text: /*
   * 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 */
  
  int xfs_read_agf(struct xfs_mount *mp, struct xfs_trans *tp,
  			xfs_agnumber_t agno, int flags, struct xfs_buf **bpp);
  
  #endif	/* __XFS_ALLOC_H__ */
  