[PATCH 1/3] fuse: invalidate page cache pages before direct write

[Hao Xu <hao.xu@linux.dev>]

From: Hao Xu <howeyxu@tencent.com>

In FOPEN_DIRECT_IO, page cache may still be there for a file since
private mmap is allowed. Direct write should respect that and invalidate
the corresponding pages so that page cache readers don't get stale data.

Signed-off-by: Hao Xu <howeyxu@tencent.com>
---
 fs/fuse/file.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index bc4115288eec..3d320fc99859 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1465,7 +1465,8 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
 	int write = flags & FUSE_DIO_WRITE;
 	int cuse = flags & FUSE_DIO_CUSE;
 	struct file *file = io->iocb->ki_filp;
-	struct inode *inode = file->f_mapping->host;
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
 	struct fuse_file *ff = file->private_data;
 	struct fuse_conn *fc = ff->fm->fc;
 	size_t nmax = write ? fc->max_write : fc->max_read;
@@ -1477,6 +1478,7 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
 	int err = 0;
 	struct fuse_io_args *ia;
 	unsigned int max_pages;
+	bool fopen_direct_io = ff->open_flags & FOPEN_DIRECT_IO;
 
 	max_pages = iov_iter_npages(iter, fc->max_pages);
 	ia = fuse_io_alloc(io, max_pages);
@@ -1491,6 +1493,14 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
 			inode_unlock(inode);
 	}
 
+	if (fopen_direct_io && write) {
+		res = invalidate_inode_pages2_range(mapping, idx_from, idx_to);
+		if (res) {
+			fuse_io_free(ia);
+			return res;
+		}
+	}
+
 	io->should_dirty = !write && user_backed_iter(iter);
 	while (count) {
 		ssize_t nres;
-- 
2.25.1