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Revision 7bf811a595a895b7a886dcf218d0d34f97df76dc authored by Josef Bacik on 08 October 2013, 02:11:09 UTC, committed by Chris Mason on 11 October 2013, 01:27:56 UTC 
Btrfs: limit delalloc pages outside of find_delalloc_range
 
Liu fixed part of this problem and unfortunately I steered him in slightly the
wrong direction and so didn't completely fix the problem.  The problem is we
limit the size of the delalloc range we are looking for to max bytes and then we
try to lock that range.  If we fail to lock the pages in that range we will
shrink the max bytes to a single page and re loop.  However if our first page is
inside of the delalloc range then we will end up limiting the end of the range
to a period before our first page.  This is illustrated below

[0 -------- delalloc range --------- 256mb]
                                  [page]

So find_delalloc_range will return with delalloc_start as 0 and end as 128mb,
and then we will notice that delalloc_start < *start and adjust it up, but not
adjust delalloc_end up, so things go sideways.  To fix this we need to not limit
the max bytes in find_delalloc_range, but in find_lock_delalloc_range and that
way we don't end up with this confusion.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
1 parent 4871c15
Raw File
sysrq.h 
/* -*- linux-c -*-
 *
 *	$Id: sysrq.h,v 1.3 1997/07/17 11:54:33 mj Exp $
 *
 *	Linux Magic System Request Key Hacks
 *
 *	(c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
 *
 *	(c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
 *	overhauled to use key registration
 *	based upon discusions in irc://irc.openprojects.net/#kernelnewbies
 */

#ifndef _LINUX_SYSRQ_H
#define _LINUX_SYSRQ_H

#include <linux/errno.h>
#include <linux/types.h>

/* Enable/disable SYSRQ support by default (0==no, 1==yes). */
#define SYSRQ_DEFAULT_ENABLE	1

/* Possible values of bitmask for enabling sysrq functions */
/* 0x0001 is reserved for enable everything */
#define SYSRQ_ENABLE_LOG	0x0002
#define SYSRQ_ENABLE_KEYBOARD	0x0004
#define SYSRQ_ENABLE_DUMP	0x0008
#define SYSRQ_ENABLE_SYNC	0x0010
#define SYSRQ_ENABLE_REMOUNT	0x0020
#define SYSRQ_ENABLE_SIGNAL	0x0040
#define SYSRQ_ENABLE_BOOT	0x0080
#define SYSRQ_ENABLE_RTNICE	0x0100

struct sysrq_key_op {
	void (*handler)(int);
	char *help_msg;
	char *action_msg;
	int enable_mask;
};

#ifdef CONFIG_MAGIC_SYSRQ

/* Generic SysRq interface -- you may call it from any device driver, supplying
 * ASCII code of the key, pointer to registers and kbd/tty structs (if they
 * are available -- else NULL's).
 */

void handle_sysrq(int key);
void __handle_sysrq(int key, bool check_mask);
int register_sysrq_key(int key, struct sysrq_key_op *op);
int unregister_sysrq_key(int key, struct sysrq_key_op *op);
struct sysrq_key_op *__sysrq_get_key_op(int key);

int sysrq_toggle_support(int enable_mask);

#else

static inline void handle_sysrq(int key)
{
}

static inline void __handle_sysrq(int key, bool check_mask)
{
}

static inline int register_sysrq_key(int key, struct sysrq_key_op *op)
{
	return -EINVAL;
}

static inline int unregister_sysrq_key(int key, struct sysrq_key_op *op)
{
	return -EINVAL;
}

#endif

#endif /* _LINUX_SYSRQ_H */
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