// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 */
#ifndef __XFS_BUF_H__
#define __XFS_BUF_H__

#include <linux/list.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/dax.h>
#include <linux/uio.h>
#include <linux/list_lru.h>

/*
 *      Base types
 */

#define XFS_BUF_DADDR_NULL      ((xfs_daddr_t) (-1LL))

#define XBF_READ         (1 << 0) /* buffer intended for reading from device */
#define XBF_WRITE        (1 << 1) /* buffer intended for writing to device */
#define XBF_READ_AHEAD   (1 << 2) /* asynchronous read-ahead */
#define XBF_NO_IOACCT    (1 << 3) /* bypass I/O accounting (non-LRU bufs) */
#define XBF_ASYNC        (1 << 4) /* initiator will not wait for completion */
#define XBF_DONE         (1 << 5) /* all pages in the buffer uptodate */
#define XBF_STALE        (1 << 6) /* buffer has been staled, do not find it */
#define XBF_WRITE_FAIL   (1 << 7) /* async writes have failed on this buffer */

/* flags used only as arguments to access routines */
#define XBF_TRYLOCK      (1 << 16)/* lock requested, but do not wait */
#define XBF_UNMAPPED     (1 << 17)/* do not map the buffer */

/* flags used only internally */
#define _XBF_PAGES       (1 << 20)/* backed by refcounted pages */
#define _XBF_KMEM        (1 << 21)/* backed by heap memory */
#define _XBF_DELWRI_Q    (1 << 22)/* buffer on a delwri queue */

typedef unsigned int xfs_buf_flags_t;

#define XFS_BUF_FLAGS \
        { XBF_READ,             "READ" }, \
        { XBF_WRITE,            "WRITE" }, \
        { XBF_READ_AHEAD,       "READ_AHEAD" }, \
        { XBF_NO_IOACCT,        "NO_IOACCT" }, \
        { XBF_ASYNC,            "ASYNC" }, \
        { XBF_DONE,             "DONE" }, \
        { XBF_STALE,            "STALE" }, \
        { XBF_WRITE_FAIL,       "WRITE_FAIL" }, \
        { XBF_TRYLOCK,          "TRYLOCK" },    /* should never be set */\
        { XBF_UNMAPPED,         "UNMAPPED" },   /* ditto */\
        { _XBF_PAGES,           "PAGES" }, \
        { _XBF_KMEM,            "KMEM" }, \
        { _XBF_DELWRI_Q,        "DELWRI_Q" }


/*
 * Internal state flags.
 */
#define XFS_BSTATE_DISPOSE       (1 << 0)       /* buffer being discarded */
#define XFS_BSTATE_IN_FLIGHT     (1 << 1)       /* I/O in flight */

/*
 * The xfs_buftarg contains 2 notions of "sector size" -
 *
 * 1) The metadata sector size, which is the minimum unit and
 *    alignment of IO which will be performed by metadata operations.
 * 2) The device logical sector size
 *
 * The first is specified at mkfs time, and is stored on-disk in the
 * superblock's sb_sectsize.
 *
 * The latter is derived from the underlying device, and controls direct IO
 * alignment constraints.
 */
typedef struct xfs_buftarg {
        dev_t                   bt_dev;
        struct block_device     *bt_bdev;
        struct dax_device       *bt_daxdev;
        struct xfs_mount        *bt_mount;
        unsigned int            bt_meta_sectorsize;
        size_t                  bt_meta_sectormask;
        size_t                  bt_logical_sectorsize;
        size_t                  bt_logical_sectormask;

        /* LRU control structures */
        struct shrinker         bt_shrinker;
        struct list_lru         bt_lru;

        struct percpu_counter   bt_io_count;
} xfs_buftarg_t;

struct xfs_buf;
typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);


#define XB_PAGES        2

struct xfs_buf_map {
        xfs_daddr_t             bm_bn;  /* block number for I/O */
        int                     bm_len; /* size of I/O */
};

