[PATCH 0/4] blkdev: blkdev_issue_fn cleanups v2

[PATCH 0/4] blkdev: blkdev_issue_fn cleanups v2

[Dmitry Monakhov]

- Convert all blkdev_issue_xxx function to common set of flags
- move common functions to block/blk-lib.c
- Add generic zeroout helper

changes from V1
Christoph is about to change discard memory payload allocation logic
so discard cleanups are no longer necessary.

[PATCH 1/4] blkdev: pass gfp_mask and flags to blkdev_issue_flush

[Dmitry Monakhov]

In some places caller don't want to wait a request to complete.
Flags make blkdev_issue_flush() more flexible. This patch just
convert existing callers to new interface without chaining
existing allocation/wait behavior.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 block/blk-barrier.c                |   43 +++++++++++++++++++++---------------
 drivers/block/drbd/drbd_int.h      |    3 +-
 drivers/block/drbd/drbd_receiver.c |    3 +-
 fs/block_dev.c                     |    3 +-
 fs/ext3/fsync.c                    |    3 +-
 fs/ext4/fsync.c                    |    6 +++-
 fs/jbd2/checkpoint.c               |    3 +-
 fs/jbd2/commit.c                   |    6 +++-
 fs/reiserfs/file.c                 |    3 +-
 fs/xfs/linux-2.6/xfs_super.c       |    3 +-
 include/linux/blkdev.h             |   10 ++++++-
 11 files changed, 55 insertions(+), 31 deletions(-)

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 8618d89..7e6e810 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -285,26 +285,31 @@ static void bio_end_empty_barrier(struct bio *bio, int err)
 			set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
 		clear_bit(BIO_UPTODATE, &bio->bi_flags);
 	}
-
-	complete(bio->bi_private);
+	if (bio->bi_private)
+		complete(bio->bi_private);
+	bio_put(bio);
 }
 
 /**
  * blkdev_issue_flush - queue a flush
  * @bdev:	blockdev to issue flush for
+ * @gfp_mask:	memory allocation flags (for bio_alloc)
  * @error_sector:	error sector
+ * @flags:	BLKDEV_IFL_* flags to control behaviour
  *
  * Description:
  *    Issue a flush for the block device in question. Caller can supply
  *    room for storing the error offset in case of a flush error, if they
- *    wish to.
+ *    wish to. If WAIT flag is not passed then caller may check only what
+ *    request was pushed in some internal queue for later handling.
  */
-int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
+int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
+		sector_t *error_sector, unsigned long flags)
 {
 	DECLARE_COMPLETION_ONSTACK(wait);
 	struct request_queue *q;
 	struct bio *bio;
-	int ret;
+	int ret = 0;
 
 	if (bdev->bd_disk == NULL)
 		return -ENXIO;
@@ -313,23 +318,25 @@ int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
 	if (!q)
 		return -ENXIO;
 
-	bio = bio_alloc(GFP_KERNEL, 0);
+	bio = bio_alloc(gfp_mask, 0);
 	bio->bi_end_io = bio_end_empty_barrier;
-	bio->bi_private = &wait;
 	bio->bi_bdev = bdev;
-	submit_bio(WRITE_BARRIER, bio);
+	if (test_bit(__BLKDEV_IFL_WAIT, &flags))
+		bio->bi_private = &wait;
 
-	wait_for_completion(&wait);
-
-	/*
-	 * The driver must store the error location in ->bi_sector, if
-	 * it supports it. For non-stacked drivers, this should be copied
-	 * from blk_rq_pos(rq).
-	 */
-	if (error_sector)
-		*error_sector = bio->bi_sector;
+	bio_get(bio);
+	submit_bio(WRITE_BARRIER, bio);
+	if (test_bit(__BLKDEV_IFL_WAIT, &flags)) {
+		wait_for_completion(&wait);
+		/*
+		 * The driver must store the error location in ->bi_sector, if
+		 * it supports it. For non-stacked drivers, this should be
+		 * copied from blk_rq_pos(rq).
+		 */
+		if (error_sector)
+			*error_sector = bio->bi_sector;
+	}
 
-	ret = 0;
 	if (bio_flagged(bio, BIO_EOPNOTSUPP))
 		ret = -EOPNOTSUPP;
 	else if (!bio_flagged(bio, BIO_UPTODATE))
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index e5e86a7..d6f1ae3 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -2251,7 +2251,8 @@ static inline void drbd_md_flush(struct drbd_conf *mdev)
 	if (test_bit(MD_NO_BARRIER, &mdev->flags))
 		return;
 
-	r = blkdev_issue_flush(mdev->ldev->md_bdev, NULL);
+	r = blkdev_issue_flush(mdev->ldev->md_bdev, GFP_KERNEL, NULL,
+			BLKDEV_IFL_WAIT);
 	if (r) {
 		set_bit(MD_NO_BARRIER, &mdev->flags);
 		dev_err(DEV, "meta data flush failed with status %d, disabling md-flushes\n", r);
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index ed9f1de..54f56ea 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -945,7 +945,8 @@ static enum finish_epoch drbd_flush_after_epoch(struct drbd_conf *mdev, struct d
 	int rv;
 
 	if (mdev->write_ordering >= WO_bdev_flush && get_ldev(mdev)) {
-		rv = blkdev_issue_flush(mdev->ldev->backing_bdev, NULL);
+		rv = blkdev_issue_flush(mdev->ldev->backing_bdev, GFP_KERNEL,
+					NULL, BLKDEV_IFL_WAIT);
 		if (rv) {
 			dev_err(DEV, "local disk flush failed with status %d\n", rv);
 			/* would rather check on EOPNOTSUPP, but that is not reliable.
diff --git a/fs/block_dev.c b/fs/block_dev.c
index d11d028..b1c8062 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -413,7 +413,8 @@ static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
 	if (error)
 		return error;
 	
-	error = blkdev_issue_flush(bdev, NULL);
+	error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL,
+				(BLKDEV_IFL_WAIT));
 	if (error == -EOPNOTSUPP)
 		error = 0;
 	return error;
diff --git a/fs/ext3/fsync.c b/fs/ext3/fsync.c
index 8209f26..9492f60 100644
--- a/fs/ext3/fsync.c
+++ b/fs/ext3/fsync.c
@@ -91,7 +91,8 @@ int ext3_sync_file(struct file * file, struct dentry *dentry, int datasync)
 	 * storage
 	 */
 	if (test_opt(inode->i_sb, BARRIER))
-		blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
+		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL,
+				BLKDEV_IFL_WAIT);
 out:
 	return ret;
 }
diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index 0d0c323..ef3d980 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -100,9 +100,11 @@ int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync)
 		if (ext4_should_writeback_data(inode) &&
 		    (journal->j_fs_dev != journal->j_dev) &&
 		    (journal->j_flags & JBD2_BARRIER))
-			blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
+			blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL,
+					NULL, BLKDEV_IFL_WAIT);
 		jbd2_log_wait_commit(journal, commit_tid);
 	} else if (journal->j_flags & JBD2_BARRIER)
-		blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
+		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL,
+			BLKDEV_IFL_WAIT);
 	return ret;
 }
diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index 30beb11..076d1cc 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -530,7 +530,8 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
 	 */
 	if ((journal->j_fs_dev != journal->j_dev) &&
 	    (journal->j_flags & JBD2_BARRIER))
-		blkdev_issue_flush(journal->j_fs_dev, NULL);
+		blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL,
+			BLKDEV_IFL_WAIT);
 	if (!(journal->j_flags & JBD2_ABORT))
 		jbd2_journal_update_superblock(journal, 1);
 	return 0;
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 671da7f..75716d3 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -717,7 +717,8 @@ start_journal_io:
 	if (commit_transaction->t_flushed_data_blocks &&
 	    (journal->j_fs_dev != journal->j_dev) &&
 	    (journal->j_flags & JBD2_BARRIER))
-		blkdev_issue_flush(journal->j_fs_dev, NULL);
+		blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL,
+			BLKDEV_IFL_WAIT);
 
