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/dax.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/uio.h>
  29 #include <linux/list_lru.h>
  30
  31 /*
  32  *      Base types
  33  */
  34
  35 #define XFS_BUF_DADDR_NULL      ((xfs_daddr_t) (-1LL))
  36
  37 typedef enum {
  38         XBRW_READ = 1,                  /* transfer into target memory */
  39         XBRW_WRITE = 2,                 /* transfer from target memory */
  40         XBRW_ZERO = 3,                  /* Zero target memory */
  41 } xfs_buf_rw_t;
  42
  43 #define XBF_READ         (1 << 0) /* buffer intended for reading from device */
  44 #define XBF_WRITE        (1 << 1) /* buffer intended for writing to device */
  45 #define XBF_READ_AHEAD   (1 << 2) /* asynchronous read-ahead */
  46 #define XBF_NO_IOACCT    (1 << 3) /* bypass I/O accounting (non-LRU bufs) */
  47 #define XBF_ASYNC        (1 << 4) /* initiator will not wait for completion */
  48 #define XBF_DONE         (1 << 5) /* all pages in the buffer uptodate */
  49 #define XBF_STALE        (1 << 6) /* buffer has been staled, do not find it */
  50 #define XBF_WRITE_FAIL   (1 << 24)/* async writes have failed on this buffer */
  51
  52 /* I/O hints for the BIO layer */
  53 #define XBF_SYNCIO       (1 << 10)/* treat this buffer as synchronous I/O */
  54 #define XBF_FUA          (1 << 11)/* force cache write through mode */
  55 #define XBF_FLUSH        (1 << 12)/* flush the disk cache before a write */
  56
  57 /* flags used only as arguments to access routines */
  58 #define XBF_TRYLOCK      (1 << 16)/* lock requested, but do not wait */
  59 #define XBF_UNMAPPED     (1 << 17)/* do not map the buffer */
  60
  61 /* flags used only internally */
  62 #define _XBF_PAGES       (1 << 20)/* backed by refcounted pages */
  63 #define _XBF_KMEM        (1 << 21)/* backed by heap memory */
  64 #define _XBF_DELWRI_Q    (1 << 22)/* buffer on a delwri queue */
  65 #define _XBF_COMPOUND    (1 << 23)/* compound buffer */
  66
  67 typedef unsigned int xfs_buf_flags_t;
  68
  69 #define XFS_BUF_FLAGS \
  70         { XBF_READ,             "READ" }, \
  71         { XBF_WRITE,            "WRITE" }, \
  72         { XBF_READ_AHEAD,       "READ_AHEAD" }, \
  73         { XBF_ASYNC,            "ASYNC" }, \
  74         { XBF_DONE,             "DONE" }, \
  75         { XBF_STALE,            "STALE" }, \
  76         { XBF_WRITE_FAIL,       "WRITE_FAIL" }, \
  77         { XBF_SYNCIO,           "SYNCIO" }, \
  78         { XBF_FUA,              "FUA" }, \
  79         { XBF_FLUSH,            "FLUSH" }, \
  80         { XBF_TRYLOCK,          "TRYLOCK" },    /* should never be set */\
  81         { XBF_UNMAPPED,         "UNMAPPED" },   /* ditto */\
  82         { _XBF_PAGES,           "PAGES" }, \
  83         { _XBF_KMEM,            "KMEM" }, \
  84         { _XBF_DELWRI_Q,        "DELWRI_Q" }, \
  85         { _XBF_COMPOUND,        "COMPOUND" }
  86
  87
  88 /*
  89  * Internal state flags.
  90  */
  91 #define XFS_BSTATE_DISPOSE       (1 << 0)       /* buffer being discarded */
  92 #define XFS_BSTATE_IN_FLIGHT     (1 << 1)       /* I/O in flight */
  93
  94 /*
  95  * The xfs_buftarg contains 2 notions of "sector size" -
  96  *
  97  * 1) The metadata sector size, which is the minimum unit and
  98  *    alignment of IO which will be performed by metadata operations.
