root/fs/xfs/xfs_buf.h

INCLUDED FROM

DEFINITIONS

1. xfs_buf_get
2. xfs_buf_read
3. xfs_buf_readahead
4. xfs_buf_submit
5. xfs_buf_oneshot
6. xfs_buf_ispinned
7. xfs_buf_relse
8. xfs_buf_verify_cksum
9. xfs_buf_update_cksum
10. xfs_buftarg_dma_alignment

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2000-2005 Silicon Graphics, Inc.
   4  * All Rights Reserved.
   5  */
   6 #ifndef __XFS_BUF_H__
   7 #define __XFS_BUF_H__
   8 
   9 #include <linux/list.h>
  10 #include <linux/types.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/mm.h>
  13 #include <linux/fs.h>
  14 #include <linux/dax.h>
  15 #include <linux/uio.h>
  16 #include <linux/list_lru.h>
  17 
  18 /*
  19  *      Base types
  20  */
  21 
  22 #define XFS_BUF_DADDR_NULL      ((xfs_daddr_t) (-1LL))
  23 
  24 #define XBF_READ         (1 << 0) /* buffer intended for reading from device */
  25 #define XBF_WRITE        (1 << 1) /* buffer intended for writing to device */
  26 #define XBF_READ_AHEAD   (1 << 2) /* asynchronous read-ahead */
  27 #define XBF_NO_IOACCT    (1 << 3) /* bypass I/O accounting (non-LRU bufs) */
  28 #define XBF_ASYNC        (1 << 4) /* initiator will not wait for completion */
  29 #define XBF_DONE         (1 << 5) /* all pages in the buffer uptodate */
  30 #define XBF_STALE        (1 << 6) /* buffer has been staled, do not find it */
  31 #define XBF_WRITE_FAIL   (1 << 7) /* async writes have failed on this buffer */
  32 
  33 /* flags used only as arguments to access routines */
  34 #define XBF_TRYLOCK      (1 << 16)/* lock requested, but do not wait */
  35 #define XBF_UNMAPPED     (1 << 17)/* do not map the buffer */
  36 
  37 /* flags used only internally */
  38 #define _XBF_PAGES       (1 << 20)/* backed by refcounted pages */
  39 #define _XBF_KMEM        (1 << 21)/* backed by heap memory */
  40 #define _XBF_DELWRI_Q    (1 << 22)/* buffer on a delwri queue */
  41 
  42 typedef unsigned int xfs_buf_flags_t;
  43 
  44 #define XFS_BUF_FLAGS \
  45         { XBF_READ,             "READ" }, \
  46         { XBF_WRITE,            "WRITE" }, \
  47         { XBF_READ_AHEAD,       "READ_AHEAD" }, \
  48         { XBF_NO_IOACCT,        "NO_IOACCT" }, \
  49         { XBF_ASYNC,            "ASYNC" }, \
  50         { XBF_DONE,             "DONE" }, \
  51         { XBF_STALE,            "STALE" }, \
  52         { XBF_WRITE_FAIL,       "WRITE_FAIL" }, \
  53         { XBF_TRYLOCK,          "TRYLOCK" },    /* should never be set */\
  54         { XBF_UNMAPPED,         "UNMAPPED" },   /* ditto */\
  55         { _XBF_PAGES,           "PAGES" }, \
  56         { _XBF_KMEM,            "KMEM" }, \
  57         { _XBF_DELWRI_Q,        "DELWRI_Q" }
  58 
  59 
  60 /*
  61  * Internal state flags.
  62  */
  63 #define XFS_BSTATE_DISPOSE       (1 << 0)       /* buffer being discarded */
  64 #define XFS_BSTATE_IN_FLIGHT     (1 << 1)       /* I/O in flight */
  65 
  66 /*
  67  * The xfs_buftarg contains 2 notions of "sector size" -
  68  *
  69  * 1) The metadata sector size, which is the minimum unit and
  70  *    alignment of IO which will be performed by metadata operations.
  71  * 2) The device logical sector size
  72  *
  73  * The first is specified at mkfs time, and is stored on-disk in the
  74  * superblock's sb_sectsize.
  75  *
  76  * The latter is derived from the underlying device, and controls direct IO
  77  * alignment constraints.
