linux/fs/xfs/xfs_buf.h
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   1/*
   2 * Copyright (c) 2000-2005 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_BUF_H__
  19#define __XFS_BUF_H__
  20
  21#include <linux/list.h>
  22#include <linux/types.h>
  23#include <linux/spinlock.h>
  24#include <linux/mm.h>
  25#include <linux/fs.h>
  26#include <linux/buffer_head.h>
  27#include <linux/uio.h>
  28
  29/*
  30 *      Base types
  31 */
  32
  33#define XFS_BUF_DADDR_NULL      ((xfs_daddr_t) (-1LL))
  34
  35typedef enum {
  36        XBRW_READ = 1,                  /* transfer into target memory */
  37        XBRW_WRITE = 2,                 /* transfer from target memory */
  38        XBRW_ZERO = 3,                  /* Zero target memory */
  39} xfs_buf_rw_t;
  40
  41#define XBF_READ         (1 << 0) /* buffer intended for reading from device */
  42#define XBF_WRITE        (1 << 1) /* buffer intended for writing to device */
  43#define XBF_READ_AHEAD   (1 << 2) /* asynchronous read-ahead */
  44#define XBF_ASYNC        (1 << 4) /* initiator will not wait for completion */
  45#define XBF_DONE         (1 << 5) /* all pages in the buffer uptodate */
  46#define XBF_STALE        (1 << 6) /* buffer has been staled, do not find it */
  47
  48/* I/O hints for the BIO layer */
  49#define XBF_SYNCIO       (1 << 10)/* treat this buffer as synchronous I/O */
  50#define XBF_FUA          (1 << 11)/* force cache write through mode */
  51#define XBF_FLUSH        (1 << 12)/* flush the disk cache before a write */
  52
  53/* flags used only as arguments to access routines */
  54#define XBF_TRYLOCK      (1 << 16)/* lock requested, but do not wait */
  55#define XBF_UNMAPPED     (1 << 17)/* do not map the buffer */
  56
  57/* flags used only internally */
  58#define _XBF_PAGES       (1 << 20)/* backed by refcounted pages */
  59#define _XBF_KMEM        (1 << 21)/* backed by heap memory */
  60#define _XBF_DELWRI_Q    (1 << 22)/* buffer on a delwri queue */
  61#define _XBF_COMPOUND    (1 << 23)/* compound buffer */
  62#define _XBF_LRU_DISPOSE (1 << 24)/* buffer being discarded */
  63
  64typedef unsigned int xfs_buf_flags_t;
  65
  66#define XFS_BUF_FLAGS \
  67        { XBF_READ,             "READ" }, \
  68        { XBF_WRITE,            "WRITE" }, \
  69        { XBF_READ_AHEAD,       "READ_AHEAD" }, \
  70        { XBF_ASYNC,            "ASYNC" }, \
  71        { XBF_DONE,             "DONE" }, \
  72        { XBF_STALE,            "STALE" }, \
  73        { XBF_SYNCIO,           "SYNCIO" }, \
  74        { XBF_FUA,              "FUA" }, \
  75        { XBF_FLUSH,            "FLUSH" }, \
  76        { XBF_TRYLOCK,          "TRYLOCK" },    /* should never be set */\
  77        { XBF_UNMAPPED,         "UNMAPPED" },   /* ditto */\
  78        { _XBF_PAGES,           "PAGES" }, \
  79        { _XBF_KMEM,            "KMEM" }, \
  80        { _XBF_DELWRI_Q,        "DELWRI_Q" }, \
  81        { _XBF_COMPOUND,        "COMPOUND" }, \
  82        { _XBF_LRU_DISPOSE,     "LRU_DISPOSE" }
  83
  84typedef struct xfs_buftarg {
  85        dev_t                   bt_dev;
  86        struct block_device     *bt_bdev;
  87        struct backing_dev_info *bt_bdi;
  88        struct xfs_mount        *bt_mount;
  89        unsigned int            bt_bsize;
  90        unsigned int            bt_sshift;
  91        size_t                  bt_smask;
  92
  93        /* LRU control structures */
  94        struct shrinker         bt_shrinker;
  95        struct list_head        bt_lru;
  96        spinlock_t              bt_lru_lock;
  97        unsigned int            bt_lru_nr;
  98} xfs_buftarg_t;
  99
 100struct xfs_buf;
 101typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
 102
 103#define XB_PAGES        2
 104
 105struct xfs_buf_map {
 106        xfs_daddr_t             bm_bn;  /* block number for I/O */
 107        int                     bm_len; /* size of I/O */
 108};
 109
 110#define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
 111        struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };
 112
 113typedef struct xfs_buf {
 114        /*
 115         * first cacheline holds all the fields needed for an uncontended cache
 116         * hit to be fully processed. The semaphore straddles the cacheline
 117         * boundary, but the counter and lock sits on the first cacheline,
 118         * which is the only bit that is touched if we hit the semaphore
 119         * fast-path on locking.
