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