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 #define _XBF_IN_FLIGHT   (1 << 25) /* I/O in flight, for accounting purposes */
  67
  68 typedef unsigned int xfs_buf_flags_t;
  69
  70 #define XFS_BUF_FLAGS \
  71         { XBF_READ,             "READ" }, \
  72         { XBF_WRITE,            "WRITE" }, \
  73         { XBF_READ_AHEAD,       "READ_AHEAD" }, \
  74         { XBF_NO_IOACCT,        "NO_IOACCT" }, \
  75         { XBF_ASYNC,            "ASYNC" }, \
  76         { XBF_DONE,             "DONE" }, \
  77         { XBF_STALE,            "STALE" }, \
  78         { XBF_WRITE_FAIL,       "WRITE_FAIL" }, \
  79         { XBF_SYNCIO,           "SYNCIO" }, \
  80         { XBF_FUA,              "FUA" }, \
  81         { XBF_FLUSH,            "FLUSH" }, \
  82         { XBF_TRYLOCK,          "TRYLOCK" },    /* should never be set */\
  83         { XBF_UNMAPPED,         "UNMAPPED" },   /* ditto */\
  84         { _XBF_PAGES,           "PAGES" }, \
  85         { _XBF_KMEM,            "KMEM" }, \
  86         { _XBF_DELWRI_Q,        "DELWRI_Q" }, \
  87         { _XBF_COMPOUND,        "COMPOUND" }, \
  88         { _XBF_IN_FLIGHT,       "IN_FLIGHT" }
  89
  90
  91 /*
  92  * Internal state flags.
  93  */
  94 #define XFS_BSTATE_DISPOSE       (1 << 0)       /* buffer being discarded */
  95
  96 /*
  97  * The xfs_buftarg contains 2 notions of "sector size" -
  98  *
  99  * 1) The metadata sector size, which is the minimum unit and
 100  *    alignment of IO which will be performed by metadata operations.
 101  * 2) The device logical sector size
 102  *
 103  * The first is specified at mkfs time, and is stored on-disk in the
 104  * superblock's sb_sectsize.
 105  *
 106  * The latter is derived from the underlying device, and controls direct IO
 107  * alignment constraints.
 108  */
 109 typedef struct xfs_buftarg {
 110         dev_t                   bt_dev;
 111         struct block_device     *bt_bdev;
 112         struct backing_dev_info *bt_bdi;
 113         struct xfs_mount        *bt_mount;
 114         unsigned int            bt_meta_sectorsize;
 115         size_t                  bt_meta_sectormask;
 116         size_t                  bt_logical_sectorsize;
 117         size_t                  bt_logical_sectormask;
 118
 119         /* LRU control structures */
 120         struct shrinker         bt_shrinker;
 121         struct list_lru         bt_lru;
 122
 123         struct percpu_counter   bt_io_count;
 124 } xfs_buftarg_t;
 125
 126 struct xfs_buf;
 127 typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
 128
 129
 130 #define XB_PAGES        2
 131
 132 struct xfs_buf_map {
 133         xfs_daddr_t             bm_bn;  /* block number for I/O */
 134         int                     bm_len; /* size of I/O */
 135 };
 136
 137 #define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
 138         struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };
 139
 140 struct xfs_buf_ops {
 141         char *name;
 142         void (*verify_read)(struct xfs_buf *);
 143         void (*verify_write)(struct xfs_buf *);
 144 };
 145
 146 typedef struct xfs_buf {
 147         /*
 148          * first cacheline holds all the fields needed for an uncontended cache
 149          * hit to be fully processed. The semaphore straddles the cacheline
 150          * boundary, but the counter and lock sits on the first cacheline,
 151          * which is the only bit that is touched if we hit the semaphore
 152          * fast-path on locking.