 	/* Done it all: now write the commit record asynchronously. */
 	if (JBD2_HAS_INCOMPAT_FEATURE(journal,
@@ -727,7 +728,8 @@ start_journal_io:
 		if (err)
 			__jbd2_journal_abort_hard(journal);
 		if (journal->j_flags & JBD2_BARRIER)
-			blkdev_issue_flush(journal->j_dev, NULL);
+			blkdev_issue_flush(journal->j_dev, GFP_KERNEL, NULL,
+				BLKDEV_IFL_WAIT);
 	}
 
 	err = journal_finish_inode_data_buffers(journal, commit_transaction);
diff --git a/fs/reiserfs/file.c b/fs/reiserfs/file.c
index 1d9c127..9977df9 100644
--- a/fs/reiserfs/file.c
+++ b/fs/reiserfs/file.c
@@ -147,7 +147,8 @@ static int reiserfs_sync_file(struct file *filp,
 	barrier_done = reiserfs_commit_for_inode(inode);
 	reiserfs_write_unlock(inode->i_sb);
 	if (barrier_done != 1 && reiserfs_barrier_flush(inode->i_sb))
-		blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
+		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL, 
+			BLKDEV_IFL_WAIT);
 	if (barrier_done < 0)
 		return barrier_done;
 	return (err < 0) ? -EIO : 0;
diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 71345a3..a98f35e 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -724,7 +724,8 @@ void
 xfs_blkdev_issue_flush(
 	xfs_buftarg_t		*buftarg)
 {
-	blkdev_issue_flush(buftarg->bt_bdev, NULL);
+	blkdev_issue_flush(buftarg->bt_bdev, GFP_KERNEL, NULL,
+			BLKDEV_IFL_WAIT);
 }
 
 STATIC void
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6690e8b..f669656 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -994,8 +994,14 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
 		return NULL;
 	return bqt->tag_index[tag];
 }
-
-extern int blkdev_issue_flush(struct block_device *, sector_t *);
+enum{
+	__BLKDEV_IFL_WAIT,	/* wait for completion */
+	__BLKDEV_IFL_BARRIER,	/*issue request with barrier */
+};
+#define BLKDEV_IFL_WAIT		(1 << __BLKDEV_IFL_WAIT)
+#define BLKDEV_IFL_BARRIER	(1 << __BLKDEV_IFL_BARRIER)
+extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *,
+			unsigned long);
 #define DISCARD_FL_WAIT		0x01	/* wait for completion */
 #define DISCARD_FL_BARRIER	0x02	/* issue DISCARD_BARRIER request */
 extern int blkdev_issue_discard(struct block_device *, sector_t sector,
-- 
1.6.6.1

[PATCH 2/4] blkdev: generalize flags for blkdev_issue_fn functions

[Dmitry Monakhov]

The patch just convert all blkdev_issue_xxx function to common
flags. Wait/allocation semantics not changed.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 block/blk-barrier.c    |   10 +++++-----
 block/ioctl.c          |    2 +-
 fs/btrfs/extent-tree.c |    2 +-
 fs/gfs2/rgrp.c         |    5 +++--
 include/linux/blkdev.h |    8 +++-----
 mm/swapfile.c          |    8 +++++---
 6 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 7e6e810..56254b1 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -368,17 +368,17 @@ static void blkdev_discard_end_io(struct bio *bio, int err)
  * @sector:	start sector
  * @nr_sects:	number of sectors to discard
  * @gfp_mask:	memory allocation flags (for bio_alloc)
- * @flags:	DISCARD_FL_* flags to control behaviour
+ * @flags:	BLKDEV_IFL_* flags to control behaviour
  *
  * Description:
  *    Issue a discard request for the sectors in question.
  */
 int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
-		sector_t nr_sects, gfp_t gfp_mask, int flags)
+		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
 {
 	DECLARE_COMPLETION_ONSTACK(wait);
 	struct request_queue *q = bdev_get_queue(bdev);
-	int type = flags & DISCARD_FL_BARRIER ?
+	int type = flags & BLKDEV_IFL_BARRIER ?
 		DISCARD_BARRIER : DISCARD_NOBARRIER;
 	struct bio *bio;
 	struct page *page;
@@ -401,7 +401,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		bio->bi_sector = sector;
 		bio->bi_end_io = blkdev_discard_end_io;
 		bio->bi_bdev = bdev;
-		if (flags & DISCARD_FL_WAIT)
+		if (flags & BLKDEV_IFL_BARRIER)
 			bio->bi_private = &wait;
 
 		/*
@@ -432,7 +432,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		bio_get(bio);
 		submit_bio(type, bio);
 
-		if (flags & DISCARD_FL_WAIT)
+		if (flags & BLKDEV_IFL_BARRIER)
 			wait_for_completion(&wait);
 
 		if (bio_flagged(bio, BIO_EOPNOTSUPP))
diff --git a/block/ioctl.c b/block/ioctl.c
index be48ea5..d803cac 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -125,7 +125,7 @@ static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
 	if (start + len > (bdev->bd_inode->i_size >> 9))
 		return -EINVAL;
 	return blkdev_issue_discard(bdev, start, len, GFP_KERNEL,
-				    DISCARD_FL_WAIT);
+				    BLKDEV_IFL_WAIT);
 }
 
 static int put_ushort(unsigned long arg, unsigned short val)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 559f724..7453ac4 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1588,7 +1588,7 @@ static void btrfs_issue_discard(struct block_device *bdev,
 				u64 start, u64 len)
 {
 	blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_KERNEL,
-			     DISCARD_FL_BARRIER);
+			BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 }
 
 static int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr,
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 503b842..bf011dc 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -854,7 +854,8 @@ static void gfs2_rgrp_send_discards(struct gfs2_sbd *sdp, u64 offset,
 				if ((start + nr_sects) != blk) {
 					rv = blkdev_issue_discard(bdev, start,
 							    nr_sects, GFP_NOFS,
-							    DISCARD_FL_BARRIER);
+							    BLKDEV_IFL_WAIT |
+							    BLKDEV_IFL_BARRIER);
 					if (rv)
 						goto fail;
 					nr_sects = 0;
@@ -869,7 +870,7 @@ start_new_extent:
 	}
 	if (nr_sects) {
 		rv = blkdev_issue_discard(bdev, start, nr_sects, GFP_NOFS,
-					 DISCARD_FL_BARRIER);
+					 BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 		if (rv)
 			goto fail;
 	}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f669656..a222351 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1002,10 +1002,8 @@ enum{
 #define BLKDEV_IFL_BARRIER	(1 << __BLKDEV_IFL_BARRIER)
 extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *,
 			unsigned long);
-#define DISCARD_FL_WAIT		0x01	/* wait for completion */
-#define DISCARD_FL_BARRIER	0x02	/* issue DISCARD_BARRIER request */
-extern int blkdev_issue_discard(struct block_device *, sector_t sector,
-		sector_t nr_sects, gfp_t, int flags);
+extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
 
 static inline int sb_issue_discard(struct super_block *sb,
 				   sector_t block, sector_t nr_blocks)
@@ -1013,7 +1011,7 @@ static inline int sb_issue_discard(struct super_block *sb,
 	block <<= (sb->s_blocksize_bits - 9);
 	nr_blocks <<= (sb->s_blocksize_bits - 9);
 	return blkdev_issue_discard(sb->s_bdev, block, nr_blocks, GFP_KERNEL,
-				    DISCARD_FL_BARRIER);
+				   BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 }
 
 extern int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 6cd0a8f..4a16fad 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -139,7 +139,8 @@ static int discard_swap(struct swap_info_struct *si)
 	nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9);
 	if (nr_blocks) {
 		err = blkdev_issue_discard(si->bdev, start_block,
-				nr_blocks, GFP_KERNEL, DISCARD_FL_BARRIER);
+				nr_blocks, GFP_KERNEL,
+				BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 		if (err)
 			return err;
 		cond_resched();
@@ -150,7 +151,8 @@ static int discard_swap(struct swap_info_struct *si)
 		nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9);
 
 		err = blkdev_issue_discard(si->bdev, start_block,
-				nr_blocks, GFP_KERNEL, DISCARD_FL_BARRIER);
+				nr_blocks, GFP_KERNEL,
+				BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 		if (err)
 			break;
 
@@ -189,7 +191,7 @@ static void discard_swap_cluster(struct swap_info_struct *si,
 			start_block <<= PAGE_SHIFT - 9;
 			nr_blocks <<= PAGE_SHIFT - 9;
 			if (blkdev_issue_discard(si->bdev, start_block,
-				    nr_blocks, GFP_NOIO, DISCARD_FL_BARRIER))
+				    nr_blocks, GFP_NOIO, BLKDEV_IFL_BARRIER))
 				break;
 		}
 
-- 
1.6.6.1

[PATCH 3/4] blkdev: add blkdev_issue helper functions

[Dmitry Monakhov]