#define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
        struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };

struct xfs_buf_ops {
        char *name;
        union {
                __be32 magic[2];        /* v4 and v5 on disk magic values */
                __be16 magic16[2];      /* v4 and v5 on disk magic values */
        };
        void (*verify_read)(struct xfs_buf *);
        void (*verify_write)(struct xfs_buf *);
        xfs_failaddr_t (*verify_struct)(struct xfs_buf *bp);
};

typedef struct xfs_buf {
        /*
         * first cacheline holds all the fields needed for an uncontended cache
         * hit to be fully processed. The semaphore straddles the cacheline
         * boundary, but the counter and lock sits on the first cacheline,
         * which is the only bit that is touched if we hit the semaphore
         * fast-path on locking.
         */
        struct rhash_head       b_rhash_head;   /* pag buffer hash node */
        xfs_daddr_t             b_bn;           /* block number of buffer */
        int                     b_length;       /* size of buffer in BBs */
        atomic_t                b_hold;         /* reference count */
        atomic_t                b_lru_ref;      /* lru reclaim ref count */
        xfs_buf_flags_t         b_flags;        /* status flags */
        struct semaphore        b_sema;         /* semaphore for lockables */

        /*
         * concurrent access to b_lru and b_lru_flags are protected by
         * bt_lru_lock and not by b_sema
         */
        struct list_head        b_lru;          /* lru list */
        spinlock_t              b_lock;         /* internal state lock */
        unsigned int            b_state;        /* internal state flags */
        int                     b_io_error;     /* internal IO error state */
        wait_queue_head_t       b_waiters;      /* unpin waiters */
        struct list_head        b_list;
        struct xfs_perag        *b_pag;         /* contains rbtree root */
        struct xfs_mount        *b_mount;
        xfs_buftarg_t           *b_target;      /* buffer target (device) */
        void                    *b_addr;        /* virtual address of buffer */
        struct work_struct      b_ioend_work;
        xfs_buf_iodone_t        b_iodone;       /* I/O completion function */
        struct completion       b_iowait;       /* queue for I/O waiters */
        struct xfs_buf_log_item *b_log_item;
        struct list_head        b_li_list;      /* Log items list head */
        struct xfs_trans        *b_transp;
        struct page             **b_pages;      /* array of page pointers */
        struct page             *b_page_array[XB_PAGES]; /* inline pages */
        struct xfs_buf_map      *b_maps;        /* compound buffer map */
        struct xfs_buf_map      __b_map;        /* inline compound buffer map */
        int                     b_map_count;
        atomic_t                b_pin_count;    /* pin count */
        atomic_t                b_io_remaining; /* #outstanding I/O requests */
        unsigned int            b_page_count;   /* size of page array */
        unsigned int            b_offset;       /* page offset in first page */
        int                     b_error;        /* error code on I/O */

        /*
         * async write failure retry count. Initialised to zero on the first
         * failure, then when it exceeds the maximum configured without a
         * success the write is considered to be failed permanently and the
         * iodone handler will take appropriate action.
         *
         * For retry timeouts, we record the jiffie of the first failure. This
         * means that we can change the retry timeout for buffers already under
         * I/O and thus avoid getting stuck in a retry loop with a long timeout.
         *
         * last_error is used to ensure that we are getting repeated errors, not
         * different errors. e.g. a block device might change ENOSPC to EIO when
         * a failure timeout occurs, so we want to re-initialise the error
         * retry behaviour appropriately when that happens.
         */
        int                     b_retries;
        unsigned long           b_first_retry_time; /* in jiffies */
        int                     b_last_error;

        const struct xfs_buf_ops        *b_ops;
} xfs_buf_t;

/* Finding and Reading Buffers */
struct xfs_buf *xfs_buf_incore(struct xfs_buftarg *target,
                           xfs_daddr_t blkno, size_t numblks,
                           xfs_buf_flags_t flags);

struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
                               struct xfs_buf_map *map, int nmaps,
                               xfs_buf_flags_t flags);
struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
                               struct xfs_buf_map *map, int nmaps,
                               xfs_buf_flags_t flags,
                               const struct xfs_buf_ops *ops);
void xfs_buf_readahead_map(struct xfs_buftarg *target,
                               struct xfs_buf_map *map, int nmaps,
                               const struct xfs_buf_ops *ops);

static inline struct xfs_buf *
xfs_buf_get(
        struct xfs_buftarg      *target,
        xfs_daddr_t             blkno,
        size_t                  numblks)
{
        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
        return xfs_buf_get_map(target, &map, 1, 0);
}

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)
{
        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
        return xfs_buf_read_map(target, &map, 1, flags, ops);
}

static inline void
xfs_buf_readahead(
        struct xfs_buftarg      *target,
        xfs_daddr_t             blkno,
        size_t                  numblks,
        const struct xfs_buf_ops *ops)
{
        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
        return xfs_buf_readahead_map(target, &map, 1, ops);
}

struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
                                int flags);
int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,
                          size_t numblks, int flags, struct xfs_buf **bpp,
                          const struct xfs_buf_ops *ops);
void xfs_buf_hold(struct xfs_buf *bp);