 120         */
 121        struct rb_node          b_rbnode;       /* rbtree node */
 122        xfs_daddr_t             b_bn;           /* block number of buffer */
 123        int                     b_length;       /* size of buffer in BBs */
 124        atomic_t                b_hold;         /* reference count */
 125        atomic_t                b_lru_ref;      /* lru reclaim ref count */
 126        xfs_buf_flags_t         b_flags;        /* status flags */
 127        struct semaphore        b_sema;         /* semaphore for lockables */
 128
 129        /*
 130         * concurrent access to b_lru and b_lru_flags are protected by
 131         * bt_lru_lock and not by b_sema
 132         */
 133        struct list_head        b_lru;          /* lru list */
 134        xfs_buf_flags_t         b_lru_flags;    /* internal lru status flags */
 135        wait_queue_head_t       b_waiters;      /* unpin waiters */
 136        struct list_head        b_list;
 137        struct xfs_perag        *b_pag;         /* contains rbtree root */
 138        xfs_buftarg_t           *b_target;      /* buffer target (device) */
 139        void                    *b_addr;        /* virtual address of buffer */
 140        struct work_struct      b_iodone_work;
 141        xfs_buf_iodone_t        b_iodone;       /* I/O completion function */
 142        struct completion       b_iowait;       /* queue for I/O waiters */
 143        void                    *b_fspriv;
 144        struct xfs_trans        *b_transp;
 145        struct page             **b_pages;      /* array of page pointers */
 146        struct page             *b_page_array[XB_PAGES]; /* inline pages */
 147        struct xfs_buf_map      *b_maps;        /* compound buffer map */
 148        struct xfs_buf_map      b_map;          /* inline compound buffer map */
 149        int                     b_map_count;
 150        int                     b_io_length;    /* IO size in BBs */
 151        atomic_t                b_pin_count;    /* pin count */
 152        atomic_t                b_io_remaining; /* #outstanding I/O requests */
 153        unsigned int            b_page_count;   /* size of page array */
 154        unsigned int            b_offset;       /* page offset in first page */
 155        unsigned short          b_error;        /* error code on I/O */
 156
 157#ifdef XFS_BUF_LOCK_TRACKING
 158        int                     b_last_holder;
 159#endif
 160} xfs_buf_t;
 161
 162
 163/* Finding and Reading Buffers */
 164struct xfs_buf *_xfs_buf_find(struct xfs_buftarg *target,
 165                              struct xfs_buf_map *map, int nmaps,
 166                              xfs_buf_flags_t flags, struct xfs_buf *new_bp);
 167
 168static inline struct xfs_buf *
 169xfs_incore(
 170        struct xfs_buftarg      *target,
 171        xfs_daddr_t             blkno,
 172        size_t                  numblks,
 173        xfs_buf_flags_t         flags)
 174{
 175        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 176        return _xfs_buf_find(target, &map, 1, flags, NULL);
 177}
 178
 179struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
 180                               struct xfs_buf_map *map, int nmaps,
 181                               xfs_buf_flags_t flags);
 182
 183static inline struct xfs_buf *
 184xfs_buf_alloc(
 185        struct xfs_buftarg      *target,
