[PATCH 3/6] block: open code __generic_file_write_iter for blkdev writes

From: Christoph Hellwig
Date: Tue Aug 01 2023 - 13:22:38 EST


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@xxxxxx>
---
block/fops.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/block/fops.c b/block/fops.c
index a286bf3325c5d8..8a05d99166e3bd 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -533,6 +533,30 @@ static int blkdev_release(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.
@@ -542,7 +566,8 @@ static int blkdev_release(struct inode *inode, struct file *filp)
*/
static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
- struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
+ struct file *file = iocb->ki_filp;
+ struct block_device *bdev = I_BDEV(file->f_mapping->host);
struct inode *bd_inode = bdev->bd_inode;
loff_t size = bdev_nr_bytes(bdev);
size_t shorted = 0;
@@ -569,7 +594,23 @@ static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
iov_iter_truncate(from, size);
}

- 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);
--
2.39.2