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 #define XBF_WRITE_FAIL   (1 << 24)/* async writes have failed on this buffer */
  49
  50 /* I/O hints for the BIO layer */
  51 #define XBF_SYNCIO       (1 << 10)/* treat this buffer as synchronous I/O */
  52 #define XBF_FUA          (1 << 11)/* force cache write through mode */
  53 #define XBF_FLUSH        (1 << 12)/* flush the disk cache before a write */
  54
  55 /* flags used only as arguments to access routines */
  56 #define XBF_TRYLOCK      (1 << 16)/* lock requested, but do not wait */
  57 #define XBF_UNMAPPED     (1 << 17)/* do not map the buffer */
  58
  59 /* flags used only internally */
  60 #define _XBF_PAGES       (1 << 20)/* backed by refcounted pages */
  61 #define _XBF_KMEM        (1 << 21)/* backed by heap memory */
  62 #define _XBF_DELWRI_Q    (1 << 22)/* buffer on a delwri queue */
  63 #define _XBF_COMPOUND    (1 << 23)/* compound buffer */
  64
  65 typedef unsigned int xfs_buf_flags_t;
  66
  67 #define XFS_BUF_FLAGS \
  68         { XBF_READ,             "READ" }, \
  69         { XBF_WRITE,            "WRITE" }, \
  70         { XBF_READ_AHEAD,       "READ_AHEAD" }, \
  71         { XBF_ASYNC,            "ASYNC" }, \
  72         { XBF_DONE,             "DONE" }, \
  73         { XBF_STALE,            "STALE" }, \
  74         { XBF_WRITE_FAIL,       "WRITE_FAIL" }, \
  75         { XBF_SYNCIO,           "SYNCIO" }, \
  76         { XBF_FUA,              "FUA" }, \
  77         { XBF_FLUSH,            "FLUSH" }, \
  78         { XBF_TRYLOCK,          "TRYLOCK" },    /* should never be set */\
  79         { XBF_UNMAPPED,         "UNMAPPED" },   /* ditto */\
  80         { _XBF_PAGES,           "PAGES" }, \
  81         { _XBF_KMEM,            "KMEM" }, \
  82         { _XBF_DELWRI_Q,        "DELWRI_Q" }, \
  83         { _XBF_COMPOUND,        "COMPOUND" }
  84
  85
  86 /*
  87  * Internal state flags.
  88  */
  89 #define XFS_BSTATE_DISPOSE       (1 << 0)       /* buffer being discarded */
  90
  91 /*
  92  * The xfs_buftarg contains 2 notions of "sector size" -
  93  *
  94  * 1) The metadata sector size, which is the minimum unit and
  95  *    alignment of IO which will be performed by metadata operations.
  96  * 2) The device logical sector size
  97  *
  98  * The first is specified at mkfs time, and is stored on-disk in the
  99  * superblock's sb_sectsize.
 100  *
 101  * The latter is derived from the underlying device, and controls direct IO
 102  * alignment constraints.
 103  */
 104 typedef struct xfs_buftarg {
 105         dev_t                   bt_dev;
 106         struct block_device     *bt_bdev;
 107         struct backing_dev_info *bt_bdi;
 108         struct xfs_mount        *bt_mount;
 109         unsigned int            bt_meta_sectorsize;
 110         size_t                  bt_meta_sectormask;
 111         size_t                  bt_logical_sectorsize;
 112         size_t                  bt_logical_sectormask;
 113
 114         /* LRU control structures */
 115         struct shrinker         bt_shrinker;
 116         struct list_lru         bt_lru;
 117 } xfs_buftarg_t;
 118
 119 struct xfs_buf;
 120 typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
 121
 122
 123 #define XB_PAGES        2
 124
 125 struct xfs_buf_map {
 126         xfs_daddr_t             bm_bn;  /* block number for I/O */
 127         int                     bm_len; /* size of I/O */
 128 };
 129
 130 #define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
 131         struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };
 132
 133 struct xfs_buf_ops {
 134         void (*verify_read)(struct xfs_buf *);
 135         void (*verify_write)(struct xfs_buf *);
 136 };
 137
 138 typedef struct xfs_buf {
 139         /*
 140          * first cacheline holds all the fields needed for an uncontended cache
 141          * hit to be fully processed. The semaphore straddles the cacheline
 142          * boundary, but the counter and lock sits on the first cacheline,
 143          * which is the only bit that is touched if we hit the semaphore
 144          * fast-path on locking.