 186        xfs_daddr_t             blkno,
 187        size_t                  numblks,
 188        xfs_buf_flags_t         flags)
 189{
 190        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 191        return _xfs_buf_alloc(target, &map, 1, flags);
 192}
 193
 194struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 195                               struct xfs_buf_map *map, int nmaps,
 196                               xfs_buf_flags_t flags);
 197struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
 198                               struct xfs_buf_map *map, int nmaps,
 199                               xfs_buf_flags_t flags);
 200void xfs_buf_readahead_map(struct xfs_buftarg *target,
 201                               struct xfs_buf_map *map, int nmaps);
 202
 203static inline struct xfs_buf *
 204xfs_buf_get(
 205        struct xfs_buftarg      *target,
 206        xfs_daddr_t             blkno,
 207        size_t                  numblks,
 208        xfs_buf_flags_t         flags)
 209{
 210        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 211        return xfs_buf_get_map(target, &map, 1, flags);
 212}
 213
 214static inline struct xfs_buf *
 215xfs_buf_read(
 216        struct xfs_buftarg      *target,
 217        xfs_daddr_t             blkno,
 218        size_t                  numblks,
 219        xfs_buf_flags_t         flags)
 220{
 221        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 222        return xfs_buf_read_map(target, &map, 1, flags);
 223}
 224
 225static inline void
 226xfs_buf_readahead(
 227        struct xfs_buftarg      *target,
 228        xfs_daddr_t             blkno,
 229        size_t                  numblks)
 230{
 231        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 232        return xfs_buf_readahead_map(target, &map, 1);
 233}
 234
 235struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
 236void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
 237int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
 238
 239struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 240                                int flags);
 241struct xfs_buf *xfs_buf_read_uncached(struct xfs_buftarg *target,
 242                                xfs_daddr_t daddr, size_t numblks, int flags);
 243void xfs_buf_hold(struct xfs_buf *bp);
 244
 245/* Releasing Buffers */
 246extern void xfs_buf_free(xfs_buf_t *);
 247extern void xfs_buf_rele(xfs_buf_t *);
 248
 249/* Locking and Unlocking Buffers */
 250extern int xfs_buf_trylock(xfs_buf_t *);
 251extern void xfs_buf_lock(xfs_buf_t *);
 252extern void xfs_buf_unlock(xfs_buf_t *);
 253#define xfs_buf_islocked(bp) \
 254        ((bp)->b_sema.count <= 0)
 255
 256/* Buffer Read and Write Routines */
 257extern int xfs_bwrite(struct xfs_buf *bp);
 258
 259extern void xfsbdstrat(struct xfs_mount *, struct xfs_buf *);
 260
 261extern void xfs_buf_ioend(xfs_buf_t *,  int);
 262extern void xfs_buf_ioerror(xfs_buf_t *, int);
 263extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
 264extern void xfs_buf_iorequest(xfs_buf_t *);
 265extern int xfs_buf_iowait(xfs_buf_t *);
 266extern void xfs_buf_iomove(xfs_buf_t *, size_t, size_t, void *,
 267                                xfs_buf_rw_t);
 268#define xfs_buf_zero(bp, off, len) \
 269            xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)
 270
