fuse: copy_file_range should truncate cache (9b46418c) · Commits · 戴 / test

fs/fuse/file.c

+22 −0

Original line number	Diff line number	Diff line
		@@ -3337,6 +3337,24 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
		if (err)
		goto out;

		/*
		* Write out dirty pages in the destination file before sending the COPY
		* request to userspace. After the request is completed, truncate off
		* pages (including partial ones) from the cache that have been copied,
		* since these contain stale data at that point.
		*
		* This should be mostly correct, but if the COPY writes to partial
		* pages (at the start or end) and the parts not covered by the COPY are
		* written through a memory map after calling fuse_writeback_range(),
		* then these partial page modifications will be lost on truncation.
		*
		* It is unlikely that someone would rely on such mixed style
		* modifications. Yet this does give less guarantees than if the
		* copying was performed with write(2).
		*
		* To fix this a i_mmap_sem style lock could be used to prevent new
		* faults while the copy is ongoing.
		*/
		err = fuse_writeback_range(inode_out, pos_out, pos_out + len - 1);
		if (err)
		goto out;
		@@ -3360,6 +3378,10 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in,
		if (err)
		goto out;

		truncate_inode_pages_range(inode_out->i_mapping,
		ALIGN_DOWN(pos_out, PAGE_SIZE),
		ALIGN(pos_out + outarg.size, PAGE_SIZE) - 1);

		if (fc->writeback_cache) {
		fuse_write_update_size(inode_out, pos_out + outarg.size);
		file_update_time(file_out);