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
 104#define XB_PAGES        2
 105
 106struct xfs_buf_map {
 107        xfs_daddr_t             bm_bn;  /* block number for I/O */
 108        int                     bm_len; /* size of I/O */
 109};
 110
 111#define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
 112        struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };
 113
 114struct xfs_buf_ops {
 115        void (*verify_read)(struct xfs_buf *);
 116        void (*verify_write)(struct xfs_buf *);
 117};
 118
 119typedef struct xfs_buf {
 120        /*
 121         * first cacheline holds all the fields needed for an uncontended cache
 122         * hit to be fully processed. The semaphore straddles the cacheline
 123         * boundary, but the counter and lock sits on the first cacheline,
 124         * which is the only bit that is touched if we hit the semaphore
 125         * fast-path on locking.
 126         */
 127        struct rb_node          b_rbnode;       /* rbtree node */
 128        xfs_daddr_t             b_bn;           /* block number of buffer */
 129        int                     b_length;       /* size of buffer in BBs */
 130        atomic_t                b_hold;         /* reference count */
 131        atomic_t                b_lru_ref;      /* lru reclaim ref count */
 132        xfs_buf_flags_t         b_flags;        /* status flags */
 133        struct semaphore        b_sema;         /* semaphore for lockables */
 134
 135        /*
 136         * concurrent access to b_lru and b_lru_flags are protected by
 137         * bt_lru_lock and not by b_sema
 138         */
 139        struct list_head        b_lru;          /* lru list */
 140        xfs_buf_flags_t         b_lru_flags;    /* internal lru status flags */
 141        wait_queue_head_t       b_waiters;      /* unpin waiters */
 142        struct list_head        b_list;
 143        struct xfs_perag        *b_pag;         /* contains rbtree root */
 144        xfs_buftarg_t           *b_target;      /* buffer target (device) */
 145        void                    *b_addr;        /* virtual address of buffer */
 146        struct work_struct      b_iodone_work;
 147        xfs_buf_iodone_t        b_iodone;       /* I/O completion function */
 148        struct completion       b_iowait;       /* queue for I/O waiters */
 149        void                    *b_fspriv;
 150        struct xfs_trans        *b_transp;
 151        struct page             **b_pages;      /* array of page pointers */
 152        struct page             *b_page_array[XB_PAGES]; /* inline pages */
 153        struct xfs_buf_map      *b_maps;        /* compound buffer map */
 154        struct xfs_buf_map      __b_map;        /* inline compound buffer map */
 155        int                     b_map_count;
 156        int                     b_io_length;    /* IO size in BBs */
 157        atomic_t                b_pin_count;    /* pin count */
 158        atomic_t                b_io_remaining; /* #outstanding I/O requests */
 159        unsigned int            b_page_count;   /* size of page array */
 160        unsigned int            b_offset;       /* page offset in first page */
 161        unsigned short          b_error;        /* error code on I/O */
 162        const struct xfs_buf_ops        *b_ops;
 163
 164#ifdef XFS_BUF_LOCK_TRACKING
 165        int                     b_last_holder;
 166#endif
 167} xfs_buf_t;
 168
 169/* Finding and Reading Buffers */
 170struct xfs_buf *_xfs_buf_find(struct xfs_buftarg *target,
 171                              struct xfs_buf_map *map, int nmaps,
 172                              xfs_buf_flags_t flags, struct xfs_buf *new_bp);
 173
 174static inline struct xfs_buf *
 175xfs_incore(
 176        struct xfs_buftarg      *target,