Move blkdev_issue_discard from blk-barrier.c because it is not barrier
related.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 block/Makefile      |    2 +-
 block/blk-barrier.c |  103 ----------------------------------------------
 block/blk-lib.c     |  114 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 115 insertions(+), 104 deletions(-)
 create mode 100644 block/blk-lib.c

diff --git a/block/Makefile b/block/Makefile
index cb2d515..0bb499a 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -5,7 +5,7 @@
 obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \
 			blk-barrier.o blk-settings.o blk-ioc.o blk-map.o \
 			blk-exec.o blk-merge.o blk-softirq.o blk-timeout.o \
-			blk-iopoll.o ioctl.o genhd.o scsi_ioctl.o
+			blk-iopoll.o blk-lib.o ioctl.o genhd.o scsi_ioctl.o
 
 obj-$(CONFIG_BLK_DEV_BSG)	+= bsg.o
 obj-$(CONFIG_BLK_CGROUP)	+= blk-cgroup.o
diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 56254b1..1242bdd 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -347,106 +347,3 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 }
 EXPORT_SYMBOL(blkdev_issue_flush);
 
-static void blkdev_discard_end_io(struct bio *bio, int err)
-{
-	if (err) {
-		if (err == -EOPNOTSUPP)
-			set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
-		clear_bit(BIO_UPTODATE, &bio->bi_flags);
-	}
-
-	if (bio->bi_private)
-		complete(bio->bi_private);
-	__free_page(bio_page(bio));
-
-	bio_put(bio);
-}
-
-/**
- * blkdev_issue_discard - queue a discard
- * @bdev:	blockdev to issue discard for
- * @sector:	start sector
- * @nr_sects:	number of sectors to discard
- * @gfp_mask:	memory allocation flags (for bio_alloc)
- * @flags:	BLKDEV_IFL_* flags to control behaviour
- *
- * Description:
- *    Issue a discard request for the sectors in question.
- */
-int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
-		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
-{
-	DECLARE_COMPLETION_ONSTACK(wait);
-	struct request_queue *q = bdev_get_queue(bdev);
-	int type = flags & BLKDEV_IFL_BARRIER ?
-		DISCARD_BARRIER : DISCARD_NOBARRIER;
-	struct bio *bio;
-	struct page *page;
-	int ret = 0;
-
-	if (!q)
-		return -ENXIO;
-
-	if (!blk_queue_discard(q))
-		return -EOPNOTSUPP;
-
-	while (nr_sects && !ret) {
-		unsigned int sector_size = q->limits.logical_block_size;
-		unsigned int max_discard_sectors =
-			min(q->limits.max_discard_sectors, UINT_MAX >> 9);
-
-		bio = bio_alloc(gfp_mask, 1);
-		if (!bio)
-			goto out;
-		bio->bi_sector = sector;
-		bio->bi_end_io = blkdev_discard_end_io;
-		bio->bi_bdev = bdev;
-		if (flags & BLKDEV_IFL_BARRIER)
-			bio->bi_private = &wait;
-
-		/*
-		 * Add a zeroed one-sector payload as that's what
-		 * our current implementations need.  If we'll ever need
-		 * more the interface will need revisiting.
-		 */
-		page = alloc_page(gfp_mask | __GFP_ZERO);
-		if (!page)
-			goto out_free_bio;
-		if (bio_add_pc_page(q, bio, page, sector_size, 0) < sector_size)
-			goto out_free_page;
-
-		/*
-		 * And override the bio size - the way discard works we
-		 * touch many more blocks on disk than the actual payload
-		 * length.
-		 */
-		if (nr_sects > max_discard_sectors) {
-			bio->bi_size = max_discard_sectors << 9;
-			nr_sects -= max_discard_sectors;
-			sector += max_discard_sectors;
-		} else {
-			bio->bi_size = nr_sects << 9;
-			nr_sects = 0;
-		}
-
-		bio_get(bio);
-		submit_bio(type, bio);
-
-		if (flags & BLKDEV_IFL_BARRIER)
-			wait_for_completion(&wait);
-
-		if (bio_flagged(bio, BIO_EOPNOTSUPP))
-			ret = -EOPNOTSUPP;
-		else if (!bio_flagged(bio, BIO_UPTODATE))
-			ret = -EIO;
-		bio_put(bio);
-	}
-	return ret;
-out_free_page:
-	__free_page(page);
-out_free_bio:
-	bio_put(bio);
-out:
-	return -ENOMEM;
-}
-EXPORT_SYMBOL(blkdev_issue_discard);
diff --git a/block/blk-lib.c b/block/blk-lib.c
new file mode 100644
index 0000000..d7827e5
--- /dev/null
+++ b/block/blk-lib.c
@@ -0,0 +1,114 @@
+/*
+ * Functions related to generic helpers functions
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/scatterlist.h>
+
+#include "blk.h"
+
+static void blkdev_discard_end_io(struct bio *bio, int err)
+{
+	if (err) {
+		if (err == -EOPNOTSUPP)
+			set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
+		clear_bit(BIO_UPTODATE, &bio->bi_flags);
+	}
+
+	if (bio->bi_private)
+		complete(bio->bi_private);
+	__free_page(bio_page(bio));
+
+	bio_put(bio);
+}
+
+/**
+ * blkdev_issue_discard - queue a discard
+ * @bdev:	blockdev to issue discard for
+ * @sector:	start sector
+ * @nr_sects:	number of sectors to discard
+ * @gfp_mask:	memory allocation flags (for bio_alloc)
+ * @flags:	BLKDEV_IFL_* flags to control behaviour
+ *
+ * Description:
+ *    Issue a discard request for the sectors in question.
+ */
+int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
+{
+	DECLARE_COMPLETION_ONSTACK(wait);
+	struct request_queue *q = bdev_get_queue(bdev);
+	int type = flags & BLKDEV_IFL_BARRIER ?
+		DISCARD_BARRIER : DISCARD_NOBARRIER;
+	struct bio *bio;
+	struct page *page;
+	int ret = 0;
+
+	if (!q)
+		return -ENXIO;
+
+	if (!blk_queue_discard(q))
+		return -EOPNOTSUPP;
+
+	while (nr_sects && !ret) {
+		unsigned int sector_size = q->limits.logical_block_size;
+		unsigned int max_discard_sectors =
+			min(q->limits.max_discard_sectors, UINT_MAX >> 9);
+
+		bio = bio_alloc(gfp_mask, 1);
+		if (!bio)
+			goto out;
+		bio->bi_sector = sector;
+		bio->bi_end_io = blkdev_discard_end_io;
+		bio->bi_bdev = bdev;
+		if (flags & BLKDEV_IFL_BARRIER)
+			bio->bi_private = &wait;
+
+		/*
+		 * Add a zeroed one-sector payload as that's what
+		 * our current implementations need.  If we'll ever need
+		 * more the interface will need revisiting.
+		 */
+		page = alloc_page(gfp_mask | __GFP_ZERO);
+		if (!page)
+			goto out_free_bio;
+		if (bio_add_pc_page(q, bio, page, sector_size, 0) < sector_size)
+			goto out_free_page;
+
+		/*
+		 * And override the bio size - the way discard works we
+		 * touch many more blocks on disk than the actual payload
+		 * length.
+		 */
+		if (nr_sects > max_discard_sectors) {
+			bio->bi_size = max_discard_sectors << 9;
+			nr_sects -= max_discard_sectors;
+			sector += max_discard_sectors;
+		} else {
+			bio->bi_size = nr_sects << 9;
+			nr_sects = 0;
+		}
+
+		bio_get(bio);
+		submit_bio(type, bio);
+
+		if (flags & BLKDEV_IFL_BARRIER)
+			wait_for_completion(&wait);
+
+		if (bio_flagged(bio, BIO_EOPNOTSUPP))
+			ret = -EOPNOTSUPP;
+		else if (!bio_flagged(bio, BIO_UPTODATE))
+			ret = -EIO;
+		bio_put(bio);
+	}
+	return ret;
+out_free_page:
+	__free_page(page);
+out_free_bio:
+	bio_put(bio);
+out:
+	return -ENOMEM;
+}
+EXPORT_SYMBOL(blkdev_issue_discard);
-- 
1.6.6.1

[PATCH 4/4] patch blk-add-zeroout-helper.patch

[Dmitry Monakhov]

