk_rq_init(q, rq);
-
- switch (blk_flush_cur_seq(q)) {
- case QUEUE_FSEQ_PREFLUSH:
- init_flush_request(rq, orig_rq->rq_disk);
- rq->end_io = pre_flush_end_io;
- break;
- case QUEUE_FSEQ_DATA:
- init_request_from_bio(rq, orig_rq->bio);
- /*
- * orig_rq->rq_disk may be different from
- * bio->bi_bdev->bd_disk if orig_rq got here through
- * remapping drivers. Make sure rq->rq_disk points
- * to the same one as orig_rq.
- */
- rq->rq_disk = orig_rq->rq_disk;
- rq->cmd_flags &= ~(REQ_FLUSH | REQ_FUA);
- rq->cmd_flags |= orig_rq->cmd_flags & (REQ_FLUSH | REQ_FUA);
- rq->end_io = flush_data_end_io;
- break;
- case QUEUE_FSEQ_POSTFLUSH:
- init_flush_request(rq, orig_rq->rq_disk);
- rq->end_io = post_flush_end_io;
- break;
- default:
- BUG();
- }
-
- elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE);
- return rq;
-}
-
-struct request *blk_do_flush(struct request_queue *q, struct request *rq)
-{
- unsigned int fflags = q->flush_flags; /* may change, cache it */
- bool has_flush = fflags & REQ_FLUSH, has_fua = fflags & REQ_FUA;
- bool do_preflush = has_flush && (rq->cmd_flags & REQ_FLUSH);
- bool do_postflush = has_flush && !has_fua && (rq->cmd_flags & REQ_FUA);
- unsigned skip = 0;
+ struct request_queue *q = rq->q;
+ bool was_empty = elv_queue_empty(q);
/*
- * Special case. If there's data but flush is not necessary,
- * the request can be issued directly.
- *
- * Flush w/o data should be able to be issued directly too but
- * currently some drivers assume that rq->bio contains
- * non-zero data if it isn't NULL and empty FLUSH requests
- * getting here usually have bio's without data.
+ * After populating an empty queue, kick it to avoid stall. Read
+ * the comment in flush_end_io().
*/
- if (blk_rq_sectors(rq) && !do_preflush && !do_postflush) {
- rq->cmd_flags &= ~REQ_FLUSH;
- if (!has_fua)
- rq->cmd_flags &= ~REQ_FUA;
- return rq;
- }
+ if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error) && was_empty)
+ __blk_run_queue(q, true);
+}
+
+/**
+ * blk_insert_flush - insert a new FLUSH/FUA request
+ * @rq: request to insert
+ *
+ * To be called from elv_insert() for %ELEVATOR_INSERT_FLUSH insertions.
+ * @rq is being submitted. Analyze what needs to be done and put it on the
+ * right queue.
+ *
+ * CONTEXT:
+ * spin_lock_irq(q->queue_lock)
+ */
+void blk_insert_flush(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+ unsigned int fflags = q->flush_flags; /* may change, cache */
+ unsigned int policy = blk_flush_policy(fflags, rq);
+
+ BUG_ON(rq->end_io);
+ BUG_ON(!rq->bio || rq->bio != rq->biotail);
/*
- * Sequenced flushes can't be processed in parallel. If
- * another one is already in progress, queue for later
- * processing.
+ * @policy now records what operations need to be done. Adjust
+ * REQ_FLUSH and FUA for the driver.
*/
- if (q->flush_seq) {
- list_move_tail(&rq->queuelist, &q->pending_flushes);
- return NULL;
- }
-
- /*
- * Start a new flush sequence
- */
- q->flush_err = 0;
- q->flush_seq |= QUEUE_FSEQ_STARTED;
-
- /* adjust FLUSH/FUA of the original request and stash it away */
rq->cmd_flags &= ~REQ_FLUSH;
- if (!has_fua)
+ if (!(fflags & REQ_FUA))
rq->cmd_flags &= ~REQ_FUA;
- blk_dequeue_request(rq);
- q->orig_flush_rq = rq;
- /* skip unneded sequences and return the first one */
- if (!do_preflush)
- skip |= QUEUE_FSEQ_PREFLUSH;
- if (!blk_rq_sectors(rq))
- skip |= QUEUE_FSEQ_DATA;
- if (!do_postflush)
- skip |= QUEUE_FSEQ_POSTFLUSH;
- return blk_flush_complete_seq(q, skip, 0);
+ /*
+ * If there's data but flush is not necessary, the request can be
+ * processed directly without going through flush machinery. Queue
+ * for normal execution.
