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
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
msg.h
#ifndef _LINUX_MSG_H
#define _LINUX_MSG_H

#include <linux/list.h>
#include <uapi/linux/msg.h>

/* one msg_msg structure for each message */
struct msg_msg {
	struct list_head m_list; 
	long  m_type;          
	int m_ts;           /* message text size */
	struct msg_msgseg* next;
	void *security;
	/* the actual message follows immediately */
};

/* one msq_queue structure for each present queue on the system */
struct msg_queue {
	struct kern_ipc_perm q_perm;
	time_t q_stime;			/* last msgsnd time */
	time_t q_rtime;			/* last msgrcv time */
	time_t q_ctime;			/* last change time */
	unsigned long q_cbytes;		/* current number of bytes on queue */
	unsigned long q_qnum;		/* number of messages in queue */
	unsigned long q_qbytes;		/* max number of bytes on queue */
	pid_t q_lspid;			/* pid of last msgsnd */
	pid_t q_lrpid;			/* last receive pid */

	struct list_head q_messages;
	struct list_head q_receivers;
	struct list_head q_senders;
};

/* Helper routines for sys_msgsnd and sys_msgrcv */
extern long do_msgsnd(int msqid, long mtype, void __user *mtext,
			size_t msgsz, int msgflg);
extern long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp,
		      int msgflg,
		      long (*msg_fill)(void __user *, struct msg_msg *,
				       size_t));

#endif /* _LINUX_MSG_H */
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