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 block/blk-lib.c        |  118 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/blkdev.h |    3 +-
 2 files changed, 120 insertions(+), 1 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index d7827e5..fa36030 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -112,3 +112,121 @@ out:
 	return -ENOMEM;
 }
 EXPORT_SYMBOL(blkdev_issue_discard);
+
+struct bio_batch
+{
+	atomic_t 		done;
+	unsigned long 		flags;
+	struct completion 	*wait;
+	bio_end_io_t		*end_io;
+};
+
+static void bio_batch_end_io(struct bio *bio, int err)
+{
+	struct bio_batch *bb = bio->bi_private;
+	if (err) {
+		if (err == -EOPNOTSUPP)
+			set_bit(BIO_EOPNOTSUPP, &bb->flags);
+		else
+			clear_bit(BIO_UPTODATE, &bb->flags);
+	}
+	if (bb) {
+		if (bb->end_io)
+			bb->end_io(bio, err);
+		atomic_inc(&bb->done);
+		complete(bb->wait);
+	}
+	bio_put(bio);
+}
+
+/**
+ * __blkdev_issue_zeroout generate number of zero filed write bios
+ * @bdev:	blockdev to issue
+ * @sector:	start sector
+ * @nr_sects:	number of sectors to write
+ * @gfp_mask:	memory allocation flags (for bio_alloc)
+ * @flags:	BLKDEV_IFL_* flags to control behaviour
+ *
+ * Description:
+ *  Generate and issue number of bios with zerofiled pages.
+ *  Send barrier at the beginning and at the end if requested. This guarantie
+ *  correct request ordering. Empty barrier allow us to avoid post queue flush.
+ */
+
+int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
+			sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
+{
+	int ret = 0;
+	struct bio *bio;
+	struct bio_batch bb;
+	unsigned int sz, issued = 0;
+	DECLARE_COMPLETION_ONSTACK(wait);
+
+	atomic_set(&bb.done, 0);
+	bb.flags = 1 << BIO_UPTODATE;
+	bb.wait = &wait;
+	bb.end_io = NULL;
+
+	if (flags & BLKDEV_IFL_BARRIER) {
+		/* issue async barrier before the data */
+		ret = blkdev_issue_flush(bdev, gfp_mask, NULL, 0);
+		if (ret)
+			return ret;
+	}
+submit:
+	while (nr_sects != 0) {
+		bio = bio_alloc(gfp_mask,
+				min(nr_sects, (sector_t)BIO_MAX_PAGES));
+		if (!bio)
+			break;
+
+		bio->bi_sector = sector;
+		bio->bi_bdev   = bdev;
+		bio->bi_end_io = bio_batch_end_io;
+		if (flags & BLKDEV_IFL_WAIT)
+			bio->bi_private = &bb;
+
+		while(nr_sects != 0) {
+			sz = min(PAGE_SIZE >> 9 , nr_sects);
+			if (sz == 0)
+				/* bio has maximum size possible */
+				break;
+			ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
+			nr_sects -= ret >> 9;
+			sector += ret >> 9;
+			if (ret < (sz << 9))
+				break;
+		}
+		issued++;
+		submit_bio(WRITE, bio);
+	}
+	/*
+	 * When all data bios are in flight. Send final barrier if requeted.
+	 */
+	if (nr_sects == 0 && flags & BLKDEV_IFL_BARRIER)
+		ret = blkdev_issue_flush(bdev, gfp_mask, NULL,
+					flags & BLKDEV_IFL_WAIT);
+
+
+	if (flags & BLKDEV_IFL_WAIT)
+		/* Wait for bios in-flight */
+		while ( issued != atomic_read(&bb.done))
+			wait_for_completion(&wait);
+
+	if (!test_bit(BIO_UPTODATE, &bb.flags))
+		/* One of bios in the batch was completed with error.*/
+		ret = -EIO;
+
+	if (ret)
+		goto out;
+
+	if (test_bit(BIO_EOPNOTSUPP, &bb.flags)) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+	if (nr_sects != 0)
+		goto submit;
+out:
+	return ret;
+}
+EXPORT_SYMBOL(__blkdev_issue_zeroout);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index a222351..787edbb 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1004,7 +1004,8 @@ extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *,
 			unsigned long);
 extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
-
+extern int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
+			sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
 static inline int sb_issue_discard(struct super_block *sb,
 				   sector_t block, sector_t nr_blocks)
 {
-- 
1.6.6.1

Re: [PATCH 4/4] patch blk-add-zeroout-helper.patch

[Christoph Hellwig]

Looks okayish to me, but it really needs:

 a) a useful patch description
 b) patches that introduce actual users

Also why does the function have a __ prefix in the name?

Re: [PATCH 3/4] blkdev: add blkdev_issue helper functions

[Christoph Hellwig]

On Mon, Apr 12, 2010 at 05:03:56PM +0400, Dmitry Monakhov wrote:
> Move blkdev_issue_discard from blk-barrier.c because it is not barrier
> related.

If you create a new file just for discard I would call it blk-discard.c.
But I can't really be bothered too much about the placement of this two
functions, so do whatever is fine with you and Jens.

Re: [PATCH 2/4] blkdev: generalize flags for blkdev_issue_fn functions

[Christoph Hellwig]

On Mon, Apr 12, 2010 at 05:03:55PM +0400, Dmitry Monakhov wrote:
> The patch just convert all blkdev_issue_xxx function to common
> flags. Wait/allocation semantics not changed.
> 
> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>

Looks good in general.  But I would re-order this to be patch 1 so you
can avoid introducing flags for blkdev_issue_flush just to replace them
in the next one.

Re: [PATCH 1/4] blkdev: pass gfp_mask and flags to blkdev_issue_flush

[Christoph Hellwig]

On Mon, Apr 12, 2010 at 05:03:54PM +0400, Dmitry Monakhov wrote:
> In some places caller don't want to wait a request to complete.
> Flags make blkdev_issue_flush() more flexible. This patch just
> convert existing callers to new interface without chaining
> existing allocation/wait behavior.

Looks okay to me, but as mention in the other review I would introduce
the comment flags first and then add the flags to blkdev_issue_flush,
not the other way around.

Re: [PATCH 1/4] blkdev: pass gfp_mask and flags to blkdev_issue_flush

[Christoph Hellwig]

> +enum{
> +	__BLKDEV_IFL_WAIT,	/* wait for completion */
> +	__BLKDEV_IFL_BARRIER,	/*issue request with barrier */
> +};
> +#define BLKDEV_IFL_WAIT		(1 << __BLKDEV_IFL_WAIT)
> +#define BLKDEV_IFL_BARRIER	(1 << __BLKDEV_IFL_BARRIER)

This is a very awkward stayle to define flags.  There really should
be no need for the __-prefixed version.  While you're using them for
test/set_bit and co there's no reason to use these atomic bitops here.

Re: [PATCH 1/4] blkdev: pass gfp_mask and flags to blkdev_issue_flush

[Dmitry Monakhov]

Christoph Hellwig <hch@infradead.org> writes:

>> +enum{
>> +	__BLKDEV_IFL_WAIT,	/* wait for completion */
>> +	__BLKDEV_IFL_BARRIER,	/*issue request with barrier */
>> +};
>> +#define BLKDEV_IFL_WAIT		(1 << __BLKDEV_IFL_WAIT)
>> +#define BLKDEV_IFL_BARRIER	(1 << __BLKDEV_IFL_BARRIER)
>
> This is a very awkward stayle to define flags.  There really should
> be no need for the __-prefixed version.  While you're using them for
> test/set_bit and co there's no reason to use these atomic bitops here.
I need both bit_num(used inside function) and flag (1<<bit_num)
which is used by function caller.
No problem, i'll change it whenever you like
do you like following?
enum{
	IFN_BLKDEV_WAIT,	/* wait for completion */
	IFN_BLKDEV_BARRIER,	/*issue request with barrier */
};
#define BLKDEV_WAIT		(1 << IFN_BLKDEV_WAIT)
#define BLKDEV_BARRIER		(1 << IFN_BLKDEV_BARRIER)

Re: [PATCH 0/4] blkdev: blkdev_issue_fn cleanups v2

[Christoph Hellwig]

Jens, are you planning on picking up a version of this?

On Mon, Apr 12, 2010 at 05:03:53PM +0400, Dmitry Monakhov wrote:
> - Convert all blkdev_issue_xxx function to common set of flags
> - move common functions to block/blk-lib.c
> - Add generic zeroout helper
> 
> changes from V1
> Christoph is about to change discard memory payload allocation logic
> so discard cleanups are no longer necessary.
---end quoted text---

Re: [PATCH 0/4] blkdev: blkdev_issue_fn cleanups v2

[Jens Axboe]

On Mon, Apr 26 2010, Christoph Hellwig wrote:
> Jens, are you planning on picking up a version of this?