+ */
+ if ((policy & REQ_FSEQ_DATA) &&
+ !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
+ list_add(&rq->queuelist, &q->queue_head);
+ return;
+ }
+
+ /*
+ * @rq should go through flush machinery. Mark it part of flush
+ * sequence and submit for further processing.
+ */
+ memset(&rq->flush, 0, sizeof(rq->flush));
+ INIT_LIST_HEAD(&rq->flush.list);
+ rq->cmd_flags |= REQ_FLUSH_SEQ;
+ rq->end_io = flush_data_end_io;
+
+ blk_flush_complete_seq(rq, REQ_FSEQ_ACTIONS & ~policy, 0);
+}
+
+/**
+ * blk_abort_flushes - @q is being aborted, abort flush requests
+ * @q: request_queue being aborted
+ *
+ * To be called from elv_abort_queue(). @q is being aborted. Prepare all
+ * FLUSH/FUA requests for abortion.
+ *
+ * CONTEXT:
+ * spin_lock_irq(q->queue_lock)
+ */
+void blk_abort_flushes(struct request_queue *q)
+{
+ struct request *rq, *n;
+ int i;
+
+ /*
+ * Requests in flight for data are already owned by the dispatch
+ * queue or the device driver. Just restore for normal completion.
+ */
+ list_for_each_entry_safe(rq, n, &q->flush_data_in_flight, flush.list) {
+ list_del_init(&rq->flush.list);
+ blk_flush_restore_request(rq);
+ }
+
+ /*
+ * We need to give away requests on flush queues. Restore for
+ * normal completion and put them on the dispatch queue.
+ */
+ for (i = 0; i < ARRAY_SIZE(q->flush_queue); i++) {
+ list_for_each_entry_safe(rq, n, &q->flush_queue[i],
+ flush.list) {
+ list_del_init(&rq->flush.list);
+ blk_flush_restore_request(rq);
+ list_add_tail(&rq->queuelist, &q->queue_head);
+ }
+ }
}
static void bio_end_flush(struct bio *bio, int err)
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 36c8c1f..df649fa 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -176,13 +176,6 @@
blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS);
/*
- * If the caller didn't supply a lock, fall back to our embedded
- * per-queue locks
- */
- if (!q->queue_lock)
- q->queue_lock = &q->__queue_lock;
-
- /*
* by default assume old behaviour and bounce for any highmem page
*/
blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 41fb691..261c75c 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -471,8 +471,6 @@
blk_sync_queue(q);
- blk_throtl_exit(q);
-
if (rl->rq_pool)
mempool_destroy(rl->rq_pool);
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index e36cc10..061dee6 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -968,7 +968,7 @@
throtl_schedule_delayed_work(td, 0);
}
-void throtl_shutdown_timer_wq(struct request_queue *q)
+static void throtl_shutdown_wq(struct request_queue *q)
{
struct throtl_data *td = q->td;
@@ -1102,7 +1102,7 @@
BUG_ON(!td);
- throtl_shutdown_timer_wq(q);
+ throtl_shutdown_wq(q);
spin_lock_irq(q->queue_lock);
throtl_release_tgs(td);
@@ -1132,7 +1132,7 @@
* update limits through cgroup and another work got queued, cancel
* it.
