fs/xfs/xfs_alloc.h

   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
  21 struct xfs_buf;
  22 struct xfs_btree_cur;
  23 struct xfs_mount;
  24 struct xfs_perag;
  25 struct xfs_trans;
  26
  27 extern 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 */
  41 typedef 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  */
  99 typedef 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 } xfs_alloc_arg_t;
 124
 125 /*
 126  * Defines for userdata
 127  */
 128 #define XFS_ALLOC_USERDATA              1       /* allocation is for user data*/
 129 #define XFS_ALLOC_INITIAL_USER_DATA     2       /* special case start of file */
 130
 131 /*
 132  * Find the length of the longest extent in an AG.
 133  */
 134 xfs_extlen_t
 135 xfs_alloc_longest_free_extent(struct xfs_mount *mp,
 136                 struct xfs_perag *pag);
 137
 138 /*
 139  * Compute and fill in value of m_ag_maxlevels.
 140  */
 141 void
 142 xfs_alloc_compute_maxlevels(
 143         struct xfs_mount        *mp);   /* file system mount structure */
 144
 145 /*
 146  * Get a block from the freelist.
 147  * Returns with the buffer for the block gotten.
 148  */
 149 int                             /* error */
 150 xfs_alloc_get_freelist(
 151         struct xfs_trans *tp,   /* transaction pointer */
 152         struct xfs_buf  *agbp,  /* buffer containing the agf structure */
 153         xfs_agblock_t   *bnop,  /* block address retrieved from freelist */
 154         int             btreeblk); /* destination is a AGF btree */
 155
 156 /*
 157  * Log the given fields from the agf structure.
 158  */
 159 void
 160 xfs_alloc_log_agf(
 161         struct xfs_trans *tp,   /* transaction pointer */
 162         struct xfs_buf  *bp,    /* buffer for a.g. freelist header */
 163         int             fields);/* mask of fields to be logged (XFS_AGF_...) */
 164
 165 /*
 166  * Interface for inode allocation to force the pag data to be initialized.
 167  */
 168 int                             /* error */
 169 xfs_alloc_pagf_init(
 170         struct xfs_mount *mp,   /* file system mount structure */
 171         struct xfs_trans *tp,   /* transaction pointer */
 172         xfs_agnumber_t  agno,   /* allocation group number */
 173         int             flags); /* XFS_ALLOC_FLAGS_... */
 174
 175 /*
 176  * Put the block on the freelist for the allocation group.
 177  */
 178 int                             /* error */
 179 xfs_alloc_put_freelist(
 180         struct xfs_trans *tp,   /* transaction pointer */
 181         struct xfs_buf  *agbp,  /* buffer for a.g. freelist header */
 182         struct xfs_buf  *agflbp,/* buffer for a.g. free block array */
 183         xfs_agblock_t   bno,    /* block being freed */
 184         int             btreeblk); /* owner was a AGF btree */
 185
 186 /*
 187  * Read in the allocation group header (free/alloc section).
 188  */
 189 int                                     /* error  */
 190 xfs_alloc_read_agf(
 191         struct xfs_mount *mp,           /* mount point structure */
 192         struct xfs_trans *tp,           /* transaction pointer */
 193         xfs_agnumber_t  agno,           /* allocation group number */
 194         int             flags,          /* XFS_ALLOC_FLAG_... */
 195         struct xfs_buf  **bpp);         /* buffer for the ag freelist header */
 196
 197 /*
 198  * Allocate an extent (variable-size).
 199  */
 200 int                             /* error */
 201 xfs_alloc_vextent(
 202         xfs_alloc_arg_t *args); /* allocation argument structure */
 203
 204 /*
 205  * Free an extent.
 206  */
 207 int                             /* error */
 208 xfs_free_extent(
 209         struct xfs_trans *tp,   /* transaction pointer */
 210         xfs_fsblock_t   bno,    /* starting block number of extent */
 211         xfs_extlen_t    len);   /* length of extent */
 212
 213 int                                     /* error */
 214 xfs_alloc_lookup_le(
 215         struct xfs_btree_cur    *cur,   /* btree cursor */
 216         xfs_agblock_t           bno,    /* starting block of extent */
 217         xfs_extlen_t            len,    /* length of extent */
 218         int                     *stat); /* success/failure */
 219
 220 int                             /* error */
 221 xfs_alloc_lookup_ge(
 222         struct xfs_btree_cur    *cur,   /* btree cursor */
 223         xfs_agblock_t           bno,    /* starting block of extent */
 224         xfs_extlen_t            len,    /* length of extent */
 225         int                     *stat); /* success/failure */
 226
 227 int                                     /* error */
 228 xfs_alloc_get_rec(
 229         struct xfs_btree_cur    *cur,   /* btree cursor */
 230         xfs_agblock_t           *bno,   /* output: starting block of extent */
 231         xfs_extlen_t            *len,   /* output: length of extent */
 232         int                     *stat); /* output: success/failure */
 233
 234 extern const struct xfs_buf_ops xfs_agf_buf_ops;
 235 extern const struct xfs_buf_ops xfs_agfl_buf_ops;
 236
 237 #endif  /* __XFS_ALLOC_H__ */