fs/xfs/linux-2.6/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 <asm/system.h>
  25 #include <linux/mm.h>
  26 #include <linux/fs.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/uio.h>
  29
  30 /*
  31  *      Base types
  32  */
  33
  34 #define XFS_BUF_DADDR_NULL      ((xfs_daddr_t) (-1LL))
  35
  36 #define xfs_buf_ctob(pp)        ((pp) * PAGE_CACHE_SIZE)
  37 #define xfs_buf_btoc(dd)        (((dd) + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT)
  38 #define xfs_buf_btoct(dd)       ((dd) >> PAGE_CACHE_SHIFT)
  39 #define xfs_buf_poff(aa)        ((aa) & ~PAGE_CACHE_MASK)
  40
  41 typedef enum {
  42         XBRW_READ = 1,                  /* transfer into target memory */
  43         XBRW_WRITE = 2,                 /* transfer from target memory */
  44         XBRW_ZERO = 3,                  /* Zero target memory */
  45 } xfs_buf_rw_t;
  46
  47 #define XBF_READ        (1 << 0) /* buffer intended for reading from device */
  48 #define XBF_WRITE       (1 << 1) /* buffer intended for writing to device */
  49 #define XBF_MAPPED      (1 << 2) /* buffer mapped (b_addr valid) */
  50 #define XBF_ASYNC       (1 << 4) /* initiator will not wait for completion */
  51 #define XBF_DONE        (1 << 5) /* all pages in the buffer uptodate */
  52 #define XBF_DELWRI      (1 << 6) /* buffer has dirty pages */
  53 #define XBF_STALE       (1 << 7) /* buffer has been staled, do not find it */
  54 #define XBF_ORDERED     (1 << 11)/* use ordered writes */
  55 #define XBF_READ_AHEAD  (1 << 12)/* asynchronous read-ahead */
  56 #define XBF_LOG_BUFFER  (1 << 13)/* this is a buffer used for the log */
  57
  58 /* flags used only as arguments to access routines */
  59 #define XBF_LOCK        (1 << 14)/* lock requested */
  60 #define XBF_TRYLOCK     (1 << 15)/* lock requested, but do not wait */
  61 #define XBF_DONT_BLOCK  (1 << 16)/* do not block in current thread */
  62
  63 /* flags used only internally */
  64 #define _XBF_PAGE_CACHE (1 << 17)/* backed by pagecache */
  65 #define _XBF_PAGES      (1 << 18)/* backed by refcounted pages */
  66 #define _XBF_RUN_QUEUES (1 << 19)/* run block device task queue */
  67 #define _XBF_DELWRI_Q   (1 << 21)/* buffer on delwri queue */
  68
  69 /*
  70  * Special flag for supporting metadata blocks smaller than a FSB.
  71  *
  72  * In this case we can have multiple xfs_buf_t on a single page and
  73  * need to lock out concurrent xfs_buf_t readers as they only
  74  * serialise access to the buffer.
  75  *
  76  * If the FSB size >= PAGE_CACHE_SIZE case, we have no serialisation
  77  * between reads of the page. Hence we can have one thread read the
  78  * page and modify it, but then race with another thread that thinks
  79  * the page is not up-to-date and hence reads it again.
  80  *
  81  * The result is that the first modifcation to the page is lost.
  82  * This sort of AGF/AGI reading race can happen when unlinking inodes
  83  * that require truncation and results in the AGI unlinked list
  84  * modifications being lost.