 153          */
 154         struct rhash_head       b_rhash_head;   /* pag buffer hash node */
 155         xfs_daddr_t             b_bn;           /* block number of buffer */
 156         int                     b_length;       /* size of buffer in BBs */
 157         atomic_t                b_hold;         /* reference count */
 158         atomic_t                b_lru_ref;      /* lru reclaim ref count */
 159         xfs_buf_flags_t         b_flags;        /* status flags */
 160         struct semaphore        b_sema;         /* semaphore for lockables */
 161
 162         /*
 163          * concurrent access to b_lru and b_lru_flags are protected by
 164          * bt_lru_lock and not by b_sema
 165          */
 166         struct list_head        b_lru;          /* lru list */
 167         spinlock_t              b_lock;         /* internal state lock */
 168         unsigned int            b_state;        /* internal state flags */
 169         int                     b_io_error;     /* internal IO error state */
 170         wait_queue_head_t       b_waiters;      /* unpin waiters */
 171         struct list_head        b_list;
 172         struct xfs_perag        *b_pag;         /* contains rbtree root */
 173         xfs_buftarg_t           *b_target;      /* buffer target (device) */
 174         void                    *b_addr;        /* virtual address of buffer */
 175         struct work_struct      b_ioend_work;
 176         struct workqueue_struct *b_ioend_wq;    /* I/O completion wq */
 177         xfs_buf_iodone_t        b_iodone;       /* I/O completion function */
 178         struct completion       b_iowait;       /* queue for I/O waiters */
 179         void                    *b_fspriv;
 180         struct xfs_trans        *b_transp;
 181         struct page             **b_pages;      /* array of page pointers */
 182         struct page             *b_page_array[XB_PAGES]; /* inline pages */
 183         struct xfs_buf_map      *b_maps;        /* compound buffer map */
 184         struct xfs_buf_map      __b_map;        /* inline compound buffer map */
 185         int                     b_map_count;
 186         int                     b_io_length;    /* IO size in BBs */
 187         atomic_t                b_pin_count;    /* pin count */
 188         atomic_t                b_io_remaining; /* #outstanding I/O requests */
 189         unsigned int            b_page_count;   /* size of page array */
 190         unsigned int            b_offset;       /* page offset in first page */
 191         int                     b_error;        /* error code on I/O */
 192
 193         /*
 194          * async write failure retry count. Initialised to zero on the first
 195          * failure, then when it exceeds the maximum configured without a
 196          * success the write is considered to be failed permanently and the
 197          * iodone handler will take appropriate action.
 198          *
 199          * For retry timeouts, we record the jiffie of the first failure. This
 200          * means that we can change the retry timeout for buffers already under
 201          * I/O and thus avoid getting stuck in a retry loop with a long timeout.
 202          *
 203          * last_error is used to ensure that we are getting repeated errors, not
 204          * different errors. e.g. a block device might change ENOSPC to EIO when
 205          * a failure timeout occurs, so we want to re-initialise the error
 206          * retry behaviour appropriately when that happens.
