Re: [PATCH 1/1] mm/block: convert rw_page users to bio op use

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On 08/05/2016 07:52 AM, Jens Axboe wrote:
On 08/05/2016 01:57 AM, Christoph Hellwig wrote:

The rw_page users were not converted to use bio/req ops. As a result
bdev_write_page is not passing down REQ_OP_WRITE and the IOs will
be sent down as reads.

Can we just get rid of REQ_OP_WRITE enum for the ->rw_page interface
and pass a 'bool write'?  If not I'd prefer to avoid using op_is_write
as much as possible - it's a confusing interface if we really want
to do a switch on read vs write vs invalid.

That's a really good point, especially since the op_flags was dropped as
well. I'll cook that up.

How about something like this? We don't bleed into the non-core bits
anymore, so we can move those back under CONFIG_BLOCK too.

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 3439b28cce8b..0c76d4016eeb 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -300,20 +300,20 @@ static void copy_from_brd(void *dst, struct brd_device *brd,
  * Process a single bvec of a bio.
  */
 static int brd_do_bvec(struct brd_device *brd, struct page *page,
-			unsigned int len, unsigned int off, int op,
+			unsigned int len, unsigned int off, bool is_write,
 			sector_t sector)
 {
 	void *mem;
 	int err = 0;

-	if (op_is_write(op)) {
+	if (is_write) {
 		err = copy_to_brd_setup(brd, sector, len);
 		if (err)
 			goto out;
 	}

 	mem = kmap_atomic(page);
-	if (!op_is_write(op)) {
+	if (!is_write) {
 		copy_from_brd(mem + off, brd, sector, len);
 		flush_dcache_page(page);
 	} else {
@@ -350,8 +350,8 @@ static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio)
 		unsigned int len = bvec.bv_len;
 		int err;

-		err = brd_do_bvec(brd, bvec.bv_page, len,
-					bvec.bv_offset, bio_op(bio), sector);
+		err = brd_do_bvec(brd, bvec.bv_page, len, bvec.bv_offset,
+					op_is_write(bio_op(bio)), sector);
 		if (err)
 			goto io_error;
 		sector += len >> SECTOR_SHIFT;
@@ -366,11 +366,11 @@ io_error:
 }

 static int brd_rw_page(struct block_device *bdev, sector_t sector,
-		       struct page *page, int op)
+		       struct page *page, bool is_write)
 {
 	struct brd_device *brd = bdev->bd_disk->private_data;
-	int err = brd_do_bvec(brd, page, PAGE_SIZE, 0, op, sector);
-	page_endio(page, op, err);
+	int err = brd_do_bvec(brd, page, PAGE_SIZE, 0, is_write, sector);
+	page_endio(page, is_write, err);
 	return err;
 }

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index ca29649c4b08..04365b17ee67 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -843,15 +843,16 @@ static void zram_bio_discard(struct zram *zram, u32 index,
 }

static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
-			int offset, int op)
+			int offset, bool is_write)
 {
 	unsigned long start_time = jiffies;
+	int rw_acct = is_write ? REQ_OP_WRITE : REQ_OP_READ;
 	int ret;

-	generic_start_io_acct(op, bvec->bv_len >> SECTOR_SHIFT,
+	generic_start_io_acct(rw_acct, bvec->bv_len >> SECTOR_SHIFT,
 			&zram->disk->part0);

-	if (!op_is_write(op)) {
+	if (!is_write) {
 		atomic64_inc(&zram->stats.num_reads);
 		ret = zram_bvec_read(zram, bvec, index, offset);
 	} else {
@@ -859,10 +860,10 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
 		ret = zram_bvec_write(zram, bvec, index, offset);
 	}

-	generic_end_io_acct(op, &zram->disk->part0, start_time);
+	generic_end_io_acct(rw_acct, &zram->disk->part0, start_time);

 	if (unlikely(ret)) {
-		if (!op_is_write(op))
+		if (!is_write)
 			atomic64_inc(&zram->stats.failed_reads);
 		else
 			atomic64_inc(&zram->stats.failed_writes);
@@ -903,17 +904,17 @@ static void __zram_make_request(struct zram *zram, struct bio *bio)
 			bv.bv_offset = bvec.bv_offset;

 			if (zram_bvec_rw(zram, &bv, index, offset,
-					 bio_op(bio)) < 0)
+					 op_is_write(bio_op(bio))) < 0)
 				goto out;

 			bv.bv_len = bvec.bv_len - max_transfer_size;
 			bv.bv_offset += max_transfer_size;
 			if (zram_bvec_rw(zram, &bv, index + 1, 0,
-					 bio_op(bio)) < 0)
+					 op_is_write(bio_op(bio))) < 0)
 				goto out;
 		} else
 			if (zram_bvec_rw(zram, &bvec, index, offset,
-					 bio_op(bio)) < 0)
+					 op_is_write(bio_op(bio))) < 0)
 				goto out;

 		update_position(&index, &offset, &bvec);
@@ -970,7 +971,7 @@ static void zram_slot_free_notify(struct block_device *bdev,
 }

 static int zram_rw_page(struct block_device *bdev, sector_t sector,
-		       struct page *page, int op)
+		       struct page *page, bool is_write)
 {
 	int offset, err = -EIO;
 	u32 index;
@@ -994,7 +995,7 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector,
 	bv.bv_len = PAGE_SIZE;
 	bv.bv_offset = 0;

