LXR linux/fs/xfs/xfs

   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#include <linux/list_lru.h>
  29
  30/*
  31 *      Base types
  32 */
  33
  34#define XFS_BUF_DADDR_NULL      ((xfs_daddr_t) (-1LL))
  35
  36typedef enum {
  37        XBRW_READ = 1,                  /* transfer into target memory */
  38        XBRW_WRITE = 2,                 /* transfer from target memory */
  39        XBRW_ZERO = 3,                  /* Zero target memory */
  40} xfs_buf_rw_t;
  41
  42#define XBF_READ         (1 << 0) /* buffer intended for reading from device */
  43#define XBF_WRITE        (1 << 1) /* buffer intended for writing to device */
  44#define XBF_READ_AHEAD   (1 << 2) /* asynchronous read-ahead */
  45#define XBF_ASYNC        (1 << 4) /* initiator will not wait for completion */
  46#define XBF_DONE         (1 << 5) /* all pages in the buffer uptodate */
  47#define XBF_STALE        (1 << 6) /* buffer has been staled, do not find it */
  48
  49/* I/O hints for the BIO layer */
  50#define XBF_SYNCIO       (1 << 10)/* treat this buffer as synchronous I/O */
  51#define XBF_FUA          (1 << 11)/* force cache write through mode */
  52#define XBF_FLUSH        (1 << 12)/* flush the disk cache before a write */
  53
  54/* flags used only as arguments to access routines */
  55#define XBF_TRYLOCK      (1 << 16)/* lock requested, but do not wait */
  56#define XBF_UNMAPPED     (1 << 17)/* do not map the buffer */
  57
  58/* flags used only internally */
  59#define _XBF_PAGES       (1 << 20)/* backed by refcounted pages */
  60#define _XBF_KMEM        (1 << 21)/* backed by heap memory */
  61#define _XBF_DELWRI_Q    (1 << 22)/* buffer on a delwri queue */
  62#define _XBF_COMPOUND    (1 << 23)/* compound buffer */
  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
  83/*
  84 * Internal state flags.
  85 */
  86#define XFS_BSTATE_DISPOSE       (1 << 0)       /* buffer being discarded */
  87
  88typedef struct xfs_buftarg {
  89        dev_t                   bt_dev;
  90        struct block_device     *bt_bdev;
  91        struct backing_dev_info *bt_bdi;
  92        struct xfs_mount        *bt_mount;
  93        unsigned int            bt_bsize;
  94        unsigned int            bt_sshift;
  95        size_t                  bt_smask;
  96
  97        /* LRU control structures */
  98        struct shrinker         bt_shrinker;
  99        struct list_lru         bt_lru;
 100} xfs_buftarg_t;
 101
 102struct xfs_buf;
 103typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
 104
 105
 106#define XB_PAGES        2
 107
 108struct xfs_buf_map {
 109        xfs_daddr_t             bm_bn;  /* block number for I/O */
 110        int                     bm_len; /* size of I/O */
 111};
 112
 113#define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
 114        struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };
 115
 116struct xfs_buf_ops {
 117        void (*verify_read)(struct xfs_buf *);
 118        void (*verify_write)(struct xfs_buf *);
 119};
 120
 121typedef struct xfs_buf {
 122        /*
 123         * first cacheline holds all the fields needed for an uncontended cache
 124         * hit to be fully processed. The semaphore straddles the cacheline
 125         * boundary, but the counter and lock sits on the first cacheline,
 126         * which is the only bit that is touched if we hit the semaphore
 127         * fast-path on locking.
