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
 104 #define XB_PAGES        2
 105
 106 struct 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
 114 struct xfs_buf_ops {
 115         void (*verify_read)(struct xfs_buf *);
 116         void (*verify_write)(struct xfs_buf *);
 117 };
 118
 119 typedef 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 */
 170 struct 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
 174 static inline struct xfs_buf *
 175 xfs_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
 185 struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
 186                                struct xfs_buf_map *map, int nmaps,
 187                                xfs_buf_flags_t flags);
 188
 189 static inline struct xfs_buf *
 190 xfs_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
 200 struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 201                                struct xfs_buf_map *map, int nmaps,
 202                                xfs_buf_flags_t flags);
 203 struct 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);
 207 void xfs_buf_readahead_map(struct xfs_buftarg *target,
 208                                struct xfs_buf_map *map, int nmaps,
 209                                const struct xfs_buf_ops *ops);
 210
 211 static inline struct xfs_buf *
 212 xfs_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
 222 static inline struct xfs_buf *
 223 xfs_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
 234 static inline void
 235 xfs_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
 245 struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
 246 void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
 247 int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
 248
 249 struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 250                                 int flags);
 251 struct 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);
 254 void xfs_buf_hold(struct xfs_buf *bp);
 255
 256 /* Releasing Buffers */
 257 extern void xfs_buf_free(xfs_buf_t *);
 258 extern void xfs_buf_rele(xfs_buf_t *);
 259
 260 /* Locking and Unlocking Buffers */
 261 extern int xfs_buf_trylock(xfs_buf_t *);
 262 extern void xfs_buf_lock(xfs_buf_t *);
 263 extern 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 */
 268 extern int xfs_bwrite(struct xfs_buf *bp);
 269
 270 extern void xfsbdstrat(struct xfs_mount *, struct xfs_buf *);
 271
 272 extern void xfs_buf_ioend(xfs_buf_t *,  int);
 273 extern void xfs_buf_ioerror(xfs_buf_t *, int);
 274 extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
 275 extern void xfs_buf_iorequest(xfs_buf_t *);
 276 extern int xfs_buf_iowait(xfs_buf_t *);
 277 extern 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
 282 static inline int xfs_buf_geterror(xfs_buf_t *bp)
 283 {
 284         return bp ? bp->b_error : ENOMEM;
 285 }
 286
 287 /* Buffer Utility Routines */
 288 extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);
 289
 290 /* Delayed Write Buffer Routines */
 291 extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
 292 extern int xfs_buf_delwri_submit(struct list_head *);
 293 extern int xfs_buf_delwri_submit_nowait(struct list_head *);
 294
 295 /* Buffer Daemon Setup Routines */
 296 extern int xfs_buf_init(void);
 297 extern 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
 303 void 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
 336 static 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
 341 static inline int xfs_buf_ispinned(struct xfs_buf *bp)
 342 {
 343         return atomic_read(&bp->b_pin_count);
 344 }
 345
 346 static 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  */
 355 extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
 356                         struct block_device *, int, const char *);
 357 extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
 358 extern void xfs_wait_buftarg(xfs_buftarg_t *);
 359 extern 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__ */