fs/xfs/xfs_buf.h

   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
  36 typedef 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
  64 typedef 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
  88 typedef 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
 102 struct xfs_buf;
 103 typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
 104
 105
 106 #define XB_PAGES        2
 107
 108 struct 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
 116 struct xfs_buf_ops {
 117         void (*verify_read)(struct xfs_buf *);
 118         void (*verify_write)(struct xfs_buf *);
 119 };
 120
 121 typedef 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 */
 173 struct 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
 177 static inline struct xfs_buf *
 178 xfs_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
 188 struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
 189                                struct xfs_buf_map *map, int nmaps,
 190                                xfs_buf_flags_t flags);
 191
 192 static inline struct xfs_buf *
 193 xfs_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
 203 struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 204                                struct xfs_buf_map *map, int nmaps,
 205                                xfs_buf_flags_t flags);
 206 struct 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);
 210 void xfs_buf_readahead_map(struct xfs_buftarg *target,
 211                                struct xfs_buf_map *map, int nmaps,
 212                                const struct xfs_buf_ops *ops);
 213
 214 static inline struct xfs_buf *
 215 xfs_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
 225 static inline struct xfs_buf *
 226 xfs_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
 237 static inline void
 238 xfs_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
 248 struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
 249 void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
 250 int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
 251
 252 struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 253                                 int flags);
 254 struct 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);
 257 void xfs_buf_hold(struct xfs_buf *bp);
 258
 259 /* Releasing Buffers */
 260 extern void xfs_buf_free(xfs_buf_t *);
 261 extern void xfs_buf_rele(xfs_buf_t *);
 262
 263 /* Locking and Unlocking Buffers */
 264 extern int xfs_buf_trylock(xfs_buf_t *);
 265 extern void xfs_buf_lock(xfs_buf_t *);
 266 extern 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 */
 271 extern int xfs_bwrite(struct xfs_buf *bp);
 272
 273 extern void xfsbdstrat(struct xfs_mount *, struct xfs_buf *);
 274
 275 extern void xfs_buf_ioend(xfs_buf_t *,  int);
 276 extern void xfs_buf_ioerror(xfs_buf_t *, int);
 277 extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
 278 extern void xfs_buf_iorequest(xfs_buf_t *);
 279 extern int xfs_buf_iowait(xfs_buf_t *);
 280 extern 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
 285 static inline int xfs_buf_geterror(xfs_buf_t *bp)
 286 {
 287         return bp ? bp->b_error : ENOMEM;
 288 }
 289
 290 /* Buffer Utility Routines */
 291 extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);
 292
 293 /* Delayed Write Buffer Routines */
 294 extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
 295 extern int xfs_buf_delwri_submit(struct list_head *);
 296 extern int xfs_buf_delwri_submit_nowait(struct list_head *);
 297
 298 /* Buffer Daemon Setup Routines */
 299 extern int xfs_buf_init(void);
 300 extern 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
 306 void 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
 339 static 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
 344 static inline int xfs_buf_ispinned(struct xfs_buf *bp)
 345 {
 346         return atomic_read(&bp->b_pin_count);
 347 }
 348
 349 static 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  */
 358 extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
 359                         struct block_device *, int, const char *);
 360 extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
 361 extern void xfs_wait_buftarg(xfs_buftarg_t *);
 362 extern 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__ */