Yes, I was waiting for a repost to address your review concerns.

> 
> On Mon, Apr 12, 2010 at 05:03:53PM +0400, Dmitry Monakhov wrote:
> > - Convert all blkdev_issue_xxx function to common set of flags
> > - move common functions to block/blk-lib.c
> > - Add generic zeroout helper
> > 
> > changes from V1
> > Christoph is about to change discard memory payload allocation logic
> > so discard cleanups are no longer necessary.
> ---end quoted text---

-- 
Jens Axboe

Re: [PATCH 0/4] blkdev: blkdev_issue_fn cleanups v2

[Dmitry Monakhov]

Jens Axboe <jens.axboe@oracle.com> writes:

> On Mon, Apr 26 2010, Christoph Hellwig wrote:
>> Jens, are you planning on picking up a version of this?
>
> Yes, I was waiting for a repost to address your review concerns.
Ok, will appear in several hours. I have to repeat full testing
cycle, I don't want to break lvm one more time :)
>
>> 
>> On Mon, Apr 12, 2010 at 05:03:53PM +0400, Dmitry Monakhov wrote:
>> > - Convert all blkdev_issue_xxx function to common set of flags
>> > - move common functions to block/blk-lib.c
>> > - Add generic zeroout helper
>> > 
>> > changes from V1
>> > Christoph is about to change discard memory payload allocation logic
>> > so discard cleanups are no longer necessary.
>> ---end quoted text---

Re: [PATCH 0/4] blkdev: blkdev_issue_fn cleanups v2

[Jens Axboe]

On Mon, Apr 26 2010, Dmitry Monakhov wrote:
> Jens Axboe <jens.axboe@oracle.com> writes:
> 
> > On Mon, Apr 26 2010, Christoph Hellwig wrote:
> >> Jens, are you planning on picking up a version of this?
> >
> > Yes, I was waiting for a repost to address your review concerns.
> Ok, will appear in several hours. I have to repeat full testing
> cycle, I don't want to break lvm one more time :)

Take your time, I would appreciate it if lvm didn't get broken again :-)

-- 
Jens Axboe

[PATCH 0/4] blkdev: blkdev_issue_fn cleanups v3

[Dmitry Monakhov]

- Convert all blkdev_issue_xxx function to common set of flags
- move common helper functions to block/blk-lib.c
- Add generic zeroout helper

Tested configuration: ext4 w -odiscard over raw_bdisk and dm-linear
changes from V2
Fix flag names, and rearange patches according to Christoph's comments.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 Makefile |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/Makefile b/Makefile
index fa1db90..285a0fa 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 VERSION = 2
 PATCHLEVEL = 6
 SUBLEVEL = 34
-EXTRAVERSION = -rc5
+EXTRAVERSION = -rc5-
 NAME = Sheep on Meth
 
 # *DOCUMENTATION*
-- 
1.6.6.1

[PATCH 1/4] blkdev: generalize flags for blkdev_issue_fn functions

[Dmitry Monakhov]

The patch just convert all blkdev_issue_xxx function to common
set of flags. Wait/allocation semantics preserved.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 block/blk-barrier.c                |   20 +++++++++++---------
 block/ioctl.c                      |    2 +-
 drivers/block/drbd/drbd_int.h      |    3 ++-
 drivers/block/drbd/drbd_receiver.c |    3 ++-
 fs/block_dev.c                     |    3 ++-
 fs/btrfs/extent-tree.c             |    2 +-
 fs/ext3/fsync.c                    |    3 ++-
 fs/ext4/fsync.c                    |    6 ++++--
 fs/gfs2/rgrp.c                     |    5 +++--
 fs/jbd2/checkpoint.c               |    3 ++-
 fs/jbd2/commit.c                   |    6 ++++--
 fs/reiserfs/file.c                 |    3 ++-
 fs/xfs/linux-2.6/xfs_super.c       |    3 ++-
 include/linux/blkdev.h             |   18 +++++++++++-------
 mm/swapfile.c                      |    9 ++++++---
 15 files changed, 55 insertions(+), 34 deletions(-)

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 6d88544..cf14311 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -293,19 +293,22 @@ static void bio_end_empty_barrier(struct bio *bio, int err)
 /**
  * blkdev_issue_flush - queue a flush
  * @bdev:	blockdev to issue flush for
+ * @gfp_mask:	memory allocation flags (for bio_alloc)
  * @error_sector:	error sector
+ * @flags:	BLKDEV_IFL_* flags to control behaviour
  *
  * Description:
  *    Issue a flush for the block device in question. Caller can supply
  *    room for storing the error offset in case of a flush error, if they
  *    wish to.
  */
-int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
+int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
+		sector_t *error_sector, unsigned long flags)
 {
 	DECLARE_COMPLETION_ONSTACK(wait);
 	struct request_queue *q;
 	struct bio *bio;
-	int ret;
+	int ret = 0;
 
 	if (bdev->bd_disk == NULL)
 		return -ENXIO;
@@ -314,7 +317,7 @@ int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
 	if (!q)
 		return -ENXIO;
 
-	bio = bio_alloc(GFP_KERNEL, 0);
+	bio = bio_alloc(gfp_mask, 0);
 	bio->bi_end_io = bio_end_empty_barrier;
 	bio->bi_private = &wait;
 	bio->bi_bdev = bdev;
@@ -330,7 +333,6 @@ int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
 	if (error_sector)
 		*error_sector = bio->bi_sector;
 
-	ret = 0;
 	if (bio_flagged(bio, BIO_EOPNOTSUPP))
 		ret = -EOPNOTSUPP;
 	else if (!bio_flagged(bio, BIO_UPTODATE))
@@ -362,17 +364,17 @@ static void blkdev_discard_end_io(struct bio *bio, int err)
  * @sector:	start sector
  * @nr_sects:	number of sectors to discard
  * @gfp_mask:	memory allocation flags (for bio_alloc)
- * @flags:	DISCARD_FL_* flags to control behaviour
+ * @flags:	BLKDEV_IFL_* flags to control behaviour
  *
  * Description:
  *    Issue a discard request for the sectors in question.
  */
 int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
-		sector_t nr_sects, gfp_t gfp_mask, int flags)
+		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
 {
 	DECLARE_COMPLETION_ONSTACK(wait);
 	struct request_queue *q = bdev_get_queue(bdev);
-	int type = flags & DISCARD_FL_BARRIER ?
+	int type = flags & BLKDEV_IFL_BARRIER ?
 		DISCARD_BARRIER : DISCARD_NOBARRIER;
 	struct bio *bio;
 	struct page *page;
@@ -395,7 +397,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		bio->bi_sector = sector;
 		bio->bi_end_io = blkdev_discard_end_io;
 		bio->bi_bdev = bdev;
-		if (flags & DISCARD_FL_WAIT)
+		if (flags & BLKDEV_IFL_WAIT)
 			bio->bi_private = &wait;
 
 		/*
@@ -426,7 +428,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		bio_get(bio);
 		submit_bio(type, bio);
 
-		if (flags & DISCARD_FL_WAIT)
+		if (flags & BLKDEV_IFL_WAIT)
 			wait_for_completion(&wait);
 
 		if (bio_flagged(bio, BIO_EOPNOTSUPP))
diff --git a/block/ioctl.c b/block/ioctl.c
index 8905d2a..e8eb679 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -126,7 +126,7 @@ static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
 	if (start + len > (bdev->bd_inode->i_size >> 9))
 		return -EINVAL;
 	return blkdev_issue_discard(bdev, start, len, GFP_KERNEL,
-				    DISCARD_FL_WAIT);
+				    BLKDEV_IFL_WAIT);
 }
 
 static int put_ushort(unsigned long arg, unsigned short val)
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index e5e86a7..d6f1ae3 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -2251,7 +2251,8 @@ static inline void drbd_md_flush(struct drbd_conf *mdev)
 	if (test_bit(MD_NO_BARRIER, &mdev->flags))
 		return;
 