 145          */
 146         struct rb_node          b_rbnode;       /* rbtree node */
 147         xfs_daddr_t             b_bn;           /* block number of buffer */
 148         int                     b_length;       /* size of buffer in BBs */
 149         atomic_t                b_hold;         /* reference count */
 150         atomic_t                b_lru_ref;      /* lru reclaim ref count */
 151         xfs_buf_flags_t         b_flags;        /* status flags */
 152         struct semaphore        b_sema;         /* semaphore for lockables */
 153
 154         /*
 155          * concurrent access to b_lru and b_lru_flags are protected by
 156          * bt_lru_lock and not by b_sema
 157          */
 158         struct list_head        b_lru;          /* lru list */
 159         spinlock_t              b_lock;         /* internal state lock */
 160         unsigned int            b_state;        /* internal state flags */
 161         int                     b_io_error;     /* internal IO error state */
 162         wait_queue_head_t       b_waiters;      /* unpin waiters */
 163         struct list_head        b_list;
 164         struct xfs_perag        *b_pag;         /* contains rbtree root */
 165         xfs_buftarg_t           *b_target;      /* buffer target (device) */
 166         void                    *b_addr;        /* virtual address of buffer */
 167         struct work_struct      b_ioend_work;
 168         struct workqueue_struct *b_ioend_wq;    /* I/O completion wq */
 169         xfs_buf_iodone_t        b_iodone;       /* I/O completion function */
 170         struct completion       b_iowait;       /* queue for I/O waiters */
 171         void                    *b_fspriv;
 172         struct xfs_trans        *b_transp;
 173         struct page             **b_pages;      /* array of page pointers */
 174         struct page             *b_page_array[XB_PAGES]; /* inline pages */
 175         struct xfs_buf_map      *b_maps;        /* compound buffer map */
 176         struct xfs_buf_map      __b_map;        /* inline compound buffer map */
 177         int                     b_map_count;
 178         int                     b_io_length;    /* IO size in BBs */
 179         atomic_t                b_pin_count;    /* pin count */
 180         atomic_t                b_io_remaining; /* #outstanding I/O requests */
 181         unsigned int            b_page_count;   /* size of page array */
 182         unsigned int            b_offset;       /* page offset in first page */
 183         int                     b_error;        /* error code on I/O */
 184         const struct xfs_buf_ops        *b_ops;
 185
 186 #ifdef XFS_BUF_LOCK_TRACKING
 187         int                     b_last_holder;
 188 #endif
 189 } xfs_buf_t;
 190
 191 /* Finding and Reading Buffers */
 192 struct xfs_buf *_xfs_buf_find(struct xfs_buftarg *target,
 193                               struct xfs_buf_map *map, int nmaps,
 194                               xfs_buf_flags_t flags, struct xfs_buf *new_bp);
 195
 196 static inline struct xfs_buf *
 197 xfs_incore(
 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_find(target, &map, 1, flags, NULL);
 205 }
 206
 207 struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
 208                                struct xfs_buf_map *map, int nmaps,
 209                                xfs_buf_flags_t flags);
 210
 211 static inline struct xfs_buf *
 212 xfs_buf_alloc(
 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_alloc(target, &map, 1, flags);
 220 }
 221
 222 struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 223                                struct xfs_buf_map *map, int nmaps,
 224                                xfs_buf_flags_t flags);
 225 struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
 226                                struct xfs_buf_map *map, int nmaps,
 227                                xfs_buf_flags_t flags,
 228                                const struct xfs_buf_ops *ops);
 229 void xfs_buf_readahead_map(struct xfs_buftarg *target,
 230                                struct xfs_buf_map *map, int nmaps,
 231                                const struct xfs_buf_ops *ops);
 232
 233 static inline struct xfs_buf *
 234 xfs_buf_get(
 235         struct xfs_buftarg      *target,
 236         xfs_daddr_t             blkno,
 237         size_t                  numblks,
 238         xfs_buf_flags_t         flags)
 239 {
 240         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 241         return xfs_buf_get_map(target, &map, 1, flags);
 242 }
 243
 244 static inline struct xfs_buf *
 245 xfs_buf_read(
 246         struct xfs_buftarg      *target,
 247         xfs_daddr_t             blkno,
 248         size_t                  numblks,
 249         xfs_buf_flags_t         flags,
 250         const struct xfs_buf_ops *ops)
 251 {
 252         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 253         return xfs_buf_read_map(target, &map, 1, flags, ops);
 254 }
 255
 256 static inline void
 257 xfs_buf_readahead(
 258         struct xfs_buftarg      *target,
 259         xfs_daddr_t             blkno,
 260         size_t                  numblks,
 261         const struct xfs_buf_ops *ops)
 262 {
 263         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 264         return xfs_buf_readahead_map(target, &map, 1, ops);