  78  */
  79 typedef struct xfs_buftarg {
  80         dev_t                   bt_dev;
  81         struct block_device     *bt_bdev;
  82         struct dax_device       *bt_daxdev;
  83         struct xfs_mount        *bt_mount;
  84         unsigned int            bt_meta_sectorsize;
  85         size_t                  bt_meta_sectormask;
  86         size_t                  bt_logical_sectorsize;
  87         size_t                  bt_logical_sectormask;
  88 
  89         /* LRU control structures */
  90         struct shrinker         bt_shrinker;
  91         struct list_lru         bt_lru;
  92 
  93         struct percpu_counter   bt_io_count;
  94 } xfs_buftarg_t;
  95 
  96 struct xfs_buf;
  97 typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
  98 
  99 
 100 #define XB_PAGES        2
 101 
 102 struct xfs_buf_map {
 103         xfs_daddr_t             bm_bn;  /* block number for I/O */
 104         int                     bm_len; /* size of I/O */
 105 };
 106 
 107 #define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
 108         struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };
 109 
 110 struct xfs_buf_ops {
 111         char *name;
 112         union {
 113                 __be32 magic[2];        /* v4 and v5 on disk magic values */
 114                 __be16 magic16[2];      /* v4 and v5 on disk magic values */
 115         };
 116         void (*verify_read)(struct xfs_buf *);
 117         void (*verify_write)(struct xfs_buf *);
 118         xfs_failaddr_t (*verify_struct)(struct xfs_buf *bp);
 119 };
 120 
 121 typedef struct xfs_buf {
 122         /*
 123          * first cacheline holds all the fields needed for an uncontended cache
 124          * hit to be fully processed. The semaphore straddles the cacheline
 125          * boundary, but the counter and lock sits on the first cacheline,
 126          * which is the only bit that is touched if we hit the semaphore
 127          * fast-path on locking.
 128          */
 129         struct rhash_head       b_rhash_head;   /* pag buffer hash node */
 130         xfs_daddr_t             b_bn;           /* block number of buffer */
 131         int                     b_length;       /* size of buffer in BBs */
 132         atomic_t                b_hold;         /* reference count */
 133         atomic_t                b_lru_ref;      /* lru reclaim ref count */
 134         xfs_buf_flags_t         b_flags;        /* status flags */
 135         struct semaphore        b_sema;         /* semaphore for lockables */
 136 
 137         /*
 138          * concurrent access to b_lru and b_lru_flags are protected by
 139          * bt_lru_lock and not by b_sema
 140          */
 141         struct list_head        b_lru;          /* lru list */
 142         spinlock_t              b_lock;         /* internal state lock */
 143         unsigned int            b_state;        /* internal state flags */
 144         int                     b_io_error;     /* internal IO error state */
 145         wait_queue_head_t       b_waiters;      /* unpin waiters */
 146         struct list_head        b_list;
 147         struct xfs_perag        *b_pag;         /* contains rbtree root */
 148         struct xfs_mount        *b_mount;
 149         xfs_buftarg_t           *b_target;      /* buffer target (device) */
 150         void                    *b_addr;        /* virtual address of buffer */
 151         struct work_struct      b_ioend_work;
 152         xfs_buf_iodone_t        b_iodone;       /* I/O completion function */
 153         struct completion       b_iowait;       /* queue for I/O waiters */
 154         struct xfs_buf_log_item *b_log_item;
 155         struct list_head        b_li_list;      /* Log items list head */
 156         struct xfs_trans        *b_transp;
 157         struct page             **b_pages;      /* array of page pointers */
 158         struct page             *b_page_array[XB_PAGES]; /* inline pages */
 159         struct xfs_buf_map      *b_maps;        /* compound buffer map */
 160         struct xfs_buf_map      __b_map;        /* inline compound buffer map */
 161         int                     b_map_count;
 162         atomic_t                b_pin_count;    /* pin count */
 163         atomic_t                b_io_remaining; /* #outstanding I/O requests */
 164         unsigned int            b_page_count;   /* size of page array */
 165         unsigned int            b_offset;       /* page offset in first page */
 166         int                     b_error;        /* error code on I/O */
 167 
 168         /*
 169          * async write failure retry count. Initialised to zero on the first
 170          * failure, then when it exceeds the maximum configured without a
 171          * success the write is considered to be failed permanently and the
 172          * iodone handler will take appropriate action.