-	r = blkdev_issue_flush(mdev->ldev->md_bdev, NULL);
+	r = blkdev_issue_flush(mdev->ldev->md_bdev, GFP_KERNEL, NULL,
+			BLKDEV_IFL_WAIT);
 	if (r) {
 		set_bit(MD_NO_BARRIER, &mdev->flags);
 		dev_err(DEV, "meta data flush failed with status %d, disabling md-flushes\n", r);
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 3f096e7..c786023 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -946,7 +946,8 @@ static enum finish_epoch drbd_flush_after_epoch(struct drbd_conf *mdev, struct d
 	int rv;
 
 	if (mdev->write_ordering >= WO_bdev_flush && get_ldev(mdev)) {
-		rv = blkdev_issue_flush(mdev->ldev->backing_bdev, NULL);
+		rv = blkdev_issue_flush(mdev->ldev->backing_bdev, GFP_KERNEL,
+					NULL, BLKDEV_IFL_WAIT);
 		if (rv) {
 			dev_err(DEV, "local disk flush failed with status %d\n", rv);
 			/* would rather check on EOPNOTSUPP, but that is not reliable.
diff --git a/fs/block_dev.c b/fs/block_dev.c
index ea8385e..dd76930 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -413,7 +413,8 @@ int blkdev_fsync(struct file *filp, struct dentry *dentry, int datasync)
 	if (error)
 		return error;
 	
-	error = blkdev_issue_flush(bdev, NULL);
+	error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL,
+				(BLKDEV_IFL_WAIT));
 	if (error == -EOPNOTSUPP)
 		error = 0;
 	return error;
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index b34d32f..c6a4f45 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1589,7 +1589,7 @@ static void btrfs_issue_discard(struct block_device *bdev,
 				u64 start, u64 len)
 {
 	blkdev_issue_discard(bdev, start >> 9, len >> 9, GFP_KERNEL,
-			     DISCARD_FL_BARRIER);
+			BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 }
 
 static int btrfs_discard_extent(struct btrfs_root *root, u64 bytenr,
diff --git a/fs/ext3/fsync.c b/fs/ext3/fsync.c
index 8209f26..9492f60 100644
--- a/fs/ext3/fsync.c
+++ b/fs/ext3/fsync.c
@@ -91,7 +91,8 @@ int ext3_sync_file(struct file * file, struct dentry *dentry, int datasync)
 	 * storage
 	 */
 	if (test_opt(inode->i_sb, BARRIER))
-		blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
+		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL,
+				BLKDEV_IFL_WAIT);
 out:
 	return ret;
 }
diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
index 0d0c323..ef3d980 100644
--- a/fs/ext4/fsync.c
+++ b/fs/ext4/fsync.c
@@ -100,9 +100,11 @@ int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync)
 		if (ext4_should_writeback_data(inode) &&
 		    (journal->j_fs_dev != journal->j_dev) &&
 		    (journal->j_flags & JBD2_BARRIER))
-			blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
+			blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL,
+					NULL, BLKDEV_IFL_WAIT);
 		jbd2_log_wait_commit(journal, commit_tid);
 	} else if (journal->j_flags & JBD2_BARRIER)
-		blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
+		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL,
+			BLKDEV_IFL_WAIT);
 	return ret;
 }
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 503b842..bf011dc 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -854,7 +854,8 @@ static void gfs2_rgrp_send_discards(struct gfs2_sbd *sdp, u64 offset,
 				if ((start + nr_sects) != blk) {
 					rv = blkdev_issue_discard(bdev, start,
 							    nr_sects, GFP_NOFS,
-							    DISCARD_FL_BARRIER);
+							    BLKDEV_IFL_WAIT |
+							    BLKDEV_IFL_BARRIER);
 					if (rv)
 						goto fail;
 					nr_sects = 0;
@@ -869,7 +870,7 @@ start_new_extent:
 	}
 	if (nr_sects) {
 		rv = blkdev_issue_discard(bdev, start, nr_sects, GFP_NOFS,
-					 DISCARD_FL_BARRIER);
+					 BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 		if (rv)
 			goto fail;
 	}
diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index 30beb11..076d1cc 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -530,7 +530,8 @@ int jbd2_cleanup_journal_tail(journal_t *journal)
 	 */
 	if ((journal->j_fs_dev != journal->j_dev) &&
 	    (journal->j_flags & JBD2_BARRIER))
-		blkdev_issue_flush(journal->j_fs_dev, NULL);
+		blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL,
+			BLKDEV_IFL_WAIT);
 	if (!(journal->j_flags & JBD2_ABORT))
 		jbd2_journal_update_superblock(journal, 1);
 	return 0;
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 671da7f..75716d3 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -717,7 +717,8 @@ start_journal_io:
 	if (commit_transaction->t_flushed_data_blocks &&
 	    (journal->j_fs_dev != journal->j_dev) &&
 	    (journal->j_flags & JBD2_BARRIER))
-		blkdev_issue_flush(journal->j_fs_dev, NULL);
+		blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL,
+			BLKDEV_IFL_WAIT);
 
 	/* Done it all: now write the commit record asynchronously. */
 	if (JBD2_HAS_INCOMPAT_FEATURE(journal,
@@ -727,7 +728,8 @@ start_journal_io:
 		if (err)
 			__jbd2_journal_abort_hard(journal);
 		if (journal->j_flags & JBD2_BARRIER)
-			blkdev_issue_flush(journal->j_dev, NULL);
+			blkdev_issue_flush(journal->j_dev, GFP_KERNEL, NULL,
+				BLKDEV_IFL_WAIT);
 	}
 
 	err = journal_finish_inode_data_buffers(journal, commit_transaction);
diff --git a/fs/reiserfs/file.c b/fs/reiserfs/file.c
index 1d9c127..9977df9 100644
--- a/fs/reiserfs/file.c
+++ b/fs/reiserfs/file.c
@@ -147,7 +147,8 @@ static int reiserfs_sync_file(struct file *filp,
 	barrier_done = reiserfs_commit_for_inode(inode);
 	reiserfs_write_unlock(inode->i_sb);
 	if (barrier_done != 1 && reiserfs_barrier_flush(inode->i_sb))
-		blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
+		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL, 
+			BLKDEV_IFL_WAIT);
 	if (barrier_done < 0)
 		return barrier_done;
 	return (err < 0) ? -EIO : 0;
diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 52e06b4..2b177c7 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -725,7 +725,8 @@ void
 xfs_blkdev_issue_flush(
 	xfs_buftarg_t		*buftarg)
 {
-	blkdev_issue_flush(buftarg->bt_bdev, NULL);
+	blkdev_issue_flush(buftarg->bt_bdev, GFP_KERNEL, NULL,
+			BLKDEV_IFL_WAIT);
 }
 
 STATIC void
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 5cf17a4..59b9aed 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -998,12 +998,16 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
 		return NULL;
 	return bqt->tag_index[tag];
 }
-
-extern int blkdev_issue_flush(struct block_device *, sector_t *);
-#define DISCARD_FL_WAIT		0x01	/* wait for completion */
-#define DISCARD_FL_BARRIER	0x02	/* issue DISCARD_BARRIER request */
-extern int blkdev_issue_discard(struct block_device *, sector_t sector,
-		sector_t nr_sects, gfp_t, int flags);
+enum{
+	BLKDEV_WAIT,	/* wait for completion */
+	BLKDEV_BARRIER,	/*issue request with barrier */
+};
+#define BLKDEV_IFL_WAIT		(1 << BLKDEV_WAIT)
+#define BLKDEV_IFL_BARRIER	(1 << BLKDEV_BARRIER)
+extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *,
+			unsigned long);
+extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
 
 static inline int sb_issue_discard(struct super_block *sb,
 				   sector_t block, sector_t nr_blocks)
@@ -1011,7 +1015,7 @@ static inline int sb_issue_discard(struct super_block *sb,
 	block <<= (sb->s_blocksize_bits - 9);
 	nr_blocks <<= (sb->s_blocksize_bits - 9);
 	return blkdev_issue_discard(sb->s_bdev, block, nr_blocks, GFP_KERNEL,
-				    DISCARD_FL_BARRIER);
+				   BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 }
 
 extern int blk_verify_command(unsigned char *cmd, fmode_t has_write_perm);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 6cd0a8f..eb086e0 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -139,7 +139,8 @@ static int discard_swap(struct swap_info_struct *si)
 	nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9);
 	if (nr_blocks) {
 		err = blkdev_issue_discard(si->bdev, start_block,
-				nr_blocks, GFP_KERNEL, DISCARD_FL_BARRIER);
+				nr_blocks, GFP_KERNEL,
+				BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 		if (err)
 			return err;
 		cond_resched();
@@ -150,7 +151,8 @@ static int discard_swap(struct swap_info_struct *si)
 		nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9);
 
 		err = blkdev_issue_discard(si->bdev, start_block,
-				nr_blocks, GFP_KERNEL, DISCARD_FL_BARRIER);
+				nr_blocks, GFP_KERNEL,
+				BLKDEV_IFL_WAIT | BLKDEV_IFL_BARRIER);
 		if (err)
 			break;
 