 128         */
 129        struct rb_node          b_rbnode;       /* rbtree node */
 130        xfs_daddr_t             b_bn;           /* block number of buffer */
 131        int                     b_length;       /* size of buffer in BBs */
 132        atomic_t                b_hold;         /* reference count */
 133        atomic_t                b_lru_ref;      /* lru reclaim ref count */
 134        xfs_buf_flags_t         b_flags;        /* status flags */
 135        struct semaphore        b_sema;         /* semaphore for lockables */
 136
 137        /*
 138         * concurrent access to b_lru and b_lru_flags are protected by
 139         * bt_lru_lock and not by b_sema
 140         */
 141        struct list_head        b_lru;          /* lru list */
 142        spinlock_t              b_lock;         /* internal state lock */
 143        unsigned int            b_state;        /* internal state flags */
 144        wait_queue_head_t       b_waiters;      /* unpin waiters */
 145        struct list_head        b_list;
 146        struct xfs_perag        *b_pag;         /* contains rbtree root */
 147        xfs_buftarg_t           *b_target;      /* buffer target (device) */
 148        void                    *b_addr;        /* virtual address of buffer */
 149        struct work_struct      b_iodone_work;
 150        xfs_buf_iodone_t        b_iodone;       /* I/O completion function */
 151        struct completion       b_iowait;       /* queue for I/O waiters */
 152        void                    *b_fspriv;
 153        struct xfs_trans        *b_transp;
 154        struct page             **b_pages;      /* array of page pointers */
 155        struct page             *b_page_array[XB_PAGES]; /* inline pages */
 156        struct xfs_buf_map      *b_maps;        /* compound buffer map */
 157        struct xfs_buf_map      __b_map;        /* inline compound buffer map */
 158        int                     b_map_count;
 159        int                     b_io_length;    /* IO size in BBs */
 160        atomic_t                b_pin_count;    /* pin count */
 161        atomic_t                b_io_remaining; /* #outstanding I/O requests */
 162        unsigned int            b_page_count;   /* size of page array */
 163        unsigned int            b_offset;       /* page offset in first page */
 164        unsigned short          b_error;        /* error code on I/O */
 165        const struct xfs_buf_ops        *b_ops;
 166
 167#ifdef XFS_BUF_LOCK_TRACKING
 168        int                     b_last_holder;
 169#endif
 170} xfs_buf_t;
 171
 172/* Finding and Reading Buffers */
 173struct xfs_buf *_xfs_buf_find(struct xfs_buftarg *target,
 174                              struct xfs_buf_map *map, int nmaps,
 175                              xfs_buf_flags_t flags, struct xfs_buf *new_bp);
 176
 177static inline struct xfs_buf *
 178xfs_incore(
 179        struct xfs_buftarg      *target,
 180        xfs_daddr_t             blkno,
 181        size_t                  numblks,
 182        xfs_buf_flags_t         flags)
 183{
 184        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 185        return _xfs_buf_find(target, &map, 1, flags, NULL);
 186}
 187
 188struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
 189                               struct xfs_buf_map *map, int nmaps,
 190                               xfs_buf_flags_t flags);
 191
 192static inline struct xfs_buf *
 193xfs_buf_alloc(
 194        struct xfs_buftarg      *target,
 195        xfs_daddr_t             blkno,
 196        size_t                  numblks,
 197        xfs_buf_flags_t         flags)
 198{
 199        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 200        return _xfs_buf_alloc(target, &map, 1, flags);
 201}
 202
 203struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 204                               struct xfs_buf_map *map, int nmaps,
 205                               xfs_buf_flags_t flags);
 206struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
 207                               struct xfs_buf_map *map, int nmaps,
 208                               xfs_buf_flags_t flags,
 209                               const struct xfs_buf_ops *ops);
 210void xfs_buf_readahead_map(struct xfs_buftarg *target,
 211                               struct xfs_buf_map *map, int nmaps,
 212                               const struct xfs_buf_ops *ops);
 213
 214static inline struct xfs_buf *
 215xfs_buf_get(
 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_get_map(target, &map, 1, flags);
 223}
 224
 225static inline struct xfs_buf *
 226xfs_buf_read(
 227        struct xfs_buftarg      *target,
 228        xfs_daddr_t             blkno,
 229        size_t                  numblks,
 230        xfs_buf_flags_t         flags,
 231        const struct xfs_buf_ops *ops)
 232{
 233        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 234        return xfs_buf_read_map(target, &map, 1, flags, ops);
 235}
 236
 237static inline void
 238xfs_buf_readahead(
 239        struct xfs_buftarg      *target,
 240        xfs_daddr_t             blkno,