 177        xfs_daddr_t             blkno,
 178        size_t                  numblks,
 179        xfs_buf_flags_t         flags)
 180{
 181        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 182        return _xfs_buf_find(target, &map, 1, flags, NULL);
 183}
 184
 185struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
 186                               struct xfs_buf_map *map, int nmaps,
 187                               xfs_buf_flags_t flags);
 188
 189static inline struct xfs_buf *
 190xfs_buf_alloc(
 191        struct xfs_buftarg      *target,
 192        xfs_daddr_t             blkno,
 193        size_t                  numblks,
 194        xfs_buf_flags_t         flags)
 195{
 196        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 197        return _xfs_buf_alloc(target, &map, 1, flags);
 198}
 199
 200struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 201                               struct xfs_buf_map *map, int nmaps,
 202                               xfs_buf_flags_t flags);
 203struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
 204                               struct xfs_buf_map *map, int nmaps,
 205                               xfs_buf_flags_t flags,
 206                               const struct xfs_buf_ops *ops);
 207void xfs_buf_readahead_map(struct xfs_buftarg *target,
 208                               struct xfs_buf_map *map, int nmaps,
 209                               const struct xfs_buf_ops *ops);
 210
 211static inline struct xfs_buf *
 212xfs_buf_get(
 213        struct xfs_buftarg      *target,
 214        xfs_daddr_t             blkno,
 215        size_t                  numblks,
 216        xfs_buf_flags_t         flags)
 217{
 218        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 219        return xfs_buf_get_map(target, &map, 1, flags);
 220}
 221
 222static inline struct xfs_buf *
 223xfs_buf_read(
 224        struct xfs_buftarg      *target,
 225        xfs_daddr_t             blkno,
 226        size_t                  numblks,
 227        xfs_buf_flags_t         flags,
 228        const struct xfs_buf_ops *ops)
 229{
 230        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 231        return xfs_buf_read_map(target, &map, 1, flags, ops);
 232}
 233
 234static inline void
 235xfs_buf_readahead(
 236        struct xfs_buftarg      *target,
 237        xfs_daddr_t             blkno,
 238        size_t                  numblks,
 239        const struct xfs_buf_ops *ops)
 240{
 241        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 242        return xfs_buf_readahead_map(target, &map, 1, ops);
 243}
 244
 245struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
 246void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
 247int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
 248
 249struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 250                                int flags);
 251struct xfs_buf *xfs_buf_read_uncached(struct xfs_buftarg *target,
 252                                xfs_daddr_t daddr, size_t numblks, int flags,
 253                                const struct xfs_buf_ops *ops);
 254void xfs_buf_hold(struct xfs_buf *bp);
 255
 256/* Releasing Buffers */
 257extern void xfs_buf_free(xfs_buf_t *);
 258extern void xfs_buf_rele(xfs_buf_t *);
 259
 260/* Locking and Unlocking Buffers */
 261extern int xfs_buf_trylock(xfs_buf_t *);
 262extern void xfs_buf_lock(xfs_buf_t *);
 263extern void xfs_buf_unlock(xfs_buf_t *);
 264#define xfs_buf_islocked(bp) \
 265        ((bp)->b_sema.count <= 0)
 266
 267/* Buffer Read and Write Routines */
 268extern int xfs_bwrite(struct xfs_buf *bp);
 269
 270extern void xfsbdstrat(struct xfs_mount *, struct xfs_buf *);
 271
 272extern void xfs_buf_ioend(xfs_buf_t *,  int);
 273extern void xfs_buf_ioerror(xfs_buf_t *, int);
