[PATCH 4/5] [RFC] fuse: Set and use IOCB_DIRECT when FOPEN_DIRECT_IO is set

[Bernd Schubert <bschubert@ddn.com>]

fuse_direct_write_iter is basically duplicating what is already
in fuse_cache_write_iter/generic_file_direct_write. That can be
avoided by setting IOCB_DIRECT in fuse_file_write_iter, after that
fuse_cache_write_iter can be used for the FOPEN_DIRECT_IO code path
and fuse_direct_write_iter can be removed.

Cc: Hao Xu <howeyxu@tencent.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Dharmendra Singh <dsingh@ddn.com>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Bernd Schubert <bschubert@ddn.com>
---
 fs/fuse/file.c | 54 ++++----------------------------------------------
 1 file changed, 4 insertions(+), 50 deletions(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 905ce3bb0047..09277a54b711 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1589,52 +1589,6 @@ static ssize_t fuse_direct_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	return res;
 }
 
-static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
-{
-	struct inode *inode = file_inode(iocb->ki_filp);
-	struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb);
-	ssize_t res;
-	bool exclusive_lock = fuse_dio_wr_exclusive_lock(iocb, from);
-
-	/*
-	 * Take exclusive lock if
-	 * - Parallel direct writes are disabled - a user space decision
-	 * - Parallel direct writes are enabled and i_size is being extended.
-	 *   This might not be needed at all, but needs further investigation.
-	 */
-	if (exclusive_lock)
-		inode_lock(inode);
-	else {
-		inode_lock_shared(inode);
-
-		/* A race with truncate might have come up as the decision for
-		 * the lock type was done without holding the lock, check again.
-		 */
-		if (fuse_direct_write_extending_i_size(iocb, from)) {
-			inode_unlock_shared(inode);
-			inode_lock(inode);
-			exclusive_lock = true;
-		}
-	}
-
-	res = generic_write_checks(iocb, from);
-	if (res > 0) {
-		if (!is_sync_kiocb(iocb) && iocb->ki_flags & IOCB_DIRECT) {
-			res = fuse_direct_IO(iocb, from);
-		} else {
-			res = fuse_direct_io(&io, from, &iocb->ki_pos,
-					     FUSE_DIO_WRITE);
-			fuse_write_update_attr(inode, iocb->ki_pos, res);
-		}
-	}
-	if (exclusive_lock)
-		inode_unlock(inode);
-	else
-		inode_unlock_shared(inode);
-
-	return res;
-}
-
 static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
 	struct file *file = iocb->ki_filp;
@@ -1665,10 +1619,10 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (FUSE_IS_DAX(inode))
 		return fuse_dax_write_iter(iocb, from);
 
-	if (!(ff->open_flags & FOPEN_DIRECT_IO))
-		return fuse_cache_write_iter(iocb, from);
-	else
-		return fuse_direct_write_iter(iocb, from);
+	if (ff->open_flags & FOPEN_DIRECT_IO)
+		iocb->ki_flags |= IOCB_DIRECT;
+
+	return fuse_cache_write_iter(iocb, from);
 }
 
 static void fuse_writepage_free(struct fuse_writepage_args *wpa)
-- 
2.39.2