*/
- throtl_shutdown_timer_wq(q);
+ throtl_shutdown_wq(q);
throtl_td_free(td);
}
diff --git a/block/blk.h b/block/blk.h
index 2db8f32..284b500 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -51,21 +51,17 @@
*/
#define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash))
-struct request *blk_do_flush(struct request_queue *q, struct request *rq);
+void blk_insert_flush(struct request *rq);
+void blk_abort_flushes(struct request_queue *q);
static inline struct request *__elv_next_request(struct request_queue *q)
{
struct request *rq;
while (1) {
- while (!list_empty(&q->queue_head)) {
+ if (!list_empty(&q->queue_head)) {
rq = list_entry_rq(q->queue_head.next);
- if (!(rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) ||
- rq == &q->flush_rq)
- return rq;
- rq = blk_do_flush(q, rq);
- if (rq)
- return rq;
+ return rq;
}
if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ea83a4f..89dc745 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -54,9 +54,9 @@
#define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8)
#define RQ_CIC(rq) \
- ((struct cfq_io_context *) (rq)->elevator_private)
-#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
-#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private3)
+ ((struct cfq_io_context *) (rq)->elevator_private[0])
+#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private[1])
+#define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private[2])
static struct kmem_cache *cfq_pool;
static struct kmem_cache *cfq_ioc_pool;
@@ -146,7 +146,6 @@
struct cfq_rb_root *service_tree;
struct cfq_queue *new_cfqq;
struct cfq_group *cfqg;
- struct cfq_group *orig_cfqg;
/* Number of sectors dispatched from queue in single dispatch round */
unsigned long nr_sectors;
};
@@ -285,7 +284,6 @@
unsigned int cfq_slice_idle;
unsigned int cfq_group_idle;
unsigned int cfq_latency;
- unsigned int cfq_group_isolation;
unsigned int cic_index;
struct list_head cic_list;
@@ -1187,32 +1185,6 @@
int new_cfqq = 1;
int group_changed = 0;
-#ifdef CONFIG_CFQ_GROUP_IOSCHED
- if (!cfqd->cfq_group_isolation
- && cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD
- && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) {
- /* Move this cfq to root group */
- cfq_log_cfqq(cfqd, cfqq, "moving to root group");
- if (!RB_EMPTY_NODE(&cfqq->rb_node))
- cfq_group_service_tree_del(cfqd, cfqq->cfqg);
- cfqq->orig_cfqg = cfqq->cfqg;
- cfqq->cfqg = &cfqd->root_group;
- cfqd->root_group.ref++;
- group_changed = 1;
- } else if (!cfqd->cfq_group_isolation
- && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) {
- /* cfqq is sequential now needs to go to its original group */
- BUG_ON(cfqq->cfqg != &cfqd->root_group);
- if (!RB_EMPTY_NODE(&cfqq->rb_node))
- cfq_group_service_tree_del(cfqd, cfqq->cfqg);
- cfq_put_cfqg(cfqq->cfqg);
- cfqq->cfqg = cfqq->orig_cfqg;
- cfqq->orig_cfqg = NULL;
- group_changed = 1;
- cfq_log_cfqq(cfqd, cfqq, "moved to origin group");
- }
-#endif
-
service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
cfqq_type(cfqq));
if (cfq_class_idle(cfqq)) {
@@ -2542,7 +2514,7 @@
static void cfq_put_queue(struct cfq_queue *cfqq)
{
struct cfq_data *cfqd = cfqq->cfqd;
- struct cfq_group *cfqg, *orig_cfqg;
+ struct cfq_group *cfqg;
BUG_ON(cfqq->ref <= 0);
@@ -2554,7 +2526,6 @@
BUG_ON(rb_first(&cfqq->sort_list));
BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
cfqg = cfqq->cfqg;
- orig_cfqg = cfqq->orig_cfqg;
if (unlikely(cfqd->active_queue == cfqq)) {
