fuse: invalidate page cache pages before direct write

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>
Tested-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 1c7599e..1aa7dde 100644 (file)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1428,7 +1428,8 @@ 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;
@@ -1440,6 +1441,7 @@ 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);
@@ -1454,6 +1456,14 @@ 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;