 274extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
 275extern void xfs_buf_iorequest(xfs_buf_t *);
 276extern int xfs_buf_iowait(xfs_buf_t *);
 277extern void xfs_buf_iomove(xfs_buf_t *, size_t, size_t, void *,
 278                                xfs_buf_rw_t);
 279#define xfs_buf_zero(bp, off, len) \
 280            xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)
 281
 282static inline int xfs_buf_geterror(xfs_buf_t *bp)
 283{
 284        return bp ? bp->b_error : ENOMEM;
 285}
 286
 287/* Buffer Utility Routines */
 288extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);
 289
 290/* Delayed Write Buffer Routines */
 291extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
 292extern int xfs_buf_delwri_submit(struct list_head *);
 293extern int xfs_buf_delwri_submit_nowait(struct list_head *);
 294
 295/* Buffer Daemon Setup Routines */
 296extern int xfs_buf_init(void);
 297extern void xfs_buf_terminate(void);
 298
 299#define XFS_BUF_ZEROFLAGS(bp) \
 300        ((bp)->b_flags &= ~(XBF_READ|XBF_WRITE|XBF_ASYNC| \
 301                            XBF_SYNCIO|XBF_FUA|XBF_FLUSH))
 302
 303void xfs_buf_stale(struct xfs_buf *bp);
 304#define XFS_BUF_UNSTALE(bp)     ((bp)->b_flags &= ~XBF_STALE)
 305#define XFS_BUF_ISSTALE(bp)     ((bp)->b_flags & XBF_STALE)
 306
 307#define XFS_BUF_DONE(bp)        ((bp)->b_flags |= XBF_DONE)
 308#define XFS_BUF_UNDONE(bp)      ((bp)->b_flags &= ~XBF_DONE)
 309#define XFS_BUF_ISDONE(bp)      ((bp)->b_flags & XBF_DONE)
 310
 311#define XFS_BUF_ASYNC(bp)       ((bp)->b_flags |= XBF_ASYNC)
 312#define XFS_BUF_UNASYNC(bp)     ((bp)->b_flags &= ~XBF_ASYNC)
 313#define XFS_BUF_ISASYNC(bp)     ((bp)->b_flags & XBF_ASYNC)
 314
 315#define XFS_BUF_READ(bp)        ((bp)->b_flags |= XBF_READ)
 316#define XFS_BUF_UNREAD(bp)      ((bp)->b_flags &= ~XBF_READ)
 317#define XFS_BUF_ISREAD(bp)      ((bp)->b_flags & XBF_READ)
 318
 319#define XFS_BUF_WRITE(bp)       ((bp)->b_flags |= XBF_WRITE)
 320#define XFS_BUF_UNWRITE(bp)     ((bp)->b_flags &= ~XBF_WRITE)
 321#define XFS_BUF_ISWRITE(bp)     ((bp)->b_flags & XBF_WRITE)
 322
 323/*
 324 * These macros use the IO block map rather than b_bn. b_bn is now really
 325 * just for the buffer cache index for cached buffers. As IO does not use b_bn
 326 * anymore, uncached buffers do not use b_bn at all and hence must modify the IO
 327 * map directly. Uncached buffers are not allowed to be discontiguous, so this
 328 * is safe to do.
 329 *
 330 * In future, uncached buffers will pass the block number directly to the io
 331 * request function and hence these macros will go away at that point.
 332 */
 333#define XFS_BUF_ADDR(bp)                ((bp)->b_maps[0].bm_bn)
 334#define XFS_BUF_SET_ADDR(bp, bno)       ((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))
 335
 336static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
 337{
 338        atomic_set(&bp->b_lru_ref, lru_ref);
 339}
 340
 341static inline int xfs_buf_ispinned(struct xfs_buf *bp)
 342{
 343        return atomic_read(&bp->b_pin_count);
 344}
 345
 346static inline void xfs_buf_relse(xfs_buf_t *bp)
 347{
 348        xfs_buf_unlock(bp);
 349        xfs_buf_rele(bp);
 350}
 351
 352/*
 353 *      Handling of buftargs.
 354 */
 355extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
 356                        struct block_device *, int, const char *);
 357extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
 358extern void xfs_wait_buftarg(xfs_buftarg_t *);
 359extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int, unsigned int);
 360
 361#define xfs_getsize_buftarg(buftarg)    block_size((buftarg)->bt_bdev)
 362#define xfs_readonly_buftarg(buftarg)   bdev_read_only((buftarg)->bt_bdev)
 363
 364#endif  /* __XFS_BUF_H__ */
 365
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