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Ensure a frozen filesystem has a clean log before writing the dummy record.

The current Linux XFS freeze code is a mess. We flush the metadata
buffers out while we are still allowing new transactions to start
and then fail to flush the dirty buffers back out before writing
the unmount and dummy records to the log.

This leads to problems when the frozen filesystem is used for
snapshots - we do log recovery on a readonly image and often
it appears that the log image in the snapshot is not correct.
Hence we end up with hangs, oops and mount failures when trying
to mount a snapshot image that has been created when the filesystem
has not been correctly frozen.

To fix this, we need to move th metadata flush to after we wait for all
current transactions to complete in teh second stage of the freeze.
This means that when we write the final log records, the log should
be clean and recovery should never occur on a snapshot image created
from a frozen filesystem.
Merge of xfs-linux-melb:xfs-kern:28010a by kenmcd.

  Add definition of SYNC_DIO_WAIT for telling the sync code
  to wait for direct I/O to complete.

/*
 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
 * 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 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef __XFS_VFS_H__
#define __XFS_VFS_H__

#include <linux/vfs.h>
#include "xfs_fs.h"

struct bhv_vfs;
struct bhv_vnode;

struct fid;
struct cred;
struct seq_file;
struct super_block;
struct xfs_mount_args;

typedef struct kstatfs	bhv_statvfs_t;

typedef struct bhv_vfs_sync_work {
	struct list_head	w_list;
	struct bhv_vfs		*w_vfs;
	void			*w_data;	/* syncer routine argument */
	void			(*w_syncer)(struct bhv_vfs *, void *);
} bhv_vfs_sync_work_t;

typedef struct bhv_vfs {
	u_int			vfs_flag;	/* flags */
	xfs_fsid_t		vfs_fsid;	/* file system ID */
	xfs_fsid_t		*vfs_altfsid;	/* An ID fixed for life of FS */
	bhv_head_t		vfs_bh;		/* head of vfs behavior chain */
	struct super_block	*vfs_super;	/* generic superblock pointer */
	struct task_struct	*vfs_sync_task;	/* generalised sync thread */
	bhv_vfs_sync_work_t	vfs_sync_work;	/* work item for VFS_SYNC */
	struct list_head	vfs_sync_list;	/* sync thread work item list */
	spinlock_t		vfs_sync_lock;	/* work item list lock */
	int			vfs_sync_seq;	/* sync thread generation no. */
	wait_queue_head_t	vfs_wait_single_sync_task;
} bhv_vfs_t;

#define bhvtovfs(bdp)		( (struct bhv_vfs *)BHV_VOBJ(bdp) )
#define bhvtovfsops(bdp)	( (struct bhv_vfsops *)BHV_OPS(bdp) )
#define VFS_BHVHEAD(vfs)	( &(vfs)->vfs_bh )
#define VFS_REMOVEBHV(vfs, bdp)	( bhv_remove(VFS_BHVHEAD(vfs), bdp) )

#define VFS_POSITION_BASE	BHV_POSITION_BASE	/* chain bottom */
#define VFS_POSITION_TOP	BHV_POSITION_TOP	/* chain top */
#define VFS_POSITION_INVALID	BHV_POSITION_INVALID	/* invalid pos. num */

typedef enum {
	VFS_BHV_UNKNOWN,	/* not specified */
	VFS_BHV_XFS,		/* xfs */
	VFS_BHV_DM,		/* data migration */
	VFS_BHV_QM,		/* quota manager */
	VFS_BHV_IO,		/* IO path */
	VFS_BHV_END		/* housekeeping end-of-range */
} bhv_vfs_type_t;

#define VFS_POSITION_XFS	(BHV_POSITION_BASE)
#define VFS_POSITION_DM		(VFS_POSITION_BASE+10)
#define VFS_POSITION_QM		(VFS_POSITION_BASE+20)
#define VFS_POSITION_IO		(VFS_POSITION_BASE+30)