 241        size_t                  numblks,
 242        const struct xfs_buf_ops *ops)
 243{
 244        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 245        return xfs_buf_readahead_map(target, &map, 1, ops);
 246}
 247
 248struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
 249void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
 250int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
 251
 252struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 253                                int flags);
 254struct xfs_buf *xfs_buf_read_uncached(struct xfs_buftarg *target,
 255                                xfs_daddr_t daddr, size_t numblks, int flags,
 256                                const struct xfs_buf_ops *ops);
 257void xfs_buf_hold(struct xfs_buf *bp);
 258
 259/* Releasing Buffers */
 260extern void xfs_buf_free(xfs_buf_t *);
 261extern void xfs_buf_rele(xfs_buf_t *);
 262
 263/* Locking and Unlocking Buffers */
 264extern int xfs_buf_trylock(xfs_buf_t *);
 265extern void xfs_buf_lock(xfs_buf_t *);
 266extern void xfs_buf_unlock(xfs_buf_t *);
 267#define xfs_buf_islocked(bp) \
 268        ((bp)->b_sema.count <= 0)
 269
 270/* Buffer Read and Write Routines */
 271extern int xfs_bwrite(struct xfs_buf *bp);
 272
 273extern void xfsbdstrat(struct xfs_mount *, struct xfs_buf *);
 274
 275extern void xfs_buf_ioend(xfs_buf_t *,  int);
 276extern void xfs_buf_ioerror(xfs_buf_t *, int);
 277extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
 278extern void xfs_buf_iorequest(xfs_buf_t *);
 279extern int xfs_buf_iowait(xfs_buf_t *);
 280extern void xfs_buf_iomove(xfs_buf_t *, size_t, size_t, void *,
 281                                xfs_buf_rw_t);
 282#define xfs_buf_zero(bp, off, len) \
 283            xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)
 284
 285static inline int xfs_buf_geterror(xfs_buf_t *bp)
 286{
 287        return bp ? bp->b_error : ENOMEM;
 288}
 289
 290/* Buffer Utility Routines */
 291extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);
 292
 293/* Delayed Write Buffer Routines */
 294extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
 295extern int xfs_buf_delwri_submit(struct list_head *);
 296extern int xfs_buf_delwri_submit_nowait(struct list_head *);
 297
 298/* Buffer Daemon Setup Routines */
 299extern int xfs_buf_init(void);
 300extern void xfs_buf_terminate(void);
 301
 302#define XFS_BUF_ZEROFLAGS(bp) \
 303        ((bp)->b_flags &= ~(XBF_READ|XBF_WRITE|XBF_ASYNC| \
 304                            XBF_SYNCIO|XBF_FUA|XBF_FLUSH))
 305
 306void xfs_buf_stale(struct xfs_buf *bp);
 307#define XFS_BUF_UNSTALE(bp)     ((bp)->b_flags &= ~XBF_STALE)
 308#define XFS_BUF_ISSTALE(bp)     ((bp)->b_flags & XBF_STALE)
 309
 310#define XFS_BUF_DONE(bp)        ((bp)->b_flags |= XBF_DONE)
 311#define XFS_BUF_UNDONE(bp)      ((bp)->b_flags &= ~XBF_DONE)
 312#define XFS_BUF_ISDONE(bp)      ((bp)->b_flags & XBF_DONE)
 313
 314#define XFS_BUF_ASYNC(bp)       ((bp)->b_flags |= XBF_ASYNC)
 315#define XFS_BUF_UNASYNC(bp)     ((bp)->b_flags &= ~XBF_ASYNC)
 316#define XFS_BUF_ISASYNC(bp)     ((bp)->b_flags & XBF_ASYNC)
 317
 318#define XFS_BUF_READ(bp)        ((bp)->b_flags |= XBF_READ)
 319#define XFS_BUF_UNREAD(bp)      ((bp)->b_flags &= ~XBF_READ)
 320#define XFS_BUF_ISREAD(bp)      ((bp)->b_flags & XBF_READ)
 321
 322#define XFS_BUF_WRITE(bp)       ((bp)->b_flags |= XBF_WRITE)
 323#define XFS_BUF_UNWRITE(bp)     ((bp)->b_flags &= ~XBF_WRITE)
 324#define XFS_BUF_ISWRITE(bp)     ((bp)->b_flags & XBF_WRITE)
 325
 326/*
 327 * These macros use the IO block map rather than b_bn. b_bn is now really
 328 * just for the buffer cache index for cached buffers. As IO does not use b_bn
 329 * anymore, uncached buffers do not use b_bn at all and hence must modify the IO
 330 * map directly. Uncached buffers are not allowed to be discontiguous, so this
 331 * is safe to do.
 332 *
 333 * In future, uncached buffers will pass the block number directly to the io
 334 * request function and hence these macros will go away at that point.
 335 */
 336#define XFS_BUF_ADDR(bp)                ((bp)->b_maps[0].bm_bn)
 337#define XFS_BUF_SET_ADDR(bp, bno)       ((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))
 338
 339static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
 340{
 341        atomic_set(&bp->b_lru_ref, lru_ref);
 342}
 343
 344static inline int xfs_buf_ispinned(struct xfs_buf *bp)
 345{
 346        return atomic_read(&bp->b_pin_count);
 347}
 348
 349static inline void xfs_buf_relse(xfs_buf_t *bp)
 350{
 351        xfs_buf_unlock(bp);
 352        xfs_buf_rele(bp);
 353}
 354
 355/*
 356 *      Handling of buftargs.
 357 */
 358extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
 359                        struct block_device *, int, const char *);
 360extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
 361extern void xfs_wait_buftarg(xfs_buftarg_t *);
 362extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int, unsigned int);
 363
 364#define xfs_getsize_buftarg(buftarg)    block_size((buftarg)->bt_bdev)
 365#define xfs_readonly_buftarg(buftarg)   bdev_read_only((buftarg)->bt_bdev)
 366
 367#endif  /* __XFS_BUF_H__ */
 368