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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 
 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 #endif  /* __XFS_ALLOC_H__ */
235 

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