 173          *
 174          * For retry timeouts, we record the jiffie of the first failure. This
 175          * means that we can change the retry timeout for buffers already under
 176          * I/O and thus avoid getting stuck in a retry loop with a long timeout.
 177          *
 178          * last_error is used to ensure that we are getting repeated errors, not
 179          * different errors. e.g. a block device might change ENOSPC to EIO when
 180          * a failure timeout occurs, so we want to re-initialise the error
 181          * retry behaviour appropriately when that happens.
 182          */
 183         int                     b_retries;
 184         unsigned long           b_first_retry_time; /* in jiffies */
 185         int                     b_last_error;
 186 
 187         const struct xfs_buf_ops        *b_ops;
 188 } xfs_buf_t;
 189 
 190 /* Finding and Reading Buffers */
 191 struct xfs_buf *xfs_buf_incore(struct xfs_buftarg *target,
 192                            xfs_daddr_t blkno, size_t numblks,
 193                            xfs_buf_flags_t flags);
 194 
 195 struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
 196                                struct xfs_buf_map *map, int nmaps,
 197                                xfs_buf_flags_t flags);
 198 struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
 199                                struct xfs_buf_map *map, int nmaps,
 200                                xfs_buf_flags_t flags,
 201                                const struct xfs_buf_ops *ops);
 202 void xfs_buf_readahead_map(struct xfs_buftarg *target,
 203                                struct xfs_buf_map *map, int nmaps,
 204                                const struct xfs_buf_ops *ops);
 205 
 206 static inline struct xfs_buf *
 207 xfs_buf_get(
 208         struct xfs_buftarg      *target,
 209         xfs_daddr_t             blkno,
 210         size_t                  numblks)
 211 {
 212         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 213         return xfs_buf_get_map(target, &map, 1, 0);
 214 }
 215 
 216 static inline struct xfs_buf *
 217 xfs_buf_read(
 218         struct xfs_buftarg      *target,
 219         xfs_daddr_t             blkno,
 220         size_t                  numblks,
 221         xfs_buf_flags_t         flags,
 222         const struct xfs_buf_ops *ops)
 223 {
 224         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 225         return xfs_buf_read_map(target, &map, 1, flags, ops);
 226 }
 227 
 228 static inline void
 229 xfs_buf_readahead(
 230         struct xfs_buftarg      *target,
 231         xfs_daddr_t             blkno,
 232         size_t                  numblks,
 233         const struct xfs_buf_ops *ops)
 234 {
 235         DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
 236         return xfs_buf_readahead_map(target, &map, 1, ops);
 237 }
 238 
 239 struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
 240                                 int flags);
 241 int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,
 242                           size_t numblks, int flags, struct xfs_buf **bpp,
 243                           const struct xfs_buf_ops *ops);
 244 void xfs_buf_hold(struct xfs_buf *bp);
 245 
 246 /* Releasing Buffers */
 247 extern void xfs_buf_free(xfs_buf_t *);
 248 extern void xfs_buf_rele(xfs_buf_t *);
 249 
 250 /* Locking and Unlocking Buffers */
 251 extern int xfs_buf_trylock(xfs_buf_t *);
 252 extern void xfs_buf_lock(xfs_buf_t *);
 253 extern void xfs_buf_unlock(xfs_buf_t *);
 254 #define xfs_buf_islocked(bp) \
 255         ((bp)->b_sema.count <= 0)
 256 
 257 /* Buffer Read and Write Routines */
 258 extern int xfs_bwrite(struct xfs_buf *bp);
 259 extern void xfs_buf_ioend(struct xfs_buf *bp);
 260 extern void __xfs_buf_ioerror(struct xfs_buf *bp, int error,
 261                 xfs_failaddr_t failaddr);
 262 #define xfs_buf_ioerror(bp, err) __xfs_buf_ioerror((bp), (err), __this_address)
