linux-ext4 - [PATCH 12/17] fuse: use direct_write

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Date:   Mon, 24 Apr 2023 07:49:21 +0200
From:   Christoph Hellwig <hch@....de>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Miklos Szeredi <miklos@...redi.hu>,
        "Darrick J. Wong" <djwong@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Howells <dhowells@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        ceph-devel@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net, cluster-devel@...hat.com,
        linux-xfs@...r.kernel.org, linux-nfs@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH 12/17] fuse: use direct_write_fallback

Refator the fuse direct write code so that the fuse_perform_write
callig convention is simplified to match generic_perform_write and
it's updating ki_pos directly, and the generic direct_write_fallback
helper is used to consolidate buffered I/O fallback code.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 fs/fuse/file.c | 44 +++++++++++---------------------------------
 1 file changed, 11 insertions(+), 33 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index de37a3a06a7169..55b64dac175d68 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1280,13 +1280,13 @@ static inline unsigned int fuse_wr_pages(loff_t pos, size_t len,
 		     max_pages);
 }
 
-static ssize_t fuse_perform_write(struct kiocb *iocb,
-				  struct address_space *mapping,
-				  struct iov_iter *ii, loff_t pos)
+static ssize_t fuse_perform_write(struct kiocb *iocb, struct iov_iter *ii)
 {
+	struct address_space *mapping = iocb->ki_filp->f_mapping;
 	struct inode *inode = mapping->host;
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_inode *fi = get_fuse_inode(inode);
+	loff_t pos = iocb->ki_pos;
 	int err = 0;
 	ssize_t res = 0;
 
@@ -1329,7 +1329,10 @@ static ssize_t fuse_perform_write(struct kiocb *iocb,
 	fuse_write_update_attr(inode, pos, res);
 	clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state);
 
-	return res > 0 ? res : err;
+	if (!res)
+		return err;
+	iocb->ki_pos += res;
+	return res;
 }
 
 static ssize_t fuse_cache_write_iter(struct kiocb *iocb, struct iov_iter *from)
@@ -1337,11 +1340,9 @@ static ssize_t fuse_cache_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
 	ssize_t written = 0;
-	ssize_t written_buffered = 0;
 	struct inode *inode = mapping->host;
 	ssize_t err;
 	struct fuse_conn *fc = get_fuse_conn(inode);
-	loff_t endbyte = 0;
 
 	if (fc->writeback_cache) {
 		/* Update size (EOF optimization) and mode (SUID clearing) */
@@ -1378,35 +1379,12 @@ static ssize_t fuse_cache_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		goto out;
 
 	if (iocb->ki_flags & IOCB_DIRECT) {
-		loff_t pos = iocb->ki_pos;
 		written = generic_file_direct_write(iocb, from);
-		if (written < 0 || !iov_iter_count(from))
-			goto out;
-
-		pos += written;
-
-		written_buffered = fuse_perform_write(iocb, mapping, from, pos);
-		if (written_buffered < 0) {
-			err = written_buffered;
-			goto out;
-		}
-		endbyte = pos + written_buffered - 1;
-
-		err = filemap_write_and_wait_range(file->f_mapping, pos,
-						   endbyte);
-		if (err)
-			goto out;
-
-		invalidate_mapping_pages(file->f_mapping,
-					 pos >> PAGE_SHIFT,
-					 endbyte >> PAGE_SHIFT);
-
-		written += written_buffered;
-		iocb->ki_pos = pos + written_buffered;
+		if (written >= 0 && iov_iter_count(from))
+			written = direct_write_fallback(iocb, from, written,
+					fuse_perform_write(iocb, from));
 	} else {
-		written = fuse_perform_write(iocb, mapping, from, iocb->ki_pos);
-		if (written >= 0)
-			iocb->ki_pos += written;
+		written = fuse_perform_write(iocb, from);
 	}
 out:
 	current->backing_dev_info = NULL;
-- 
2.39.2