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Commit 515df9b9 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Greg Kroah-Hartman
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fuse: truncate pagecache on atomic_o_trunc 



commit 76224355db7570cbe6b6f75c8929a1558828dd55 upstream.

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: e4648309b85a ("fuse: truncate pending writes on O_TRUNC")
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a5153fb8

fs/fuse/file.c

+5 −2
Original line number Diff line number Diff line
@@ -178,12 +178,11 @@ void fuse_finish_open(struct inode *inode, struct file *file) 


	if (ff->open_flags & FOPEN_DIRECT_IO)

		file->f_op = &fuse_direct_io_file_operations;

	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);
@@ -191,10 +190,14 @@ void fuse_finish_open(struct inode *inode, struct file *file) 
		fi->attr_version = ++fc->attr_version;

		i_size_write(inode, 0);

		spin_unlock(&fc->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);

}