block: add REQ_FLUSH_SEQ

rq == &q->flush_rq was used to determine whether a rq is part of a
flush sequence, which worked because all requests in a flush sequence
were sequenced using the single dedicated request.  This is about to
change, so introduce REQ_FLUSH_SEQ flag to distinguish flush sequence
requests.

This patch doesn't cause any behavior change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

diff --git a/block/blk-core.c b/block/blk-core.c
index 4ce953f..fc7d8ad 100644 (file)
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -136,7 +136,7 @@ static void req_bio_endio(struct request *rq, struct bio *bio,
 {
        struct request_queue *q = rq->q;
 
-       if (&q->flush_rq != rq) {
+       if (!(rq->cmd_flags & REQ_FLUSH_SEQ)) {
                if (error)
                        clear_bit(BIO_UPTODATE, &bio->bi_flags);
                else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
@@ -1789,7 +1789,7 @@ static void blk_account_io_done(struct request *req)
         * 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 54b123d..8592869 100644 (file)
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -130,6 +130,7 @@ static struct request *queue_next_fseq(struct request_queue *q)
                BUG();
        }
 
+       rq->cmd_flags |= REQ_FLUSH_SEQ;
        elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
        return rq;
 }

diff --git a/block/blk.h b/block/blk.h
index 2db8f32..9d2ee8f 100644 (file)
--- a/block/blk.h
+++ b/block/blk.h
@@ -61,7 +61,7 @@ static inline struct request *__elv_next_request(struct request_queue *q)
                while (!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)
+                           (rq->cmd_flags & REQ_FLUSH_SEQ))
                                return rq;
                        rq = blk_do_flush(q, rq);
                        if (rq)

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 46ad519..dddedfc 100644 (file)
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -148,6 +148,7 @@ enum rq_flag_bits {
        __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 @@ enum rq_flag_bits {
 #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)