1. 根目录:
2. fs
3. xfs
4. xfs_alloc.h

/*
 * Copyright (c) 2000-2002,2005 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_ALLOC_H__
#define	__XFS_ALLOC_H__

struct xfs_buf;
struct xfs_btree_cur;
struct xfs_mount;
struct xfs_perag;
struct xfs_trans;

extern struct workqueue_struct *xfs_alloc_wq;

/*
 * Freespace allocation types.  Argument to xfs_alloc_[v]extent.
 */
#define XFS_ALLOCTYPE_ANY_AG	0x01	/* allocate anywhere, use rotor */
#define XFS_ALLOCTYPE_FIRST_AG	0x02	/* ... start at ag 0 */
#define XFS_ALLOCTYPE_START_AG	0x04	/* anywhere, start in this a.g. */
#define XFS_ALLOCTYPE_THIS_AG	0x08	/* anywhere in this a.g. */
#define XFS_ALLOCTYPE_START_BNO	0x10	/* near this block else anywhere */
#define XFS_ALLOCTYPE_NEAR_BNO	0x20	/* in this a.g. and near this block */
#define XFS_ALLOCTYPE_THIS_BNO	0x40	/* at exactly this block */

/* this should become an enum again when the tracing code is fixed */
typedef unsigned int xfs_alloctype_t;

#define XFS_ALLOC_TYPES \
	{ XFS_ALLOCTYPE_ANY_AG,		"ANY_AG" }, \
	{ XFS_ALLOCTYPE_FIRST_AG,	"FIRST_AG" }, \
	{ XFS_ALLOCTYPE_START_AG,	"START_AG" }, \
	{ XFS_ALLOCTYPE_THIS_AG,	"THIS_AG" }, \
	{ XFS_ALLOCTYPE_START_BNO,	"START_BNO" }, \
	{ XFS_ALLOCTYPE_NEAR_BNO,	"NEAR_BNO" }, \
	{ XFS_ALLOCTYPE_THIS_BNO,	"THIS_BNO" }

/*
 * Flags for xfs_alloc_fix_freelist.
 */
#define	XFS_ALLOC_FLAG_TRYLOCK	0x00000001  /* use trylock for buffer locking */
#define	XFS_ALLOC_FLAG_FREEING	0x00000002  /* indicate caller is freeing extents*/

/*
 * In order to avoid ENOSPC-related deadlock caused by
 * out-of-order locking of AGF buffer (PV 947395), we place
 * constraints on the relationship among actual allocations for
 * data blocks, freelist blocks, and potential file data bmap
 * btree blocks. However, these restrictions may result in no
 * actual space allocated for a delayed extent, for example, a data
 * block in a certain AG is allocated but there is no additional
 * block for the additional bmap btree block due to a split of the
 * bmap btree of the file. The result of this may lead to an
 * infinite loop in xfssyncd when the file gets flushed to disk and
 * all delayed extents need to be actually allocated. To get around
 * this, we explicitly set aside a few blocks which will not be
 * reserved in delayed allocation. Considering the minimum number of
 * needed freelist blocks is 4 fsbs _per AG_, a potential split of file's bmap
 * btree requires 1 fsb, so we set the number of set-aside blocks
 * to 4 + 4*agcount.
 */
#define XFS_ALLOC_SET_ASIDE(mp)  (4 + ((mp)->m_sb.sb_agcount * 4))

/*
 * When deciding how much space to allocate out of an AG, we limit the
 * allocation maximum size to the size the AG. However, we cannot use all the
 * blocks in the AG - some are permanently used by metadata. These
 * blocks are generally:
 *	- the AG superblock, AGF, AGI and AGFL
 *	- the AGF (bno and cnt) and AGI btree root blocks
 *	- 4 blocks on the AGFL according to XFS_ALLOC_SET_ASIDE() limits
 *
 * The AG headers are sector sized, so the amount of space they take up is
 * dependent on filesystem geometry. The others are all single blocks.
 */
#define XFS_ALLOC_AG_MAX_USABLE(mp)	\
	((mp)->m_sb.sb_agblocks - XFS_BB_TO_FSB(mp, XFS_FSS_TO_BB(mp, 4)) - 7)


