linux/fs/xfs/xfs_alloc.h
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   1/*
   2 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#ifndef __XFS_ALLOC_H__
  19#define __XFS_ALLOC_H__
  20
  21struct xfs_buf;
  22struct xfs_btree_cur;
  23struct xfs_mount;
  24struct xfs_perag;
  25struct xfs_trans;
  26
  27extern struct workqueue_struct *xfs_alloc_wq;
  28
  29/*
  30 * Freespace allocation types.  Argument to xfs_alloc_[v]extent.
  31 */
  32#define XFS_ALLOCTYPE_ANY_AG    0x01    /* allocate anywhere, use rotor */
  33#define XFS_ALLOCTYPE_FIRST_AG  0x02    /* ... start at ag 0 */
  34#define XFS_ALLOCTYPE_START_AG  0x04    /* anywhere, start in this a.g. */
  35#define XFS_ALLOCTYPE_THIS_AG   0x08    /* anywhere in this a.g. */
  36#define XFS_ALLOCTYPE_START_BNO 0x10    /* near this block else anywhere */
  37#define XFS_ALLOCTYPE_NEAR_BNO  0x20    /* in this a.g. and near this block */
  38#define XFS_ALLOCTYPE_THIS_BNO  0x40    /* at exactly this block */
  39
  40/* this should become an enum again when the tracing code is fixed */
  41typedef unsigned int xfs_alloctype_t;
  42
  43#define XFS_ALLOC_TYPES \
  44        { XFS_ALLOCTYPE_ANY_AG,         "ANY_AG" }, \
  45        { XFS_ALLOCTYPE_FIRST_AG,       "FIRST_AG" }, \
  46        { XFS_ALLOCTYPE_START_AG,       "START_AG" }, \
  47        { XFS_ALLOCTYPE_THIS_AG,        "THIS_AG" }, \
  48        { XFS_ALLOCTYPE_START_BNO,      "START_BNO" }, \
  49        { XFS_ALLOCTYPE_NEAR_BNO,       "NEAR_BNO" }, \
  50        { XFS_ALLOCTYPE_THIS_BNO,       "THIS_BNO" }
  51
  52/*
  53 * Flags for xfs_alloc_fix_freelist.
  54 */
  55#define XFS_ALLOC_FLAG_TRYLOCK  0x00000001  /* use trylock for buffer locking */
  56#define XFS_ALLOC_FLAG_FREEING  0x00000002  /* indicate caller is freeing extents*/
  57
  58/*
  59 * In order to avoid ENOSPC-related deadlock caused by
  60 * out-of-order locking of AGF buffer (PV 947395), we place
  61 * constraints on the relationship among actual allocations for
  62 * data blocks, freelist blocks, and potential file data bmap
  63 * btree blocks. However, these restrictions may result in no
  64 * actual space allocated for a delayed extent, for example, a data
  65 * block in a certain AG is allocated but there is no additional
  66 * block for the additional bmap btree block due to a split of the
  67 * bmap btree of the file. The result of this may lead to an
  68 * infinite loop in xfssyncd when the file gets flushed to disk and
  69 * all delayed extents need to be actually allocated. To get around
  70 * this, we explicitly set aside a few blocks which will not be
  71 * reserved in delayed allocation. Considering the minimum number of
  72 * needed freelist blocks is 4 fsbs _per AG_, a potential split of file's bmap
  73 * btree requires 1 fsb, so we set the number of set-aside blocks
  74 * to 4 + 4*agcount.
  75 */
  76#define XFS_ALLOC_SET_ASIDE(mp)  (4 + ((mp)->m_sb.sb_agcount * 4))
  77
  78/*
  79 * When deciding how much space to allocate out of an AG, we limit the
  80 * allocation maximum size to the size the AG. However, we cannot use all the
  81 * blocks in the AG - some are permanently used by metadata. These
  82 * blocks are generally:
  83 *      - the AG superblock, AGF, AGI and AGFL
  84 *      - the AGF (bno and cnt) and AGI btree root blocks
  85 *      - 4 blocks on the AGFL according to XFS_ALLOC_SET_ASIDE() limits
  86 *
  87 * The AG headers are sector sized, so the amount of space they take up is
  88 * dependent on filesystem geometry. The others are all single blocks.
  89 */
  90#define XFS_ALLOC_AG_MAX_USABLE(mp)     \
  91        ((mp)->m_sb.sb_agblocks - XFS_BB_TO_FSB(mp, XFS_FSS_TO_BB(mp, 4)) - 7)
  92
  93
  94/*
  95 * Argument structure for xfs_alloc routines.
  96 * This is turned into a structure to avoid having 20 arguments passed
  97 * down several levels of the stack.