@@ -189,7 +191,8 @@ static void discard_swap_cluster(struct swap_info_struct *si,
 			start_block <<= PAGE_SHIFT - 9;
 			nr_blocks <<= PAGE_SHIFT - 9;
 			if (blkdev_issue_discard(si->bdev, start_block,
-				    nr_blocks, GFP_NOIO, DISCARD_FL_BARRIER))
+				    nr_blocks, GFP_NOIO, BLKDEV_IFL_WAIT |
+							BLKDEV_IFL_BARRIER))
 				break;
 		}
 
-- 
1.6.6.1

[PATCH 2/4] blkdev: allow async blkdev_issue_flush requests

[Dmitry Monakhov]

In some places caller don't want to wait a request to complete.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 block/blk-barrier.c |   33 +++++++++++++++++++--------------
 1 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index cf14311..f11eec9 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -286,8 +286,9 @@ static void bio_end_empty_barrier(struct bio *bio, int err)
 			set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
 		clear_bit(BIO_UPTODATE, &bio->bi_flags);
 	}
-
-	complete(bio->bi_private);
+	if (bio->bi_private)
+		complete(bio->bi_private);
+	bio_put(bio);
 }
 
 /**
@@ -300,7 +301,8 @@ static void bio_end_empty_barrier(struct bio *bio, int err)
  * Description:
  *    Issue a flush for the block device in question. Caller can supply
  *    room for storing the error offset in case of a flush error, if they
- *    wish to.
+ *    wish to. If WAIT flag is not passed then caller may check only what
+ *    request was pushed in some internal queue for later handling.
  */
 int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 		sector_t *error_sector, unsigned long flags)
@@ -319,19 +321,22 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 
 	bio = bio_alloc(gfp_mask, 0);
 	bio->bi_end_io = bio_end_empty_barrier;
-	bio->bi_private = &wait;
 	bio->bi_bdev = bdev;
-	submit_bio(WRITE_BARRIER, bio);
-
-	wait_for_completion(&wait);
+	if (test_bit(BLKDEV_WAIT, &flags))
+		bio->bi_private = &wait;
 
-	/*
-	 * The driver must store the error location in ->bi_sector, if
-	 * it supports it. For non-stacked drivers, this should be copied
-	 * from blk_rq_pos(rq).
-	 */
-	if (error_sector)
-		*error_sector = bio->bi_sector;
+	bio_get(bio);
+	submit_bio(WRITE_BARRIER, bio);
+	if (test_bit(BLKDEV_WAIT, &flags)) {
+		wait_for_completion(&wait);
+		/*
+		 * The driver must store the error location in ->bi_sector, if
+		 * it supports it. For non-stacked drivers, this should be
+		 * copied from blk_rq_pos(rq).
+		 */
+		if (error_sector)
+			*error_sector = bio->bi_sector;
+	}
 
 	if (bio_flagged(bio, BIO_EOPNOTSUPP))
 		ret = -EOPNOTSUPP;
-- 
1.6.6.1

[PATCH 3/4] blkdev: move blkdev_issue helper functions to separate file

[Dmitry Monakhov]

Move blkdev_issue_discard from blk-barrier.c because it is
not barrier related.
Later the file will be populated by other helpers.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 block/Makefile      |    2 +-
 block/blk-barrier.c |  104 ----------------------------------------------
 block/blk-lib.c     |  114 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 115 insertions(+), 105 deletions(-)
 create mode 100644 block/blk-lib.c

diff --git a/block/Makefile b/block/Makefile
index cb2d515..0bb499a 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -5,7 +5,7 @@
 obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \
 			blk-barrier.o blk-settings.o blk-ioc.o blk-map.o \
 			blk-exec.o blk-merge.o blk-softirq.o blk-timeout.o \
-			blk-iopoll.o ioctl.o genhd.o scsi_ioctl.o
+			blk-iopoll.o blk-lib.o ioctl.o genhd.o scsi_ioctl.o
 
 obj-$(CONFIG_BLK_DEV_BSG)	+= bsg.o
 obj-$(CONFIG_BLK_CGROUP)	+= blk-cgroup.o
diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index f11eec9..0d710c9 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -347,107 +347,3 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
 	return ret;
 }
 EXPORT_SYMBOL(blkdev_issue_flush);
-
-static void blkdev_discard_end_io(struct bio *bio, int err)
-{
-	if (err) {
-		if (err == -EOPNOTSUPP)
-			set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
-		clear_bit(BIO_UPTODATE, &bio->bi_flags);
-	}
-
-	if (bio->bi_private)
-		complete(bio->bi_private);
-	__free_page(bio_page(bio));
-
-	bio_put(bio);
-}
-
-/**
- * blkdev_issue_discard - queue a discard
- * @bdev:	blockdev to issue discard for
- * @sector:	start sector
- * @nr_sects:	number of sectors to discard
- * @gfp_mask:	memory allocation flags (for bio_alloc)
- * @flags:	BLKDEV_IFL_* flags to control behaviour
- *
- * Description:
- *    Issue a discard request for the sectors in question.
- */
-int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
-		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
-{
-	DECLARE_COMPLETION_ONSTACK(wait);
-	struct request_queue *q = bdev_get_queue(bdev);
-	int type = flags & BLKDEV_IFL_BARRIER ?
-		DISCARD_BARRIER : DISCARD_NOBARRIER;
-	struct bio *bio;
-	struct page *page;
-	int ret = 0;
-
-	if (!q)
-		return -ENXIO;
-
-	if (!blk_queue_discard(q))
-		return -EOPNOTSUPP;
-
-	while (nr_sects && !ret) {
-		unsigned int sector_size = q->limits.logical_block_size;
-		unsigned int max_discard_sectors =
-			min(q->limits.max_discard_sectors, UINT_MAX >> 9);
-
-		bio = bio_alloc(gfp_mask, 1);
-		if (!bio)
-			goto out;
-		bio->bi_sector = sector;
-		bio->bi_end_io = blkdev_discard_end_io;
-		bio->bi_bdev = bdev;
-		if (flags & BLKDEV_IFL_WAIT)
-			bio->bi_private = &wait;
-
-		/*
-		 * Add a zeroed one-sector payload as that's what
-		 * our current implementations need.  If we'll ever need
-		 * more the interface will need revisiting.
-		 */
-		page = alloc_page(gfp_mask | __GFP_ZERO);
-		if (!page)
-			goto out_free_bio;
-		if (bio_add_pc_page(q, bio, page, sector_size, 0) < sector_size)
-			goto out_free_page;
-
-		/*
-		 * And override the bio size - the way discard works we
-		 * touch many more blocks on disk than the actual payload
-		 * length.
-		 */
-		if (nr_sects > max_discard_sectors) {
-			bio->bi_size = max_discard_sectors << 9;
-			nr_sects -= max_discard_sectors;
-			sector += max_discard_sectors;
-		} else {
-			bio->bi_size = nr_sects << 9;
-			nr_sects = 0;
-		}
-
-		bio_get(bio);
-		submit_bio(type, bio);
-
-		if (flags & BLKDEV_IFL_WAIT)
-			wait_for_completion(&wait);
-
-		if (bio_flagged(bio, BIO_EOPNOTSUPP))
-			ret = -EOPNOTSUPP;
-		else if (!bio_flagged(bio, BIO_UPTODATE))
-			ret = -EIO;
-		bio_put(bio);
-	}
-	return ret;
-out_free_page:
-	__free_page(page);
-out_free_bio:
-	bio_put(bio);
-out:
-	return -ENOMEM;
-}
-EXPORT_SYMBOL(blkdev_issue_discard);
diff --git a/block/blk-lib.c b/block/blk-lib.c
new file mode 100644
index 0000000..0dc4388
--- /dev/null
+++ b/block/blk-lib.c
@@ -0,0 +1,114 @@
+/*
+ * Functions related to generic helpers functions
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/scatterlist.h>
+
+#include "blk.h"
+
+static void blkdev_discard_end_io(struct bio *bio, int err)
+{
+	if (err) {
+		if (err == -EOPNOTSUPP)
+			set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
+		clear_bit(BIO_UPTODATE, &bio->bi_flags);
+	}
+
+	if (bio->bi_private)
+		complete(bio->bi_private);
+	__free_page(bio_page(bio));
+
+	bio_put(bio);
+}
+
+/**
+ * blkdev_issue_discard - queue a discard
+ * @bdev:	blockdev to issue discard for
+ * @sector:	start sector
+ * @nr_sects:	number of sectors to discard
+ * @gfp_mask:	memory allocation flags (for bio_alloc)
+ * @flags:	BLKDEV_IFL_* flags to control behaviour
+ *
+ * Description:
+ *    Issue a discard request for the sectors in question.
+ */
+int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
+		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
+{
+	DECLARE_COMPLETION_ONSTACK(wait);
+	struct request_queue *q = bdev_get_queue(bdev);
+	int type = flags & BLKDEV_IFL_BARRIER ?
+		DISCARD_BARRIER : DISCARD_NOBARRIER;
+	struct bio *bio;
+	struct page *page;
+	int ret = 0;
+
+	if (!q)
+		return -ENXIO;
+
+	if (!blk_queue_discard(q))
+		return -EOPNOTSUPP;
+
+	while (nr_sects && !ret) {
+		unsigned int sector_size = q->limits.logical_block_size;
+		unsigned int max_discard_sectors =
+			min(q->limits.max_discard_sectors, UINT_MAX >> 9);
+
+		bio = bio_alloc(gfp_mask, 1);
+		if (!bio)
+			goto out;
+		bio->bi_sector = sector;
+		bio->bi_end_io = blkdev_discard_end_io;
+		bio->bi_bdev = bdev;
+		if (flags & BLKDEV_IFL_WAIT)
+			bio->bi_private = &wait;
+
+		/*
+		 * Add a zeroed one-sector payload as that's what
+		 * our current implementations need.  If we'll ever need
+		 * more the interface will need revisiting.
+		 */
+		page = alloc_page(gfp_mask | __GFP_ZERO);
+		if (!page)
+			goto out_free_bio;
+		if (bio_add_pc_page(q, bio, page, sector_size, 0) < sector_size)
+			goto out_free_page;
+
+		/*
+		 * And override the bio size - the way discard works we
+		 * touch many more blocks on disk than the actual payload
+		 * length.
+		 */
+		if (nr_sects > max_discard_sectors) {
+			bio->bi_size = max_discard_sectors << 9;
+			nr_sects -= max_discard_sectors;
+			sector += max_discard_sectors;
+		} else {
+			bio->bi_size = nr_sects << 9;
+			nr_sects = 0;
+		}
+
+		bio_get(bio);
+		submit_bio(type, bio);
+
+		if (flags & BLKDEV_IFL_WAIT)
+			wait_for_completion(&wait);
+
+		if (bio_flagged(bio, BIO_EOPNOTSUPP))
+			ret = -EOPNOTSUPP;
+		else if (!bio_flagged(bio, BIO_UPTODATE))
+			ret = -EIO;
+		bio_put(bio);
+	}
+	return ret;
+out_free_page:
+	__free_page(page);
+out_free_bio:
+	bio_put(bio);
+out:
+	return -ENOMEM;
+}
+EXPORT_SYMBOL(blkdev_issue_discard);
-- 
1.6.6.1