#define VFS_RDONLY		0x0001	/* read-only vfs */
#define VFS_GRPID		0x0002	/* group-ID assigned from directory */
#define VFS_DMI			0x0004	/* filesystem has the DMI enabled */
/* ---- VFS_UMOUNT ----		0x0008	-- unneeded, fixed via kthread APIs */
#define VFS_32BITINODES		0x0010	/* do not use inums above 32 bits */
#define VFS_END			0x0010	/* max flag */

#define SYNC_ATTR		0x0001	/* sync attributes */
#define SYNC_CLOSE		0x0002	/* close file system down */
#define SYNC_DELWRI		0x0004	/* look at delayed writes */
#define SYNC_WAIT		0x0008	/* wait for i/o to complete */
#define SYNC_BDFLUSH		0x0010	/* BDFLUSH is calling -- don't block */
#define SYNC_FSDATA		0x0020	/* flush fs data (e.g. superblocks) */
#define SYNC_REFCACHE		0x0040  /* prune some of the nfs ref cache */
#define SYNC_REMOUNT		0x0080  /* remount readonly, no dummy LRs */
#define SYNC_QUIESCE		0x0100  /* quiesce fileystem for a snapshot */
#define SYNC_DIO_WAIT		0x0200  /* wait for direct I/O to complete */

#define SHUTDOWN_META_IO_ERROR	0x0001	/* write attempt to metadata failed */
#define SHUTDOWN_LOG_IO_ERROR	0x0002	/* write attempt to the log failed */
#define SHUTDOWN_FORCE_UMOUNT	0x0004	/* shutdown from a forced unmount */
#define SHUTDOWN_CORRUPT_INCORE	0x0008	/* corrupt in-memory data structures */
#define SHUTDOWN_REMOTE_REQ	0x0010	/* shutdown came from remote cell */
#define SHUTDOWN_DEVICE_REQ	0x0020	/* failed all paths to the device */

typedef int	(*vfs_mount_t)(bhv_desc_t *,
				struct xfs_mount_args *, struct cred *);
typedef int	(*vfs_parseargs_t)(bhv_desc_t *, char *,
				struct xfs_mount_args *, int);
typedef	int	(*vfs_showargs_t)(bhv_desc_t *, struct seq_file *);
typedef int	(*vfs_unmount_t)(bhv_desc_t *, int, struct cred *);
typedef int	(*vfs_mntupdate_t)(bhv_desc_t *, int *,
				struct xfs_mount_args *);
typedef int	(*vfs_root_t)(bhv_desc_t *, struct bhv_vnode **);
typedef int	(*vfs_statvfs_t)(bhv_desc_t *, bhv_statvfs_t *,
				struct bhv_vnode *);
typedef int	(*vfs_sync_t)(bhv_desc_t *, int, struct cred *);
typedef int	(*vfs_vget_t)(bhv_desc_t *, struct bhv_vnode **, struct fid *);
typedef int	(*vfs_dmapiops_t)(bhv_desc_t *, caddr_t);
typedef int	(*vfs_quotactl_t)(bhv_desc_t *, int, int, caddr_t);
typedef void	(*vfs_init_vnode_t)(bhv_desc_t *,
				struct bhv_vnode *, bhv_desc_t *, int);
typedef void	(*vfs_force_shutdown_t)(bhv_desc_t *, int, char *, int);
typedef void	(*vfs_freeze_t)(bhv_desc_t *);
typedef	struct inode * (*vfs_get_inode_t)(bhv_desc_t *, xfs_ino_t, int);