  99  * 2) The device logical sector size
 100  *
 101  * The first is specified at mkfs time, and is stored on-disk in the
 102  * superblock's sb_sectsize.
 103  *
 104  * The latter is derived from the underlying device, and controls direct IO
 105  * alignment constraints.
 106  */
 107 typedef struct xfs_buftarg {
 108         dev_t                   bt_dev;
 109         struct block_device     *bt_bdev;
 110         struct backing_dev_info *bt_bdi;
 111         struct xfs_mount        *bt_mount;
 112         unsigned int            bt_meta_sectorsize;
 113         size_t                  bt_meta_sectormask;
 114         size_t                  bt_logical_sectorsize;
 115         size_t                  bt_logical_sectormask;
 116
 117         /* LRU control structures */
 118         struct shrinker         bt_shrinker;
 119         struct list_lru         bt_lru;
 120
 121         struct percpu_counter   bt_io_count;
 122 } xfs_buftarg_t;
 123
 124 struct xfs_buf;
 125 typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
 126
 127
 128 #define XB_PAGES        2
 129
 130 struct xfs_buf_map {
 131         xfs_daddr_t             bm_bn;  /* block number for I/O */
 132         int                     bm_len; /* size of I/O */
 133 };
 134
 135 #define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
 136         struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };
 137
 138 struct xfs_buf_ops {
 139         char *name;
 140         void (*verify_read)(struct xfs_buf *);
 141         void (*verify_write)(struct xfs_buf *);
 142 };
 143
 144 typedef struct xfs_buf {
 145         /*
 146          * first cacheline holds all the fields needed for an uncontended cache
 147          * hit to be fully processed. The semaphore straddles the cacheline
 148          * boundary, but the counter and lock sits on the first cacheline,
 149          * which is the only bit that is touched if we hit the semaphore
 150          * fast-path on locking.
 151          */
 152         struct rb_node          b_rbnode;       /* rbtree node */
 153         xfs_daddr_t             b_bn;           /* block number of buffer */
 154         int                     b_length;       /* size of buffer in BBs */
 155         atomic_t                b_hold;         /* reference count */
 156         atomic_t                b_lru_ref;      /* lru reclaim ref count */
 157         xfs_buf_flags_t         b_flags;        /* status flags */
 158         struct semaphore        b_sema;         /* semaphore for lockables */
 159
 160         /*
 161          * concurrent access to b_lru and b_lru_flags are protected by
 162          * bt_lru_lock and not by b_sema
 163          */
 164         struct list_head        b_lru;          /* lru list */
 165         spinlock_t              b_lock;         /* internal state lock */
 166         unsigned int            b_state;        /* internal state flags */
 167         int                     b_io_error;     /* internal IO error state */
 168         wait_queue_head_t       b_waiters;      /* unpin waiters */
 169         struct list_head        b_list;
 170         struct xfs_perag        *b_pag;         /* contains rbtree root */
 171         xfs_buftarg_t           *b_target;      /* buffer target (device) */
 172         void                    *b_addr;        /* virtual address of buffer */
 173         struct work_struct      b_ioend_work;
 174         struct workqueue_struct *b_ioend_wq;    /* I/O completion wq */
 175         xfs_buf_iodone_t        b_iodone;       /* I/O completion function */
 176         struct completion       b_iowait;       /* queue for I/O waiters */
 177         void                    *b_fspriv;
 178         struct xfs_trans        *b_transp;
 179         struct page             **b_pages;      /* array of page pointers */
 180         struct page             *b_page_array[XB_PAGES]; /* inline pages */
 181         struct xfs_buf_map      *b_maps;        /* compound buffer map */
 182         struct xfs_buf_map      __b_map;        /* inline compound buffer map */
 183         int                     b_map_count;
 184         int                     b_io_length;    /* IO size in BBs */
 185         atomic_t                b_pin_count;    /* pin count */
 186         atomic_t                b_io_remaining; /* #outstanding I/O requests */
 187         unsigned int            b_page_count;   /* size of page array */
 188         unsigned int            b_offset;       /* page offset in first page */
 189         int                     b_error;        /* error code on I/O */
 190
 191         /*
 192          * async write failure retry count. Initialised to zero on the first
 193          * failure, then when it exceeds the maximum configured without a
 194          * success the write is considered to be failed permanently and the
 195          * iodone handler will take appropriate action.
