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
  29 /*
  30  *      Base types
  31  */
  32
  33 #define XFS_BUF_DADDR_NULL      ((xfs_daddr_t) (-1LL))
  34
  35 typedef 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
  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         { _XBF_LRU_DISPOSE,     "LRU_DISPOSE" }
  83
  84 typedef 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
 100 struct xfs_buf;
 101 typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
 102
 103 #define XB_PAGES        2
 104
 105 struct 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
 113 typedef 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 */
 164 struct 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
 168 static inline struct xfs_buf *
 169 xfs_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
 179 struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
 180                                struct xfs_buf_map *map, int nmaps,
 181                                xfs_buf_flags_t flags);
 182
 183 static inline struct xfs_buf *
 184 xfs_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
 194 struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 195                                struct xfs_buf_map *map, int nmaps,
 196                                xfs_buf_flags_t flags);
 197 struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
 198                                struct xfs_buf_map *map, int nmaps,
 199                                xfs_buf_flags_t flags);
 200 void xfs_buf_readahead_map(struct xfs_buftarg *target,
 201                                struct xfs_buf_map *map, int nmaps);
 202
 203 static inline struct xfs_buf *
 204 xfs_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
 214 static inline struct xfs_buf *
 215 xfs_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
 225 static inline void
 226 xfs_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
 235 struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
 236 void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
 237 int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
 238
 239 struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 240                                 int flags);
 241 struct xfs_buf *xfs_buf_read_uncached(struct xfs_buftarg *target,
 242                                 xfs_daddr_t daddr, size_t numblks, int flags);
 243 void xfs_buf_hold(struct xfs_buf *bp);
 244
 245 /* Releasing Buffers */
 246 extern void xfs_buf_free(xfs_buf_t *);
 247 extern void xfs_buf_rele(xfs_buf_t *);
 248
 249 /* Locking and Unlocking Buffers */
 250 extern int xfs_buf_trylock(xfs_buf_t *);
 251 extern void xfs_buf_lock(xfs_buf_t *);
 252 extern 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 */
 257 extern int xfs_bwrite(struct xfs_buf *bp);
 258
 259 extern void xfsbdstrat(struct xfs_mount *, struct xfs_buf *);
 260
 261 extern void xfs_buf_ioend(xfs_buf_t *,  int);
 262 extern void xfs_buf_ioerror(xfs_buf_t *, int);
 263 extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
 264 extern void xfs_buf_iorequest(xfs_buf_t *);
 265 extern int xfs_buf_iowait(xfs_buf_t *);
 266 extern 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
 271 static inline int xfs_buf_geterror(xfs_buf_t *bp)
 272 {
 273         return bp ? bp->b_error : ENOMEM;
 274 }
 275
 276 /* Buffer Utility Routines */
 277 extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);
 278
 279 /* Delayed Write Buffer Routines */
 280 extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
 281 extern int xfs_buf_delwri_submit(struct list_head *);
 282 extern int xfs_buf_delwri_submit_nowait(struct list_head *);
 283
 284 /* Buffer Daemon Setup Routines */
 285 extern int xfs_buf_init(void);
 286 extern 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
 292 void 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
 325 static 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
 330 static inline int xfs_buf_ispinned(struct xfs_buf *bp)
 331 {
 332         return atomic_read(&bp->b_pin_count);
 333 }
 334
 335 static 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  */
 344 extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
 345                         struct block_device *, int, const char *);
 346 extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
 347 extern void xfs_wait_buftarg(xfs_buftarg_t *);
 348 extern 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__ */