[PATCH 6.1 6/8] block: open code __generic_file_write_iter for blkdev writes

[Mahmoud Adam <mngyadam@amazon.de>]

From: Christoph Hellwig <hch@lst.de>

commit 727cfe976758b79f8d2f8051c75a5ccb14539a56 upstream.

Open code __generic_file_write_iter to remove the indirect call into
->direct_IO and to prepare using the iomap based write code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20230801172201.1923299-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[fix contextual changes]
Signed-off-by: Mahmoud Adam <mngyadam@amazon.de>
---
 block/fops.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/block/fops.c b/block/fops.c
index b02fe200c3ecd0..fb7a57ed42d995 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -515,6 +515,30 @@ static int blkdev_close(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+static ssize_t
+blkdev_direct_write(struct kiocb *iocb, struct iov_iter *from)
+{
+	size_t count = iov_iter_count(from);
+	ssize_t written;
+
+	written = kiocb_invalidate_pages(iocb, count);
+	if (written) {
+		if (written == -EBUSY)
+			return 0;
+		return written;
+	}
+
+	written = blkdev_direct_IO(iocb, from);
+	if (written > 0) {
+		kiocb_invalidate_post_direct_write(iocb, count);
+		iocb->ki_pos += written;
+		count -= written;
+	}
+	if (written != -EIOCBQUEUED)
+		iov_iter_revert(from, count - iov_iter_count(from));
+	return written;
+}
+
 /*
  * Write data to the block device.  Only intended for the block device itself
  * and the raw driver which basically is a fake block device.
@@ -524,7 +548,8 @@ static int blkdev_close(struct inode *inode, struct file *filp)
  */
 static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
-	struct block_device *bdev = iocb->ki_filp->private_data;
+	struct file *file = iocb->ki_filp;
+	struct block_device *bdev = file->private_data;
 	struct inode *bd_inode = bdev->bd_inode;
 	loff_t size = bdev_nr_bytes(bdev);
 	struct blk_plug plug;
@@ -553,7 +578,23 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	}
 
 	blk_start_plug(&plug);
-	ret = __generic_file_write_iter(iocb, from);
+	ret = file_remove_privs(file);
+	if (ret)
+		return ret;
+
+	ret = file_update_time(file);
+	if (ret)
+		return ret;
+
+	if (iocb->ki_flags & IOCB_DIRECT) {
+		ret = blkdev_direct_write(iocb, from);
+		if (ret >= 0 && iov_iter_count(from))
+			ret = direct_write_fallback(iocb, from, ret,
+					generic_perform_write(iocb, from));
+	} else {
+		ret = generic_perform_write(iocb, from);
+	}
+
 	if (ret > 0)
 		ret = generic_write_sync(iocb, ret);
 	iov_iter_reexpand(from, iov_iter_count(from) + shorted);
-- 
2.47.3




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