 196          *
 197          * For retry timeouts, we record the jiffie of the first failure. This
 198          * means that we can change the retry timeout for buffers already under
 199          * I/O and thus avoid getting stuck in a retry loop with a long timeout.
 200          *
 201          * last_error is used to ensure that we are getting repeated errors, not
 202          * different errors. e.g. a block device might change ENOSPC to EIO when
 203          * a failure timeout occurs, so we want to re-initialise the error
 204          * retry behaviour appropriately when that happens.
 205          */
 206         int                     b_retries;
 207         unsigned long           b_first_retry_time; /* in jiffies */
 208         int                     b_last_error;
 209
 210         const struct xfs_buf_ops        *b_ops;
 211
 212 #ifdef XFS_BUF_LOCK_TRACKING
 213         int                     b_last_holder;
 214 #endif
 215 } xfs_buf_t;
 216
 217 /* Finding and Reading Buffers */
 218 struct xfs_buf *_xfs_buf_find(struct xfs_buftarg *target,
 219                               struct xfs_buf_map *map, int nmaps,
 220                               xfs_buf_flags_t flags, struct xfs_buf *new_bp);
 221
 222 static inline struct xfs_buf *
 223 xfs_incore(
 224         struct xfs_buftarg      *target,
 225         xfs_daddr_t             blkno,
 226         size_t                  numblks,
 227         xfs_buf_flags_t         flags)
 228 {
 229         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 230         return _xfs_buf_find(target, &map, 1, flags, NULL);
 231 }
 232
 233 struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
 234                                struct xfs_buf_map *map, int nmaps,
 235                                xfs_buf_flags_t flags);
 236
 237 static inline struct xfs_buf *
 238 xfs_buf_alloc(
 239         struct xfs_buftarg      *target,
 240         xfs_daddr_t             blkno,
 241         size_t                  numblks,
 242         xfs_buf_flags_t         flags)
 243 {
 244         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 245         return _xfs_buf_alloc(target, &map, 1, flags);
 246 }
 247
 248 struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 249                                struct xfs_buf_map *map, int nmaps,
 250                                xfs_buf_flags_t flags);
 251 struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
 252                                struct xfs_buf_map *map, int nmaps,
 253                                xfs_buf_flags_t flags,
 254                                const struct xfs_buf_ops *ops);
 255 void xfs_buf_readahead_map(struct xfs_buftarg *target,
 256                                struct xfs_buf_map *map, int nmaps,
 257                                const struct xfs_buf_ops *ops);
 258
 259 static inline struct xfs_buf *
 260 xfs_buf_get(
 261         struct xfs_buftarg      *target,
 262         xfs_daddr_t             blkno,
 263         size_t                  numblks,
 264         xfs_buf_flags_t         flags)
 265 {
 266         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 267         return xfs_buf_get_map(target, &map, 1, flags);
 268 }
 269
 270 static inline struct xfs_buf *
 271 xfs_buf_read(
 272         struct xfs_buftarg      *target,
 273         xfs_daddr_t             blkno,
 274         size_t                  numblks,
 275         xfs_buf_flags_t         flags,
 276         const struct xfs_buf_ops *ops)
 277 {
 278         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 279         return xfs_buf_read_map(target, &map, 1, flags, ops);
 280 }
 281
 282 static inline void
 283 xfs_buf_readahead(
 284         struct xfs_buftarg      *target,
 285         xfs_daddr_t             blkno,
 286         size_t                  numblks,
 287         const struct xfs_buf_ops *ops)
 288 {
 289         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 290         return xfs_buf_readahead_map(target, &map, 1, ops);
 291 }
 292
 293 struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
 294 void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