-	err = zram_bvec_rw(zram, &bv, index, offset, op);
+	err = zram_bvec_rw(zram, &bv, index, offset, is_write);
 put_zram:
 	zram_meta_put(zram);
 out:
@@ -1007,7 +1008,7 @@ out:
 	 * (e.g., SetPageError, set_page_dirty and extra works).
 	 */
 	if (err == 0)
-		page_endio(page, op, 0);
+		page_endio(page, is_write, 0);
 	return err;
 }

diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 7cf3bdfaf809..88e91666f145 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1133,11 +1133,11 @@ static int btt_write_pg(struct btt *btt, struct bio_integrity_payload *bip,

 static int btt_do_bvec(struct btt *btt, struct bio_integrity_payload *bip,
 			struct page *page, unsigned int len, unsigned int off,
-			int op, sector_t sector)
+			bool is_write, sector_t sector)
 {
 	int ret;

-	if (!op_is_write(op)) {
+	if (!is_write) {
 		ret = btt_read_pg(btt, bip, page, off, sector, len);
 		flush_dcache_page(page);
 	} else {
@@ -1180,7 +1180,7 @@ static blk_qc_t btt_make_request(struct request_queue *q, struct bio *bio)
 		BUG_ON(len % btt->sector_size);

 		err = btt_do_bvec(btt, bip, bvec.bv_page, len, bvec.bv_offset,
-				  bio_op(bio), iter.bi_sector);
+				  op_is_write(bio_op(bio)), iter.bi_sector);
 		if (err) {
 			dev_info(&btt->nd_btt->dev,
 					"io error in %s sector %lld, len %d,\n",
@@ -1200,12 +1200,12 @@ out:
 }

 static int btt_rw_page(struct block_device *bdev, sector_t sector,
-		struct page *page, int op)
+		struct page *page, bool is_write)
 {
 	struct btt *btt = bdev->bd_disk->private_data;

-	btt_do_bvec(btt, NULL, page, PAGE_SIZE, 0, op, sector);
-	page_endio(page, op, 0);
+	btt_do_bvec(btt, NULL, page, PAGE_SIZE, 0, is_write, sector);
+	page_endio(page, is_write, 0);
 	return 0;
 }

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index d64d92481c1d..20bae50c231d 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -67,7 +67,7 @@ static void pmem_clear_poison(struct pmem_device *pmem, phys_addr_t offset,
 }

 static int pmem_do_bvec(struct pmem_device *pmem, struct page *page,
-			unsigned int len, unsigned int off, int op,
+			unsigned int len, unsigned int off, bool is_write,
 			sector_t sector)
 {
 	int rc = 0;
@@ -79,7 +79,7 @@ static int pmem_do_bvec(struct pmem_device *pmem, struct page *page,
 	if (unlikely(is_bad_pmem(&pmem->bb, sector, len)))
 		bad_pmem = true;

-	if (!op_is_write(op)) {
+	if (!is_write) {
 		if (unlikely(bad_pmem))
 			rc = -EIO;
 		else {
@@ -134,7 +134,7 @@ static blk_qc_t pmem_make_request(struct request_queue *q, struct bio *bio)
 	do_acct = nd_iostat_start(bio, &start);
 	bio_for_each_segment(bvec, bio, iter) {
 		rc = pmem_do_bvec(pmem, bvec.bv_page, bvec.bv_len,
-				bvec.bv_offset, bio_op(bio),
+				bvec.bv_offset, op_is_write(bio_op(bio)),
 				iter.bi_sector);
 		if (rc) {
 			bio->bi_error = rc;
@@ -152,12 +152,12 @@ static blk_qc_t pmem_make_request(struct request_queue *q, struct bio *bio)
 }

 static int pmem_rw_page(struct block_device *bdev, sector_t sector,
-		       struct page *page, int op)
+		       struct page *page, bool is_write)
 {
 	struct pmem_device *pmem = bdev->bd_queue->queuedata;
 	int rc;

-	rc = pmem_do_bvec(pmem, page, PAGE_SIZE, 0, op, sector);
+	rc = pmem_do_bvec(pmem, page, PAGE_SIZE, 0, is_write, sector);

