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Revision 9f141d6ef6258a3a37a045842d9ba7e68f368956 authored by Jan Kara on 19 October 2016, 12:34:31 UTC, committed by Dan Williams on 27 December 2016, 04:29:25 UTC 
dax: Call ->iomap_begin without entry lock during dax fault
 
Currently ->iomap_begin() handler is called with entry lock held. If the
filesystem held any locks between ->iomap_begin() and ->iomap_end()
(such as ext4 which will want to hold transaction open), this would cause
lock inversion with the iomap_apply() from standard IO path which first
calls ->iomap_begin() and only then calls ->actor() callback which grabs
entry locks for DAX (if it faults when copying from/to user provided
buffers).

Fix the problem by nesting grabbing of entry lock inside ->iomap_begin()
- ->iomap_end() pair.

Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
1 parent f449b93
Raw File
sysfs.h 
/*
 * fs/sysfs/sysfs.h - sysfs internal header file
 *
 * Copyright (c) 2001-3 Patrick Mochel
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
 *
 * This file is released under the GPLv2.
 */

#ifndef __SYSFS_INTERNAL_H
#define __SYSFS_INTERNAL_H

#include <linux/sysfs.h>

/*
 * mount.c
 */
extern struct kernfs_node *sysfs_root_kn;

/*
 * dir.c
 */
extern spinlock_t sysfs_symlink_target_lock;

void sysfs_warn_dup(struct kernfs_node *parent, const char *name);

/*
 * file.c
 */
int sysfs_add_file(struct kernfs_node *parent,
		   const struct attribute *attr, bool is_bin);
int sysfs_add_file_mode_ns(struct kernfs_node *parent,
			   const struct attribute *attr, bool is_bin,
			   umode_t amode, const void *ns);

/*
 * symlink.c
 */
int sysfs_create_link_sd(struct kernfs_node *kn, struct kobject *target,
			 const char *name);

#endif	/* __SYSFS_INTERNAL_H */
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