 295 int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
 296
 297 struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 298                                 int flags);
 299 int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,
 300                           size_t numblks, int flags, struct xfs_buf **bpp,
 301                           const struct xfs_buf_ops *ops);
 302 void xfs_buf_hold(struct xfs_buf *bp);
 303
 304 /* Releasing Buffers */
 305 extern void xfs_buf_free(xfs_buf_t *);
 306 extern void xfs_buf_rele(xfs_buf_t *);
 307
 308 /* Locking and Unlocking Buffers */
 309 extern int xfs_buf_trylock(xfs_buf_t *);
 310 extern void xfs_buf_lock(xfs_buf_t *);
 311 extern void xfs_buf_unlock(xfs_buf_t *);
 312 #define xfs_buf_islocked(bp) \
 313         ((bp)->b_sema.count <= 0)
 314
 315 /* Buffer Read and Write Routines */
 316 extern int xfs_bwrite(struct xfs_buf *bp);
 317 extern void xfs_buf_ioend(struct xfs_buf *bp);
 318 extern void xfs_buf_ioerror(xfs_buf_t *, int);
 319 extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
 320 extern void xfs_buf_submit(struct xfs_buf *bp);
 321 extern int xfs_buf_submit_wait(struct xfs_buf *bp);
 322 extern void xfs_buf_iomove(xfs_buf_t *, size_t, size_t, void *,
 323                                 xfs_buf_rw_t);
 324 #define xfs_buf_zero(bp, off, len) \
 325             xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)
 326
 327 /* Buffer Utility Routines */
 328 extern void *xfs_buf_offset(struct xfs_buf *, size_t);
 329 extern void xfs_buf_stale(struct xfs_buf *bp);
 330
 331 /* Delayed Write Buffer Routines */
 332 extern void xfs_buf_delwri_cancel(struct list_head *);
 333 extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
 334 extern int xfs_buf_delwri_submit(struct list_head *);
 335 extern int xfs_buf_delwri_submit_nowait(struct list_head *);
 336 extern int xfs_buf_delwri_pushbuf(struct xfs_buf *, struct list_head *);
 337
 338 /* Buffer Daemon Setup Routines */
 339 extern int xfs_buf_init(void);
 340 extern void xfs_buf_terminate(void);
 341
 342 /*
 343  * These macros use the IO block map rather than b_bn. b_bn is now really
 344  * just for the buffer cache index for cached buffers. As IO does not use b_bn
 345  * anymore, uncached buffers do not use b_bn at all and hence must modify the IO
 346  * map directly. Uncached buffers are not allowed to be discontiguous, so this
 347  * is safe to do.
 348  *
 349  * In future, uncached buffers will pass the block number directly to the io
 350  * request function and hence these macros will go away at that point.
 351  */
 352 #define XFS_BUF_ADDR(bp)                ((bp)->b_maps[0].bm_bn)
 353 #define XFS_BUF_SET_ADDR(bp, bno)       ((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))
 354
 355 static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
 356 {
 357         atomic_set(&bp->b_lru_ref, lru_ref);
 358 }
 359
 360 static inline int xfs_buf_ispinned(struct xfs_buf *bp)
 361 {
 362         return atomic_read(&bp->b_pin_count);
 363 }
 364
 365 static inline void xfs_buf_relse(xfs_buf_t *bp)
 366 {
 367         xfs_buf_unlock(bp);
 368         xfs_buf_rele(bp);
 369 }
 370
 371 static inline int
 372 xfs_buf_verify_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
 373 {
 374         return xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
 375                                 cksum_offset);
 376 }
 377
 378 static inline void
 379 xfs_buf_update_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
 380 {
 381         xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
 382                          cksum_offset);
 383 }
 384
 385 /*
 386  *      Handling of buftargs.
 387  */
 388 extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
 389                         struct block_device *);
 390 extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
 391 extern void xfs_wait_buftarg(xfs_buftarg_t *);
 392 extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int);
 393
 394 #define xfs_getsize_buftarg(buftarg)    block_size((buftarg)->bt_bdev)
 395 #define xfs_readonly_buftarg(buftarg)   bdev_read_only((buftarg)->bt_bdev)
 396
 397 #endif  /* __XFS_BUF_H__ */