  85  */
  86 #define _XBF_PAGE_LOCKED        (1 << 22)
  87
  88 typedef unsigned int xfs_buf_flags_t;
  89
  90 #define XFS_BUF_FLAGS \
  91         { XBF_READ,             "READ" }, \
  92         { XBF_WRITE,            "WRITE" }, \
  93         { XBF_MAPPED,           "MAPPED" }, \
  94         { XBF_ASYNC,            "ASYNC" }, \
  95         { XBF_DONE,             "DONE" }, \
  96         { XBF_DELWRI,           "DELWRI" }, \
  97         { XBF_STALE,            "STALE" }, \
  98         { XBF_ORDERED,          "ORDERED" }, \
  99         { XBF_READ_AHEAD,       "READ_AHEAD" }, \
 100         { XBF_LOCK,             "LOCK" },       /* should never be set */\
 101         { XBF_TRYLOCK,          "TRYLOCK" },    /* ditto */\
 102         { XBF_DONT_BLOCK,       "DONT_BLOCK" }, /* ditto */\
 103         { _XBF_PAGE_CACHE,      "PAGE_CACHE" }, \
 104         { _XBF_PAGES,           "PAGES" }, \
 105         { _XBF_RUN_QUEUES,      "RUN_QUEUES" }, \
 106         { _XBF_DELWRI_Q,        "DELWRI_Q" }, \
 107         { _XBF_PAGE_LOCKED,     "PAGE_LOCKED" }
 108
 109
 110 typedef enum {
 111         XBT_FORCE_SLEEP = 0,
 112         XBT_FORCE_FLUSH = 1,
 113 } xfs_buftarg_flags_t;
 114
 115 typedef struct xfs_bufhash {
 116         struct list_head        bh_list;
 117         spinlock_t              bh_lock;
 118 } xfs_bufhash_t;
 119
 120 typedef struct xfs_buftarg {
 121         dev_t                   bt_dev;
 122         struct block_device     *bt_bdev;
 123         struct address_space    *bt_mapping;
 124         struct xfs_mount        *bt_mount;
 125         unsigned int            bt_bsize;
 126         unsigned int            bt_sshift;
 127         size_t                  bt_smask;
 128
 129         /* per device delwri queue */
 130         struct task_struct      *bt_task;
 131         struct list_head        bt_delwrite_queue;
 132         spinlock_t              bt_delwrite_lock;
 133         unsigned long           bt_flags;
 134
 135         /* LRU control structures */
 136         struct shrinker         bt_shrinker;
 137         struct list_head        bt_lru;
 138         spinlock_t              bt_lru_lock;
 139         unsigned int            bt_lru_nr;
 140 } xfs_buftarg_t;
 141
 142 /*
 143  *      xfs_buf_t:  Buffer structure for pagecache-based buffers
 144  *
 145  * This buffer structure is used by the pagecache buffer management routines
 146  * to refer to an assembly of pages forming a logical buffer.
 147  *
 148  * The buffer structure is used on a temporary basis only, and discarded when
 149  * released.  The real data storage is recorded in the pagecache. Buffers are
 150  * hashed to the block device on which the file system resides.
 151  */
 152
 153 struct xfs_buf;
 154 typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
 155
 156 #define XB_PAGES        2
 157
 158 typedef struct xfs_buf {
 159         /*
 160          * first cacheline holds all the fields needed for an uncontended cache
 161          * hit to be fully processed. The semaphore straddles the cacheline
 162          * boundary, but the counter and lock sits on the first cacheline,
 163          * which is the only bit that is touched if we hit the semaphore
 164          * fast-path on locking.
 165          */
 166         struct rb_node          b_rbnode;       /* rbtree node */
 167         xfs_off_t               b_file_offset;  /* offset in file */
 168         size_t                  b_buffer_length;/* size of buffer in bytes */