 	/*
 	 * The ->rw_page interface is subtle and tricky.  The core
@@ -166,7 +166,7 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector,
 	 * caused by double completion.
 	 */
 	if (rc == 0)
-		page_endio(page, op, 0);
+		page_endio(page, is_write, 0);

 	return rc;
 }
diff --git a/fs/block_dev.c b/fs/block_dev.c
index d402899ba135..c3cdde87cc8c 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -416,8 +416,7 @@ int bdev_read_page(struct block_device *bdev, sector_t sector,
 	result = blk_queue_enter(bdev->bd_queue, false);
 	if (result)
 		return result;
-	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
-			      REQ_OP_READ);
+	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, false);
 	blk_queue_exit(bdev->bd_queue);
 	return result;
 }
@@ -455,8 +454,7 @@ int bdev_write_page(struct block_device *bdev, sector_t sector,
 		return result;

 	set_page_writeback(page);
-	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
-			      REQ_OP_WRITE);
+	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, true);
 	if (result)
 		end_page_writeback(page);
 	else
diff --git a/fs/mpage.c b/fs/mpage.c
index 7a09c55b4bd0..d2413af0823a 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -50,7 +50,7 @@ static void mpage_end_io(struct bio *bio)

 	bio_for_each_segment_all(bv, bio, i) {
 		struct page *page = bv->bv_page;
-		page_endio(page, bio_op(bio), bio->bi_error);
+		page_endio(page, op_is_write(bio_op(bio)), bio->bi_error);
 	}

 	bio_put(bio);
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 14b28ff2caf8..f254eb264924 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -18,17 +18,6 @@ struct cgroup_subsys_state;
 typedef void (bio_end_io_t) (struct bio *);
 typedef void (bio_destructor_t) (struct bio *);

-enum req_op {
-	REQ_OP_READ,
-	REQ_OP_WRITE,
-	REQ_OP_DISCARD,		/* request to discard sectors */
-	REQ_OP_SECURE_ERASE,	/* request to securely erase sectors */
-	REQ_OP_WRITE_SAME,	/* write same block many times */
-	REQ_OP_FLUSH,		/* request for cache flush */
-};
-
-#define REQ_OP_BITS 3
-
 #ifdef CONFIG_BLOCK
 /*
  * main unit of I/O for the block layer and lower layers (ie drivers and
@@ -239,6 +228,17 @@ enum rq_flag_bits {
 #define REQ_HASHED		(1ULL << __REQ_HASHED)
 #define REQ_MQ_INFLIGHT		(1ULL << __REQ_MQ_INFLIGHT)

+enum req_op {
+	REQ_OP_READ,
+	REQ_OP_WRITE,
+	REQ_OP_DISCARD,		/* request to discard sectors */
+	REQ_OP_SECURE_ERASE,	/* request to securely erase sectors */
+	REQ_OP_WRITE_SAME,	/* write same block many times */
+	REQ_OP_FLUSH,		/* request for cache flush */
+};
+
+#define REQ_OP_BITS 3
+
 typedef unsigned int blk_qc_t;
 #define BLK_QC_T_NONE	-1U
 #define BLK_QC_T_SHIFT	16
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ccd68c0d01de..2c210b6a7bcf 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1672,7 +1672,7 @@ struct blk_dax_ctl {
 struct block_device_operations {
 	int (*open) (struct block_device *, fmode_t);
 	void (*release) (struct gendisk *, fmode_t);
-	int (*rw_page)(struct block_device *, sector_t, struct page *, int op);
+	int (*rw_page)(struct block_device *, sector_t, struct page *, bool);
 	int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
 	long (*direct_access)(struct block_device *, sector_t, void **, pfn_t *,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 498255e6914e..f3f0b4c8e8ac 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2480,13 +2480,12 @@ extern void init_special_inode(struct inode *, umode_t, dev_t);
 extern void make_bad_inode(struct inode *);
 extern bool is_bad_inode(struct inode *);

+#ifdef CONFIG_BLOCK
 static inline bool op_is_write(unsigned int op)
 {
 	return op == REQ_OP_READ ? false : true;
 }

-#ifdef CONFIG_BLOCK
-
 /*
  * return data direction, READ or WRITE
  */
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 45786374abbd..66a1260b33de 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -510,7 +510,7 @@ static inline void wait_on_page_writeback(struct page *page)
 extern void end_page_writeback(struct page *page);
 void wait_for_stable_page(struct page *page);

-void page_endio(struct page *page, int op, int err);
+void page_endio(struct page *page, bool is_write, int err);

 /*
  * Add an arbitrary waiter to a page's wait queue
diff --git a/mm/filemap.c b/mm/filemap.c
index daef091d4c50..8a287dfc5372 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -887,9 +887,9 @@ EXPORT_SYMBOL(end_page_writeback);
  * After completing I/O on a page, call this routine to update the page
  * flags appropriately
  */
-void page_endio(struct page *page, int op, int err)
+void page_endio(struct page *page, bool is_write, int err)
 {
-	if (!op_is_write(op)) {
+	if (!is_write) {
 		if (!err) {
 			SetPageUptodate(page);
 		} else {

--
Jens Axboe

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