/*
 * Argument structure for xfs_alloc routines.
 * This is turned into a structure to avoid having 20 arguments passed
 * down several levels of the stack.
 */
typedef struct xfs_alloc_arg {
	struct xfs_trans *tp;		/* transaction pointer */
	struct xfs_mount *mp;		/* file system mount point */
	struct xfs_buf	*agbp;		/* buffer for a.g. freelist header */
	struct xfs_perag *pag;		/* per-ag struct for this agno */
	xfs_fsblock_t	fsbno;		/* file system block number */
	xfs_agnumber_t	agno;		/* allocation group number */
	xfs_agblock_t	agbno;		/* allocation group-relative block # */
	xfs_extlen_t	minlen;		/* minimum size of extent */
	xfs_extlen_t	maxlen;		/* maximum size of extent */
	xfs_extlen_t	mod;		/* mod value for extent size */
	xfs_extlen_t	prod;		/* prod value for extent size */
	xfs_extlen_t	minleft;	/* min blocks must be left after us */
	xfs_extlen_t	total;		/* total blocks needed in xaction */
	xfs_extlen_t	alignment;	/* align answer to multiple of this */
	xfs_extlen_t	minalignslop;	/* slop for minlen+alignment calcs */
	xfs_extlen_t	len;		/* output: actual size of extent */
	xfs_alloctype_t	type;		/* allocation type XFS_ALLOCTYPE_... */
	xfs_alloctype_t	otype;		/* original allocation type */
	char		wasdel;		/* set if allocation was prev delayed */
	char		wasfromfl;	/* set if allocation is from freelist */
	char		isfl;		/* set if is freelist blocks - !acctg */
	char		userdata;	/* set if this is user data */
	xfs_fsblock_t	firstblock;	/* io first block allocated */
} xfs_alloc_arg_t;

/*
 * Defines for userdata
 */
#define XFS_ALLOC_USERDATA		1	/* allocation is for user data*/
#define XFS_ALLOC_INITIAL_USER_DATA	2	/* special case start of file */

/*
 * Find the length of the longest extent in an AG.
 */
xfs_extlen_t
xfs_alloc_longest_free_extent(struct xfs_mount *mp,
		struct xfs_perag *pag);

/*
 * Compute and fill in value of m_ag_maxlevels.
 */
void
xfs_alloc_compute_maxlevels(
	struct xfs_mount	*mp);	/* file system mount structure */

/*
 * Get a block from the freelist.
 * Returns with the buffer for the block gotten.
 */
int				/* error */
xfs_alloc_get_freelist(
	struct xfs_trans *tp,	/* transaction pointer */
	struct xfs_buf	*agbp,	/* buffer containing the agf structure */
	xfs_agblock_t	*bnop,	/* block address retrieved from freelist */
	int		btreeblk); /* destination is a AGF btree */

/*
 * Log the given fields from the agf structure.
 */
void
xfs_alloc_log_agf(
	struct xfs_trans *tp,	/* transaction pointer */
	struct xfs_buf	*bp,	/* buffer for a.g. freelist header */
	int		fields);/* mask of fields to be logged (XFS_AGF_...) */

/*
 * Interface for inode allocation to force the pag data to be initialized.
 */
int				/* error */
xfs_alloc_pagf_init(
	struct xfs_mount *mp,	/* file system mount structure */
	struct xfs_trans *tp,	/* transaction pointer */
	xfs_agnumber_t	agno,	/* allocation group number */
	int		flags);	/* XFS_ALLOC_FLAGS_... */

/*
 * Put the block on the freelist for the allocation group.
 */
int				/* error */
xfs_alloc_put_freelist(
	struct xfs_trans *tp,	/* transaction pointer */
	struct xfs_buf	*agbp,	/* buffer for a.g. freelist header */
	struct xfs_buf	*agflbp,/* buffer for a.g. free block array */
	xfs_agblock_t	bno,	/* block being freed */
	int		btreeblk); /* owner was a AGF btree */

/*
 * Read in the allocation group header (free/alloc section).
 */
int					/* error  */
xfs_alloc_read_agf(
	struct xfs_mount *mp,		/* mount point structure */
	struct xfs_trans *tp,		/* transaction pointer */
	xfs_agnumber_t	agno,		/* allocation group number */
	int		flags,		/* XFS_ALLOC_FLAG_... */
	struct xfs_buf	**bpp);		/* buffer for the ag freelist header */

/*
 * Allocate an extent (variable-size).
 */
int				/* error */
xfs_alloc_vextent(
	xfs_alloc_arg_t	*args);	/* allocation argument structure */

/*
 * Free an extent.
 */
int				/* error */
xfs_free_extent(
	struct xfs_trans *tp,	/* transaction pointer */
	xfs_fsblock_t	bno,	/* starting block number of extent */
	xfs_extlen_t	len);	/* length of extent */

int					/* error */
xfs_alloc_lookup_le(
	struct xfs_btree_cur	*cur,	/* btree cursor */
	xfs_agblock_t		bno,	/* starting block of extent */
	xfs_extlen_t		len,	/* length of extent */
	int			*stat);	/* success/failure */

int				/* error */
xfs_alloc_lookup_ge(
	struct xfs_btree_cur	*cur,	/* btree cursor */
	xfs_agblock_t		bno,	/* starting block of extent */
	xfs_extlen_t		len,	/* length of extent */
	int			*stat);	/* success/failure */

int					/* error */
xfs_alloc_get_rec(
	struct xfs_btree_cur	*cur,	/* btree cursor */
	xfs_agblock_t		*bno,	/* output: starting block of extent */
	xfs_extlen_t		*len,	/* output: length of extent */
	int			*stat);	/* output: success/failure */

#endif	/* __XFS_ALLOC_H__ */