 169         atomic_t                b_hold;         /* reference count */
 170         atomic_t                b_lru_ref;      /* lru reclaim ref count */
 171         xfs_buf_flags_t         b_flags;        /* status flags */
 172         struct semaphore        b_sema;         /* semaphore for lockables */
 173
 174         struct list_head        b_lru;          /* lru list */
 175         wait_queue_head_t       b_waiters;      /* unpin waiters */
 176         struct list_head        b_list;
 177         struct xfs_perag        *b_pag;         /* contains rbtree root */
 178         xfs_buftarg_t           *b_target;      /* buffer target (device) */
 179         xfs_daddr_t             b_bn;           /* block number for I/O */
 180         size_t                  b_count_desired;/* desired transfer size */
 181         void                    *b_addr;        /* virtual address of buffer */
 182         struct work_struct      b_iodone_work;
 183         xfs_buf_iodone_t        b_iodone;       /* I/O completion function */
 184         struct completion       b_iowait;       /* queue for I/O waiters */
 185         void                    *b_fspriv;
 186         void                    *b_fspriv2;
 187         struct page             **b_pages;      /* array of page pointers */
 188         struct page             *b_page_array[XB_PAGES]; /* inline pages */
 189         unsigned long           b_queuetime;    /* time buffer was queued */
 190         atomic_t                b_pin_count;    /* pin count */
 191         atomic_t                b_io_remaining; /* #outstanding I/O requests */
 192         unsigned int            b_page_count;   /* size of page array */
 193         unsigned int            b_offset;       /* page offset in first page */
 194         unsigned short          b_error;        /* error code on I/O */
 195 #ifdef XFS_BUF_LOCK_TRACKING
 196         int                     b_last_holder;
 197 #endif
 198 } xfs_buf_t;
 199
 200
 201 /* Finding and Reading Buffers */
 202 extern xfs_buf_t *_xfs_buf_find(xfs_buftarg_t *, xfs_off_t, size_t,
 203                                 xfs_buf_flags_t, xfs_buf_t *);
 204 #define xfs_incore(buftarg,blkno,len,lockit) \
 205         _xfs_buf_find(buftarg, blkno ,len, lockit, NULL)
 206
 207 extern xfs_buf_t *xfs_buf_get(xfs_buftarg_t *, xfs_off_t, size_t,
 208                                 xfs_buf_flags_t);
 209 extern xfs_buf_t *xfs_buf_read(xfs_buftarg_t *, xfs_off_t, size_t,
 210                                 xfs_buf_flags_t);
 211
 212 extern xfs_buf_t *xfs_buf_get_empty(size_t, xfs_buftarg_t *);
 213 extern xfs_buf_t *xfs_buf_get_uncached(struct xfs_buftarg *, size_t, int);
 214 extern int xfs_buf_associate_memory(xfs_buf_t *, void *, size_t);
 215 extern void xfs_buf_hold(xfs_buf_t *);
 216 extern void xfs_buf_readahead(xfs_buftarg_t *, xfs_off_t, size_t);
 217 struct xfs_buf *xfs_buf_read_uncached(struct xfs_mount *mp,
 218                                 struct xfs_buftarg *target,
 219                                 xfs_daddr_t daddr, size_t length, int flags);
 220
 221 /* Releasing Buffers */
 222 extern void xfs_buf_free(xfs_buf_t *);
 223 extern void xfs_buf_rele(xfs_buf_t *);
 224
 225 /* Locking and Unlocking Buffers */
 226 extern int xfs_buf_cond_lock(xfs_buf_t *);
 227 extern int xfs_buf_lock_value(xfs_buf_t *);
 228 extern void xfs_buf_lock(xfs_buf_t *);
 229 extern void xfs_buf_unlock(xfs_buf_t *);
