xfs_alloc.h

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/*
 * 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__ */