[PATCH 4/4] blkdev: add blkdev_issue_zeroout helper function

[Dmitry Monakhov]

- Add bio_batch helper primitive. This is rather generic primitive
  for submitting/waiting a complex request which consists of several
  bios.
- blkdev_issue_zeroout() generate number of zero filed write bios.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
 block/blk-lib.c        |  118 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/blkdev.h |    3 +-
 2 files changed, 120 insertions(+), 1 deletions(-)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 0dc4388..886c3f9 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -112,3 +112,121 @@ out:
 	return -ENOMEM;
 }
 EXPORT_SYMBOL(blkdev_issue_discard);
+
+struct bio_batch
+{
+	atomic_t 		done;
+	unsigned long 		flags;
+	struct completion 	*wait;
+	bio_end_io_t		*end_io;
+};
+
+static void bio_batch_end_io(struct bio *bio, int err)
+{
+	struct bio_batch *bb = bio->bi_private;
+	if (err) {
+		if (err == -EOPNOTSUPP)
+			set_bit(BIO_EOPNOTSUPP, &bb->flags);
+		else
+			clear_bit(BIO_UPTODATE, &bb->flags);
+	}
+	if (bb) {
+		if (bb->end_io)
+			bb->end_io(bio, err);
+		atomic_inc(&bb->done);
+		complete(bb->wait);
+	}
+	bio_put(bio);
+}
+
+/**
+ * blkdev_issue_zeroout generate number of zero filed write bios
+ * @bdev:	blockdev to issue
+ * @sector:	start sector
+ * @nr_sects:	number of sectors to write
+ * @gfp_mask:	memory allocation flags (for bio_alloc)
+ * @flags:	BLKDEV_IFL_* flags to control behaviour
+ *
+ * Description:
+ *  Generate and issue number of bios with zerofiled pages.
+ *  Send barrier at the beginning and at the end if requested. This guarantie
+ *  correct request ordering. Empty barrier allow us to avoid post queue flush.
+ */
+
+int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
+			sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
+{
+	int ret = 0;
+	struct bio *bio;
+	struct bio_batch bb;
+	unsigned int sz, issued = 0;
+	DECLARE_COMPLETION_ONSTACK(wait);
+
+	atomic_set(&bb.done, 0);
+	bb.flags = 1 << BIO_UPTODATE;
+	bb.wait = &wait;
+	bb.end_io = NULL;
+
+	if (flags & BLKDEV_IFL_BARRIER) {
+		/* issue async barrier before the data */
+		ret = blkdev_issue_flush(bdev, gfp_mask, NULL, 0);
+		if (ret)
+			return ret;
+	}
+submit:
+	while (nr_sects != 0) {
+		bio = bio_alloc(gfp_mask,
+				min(nr_sects, (sector_t)BIO_MAX_PAGES));
+		if (!bio)
+			break;
+
+		bio->bi_sector = sector;
+		bio->bi_bdev   = bdev;
+		bio->bi_end_io = bio_batch_end_io;
+		if (flags & BLKDEV_IFL_WAIT)
+			bio->bi_private = &bb;
+
+		while(nr_sects != 0) {
+			sz = min(PAGE_SIZE >> 9 , nr_sects);
+			if (sz == 0)
+				/* bio has maximum size possible */
+				break;
+			ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
+			nr_sects -= ret >> 9;
+			sector += ret >> 9;
+			if (ret < (sz << 9))
+				break;
+		}
+		issued++;
+		submit_bio(WRITE, bio);
+	}
+	/*
+	 * When all data bios are in flight. Send final barrier if requeted.
+	 */
+	if (nr_sects == 0 && flags & BLKDEV_IFL_BARRIER)
+		ret = blkdev_issue_flush(bdev, gfp_mask, NULL,
+					flags & BLKDEV_IFL_WAIT);
+
+
+	if (flags & BLKDEV_IFL_WAIT)
+		/* Wait for bios in-flight */
+		while ( issued != atomic_read(&bb.done))
+			wait_for_completion(&wait);
+
+	if (!test_bit(BIO_UPTODATE, &bb.flags))
+		/* One of bios in the batch was completed with error.*/
+		ret = -EIO;
+
+	if (ret)
+		goto out;
+
+	if (test_bit(BIO_EOPNOTSUPP, &bb.flags)) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+	if (nr_sects != 0)
+		goto submit;
+out:
+	return ret;
+}
+EXPORT_SYMBOL(blkdev_issue_zeroout);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 59b9aed..3ac2bd2 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1008,7 +1008,8 @@ extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *,
 			unsigned long);
 extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
-
+extern int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
+			sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
 static inline int sb_issue_discard(struct super_block *sb,
 				   sector_t block, sector_t nr_blocks)
 {
-- 
1.6.6.1

Re: [PATCH 0/4] blkdev: blkdev_issue_fn cleanups v3

[Jens Axboe]

On Wed, Apr 28 2010, Dmitry Monakhov wrote:
> - Convert all blkdev_issue_xxx function to common set of flags
> - move common helper functions to block/blk-lib.c
> - Add generic zeroout helper
> 
> Tested configuration: ext4 w -odiscard over raw_bdisk and dm-linear
> changes from V2
> Fix flag names, and rearange patches according to Christoph's comments.

Thanks, I've applied the series.

-- 
Jens Axboe