 230
 231 /* Buffer Read and Write Routines */
 232 extern int xfs_bwrite(struct xfs_mount *mp, struct xfs_buf *bp);
 233 extern void xfs_bdwrite(void *mp, xfs_buf_t *bp);
 234
 235 extern void xfsbdstrat(struct xfs_mount *, struct xfs_buf *);
 236 extern int xfs_bdstrat_cb(struct xfs_buf *);
 237
 238 extern void xfs_buf_ioend(xfs_buf_t *,  int);
 239 extern void xfs_buf_ioerror(xfs_buf_t *, int);
 240 extern int xfs_buf_iorequest(xfs_buf_t *);
 241 extern int xfs_buf_iowait(xfs_buf_t *);
 242 extern void xfs_buf_iomove(xfs_buf_t *, size_t, size_t, void *,
 243                                 xfs_buf_rw_t);
 244 #define xfs_buf_zero(bp, off, len) \
 245             xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)
 246
 247 static inline int xfs_buf_geterror(xfs_buf_t *bp)
 248 {
 249         return bp ? bp->b_error : ENOMEM;
 250 }
 251
 252 /* Buffer Utility Routines */
 253 extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);
 254
 255 /* Delayed Write Buffer Routines */
 256 extern void xfs_buf_delwri_dequeue(xfs_buf_t *);
 257 extern void xfs_buf_delwri_promote(xfs_buf_t *);
 258
 259 /* Buffer Daemon Setup Routines */
 260 extern int xfs_buf_init(void);
 261 extern void xfs_buf_terminate(void);
 262
 263 #define xfs_buf_target_name(target)     \
 264         ({ char __b[BDEVNAME_SIZE]; bdevname((target)->bt_bdev, __b); __b; })
 265
 266
 267 #define XFS_BUF_BFLAGS(bp)      ((bp)->b_flags)
 268 #define XFS_BUF_ZEROFLAGS(bp)   ((bp)->b_flags &= \
 269                 ~(XBF_READ|XBF_WRITE|XBF_ASYNC|XBF_DELWRI|XBF_ORDERED))
 270
 271 void xfs_buf_stale(struct xfs_buf *bp);
 272 #define XFS_BUF_STALE(bp)       xfs_buf_stale(bp);
 273 #define XFS_BUF_UNSTALE(bp)     ((bp)->b_flags &= ~XBF_STALE)
 274 #define XFS_BUF_ISSTALE(bp)     ((bp)->b_flags & XBF_STALE)
 275 #define XFS_BUF_SUPER_STALE(bp) do {                            \
 276                                         XFS_BUF_STALE(bp);      \
 277                                         xfs_buf_delwri_dequeue(bp);     \
 278                                         XFS_BUF_DONE(bp);       \
 279                                 } while (0)
 280
 281 #define XFS_BUF_DELAYWRITE(bp)          ((bp)->b_flags |= XBF_DELWRI)
 282 #define XFS_BUF_UNDELAYWRITE(bp)        xfs_buf_delwri_dequeue(bp)
 283 #define XFS_BUF_ISDELAYWRITE(bp)        ((bp)->b_flags & XBF_DELWRI)
 284
 285 #define XFS_BUF_ERROR(bp,no)    xfs_buf_ioerror(bp,no)
 286 #define XFS_BUF_GETERROR(bp)    xfs_buf_geterror(bp)
 287 #define XFS_BUF_ISERROR(bp)     (xfs_buf_geterror(bp) ? 1 : 0)
 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_BUSY(bp)        do { } while (0)
 294 #define XFS_BUF_UNBUSY(bp)      do { } while (0)
 295 #define XFS_BUF_ISBUSY(bp)      (1)
 296
 297 #define XFS_BUF_ASYNC(bp)       ((bp)->b_flags |= XBF_ASYNC)
 298 #define XFS_BUF_UNASYNC(bp)     ((bp)->b_flags &= ~XBF_ASYNC)
 299 #define XFS_BUF_ISASYNC(bp)     ((bp)->b_flags & XBF_ASYNC)
 300
 301 #define XFS_BUF_ORDERED(bp)     ((bp)->b_flags |= XBF_ORDERED)
 302 #define XFS_BUF_UNORDERED(bp)   ((bp)->b_flags &= ~XBF_ORDERED)
 303 #define XFS_BUF_ISORDERED(bp)   ((bp)->b_flags & XBF_ORDERED)
 304
 305 #define XFS_BUF_HOLD(bp)        xfs_buf_hold(bp)
 306 #define XFS_BUF_READ(bp)        ((bp)->b_flags |= XBF_READ)
 307 #define XFS_BUF_UNREAD(bp)      ((bp)->b_flags &= ~XBF_READ)
 308 #define XFS_BUF_ISREAD(bp)      ((bp)->b_flags & XBF_READ)
 309
 310 #define XFS_BUF_WRITE(bp)       ((bp)->b_flags |= XBF_WRITE)
