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Commit c6d17008 authored by Nikhilesh Reddy's avatar Nikhilesh Reddy
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fuse: Grab the fc->lock for inode updates in shortcircuit 



The function fsstack_copy_inode_size uses the inode->i_lock to
serialize the inode updates. This lock is not used in the FUSE
filesystem and thus it is not enough to just grab this lock
before updating a FUSE inode.

Grab the fc->lock for inode updates in shortcircuit to ensure
that there are no races between inode size updates in 32 bit
architectures with SMP.

Change-Id: I83cb2380b6ca56768c06e70ef1bf9ea3976b514a
Signed-off-by: default avatarNikhilesh Reddy <reddyn@codeaurora.org>
parent 338e6cc3

fs/fuse/shortcircuit.c

+5 −1
Original line number Diff line number Diff line 
/*

 * Copyright (c) 2015, The Linux Foundation. All rights reserved.

 * Copyright (c) 2015-2016, The Linux Foundation. All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 and
@@ -58,10 +58,12 @@ static ssize_t fuse_shortcircuit_read_write_iter(struct kiocb *iocb, 
	struct fuse_file *ff;

	struct file *fuse_file, *lower_file;

	struct inode *fuse_inode, *lower_inode;

	struct fuse_conn *fc;



	ff = iocb->ki_filp->private_data;

	fuse_file = iocb->ki_filp;

	lower_file = ff->rw_lower_file;

	fc = ff->fc;



	/* lock lower file to prevent it from being released */

	get_file(lower_file);
@@ -75,7 +77,9 @@ static ssize_t fuse_shortcircuit_read_write_iter(struct kiocb *iocb, 
		ret_val = lower_file->f_op->write_iter(iocb, iter);



		if (ret_val >= 0 || ret_val == -EIOCBQUEUED) {

			spin_lock(&fc->lock);

			fsstack_copy_inode_size(fuse_inode, lower_inode);

			spin_unlock(&fc->lock);

			fsstack_copy_attr_times(fuse_inode, lower_inode);

		}

	} else {