 207          */
 208         int                     b_retries;
 209         unsigned long           b_first_retry_time; /* in jiffies */
 210         int                     b_last_error;
 211
 212         const struct xfs_buf_ops        *b_ops;
 213
 214 #ifdef XFS_BUF_LOCK_TRACKING
 215         int                     b_last_holder;
 216 #endif
 217 } xfs_buf_t;
 218
 219 /* Finding and Reading Buffers */
 220 struct xfs_buf *_xfs_buf_find(struct xfs_buftarg *target,
 221                               struct xfs_buf_map *map, int nmaps,
 222                               xfs_buf_flags_t flags, struct xfs_buf *new_bp);
 223
 224 static inline struct xfs_buf *
 225 xfs_incore(
 226         struct xfs_buftarg      *target,
 227         xfs_daddr_t             blkno,
 228         size_t                  numblks,
 229         xfs_buf_flags_t         flags)
 230 {
 231         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 232         return _xfs_buf_find(target, &map, 1, flags, NULL);
 233 }
 234
 235 struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
 236                                struct xfs_buf_map *map, int nmaps,
 237                                xfs_buf_flags_t flags);
 238
 239 static inline struct xfs_buf *
 240 xfs_buf_alloc(
 241         struct xfs_buftarg      *target,
 242         xfs_daddr_t             blkno,
 243         size_t                  numblks,
 244         xfs_buf_flags_t         flags)
 245 {
 246         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 247         return _xfs_buf_alloc(target, &map, 1, flags);
 248 }
 249
 250 struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 251                                struct xfs_buf_map *map, int nmaps,
 252                                xfs_buf_flags_t flags);
 253 struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
 254                                struct xfs_buf_map *map, int nmaps,
 255                                xfs_buf_flags_t flags,
 256                                const struct xfs_buf_ops *ops);
 257 void xfs_buf_readahead_map(struct xfs_buftarg *target,
 258                                struct xfs_buf_map *map, int nmaps,
 259                                const struct xfs_buf_ops *ops);
 260
 261 static inline struct xfs_buf *
 262 xfs_buf_get(
 263         struct xfs_buftarg      *target,
 264         xfs_daddr_t             blkno,
 265         size_t                  numblks,
 266         xfs_buf_flags_t         flags)
 267 {
 268         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 269         return xfs_buf_get_map(target, &map, 1, flags);
 270 }
 271
 272 static inline struct xfs_buf *
 273 xfs_buf_read(
 274         struct xfs_buftarg      *target,
 275         xfs_daddr_t             blkno,
 276         size_t                  numblks,
 277         xfs_buf_flags_t         flags,
 278         const struct xfs_buf_ops *ops)
 279 {
 280         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 281         return xfs_buf_read_map(target, &map, 1, flags, ops);
 282 }
 283
 284 static inline void
 285 xfs_buf_readahead(
 286         struct xfs_buftarg      *target,
 287         xfs_daddr_t             blkno,
 288         size_t                  numblks,
 289         const struct xfs_buf_ops *ops)
 290 {
 291         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 292         return xfs_buf_readahead_map(target, &map, 1, ops);
 293 }
 294
 295 struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
 296 void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
 297 int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
 298
 299 struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 300                                 int flags);
 301 int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,
 302                           size_t numblks, int flags, struct xfs_buf **bpp,
 303                           const struct xfs_buf_ops *ops);
 304 void xfs_buf_hold(struct xfs_buf *bp);
 305
 306 /* Releasing Buffers */
 307 extern void xfs_buf_free(xfs_buf_t *);
 308 extern void xfs_buf_rele(xfs_buf_t *);
 309
 310 /* Locking and Unlocking Buffers */
 311 extern int xfs_buf_trylock(xfs_buf_t *);
 312 extern void xfs_buf_lock(xfs_buf_t *);
 313 extern void xfs_buf_unlock(xfs_buf_t *);
 314 #define xfs_buf_islocked(bp) \
 315         ((bp)->b_sema.count <= 0)
 316
 317 /* Buffer Read and Write Routines */
 318 extern int xfs_bwrite(struct xfs_buf *bp);
 319 extern void xfs_buf_ioend(struct xfs_buf *bp);
 320 extern void xfs_buf_ioerror(xfs_buf_t *, int);
 321 extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
 322 extern void xfs_buf_submit(struct xfs_buf *bp);
 323 extern int xfs_buf_submit_wait(struct xfs_buf *bp);
 324 extern void xfs_buf_iomove(xfs_buf_t *, size_t, size_t, void *,
 325                                 xfs_buf_rw_t);
 326 #define xfs_buf_zero(bp, off, len) \
 327             xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)
 328
 329 /* Buffer Utility Routines */
 330 extern void *xfs_buf_offset(struct xfs_buf *, size_t);
 331 extern void xfs_buf_stale(struct xfs_buf *bp);
 332
 333 /* Delayed Write Buffer Routines */
 334 extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
 335 extern int xfs_buf_delwri_submit(struct list_head *);
 336 extern int xfs_buf_delwri_submit_nowait(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__ */