typedef struct bhv_vfsops {
	bhv_position_t		vf_position;	/* behavior chain position */
	vfs_mount_t		vfs_mount;	/* mount file system */
	vfs_parseargs_t		vfs_parseargs;	/* parse mount options */
	vfs_showargs_t		vfs_showargs;	/* unparse mount options */
	vfs_unmount_t		vfs_unmount;	/* unmount file system */
	vfs_mntupdate_t		vfs_mntupdate;	/* update file system options */
	vfs_root_t		vfs_root;	/* get root vnode */
	vfs_statvfs_t		vfs_statvfs;	/* file system statistics */
	vfs_sync_t		vfs_sync;	/* flush files */
	vfs_vget_t		vfs_vget;	/* get vnode from fid */
	vfs_dmapiops_t		vfs_dmapiops;	/* data migration */
	vfs_quotactl_t		vfs_quotactl;	/* disk quota */
	vfs_get_inode_t		vfs_get_inode;	/* bhv specific iget */
	vfs_init_vnode_t	vfs_init_vnode;	/* initialize a new vnode */
	vfs_force_shutdown_t	vfs_force_shutdown;	/* crash and burn */
	vfs_freeze_t		vfs_freeze;	/* freeze fs for snapshot */
} bhv_vfsops_t;

/*
 * Virtual filesystem operations, operating from head bhv.
 */
#define VFSHEAD(v)			((v)->vfs_bh.bh_first)
#define bhv_vfs_mount(v, ma,cr)		vfs_mount(VFSHEAD(v), ma,cr)
#define bhv_vfs_parseargs(v, o,ma,f)	vfs_parseargs(VFSHEAD(v), o,ma,f)
#define bhv_vfs_showargs(v, m)		vfs_showargs(VFSHEAD(v), m)
#define bhv_vfs_unmount(v, f,cr)	vfs_unmount(VFSHEAD(v), f,cr)
#define bhv_vfs_mntupdate(v, fl,args)	vfs_mntupdate(VFSHEAD(v), fl,args)
#define bhv_vfs_root(v, vpp)		vfs_root(VFSHEAD(v), vpp)
#define bhv_vfs_statvfs(v, sp,vp)	vfs_statvfs(VFSHEAD(v), sp,vp)
#define bhv_vfs_sync(v, flag,cr)	vfs_sync(VFSHEAD(v), flag,cr)
#define bhv_vfs_vget(v, vpp,fidp)	vfs_vget(VFSHEAD(v), vpp,fidp)
#define bhv_vfs_dmapiops(v, p)		vfs_dmapiops(VFSHEAD(v), p)
#define bhv_vfs_quotactl(v, c,id,p)	vfs_quotactl(VFSHEAD(v), c,id,p)
#define bhv_vfs_get_inode(v, ino, fl)	vfs_get_inode(VFSHEAD(v), ino,fl)
#define bhv_vfs_init_vnode(v, vp,b,ul)	vfs_init_vnode(VFSHEAD(v), vp,b,ul)
#define bhv_vfs_force_shutdown(v,u,f,l)	vfs_force_shutdown(VFSHEAD(v), u,f,l)
#define bhv_vfs_freeze(v)		vfs_freeze(VFSHEAD(v))

/*
 * Virtual filesystem operations, operating from next bhv.
 */
#define bhv_next_vfs_mount(b, ma,cr)		vfs_mount(b, ma,cr)
#define bhv_next_vfs_parseargs(b, o,ma,f)	vfs_parseargs(b, o,ma,f)
#define bhv_next_vfs_showargs(b, m)		vfs_showargs(b, m)
#define bhv_next_vfs_unmount(b, f,cr)		vfs_unmount(b, f,cr)
#define bhv_next_vfs_mntupdate(b, fl,args)	vfs_mntupdate(b, fl, args)
#define bhv_next_vfs_root(b, vpp)		vfs_root(b, vpp)
#define bhv_next_vfs_statvfs(b, sp,vp)		vfs_statvfs(b, sp,vp)
#define bhv_next_vfs_sync(b, flag,cr)		vfs_sync(b, flag,cr)
#define bhv_next_vfs_vget(b, vpp,fidp)		vfs_vget(b, vpp,fidp)
#define bhv_next_vfs_dmapiops(b, p)		vfs_dmapiops(b, p)
#define bhv_next_vfs_quotactl(b, c,id,p)	vfs_quotactl(b, c,id,p)
#define bhv_next_vfs_get_inode(b, ino,fl)	vfs_get_inode(b, ino,fl)
#define bhv_next_vfs_init_vnode(b, vp,b2,ul)	vfs_init_vnode(b, vp,b2,ul)
#define bhv_next_force_shutdown(b, fl,f,l)	vfs_force_shutdown(b, fl,f,l)
#define bhv_next_vfs_freeze(b)			vfs_freeze(b)