 263 extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
 264 
 265 extern int __xfs_buf_submit(struct xfs_buf *bp, bool);
 266 static inline int xfs_buf_submit(struct xfs_buf *bp)
 267 {
 268         bool wait = bp->b_flags & XBF_ASYNC ? false : true;
 269         return __xfs_buf_submit(bp, wait);
 270 }
 271 
 272 void xfs_buf_zero(struct xfs_buf *bp, size_t boff, size_t bsize);
 273 
 274 /* Buffer Utility Routines */
 275 extern void *xfs_buf_offset(struct xfs_buf *, size_t);
 276 extern void xfs_buf_stale(struct xfs_buf *bp);
 277 
 278 /* Delayed Write Buffer Routines */
 279 extern void xfs_buf_delwri_cancel(struct list_head *);
 280 extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
 281 extern int xfs_buf_delwri_submit(struct list_head *);
 282 extern int xfs_buf_delwri_submit_nowait(struct list_head *);
 283 extern int xfs_buf_delwri_pushbuf(struct xfs_buf *, struct list_head *);
 284 
 285 /* Buffer Daemon Setup Routines */
 286 extern int xfs_buf_init(void);
 287 extern void xfs_buf_terminate(void);
 288 
 289 /*
 290  * These macros use the IO block map rather than b_bn. b_bn is now really
 291  * just for the buffer cache index for cached buffers. As IO does not use b_bn
 292  * anymore, uncached buffers do not use b_bn at all and hence must modify the IO
 293  * map directly. Uncached buffers are not allowed to be discontiguous, so this
 294  * is safe to do.
 295  *
 296  * In future, uncached buffers will pass the block number directly to the io
 297  * request function and hence these macros will go away at that point.
 298  */
 299 #define XFS_BUF_ADDR(bp)                ((bp)->b_maps[0].bm_bn)
 300 #define XFS_BUF_SET_ADDR(bp, bno)       ((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))
 301 
 302 void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref);
 303 
 304 /*
 305  * If the buffer is already on the LRU, do nothing. Otherwise set the buffer
 306  * up with a reference count of 0 so it will be tossed from the cache when
 307  * released.
 308  */
 309 static inline void xfs_buf_oneshot(struct xfs_buf *bp)
 310 {
 311         if (!list_empty(&bp->b_lru) || atomic_read(&bp->b_lru_ref) > 1)
 312                 return;
 313         atomic_set(&bp->b_lru_ref, 0);
 314 }
 315 
 316 static inline int xfs_buf_ispinned(struct xfs_buf *bp)
 317 {
 318         return atomic_read(&bp->b_pin_count);
 319 }
 320 
 321 static inline void xfs_buf_relse(xfs_buf_t *bp)
 322 {
 323         xfs_buf_unlock(bp);
 324         xfs_buf_rele(bp);
 325 }
 326 
 327 static inline int
 328 xfs_buf_verify_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
 329 {
 330         return xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
 331                                 cksum_offset);
 332 }
 333 
 334 static inline void
 335 xfs_buf_update_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
 336 {
 337         xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
 338                          cksum_offset);
 339 }
 340 
 341 /*
 342  *      Handling of buftargs.
 343  */
 344 extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
 345                         struct block_device *, struct dax_device *);
 346 extern void xfs_free_buftarg(struct xfs_buftarg *);
 347 extern void xfs_wait_buftarg(xfs_buftarg_t *);
 348 extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int);
 349 
 350 #define xfs_getsize_buftarg(buftarg)    block_size((buftarg)->bt_bdev)
 351 #define xfs_readonly_buftarg(buftarg)   bdev_read_only((buftarg)->bt_bdev)
 352 
 353 static inline int
 354 xfs_buftarg_dma_alignment(struct xfs_buftarg *bt)
 355 {
 356         return queue_dma_alignment(bt->bt_bdev->bd_disk->queue);
 357 }
 358 
 359 int xfs_buf_reverify(struct xfs_buf *bp, const struct xfs_buf_ops *ops);
 360 bool xfs_verify_magic(struct xfs_buf *bp, __be32 dmagic);
 361 bool xfs_verify_magic16(struct xfs_buf *bp, __be16 dmagic);
 362 
 363 #endif  /* __XFS_BUF_H__ */