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 *
xfs_buf_get(struct xfs_buftarg * target,xfs_daddr_t blkno,size_t numblks)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 *
xfs_buf_read(struct xfs_buftarg * target,xfs_daddr_t blkno,size_t numblks,xfs_buf_flags_t flags,const struct xfs_buf_ops * ops)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
xfs_buf_readahead(struct xfs_buftarg * target,xfs_daddr_t blkno,size_t numblks,const struct xfs_buf_ops * ops)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);
xfs_buf_submit(struct xfs_buf * bp)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   */
xfs_buf_oneshot(struct xfs_buf * bp)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  
xfs_buf_ispinned(struct xfs_buf * bp)316  static inline int xfs_buf_ispinned(struct xfs_buf *bp)
317  {
318  	return atomic_read(&bp->b_pin_count);
319  }
320  
xfs_buf_relse(xfs_buf_t * bp)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
xfs_buf_verify_cksum(struct xfs_buf * bp,unsigned long cksum_offset)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
xfs_buf_update_cksum(struct xfs_buf * bp,unsigned long cksum_offset)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
xfs_buftarg_dma_alignment(struct xfs_buftarg * bt)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__ */
364