extern int vfs_mount(bhv_desc_t *, struct xfs_mount_args *, struct cred *);
extern int vfs_parseargs(bhv_desc_t *, char *, struct xfs_mount_args *, int);
extern int vfs_showargs(bhv_desc_t *, struct seq_file *);
extern int vfs_unmount(bhv_desc_t *, int, struct cred *);
extern int vfs_mntupdate(bhv_desc_t *, int *, struct xfs_mount_args *);
extern int vfs_root(bhv_desc_t *, struct bhv_vnode **);
extern int vfs_statvfs(bhv_desc_t *, bhv_statvfs_t *, struct bhv_vnode *);
extern int vfs_sync(bhv_desc_t *, int, struct cred *);
extern int vfs_vget(bhv_desc_t *, struct bhv_vnode **, struct fid *);
extern int vfs_dmapiops(bhv_desc_t *, caddr_t);
extern int vfs_quotactl(bhv_desc_t *, int, int, caddr_t);
extern struct inode *vfs_get_inode(bhv_desc_t *, xfs_ino_t, int);
extern void vfs_init_vnode(bhv_desc_t *, struct bhv_vnode *, bhv_desc_t *, int);
extern void vfs_force_shutdown(bhv_desc_t *, int, char *, int);
extern void vfs_freeze(bhv_desc_t *);

#define vfs_test_for_freeze(vfs)	((vfs)->vfs_super->s_frozen)
#define vfs_wait_for_freeze(vfs,l)	vfs_check_frozen((vfs)->vfs_super, (l))

#define XFS_DMOPS		"xfs_dm_operations"	/* Data Migration */
#define XFS_QMOPS		"xfs_qm_operations"	/* Quota Manager  */
#define XFS_IOOPS		"xfs_io_operations"	/* I/O subsystem  */
#define XFS_DM_MODULE		"xfs_dmapi"
#define XFS_QM_MODULE		"xfs_quota"
#define XFS_IO_MODULE		"xfs_ioops"

typedef struct bhv_module_vfsops {
	struct bhv_vfsops	bhv_common;
	void *			bhv_custom;
} bhv_module_vfsops_t;

typedef struct bhv_module {
	bhv_desc_t		bm_desc;
	const char *		bm_name;
	bhv_module_vfsops_t *	bm_ops;
} bhv_module_t;

#define vfs_bhv_lookup(v, id)	(bhv_lookup_range(&(v)->vfs_bh, (id), (id)))
#define vfs_bhv_custom(b)	(((bhv_module_vfsops_t*)BHV_OPS(b))->bhv_custom)
#define vfs_bhv_set_custom(b,o)	((b)->bhv_custom = (void *)(o))
#define vfs_bhv_clr_custom(b)	((b)->bhv_custom = NULL)

extern bhv_vfs_t *vfs_allocate(struct super_block *);
extern bhv_vfs_t *vfs_from_sb(struct super_block *);
extern void vfs_deallocate(bhv_vfs_t *);
extern void vfs_insertbhv(bhv_vfs_t *, bhv_desc_t *, bhv_vfsops_t *, void *);

extern void bhv_module_init(const char *, struct module *, const void *);
extern void bhv_module_exit(const char *);
extern void bhv_get_vfsops(struct bhv_vfs *, const char *, const char *);
extern void bhv_insert_all_vfsops(struct bhv_vfs *);
extern void bhv_remove_all_vfsops(struct bhv_vfs *, int);
extern void bhv_remove_vfsops(struct bhv_vfs *, int);

#endif	/* __XFS_VFS_H__ */