 271static inline int xfs_buf_geterror(xfs_buf_t *bp)
 272{
 273        return bp ? bp->b_error : ENOMEM;
 274}
 275
 276/* Buffer Utility Routines */
 277extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);
 278
 279/* Delayed Write Buffer Routines */
 280extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
 281extern int xfs_buf_delwri_submit(struct list_head *);
 282extern int xfs_buf_delwri_submit_nowait(struct list_head *);
 283
 284/* Buffer Daemon Setup Routines */
 285extern int xfs_buf_init(void);
 286extern void xfs_buf_terminate(void);
 287
 288#define XFS_BUF_ZEROFLAGS(bp) \
 289        ((bp)->b_flags &= ~(XBF_READ|XBF_WRITE|XBF_ASYNC| \
 290                            XBF_SYNCIO|XBF_FUA|XBF_FLUSH))
 291
 292void xfs_buf_stale(struct xfs_buf *bp);
 293#define XFS_BUF_UNSTALE(bp)     ((bp)->b_flags &= ~XBF_STALE)
 294#define XFS_BUF_ISSTALE(bp)     ((bp)->b_flags & XBF_STALE)
 295
 296#define XFS_BUF_DONE(bp)        ((bp)->b_flags |= XBF_DONE)
 297#define XFS_BUF_UNDONE(bp)      ((bp)->b_flags &= ~XBF_DONE)
 298#define XFS_BUF_ISDONE(bp)      ((bp)->b_flags & XBF_DONE)
 299
 300#define XFS_BUF_ASYNC(bp)       ((bp)->b_flags |= XBF_ASYNC)
 301#define XFS_BUF_UNASYNC(bp)     ((bp)->b_flags &= ~XBF_ASYNC)
 302#define XFS_BUF_ISASYNC(bp)     ((bp)->b_flags & XBF_ASYNC)
 303
 304#define XFS_BUF_READ(bp)        ((bp)->b_flags |= XBF_READ)
 305#define XFS_BUF_UNREAD(bp)      ((bp)->b_flags &= ~XBF_READ)
 306#define XFS_BUF_ISREAD(bp)      ((bp)->b_flags & XBF_READ)
 307
 308#define XFS_BUF_WRITE(bp)       ((bp)->b_flags |= XBF_WRITE)
 309#define XFS_BUF_UNWRITE(bp)     ((bp)->b_flags &= ~XBF_WRITE)
 310#define XFS_BUF_ISWRITE(bp)     ((bp)->b_flags & XBF_WRITE)
 311
 312/*
 313 * These macros use the IO block map rather than b_bn. b_bn is now really
 314 * just for the buffer cache index for cached buffers. As IO does not use b_bn
 315 * anymore, uncached buffers do not use b_bn at all and hence must modify the IO
 316 * map directly. Uncached buffers are not allowed to be discontiguous, so this
 317 * is safe to do.
 318 *
 319 * In future, uncached buffers will pass the block number directly to the io
 320 * request function and hence these macros will go away at that point.
 321 */
 322#define XFS_BUF_ADDR(bp)                ((bp)->b_map.bm_bn)
 323#define XFS_BUF_SET_ADDR(bp, bno)       ((bp)->b_map.bm_bn = (xfs_daddr_t)(bno))
 324
 325static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
 326{
 327        atomic_set(&bp->b_lru_ref, lru_ref);
 328}
 329
 330static inline int xfs_buf_ispinned(struct xfs_buf *bp)
 331{
 332        return atomic_read(&bp->b_pin_count);
 333}
 334
 335static inline void xfs_buf_relse(xfs_buf_t *bp)
 336{
 337        xfs_buf_unlock(bp);
 338        xfs_buf_rele(bp);
 339}
 340
 341/*
 342 *      Handling of buftargs.
 343 */
 344extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
 345                        struct block_device *, int, const char *);
 346extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
 347extern void xfs_wait_buftarg(xfs_buftarg_t *);
 348extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int, unsigned int);
 349
 350#define xfs_getsize_buftarg(buftarg)    block_size((buftarg)->bt_bdev)
 351#define xfs_readonly_buftarg(buftarg)   bdev_read_only((buftarg)->bt_bdev)
 352
 353#endif  /* __XFS_BUF_H__ */
 354
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