Commit 76224355 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

fuse: truncate pagecache on atomic_o_trunc 



fuse_finish_open() will be called with FUSE_NOWRITE in case of atomic
O_TRUNC.  This can deadlock with fuse_wait_on_page_writeback() in
fuse_launder_page() triggered by invalidate_inode_pages2().

Fix by replacing invalidate_inode_pages2() in fuse_finish_open() with a
truncate_pagecache() call.  This makes sense regardless of FOPEN_KEEP_CACHE
or fc->writeback cache, so do it unconditionally.

Reported-by: default avatarXie Yongji <xieyongji@bytedance.com>
Reported-and-tested-by: default avatar <syzbot+bea44a5189836d956894@syzkaller.appspotmail.com>
Fixes: e4648309 ("fuse: truncate pending writes on O_TRUNC")
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 5d5b74aa

fs/fuse/file.c

+5 −2
Original line number Diff line number Diff line
@@ -198,12 +198,11 @@ void fuse_finish_open(struct inode *inode, struct file *file) 
	struct fuse_file *ff = file->private_data;

	struct fuse_conn *fc = get_fuse_conn(inode);



	if (!(ff->open_flags & FOPEN_KEEP_CACHE))

		invalidate_inode_pages2(inode->i_mapping);

	if (ff->open_flags & FOPEN_STREAM)

		stream_open(inode, file);

	else if (ff->open_flags & FOPEN_NONSEEKABLE)

		nonseekable_open(inode, file);



	if (fc->atomic_o_trunc && (file->f_flags & O_TRUNC)) {

		struct fuse_inode *fi = get_fuse_inode(inode);
@@ -211,10 +210,14 @@ void fuse_finish_open(struct inode *inode, struct file *file) 
		fi->attr_version = atomic64_inc_return(&fc->attr_version);

		i_size_write(inode, 0);

		spin_unlock(&fi->lock);

		truncate_pagecache(inode, 0);

		fuse_invalidate_attr(inode);

		if (fc->writeback_cache)

			file_update_time(file);

	} else if (!(ff->open_flags & FOPEN_KEEP_CACHE)) {

		invalidate_inode_pages2(inode->i_mapping);

	}



	if ((file->f_mode & FMODE_WRITE) && fc->writeback_cache)

		fuse_link_write_file(file);

}