__cfq_slice_expired(cfqd, cfqq, 0);
@@ -2564,8 +2535,6 @@
BUG_ON(cfq_cfqq_on_rr(cfqq));
kmem_cache_free(cfq_pool, cfqq);
cfq_put_cfqg(cfqg);
- if (orig_cfqg)
- cfq_put_cfqg(orig_cfqg);
}
/*
@@ -3613,12 +3582,12 @@
put_io_context(RQ_CIC(rq)->ioc);
- rq->elevator_private = NULL;
- rq->elevator_private2 = NULL;
+ rq->elevator_private[0] = NULL;
+ rq->elevator_private[1] = NULL;
/* Put down rq reference on cfqg */
cfq_put_cfqg(RQ_CFQG(rq));
- rq->elevator_private3 = NULL;
+ rq->elevator_private[2] = NULL;
cfq_put_queue(cfqq);
}
@@ -3705,13 +3674,13 @@
}
cfqq->allocated[rw]++;
- cfqq->ref++;
- rq->elevator_private = cic;
- rq->elevator_private2 = cfqq;
- rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg);
spin_unlock_irqrestore(q->queue_lock, flags);
+ cfqq->ref++;
+ rq->elevator_private[0] = cic;
+ rq->elevator_private[1] = cfqq;
+ rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
return 0;
queue_fail:
@@ -3953,7 +3922,6 @@
cfqd->cfq_slice_idle = cfq_slice_idle;
cfqd->cfq_group_idle = cfq_group_idle;
cfqd->cfq_latency = 1;
- cfqd->cfq_group_isolation = 0;
cfqd->hw_tag = -1;
/*
* we optimistically start assuming sync ops weren't delayed in last
@@ -4029,7 +3997,6 @@
SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
-SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0);
#undef SHOW_FUNCTION
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
@@ -4063,7 +4030,6 @@
STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
UINT_MAX, 0);
STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
-STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0);
#undef STORE_FUNCTION
#define CFQ_ATTR(name) \
@@ -4081,7 +4047,6 @@
CFQ_ATTR(slice_idle),
CFQ_ATTR(group_idle),
CFQ_ATTR(low_latency),
- CFQ_ATTR(group_isolation),
__ATTR_NULL
};
diff --git a/block/elevator.c b/block/elevator.c
index 236e93c..fabf367 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -673,6 +673,11 @@
q->elevator->ops->elevator_add_req_fn(q, rq);
break;
+ case ELEVATOR_INSERT_FLUSH:
+ rq->cmd_flags |= REQ_SOFTBARRIER;
+ blk_insert_flush(rq);
+ break;
+
default:
printk(KERN_ERR "%s: bad insertion point %d\n",
__func__, where);
@@ -759,7 +764,7 @@
if (e->ops->elevator_set_req_fn)
return e->ops->elevator_set_req_fn(q, rq, gfp_mask);
- rq->elevator_private = NULL;
+ rq->elevator_private[0] = NULL;
return 0;
}
@@ -785,6 +790,8 @@
{
struct request *rq;
+ blk_abort_flushes(q);
+
while (!list_empty(&q->queue_head)) {
rq = list_entry_rq(q->queue_head.next);
rq->cmd_flags |= REQ_QUIET;
diff --git a/block/genhd.c b/block/genhd.c
index cbf1112..3e2b57b 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1158,14 +1158,14 @@
"%u %lu %lu %llu %u %u %u %u\n",
MAJOR(part_devt(hd)), MINOR(part_devt(hd)),
disk_name(gp, hd->partno, buf),
- part_stat_read(hd, ios[0]),
- part_stat_read(hd, merges[0]),
- (unsigned long long)part_stat_read(hd, sectors[0]),
- jiffies_to_msecs(part_stat_read(hd, ticks[0])),
- part_stat_read(hd, ios[1]),
- part_stat_read(hd, merges[1]),
- (unsigned long long)part_stat_read(hd, sectors[1]),
- jiffies_to_msecs(part_stat_read(hd, ticks[1])),
+ part_stat_read(hd, ios[READ]),
+ part_stat_read(hd, merges[READ]),
+ (unsigned long long)part_stat_read(hd, sectors[READ]),
+ jiffies_to_msecs(part_stat_read(hd, ticks[READ])),
+ part_stat_read(hd, ios[WRITE]),
+ part_stat_read(hd, merges[WRITE]),
+ (unsigned long long)part_stat_read(hd, sectors[WRITE]),
+ jiffies_to_msecs(part_stat_read(hd, ticks[WRITE])),