 265 }
 266
 267 struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
 268 void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
 269 int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
 270
 271 struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 272                                 int flags);
 273 int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,
 274                           size_t numblks, int flags, struct xfs_buf **bpp,
 275                           const struct xfs_buf_ops *ops);
 276 void xfs_buf_hold(struct xfs_buf *bp);
 277
 278 /* Releasing Buffers */
 279 extern void xfs_buf_free(xfs_buf_t *);
 280 extern void xfs_buf_rele(xfs_buf_t *);
 281
 282 /* Locking and Unlocking Buffers */
 283 extern int xfs_buf_trylock(xfs_buf_t *);
 284 extern void xfs_buf_lock(xfs_buf_t *);
 285 extern void xfs_buf_unlock(xfs_buf_t *);
 286 #define xfs_buf_islocked(bp) \
 287         ((bp)->b_sema.count <= 0)
 288
 289 /* Buffer Read and Write Routines */
 290 extern int xfs_bwrite(struct xfs_buf *bp);
 291 extern void xfs_buf_ioend(struct xfs_buf *bp);
 292 extern void xfs_buf_ioerror(xfs_buf_t *, int);
 293 extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
 294 extern void xfs_buf_submit(struct xfs_buf *bp);
 295 extern int xfs_buf_submit_wait(struct xfs_buf *bp);
 296 extern void xfs_buf_iomove(xfs_buf_t *, size_t, size_t, void *,
 297                                 xfs_buf_rw_t);
 298 #define xfs_buf_zero(bp, off, len) \
 299             xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)
 300
 301 /* Buffer Utility Routines */
 302 extern void *xfs_buf_offset(struct xfs_buf *, size_t);
 303
 304 /* Delayed Write Buffer Routines */
 305 extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
 306 extern int xfs_buf_delwri_submit(struct list_head *);
 307 extern int xfs_buf_delwri_submit_nowait(struct list_head *);
 308
 309 /* Buffer Daemon Setup Routines */
 310 extern int xfs_buf_init(void);
 311 extern void xfs_buf_terminate(void);
 312
 313 #define XFS_BUF_ZEROFLAGS(bp) \
 314         ((bp)->b_flags &= ~(XBF_READ|XBF_WRITE|XBF_ASYNC| \
 315                             XBF_SYNCIO|XBF_FUA|XBF_FLUSH| \
 316                             XBF_WRITE_FAIL))
 317
 318 void xfs_buf_stale(struct xfs_buf *bp);
 319 #define XFS_BUF_UNSTALE(bp)     ((bp)->b_flags &= ~XBF_STALE)
 320 #define XFS_BUF_ISSTALE(bp)     ((bp)->b_flags & XBF_STALE)
 321
 322 #define XFS_BUF_DONE(bp)        ((bp)->b_flags |= XBF_DONE)
 323 #define XFS_BUF_UNDONE(bp)      ((bp)->b_flags &= ~XBF_DONE)
 324 #define XFS_BUF_ISDONE(bp)      ((bp)->b_flags & XBF_DONE)
 325
 326 #define XFS_BUF_ASYNC(bp)       ((bp)->b_flags |= XBF_ASYNC)
 327 #define XFS_BUF_UNASYNC(bp)     ((bp)->b_flags &= ~XBF_ASYNC)
 328 #define XFS_BUF_ISASYNC(bp)     ((bp)->b_flags & XBF_ASYNC)
 329
 330 #define XFS_BUF_READ(bp)        ((bp)->b_flags |= XBF_READ)
 331 #define XFS_BUF_UNREAD(bp)      ((bp)->b_flags &= ~XBF_READ)
 332 #define XFS_BUF_ISREAD(bp)      ((bp)->b_flags & XBF_READ)
 333
 334 #define XFS_BUF_WRITE(bp)       ((bp)->b_flags |= XBF_WRITE)
 335 #define XFS_BUF_UNWRITE(bp)     ((bp)->b_flags &= ~XBF_WRITE)
 336 #define XFS_BUF_ISWRITE(bp)     ((bp)->b_flags & XBF_WRITE)
 337
 338 /*
 339  * These macros use the IO block map rather than b_bn. b_bn is now really
 340  * just for the buffer cache index for cached buffers. As IO does not use b_bn
 341  * anymore, uncached buffers do not use b_bn at all and hence must modify the IO
 342  * map directly. Uncached buffers are not allowed to be discontiguous, so this
 343  * is safe to do.
 344  *
 345  * In future, uncached buffers will pass the block number directly to the io
 346  * request function and hence these macros will go away at that point.
 347  */
 348 #define XFS_BUF_ADDR(bp)                ((bp)->b_maps[0].bm_bn)
 349 #define XFS_BUF_SET_ADDR(bp, bno)       ((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))
 350
 351 static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
 352 {
 353         atomic_set(&bp->b_lru_ref, lru_ref);
 354 }
 355
 356 static inline int xfs_buf_ispinned(struct xfs_buf *bp)
 357 {
 358         return atomic_read(&bp->b_pin_count);
 359 }
 360
 361 static inline void xfs_buf_relse(xfs_buf_t *bp)
 362 {
 363         xfs_buf_unlock(bp);
 364         xfs_buf_rele(bp);
 365 }
 366
 367 static inline int
 368 xfs_buf_verify_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
 369 {
 370         return xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
 371                                 cksum_offset);
 372 }
 373
 374 static inline void
 375 xfs_buf_update_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
 376 {
 377         xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
 378                          cksum_offset);
 379 }
 380
 381 /*
 382  *      Handling of buftargs.
 383  */
 384 extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
 385                         struct block_device *);
 386 extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
 387 extern void xfs_wait_buftarg(xfs_buftarg_t *);
 388 extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int);
 389
 390 #define xfs_getsize_buftarg(buftarg)    block_size((buftarg)->bt_bdev)
 391 #define xfs_readonly_buftarg(buftarg)   bdev_read_only((buftarg)->bt_bdev)
 392
 393 #endif  /* __XFS_BUF_H__ */