 311 #define XFS_BUF_UNWRITE(bp)     ((bp)->b_flags &= ~XBF_WRITE)
 312 #define XFS_BUF_ISWRITE(bp)     ((bp)->b_flags & XBF_WRITE)
 313
 314 #define XFS_BUF_IODONE_FUNC(bp)                 ((bp)->b_iodone)
 315 #define XFS_BUF_SET_IODONE_FUNC(bp, func)       ((bp)->b_iodone = (func))
 316 #define XFS_BUF_CLR_IODONE_FUNC(bp)             ((bp)->b_iodone = NULL)
 317
 318 #define XFS_BUF_FSPRIVATE(bp, type)             ((type)(bp)->b_fspriv)
 319 #define XFS_BUF_SET_FSPRIVATE(bp, val)          ((bp)->b_fspriv = (void*)(val))
 320 #define XFS_BUF_FSPRIVATE2(bp, type)            ((type)(bp)->b_fspriv2)
 321 #define XFS_BUF_SET_FSPRIVATE2(bp, val)         ((bp)->b_fspriv2 = (void*)(val))
 322 #define XFS_BUF_SET_START(bp)                   do { } while (0)
 323
 324 #define XFS_BUF_PTR(bp)                 (xfs_caddr_t)((bp)->b_addr)
 325 #define XFS_BUF_SET_PTR(bp, val, cnt)   xfs_buf_associate_memory(bp, val, cnt)
 326 #define XFS_BUF_ADDR(bp)                ((bp)->b_bn)
 327 #define XFS_BUF_SET_ADDR(bp, bno)       ((bp)->b_bn = (xfs_daddr_t)(bno))
 328 #define XFS_BUF_OFFSET(bp)              ((bp)->b_file_offset)
 329 #define XFS_BUF_SET_OFFSET(bp, off)     ((bp)->b_file_offset = (off))
 330 #define XFS_BUF_COUNT(bp)               ((bp)->b_count_desired)
 331 #define XFS_BUF_SET_COUNT(bp, cnt)      ((bp)->b_count_desired = (cnt))
 332 #define XFS_BUF_SIZE(bp)                ((bp)->b_buffer_length)
 333 #define XFS_BUF_SET_SIZE(bp, cnt)       ((bp)->b_buffer_length = (cnt))
 334
 335 static inline void
 336 xfs_buf_set_ref(
 337         struct xfs_buf  *bp,
 338         int             lru_ref)
 339 {
 340         atomic_set(&bp->b_lru_ref, lru_ref);
 341 }
 342 #define XFS_BUF_SET_VTYPE_REF(bp, type, ref)    xfs_buf_set_ref(bp, ref)
 343 #define XFS_BUF_SET_VTYPE(bp, type)             do { } while (0)
 344
 345 #define XFS_BUF_ISPINNED(bp)    atomic_read(&((bp)->b_pin_count))
 346
 347 #define XFS_BUF_VALUSEMA(bp)    xfs_buf_lock_value(bp)
 348 #define XFS_BUF_CPSEMA(bp)      (xfs_buf_cond_lock(bp) == 0)
 349 #define XFS_BUF_VSEMA(bp)       xfs_buf_unlock(bp)
 350 #define XFS_BUF_PSEMA(bp,x)     xfs_buf_lock(bp)
 351 #define XFS_BUF_FINISH_IOWAIT(bp)       complete(&bp->b_iowait);
 352
 353 #define XFS_BUF_SET_TARGET(bp, target)  ((bp)->b_target = (target))
 354 #define XFS_BUF_TARGET(bp)              ((bp)->b_target)
 355 #define XFS_BUFTARG_NAME(target)        xfs_buf_target_name(target)
 356
 357 static inline void xfs_buf_relse(xfs_buf_t *bp)
 358 {
 359         xfs_buf_unlock(bp);
 360         xfs_buf_rele(bp);
 361 }
 362
 363 /*
 364  *      Handling of buftargs.
 365  */
 366 extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
 367                         struct block_device *, int, const char *);
 368 extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
 369 extern void xfs_wait_buftarg(xfs_buftarg_t *);
 370 extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int, unsigned int);
 371 extern int xfs_flush_buftarg(xfs_buftarg_t *, int);
 372
 373 #ifdef CONFIG_KDB_MODULES
 374 extern struct list_head *xfs_get_buftarg_list(void);
 375 #endif
 376
 377 #define xfs_getsize_buftarg(buftarg)    block_size((buftarg)->bt_bdev)
 378 #define xfs_readonly_buftarg(buftarg)   bdev_read_only((buftarg)->bt_bdev)
 379
 380 #define xfs_binval(buftarg)             xfs_flush_buftarg(buftarg, 1)
 381 #define XFS_bflush(buftarg)             xfs_flush_buftarg(buftarg, 1)
 382
 383 #endif  /* __XFS_BUF_H__ */