/* Releasing Buffers */
extern void xfs_buf_free(xfs_buf_t *);
extern void xfs_buf_rele(xfs_buf_t *);

/* Locking and Unlocking Buffers */
extern int xfs_buf_trylock(xfs_buf_t *);
extern void xfs_buf_lock(xfs_buf_t *);
extern void xfs_buf_unlock(xfs_buf_t *);
#define xfs_buf_islocked(bp) \
        ((bp)->b_sema.count <= 0)

/* Buffer Read and Write Routines */
extern int xfs_bwrite(struct xfs_buf *bp);
extern void xfs_buf_ioend(struct xfs_buf *bp);
extern void __xfs_buf_ioerror(struct xfs_buf *bp, int error,
                xfs_failaddr_t failaddr);
#define xfs_buf_ioerror(bp, err) __xfs_buf_ioerror((bp), (err), __this_address)
extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);

extern int __xfs_buf_submit(struct xfs_buf *bp, bool);
static inline int xfs_buf_submit(struct xfs_buf *bp)
{
        bool wait = bp->b_flags & XBF_ASYNC ? false : true;
        return __xfs_buf_submit(bp, wait);
}

void xfs_buf_zero(struct xfs_buf *bp, size_t boff, size_t bsize);

/* Buffer Utility Routines */
extern void *xfs_buf_offset(struct xfs_buf *, size_t);
extern void xfs_buf_stale(struct xfs_buf *bp);

/* Delayed Write Buffer Routines */
extern void xfs_buf_delwri_cancel(struct list_head *);
extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
extern int xfs_buf_delwri_submit(struct list_head *);
extern int xfs_buf_delwri_submit_nowait(struct list_head *);
extern int xfs_buf_delwri_pushbuf(struct xfs_buf *, struct list_head *);

/* Buffer Daemon Setup Routines */
extern int xfs_buf_init(void);
extern void xfs_buf_terminate(void);

/*
 * These macros use the IO block map rather than b_bn. b_bn is now really
 * just for the buffer cache index for cached buffers. As IO does not use b_bn
 * anymore, uncached buffers do not use b_bn at all and hence must modify the IO
 * map directly. Uncached buffers are not allowed to be discontiguous, so this
 * is safe to do.
 *
 * In future, uncached buffers will pass the block number directly to the io
 * request function and hence these macros will go away at that point.
 */
#define XFS_BUF_ADDR(bp)                ((bp)->b_maps[0].bm_bn)
#define XFS_BUF_SET_ADDR(bp, bno)       ((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))

void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref);

/*
 * If the buffer is already on the LRU, do nothing. Otherwise set the buffer
 * up with a reference count of 0 so it will be tossed from the cache when
 * released.
 */
static inline void xfs_buf_oneshot(struct xfs_buf *bp)
{
        if (!list_empty(&bp->b_lru) || atomic_read(&bp->b_lru_ref) > 1)
                return;
        atomic_set(&bp->b_lru_ref, 0);
}

static inline int xfs_buf_ispinned(struct xfs_buf *bp)
{
        return atomic_read(&bp->b_pin_count);
}

static inline void xfs_buf_relse(xfs_buf_t *bp)
{
        xfs_buf_unlock(bp);
        xfs_buf_rele(bp);
}

static inline int
xfs_buf_verify_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
{
        return xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
                                cksum_offset);
}

static inline void
xfs_buf_update_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
{
        xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
                         cksum_offset);
}

/*
 *      Handling of buftargs.
 */
extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
                        struct block_device *, struct dax_device *);
extern void xfs_free_buftarg(struct xfs_buftarg *);
extern void xfs_wait_buftarg(xfs_buftarg_t *);
extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int);

#define xfs_getsize_buftarg(buftarg)    block_size((buftarg)->bt_bdev)
#define xfs_readonly_buftarg(buftarg)   bdev_read_only((buftarg)->bt_bdev)

static inline int
xfs_buftarg_dma_alignment(struct xfs_buftarg *bt)
{
        return queue_dma_alignment(bt->bt_bdev->bd_disk->queue);
}

int xfs_buf_reverify(struct xfs_buf *bp, const struct xfs_buf_ops *ops);
bool xfs_verify_magic(struct xfs_buf *bp, __be32 dmagic);
bool xfs_verify_magic16(struct xfs_buf *bp, __be16 dmagic);

#endif  /* __XFS_BUF_H__ */