Re: [RFC][PATCH 1/3] Add flag and sysfs interfaces

[Alan D. Brunelle]

Signed-off-by: Alan D. Brunelle <alan.brunelle@xxxxxx>
---
 block/blk-sysfs.c      |   27 +++++++++++++++++++++++++++
 include/linux/blkdev.h |    2 ++
 2 files changed, 29 insertions(+), 0 deletions(-)

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 54d0db1..32d917c 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -135,6 +135,26 @@ static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
 	return queue_var_show(max_hw_sectors_kb, (page));
 }
 
+static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
+{
+	int nm = test_bit(QUEUE_FLAG_NOMERGES, &q->queue_flags);
+	return queue_var_show(nm, page);
+}
+
+static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
+				    size_t count)
+{
+	unsigned long nm;
+	ssize_t ret = queue_var_store(&nm, page, count);
+
+	if (nm)
+	       set_bit(QUEUE_FLAG_NOMERGES, &q->queue_flags);
+	else
+	       clear_bit(QUEUE_FLAG_NOMERGES, &q->queue_flags);
+
+	return ret;
+}
+
 
 static struct queue_sysfs_entry queue_requests_entry = {
 	.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
@@ -170,6 +190,12 @@ static struct queue_sysfs_entry queue_hw_sector_size_entry = {
 	.show = queue_hw_sector_size_show,
 };
 
+static struct queue_sysfs_entry queue_nomerges_entry = {
+	.attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
+	.show = queue_nomerges_show,
+	.store = queue_nomerges_store,
+};
+
 static struct attribute *default_attrs[] = {
 	&queue_requests_entry.attr,
 	&queue_ra_entry.attr,
@@ -177,6 +203,7 @@ static struct attribute *default_attrs[] = {
 	&queue_max_sectors_entry.attr,
 	&queue_iosched_entry.attr,
 	&queue_hw_sector_size_entry.attr,
+	&queue_nomerges_entry.attr,
 	NULL,
 };
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6f79d40..ee577f9 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -405,6 +405,7 @@ struct request_queue
 #define QUEUE_FLAG_PLUGGED	7	/* queue is plugged */
 #define QUEUE_FLAG_ELVSWITCH	8	/* don't use elevator, just do FIFO */
 #define QUEUE_FLAG_BIDI		9	/* queue supports bidi requests */
+#define QUEUE_FLAG_NOMERGES    10	/* disable merge attempts */
 
 enum {
 	/*
@@ -449,6 +450,7 @@ enum {
 #define blk_queue_plugged(q)	test_bit(QUEUE_FLAG_PLUGGED, &(q)->queue_flags)
 #define blk_queue_tagged(q)	test_bit(QUEUE_FLAG_QUEUED, &(q)->queue_flags)
 #define blk_queue_stopped(q)	test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags)
+#define blk_queue_nomerges(q)	test_bit(QUEUE_FLAG_NOMERGES, &(q)->queue_flags)
 #define blk_queue_flushing(q)	((q)->ordseq)
 
 #define blk_fs_request(rq)	((rq)->cmd_type == REQ_TYPE_FS)
-- 
1.5.2.5