  98 */
  99typedef struct xfs_alloc_arg {
 100        struct xfs_trans *tp;           /* transaction pointer */
 101        struct xfs_mount *mp;           /* file system mount point */
 102        struct xfs_buf  *agbp;          /* buffer for a.g. freelist header */
 103        struct xfs_perag *pag;          /* per-ag struct for this agno */
 104        xfs_fsblock_t   fsbno;          /* file system block number */
 105        xfs_agnumber_t  agno;           /* allocation group number */
 106        xfs_agblock_t   agbno;          /* allocation group-relative block # */
 107        xfs_extlen_t    minlen;         /* minimum size of extent */
 108        xfs_extlen_t    maxlen;         /* maximum size of extent */
 109        xfs_extlen_t    mod;            /* mod value for extent size */
 110        xfs_extlen_t    prod;           /* prod value for extent size */
 111        xfs_extlen_t    minleft;        /* min blocks must be left after us */
 112        xfs_extlen_t    total;          /* total blocks needed in xaction */
 113        xfs_extlen_t    alignment;      /* align answer to multiple of this */
 114        xfs_extlen_t    minalignslop;   /* slop for minlen+alignment calcs */
 115        xfs_extlen_t    len;            /* output: actual size of extent */
 116        xfs_alloctype_t type;           /* allocation type XFS_ALLOCTYPE_... */
 117        xfs_alloctype_t otype;          /* original allocation type */
 118        char            wasdel;         /* set if allocation was prev delayed */
 119        char            wasfromfl;      /* set if allocation is from freelist */
 120        char            isfl;           /* set if is freelist blocks - !acctg */
 121        char            userdata;       /* set if this is user data */
 122        xfs_fsblock_t   firstblock;     /* io first block allocated */
 123        struct completion *done;
 124        struct work_struct work;
 125        int             result;
 126} xfs_alloc_arg_t;
 127
 128/*
 129 * Defines for userdata
 130 */
 131#define XFS_ALLOC_USERDATA              1       /* allocation is for user data*/
 132#define XFS_ALLOC_INITIAL_USER_DATA     2       /* special case start of file */
 133
 134/*
 135 * Find the length of the longest extent in an AG.
 136 */
 137xfs_extlen_t
 138xfs_alloc_longest_free_extent(struct xfs_mount *mp,
 139                struct xfs_perag *pag);
 140
 141/*
 142 * Compute and fill in value of m_ag_maxlevels.
 143 */
 144void
 145xfs_alloc_compute_maxlevels(
 146        struct xfs_mount        *mp);   /* file system mount structure */
 147
 148/*
 149 * Get a block from the freelist.
 150 * Returns with the buffer for the block gotten.
 151 */
 152int                             /* error */
 153xfs_alloc_get_freelist(
 154        struct xfs_trans *tp,   /* transaction pointer */
 155        struct xfs_buf  *agbp,  /* buffer containing the agf structure */
 156        xfs_agblock_t   *bnop,  /* block address retrieved from freelist */
 157        int             btreeblk); /* destination is a AGF btree */
 158
 159/*
 160 * Log the given fields from the agf structure.
 161 */
 162void
 163xfs_alloc_log_agf(
 164        struct xfs_trans *tp,   /* transaction pointer */
 165        struct xfs_buf  *bp,    /* buffer for a.g. freelist header */
 166        int             fields);/* mask of fields to be logged (XFS_AGF_...) */
 167
 168/*
 169 * Interface for inode allocation to force the pag data to be initialized.
 170 */
 171int                             /* error */
 172xfs_alloc_pagf_init(
 173        struct xfs_mount *mp,   /* file system mount structure */
 174        struct xfs_trans *tp,   /* transaction pointer */
 175        xfs_agnumber_t  agno,   /* allocation group number */
 176        int             flags); /* XFS_ALLOC_FLAGS_... */
 177
 178/*
 179 * Put the block on the freelist for the allocation group.
 180 */
 181int                             /* error */
 182xfs_alloc_put_freelist(
 183        struct xfs_trans *tp,   /* transaction pointer */
 184        struct xfs_buf  *agbp,  /* buffer for a.g. freelist header */
 185        struct xfs_buf  *agflbp,/* buffer for a.g. free block array */
 186        xfs_agblock_t   bno,    /* block being freed */
 187        int             btreeblk); /* owner was a AGF btree */
 188
 189/*
 190 * Read in the allocation group header (free/alloc section).
 191 */
 192int                                     /* error  */
 193xfs_alloc_read_agf(
 194        struct xfs_mount *mp,           /* mount point structure */
 195        struct xfs_trans *tp,           /* transaction pointer */
 196        xfs_agnumber_t  agno,           /* allocation group number */
 197        int             flags,          /* XFS_ALLOC_FLAG_... */
 198        struct xfs_buf  **bpp);         /* buffer for the ag freelist header */
 199
 200/*
 201 * Allocate an extent (variable-size).
 202 */
 203int                             /* error */
 204xfs_alloc_vextent(
 205        xfs_alloc_arg_t *args); /* allocation argument structure */
 206
 207/*
 208 * Free an extent.
 209 */
 210int                             /* error */
 211xfs_free_extent(
 212        struct xfs_trans *tp,   /* transaction pointer */
 213        xfs_fsblock_t   bno,    /* starting block number of extent */
 214        xfs_extlen_t    len);   /* length of extent */
 215
 216int                                     /* error */
 217xfs_alloc_lookup_le(
 218        struct xfs_btree_cur    *cur,   /* btree cursor */
 219        xfs_agblock_t           bno,    /* starting block of extent */
 220        xfs_extlen_t            len,    /* length of extent */
 221        int                     *stat); /* success/failure */
 222
 223int                             /* error */
 224xfs_alloc_lookup_ge(
 225        struct xfs_btree_cur    *cur,   /* btree cursor */
 226        xfs_agblock_t           bno,    /* starting block of extent */
 227        xfs_extlen_t            len,    /* length of extent */
 228        int                     *stat); /* success/failure */
 229
 230int                                     /* error */
 231xfs_alloc_get_rec(
 232        struct xfs_btree_cur    *cur,   /* btree cursor */
 233        xfs_agblock_t           *bno,   /* output: starting block of extent */
 234        xfs_extlen_t            *len,   /* output: length of extent */
 235        int                     *stat); /* output: success/failure */
 236
 237#endif  /* __XFS_ALLOC_H__ */
 238
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