part_in_flight(hd),
jiffies_to_msecs(part_stat_read(hd, io_ticks)),
jiffies_to_msecs(part_stat_read(hd, time_in_queue))
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index dbf31ec..79c3079 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1636,9 +1636,6 @@
static void loop_free(struct loop_device *lo)
{
- if (!lo->lo_queue->queue_lock)
- lo->lo_queue->queue_lock = &lo->lo_queue->__queue_lock;
-
blk_cleanup_queue(lo->lo_queue);
put_disk(lo->lo_disk);
list_del(&lo->lo_list);
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 46ad519..dddedfc 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -148,6 +148,7 @@
__REQ_ALLOCED, /* request came from our alloc pool */
__REQ_COPY_USER, /* contains copies of user pages */
__REQ_FLUSH, /* request for cache flush */
+ __REQ_FLUSH_SEQ, /* request for flush sequence */
__REQ_IO_STAT, /* account I/O stat */
__REQ_MIXED_MERGE, /* merge of different types, fail separately */
__REQ_SECURE, /* secure discard (used with __REQ_DISCARD) */
@@ -188,6 +189,7 @@
#define REQ_ALLOCED (1 << __REQ_ALLOCED)
#define REQ_COPY_USER (1 << __REQ_COPY_USER)
#define REQ_FLUSH (1 << __REQ_FLUSH)
+#define REQ_FLUSH_SEQ (1 << __REQ_FLUSH_SEQ)
#define REQ_IO_STAT (1 << __REQ_IO_STAT)
#define REQ_MIXED_MERGE (1 << __REQ_MIXED_MERGE)
#define REQ_SECURE (1 << __REQ_SECURE)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d5063e1..13b75ca 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -108,11 +108,17 @@
/*
* Three pointers are available for the IO schedulers, if they need
- * more they have to dynamically allocate it.
+ * more they have to dynamically allocate it. Flush requests are
+ * never put on the IO scheduler. So let the flush fields share
+ * space with the three elevator_private pointers.
*/
- void *elevator_private;
- void *elevator_private2;
- void *elevator_private3;
+ union {
+ void *elevator_private[3];
+ struct {
+ unsigned int seq;
+ struct list_head list;
+ } flush;
+ };
struct gendisk *rq_disk;
struct hd_struct *part;
@@ -363,11 +369,12 @@
* for flush operations
*/
unsigned int flush_flags;
- unsigned int flush_seq;
- int flush_err;
+ unsigned int flush_pending_idx:1;
+ unsigned int flush_running_idx:1;
+ unsigned long flush_pending_since;
+ struct list_head flush_queue[2];
+ struct list_head flush_data_in_flight;
struct request flush_rq;
- struct request *orig_flush_rq;
- struct list_head pending_flushes;
struct mutex sysfs_lock;
@@ -1135,7 +1142,6 @@
extern int blk_throtl_init(struct request_queue *q);
extern void blk_throtl_exit(struct request_queue *q);
extern int blk_throtl_bio(struct request_queue *q, struct bio **bio);
-extern void throtl_shutdown_timer_wq(struct request_queue *q);
#else /* CONFIG_BLK_DEV_THROTTLING */
static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio)
{
@@ -1144,7 +1150,6 @@
static inline int blk_throtl_init(struct request_queue *q) { return 0; }
static inline int blk_throtl_exit(struct request_queue *q) { return 0; }
-static inline void throtl_shutdown_timer_wq(struct request_queue *q) {}
#endif /* CONFIG_BLK_DEV_THROTTLING */
#define MODULE_ALIAS_BLOCKDEV(major,minor) \
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 4d85797..39b68ed 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -167,6 +167,7 @@
#define ELEVATOR_INSERT_BACK 2
#define ELEVATOR_INSERT_SORT 3
#define ELEVATOR_INSERT_REQUEUE 4
+#define ELEVATOR_INSERT_FLUSH 5
/*
* return values from elevator_may_queue_fn