// 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>

extern struct kmem_cache *xfs_buf_cache;

/*
 *      Base types
 */
struct xfs_buf;

#define XFS_BUF_DADDR_MAX       ((xfs_daddr_t) S64_MAX)
#define XFS_BUF_DADDR_NULL      ((xfs_daddr_t) (-1LL))

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

/* buffer type flags for write callbacks */
#define _XBF_LOGRECOVERY (1u << 18)/* log recovery buffer */

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

/* flags used only as arguments to access routines */
/*
 * Online fsck is scanning the buffer cache for live buffers.  Do not warn
 * about length mismatches during lookups and do not return stale buffers.
 */
#define XBF_LIVESCAN     (1u << 28)
#define XBF_INCORE       (1u << 29)/* lookup only, return if found in cache */
#define XBF_TRYLOCK      (1u << 30)/* lock requested, but do not wait */


typedef unsigned int xfs_buf_flags_t;

#define XFS_BUF_FLAGS \
        { XBF_READ,             "READ" }, \
        { XBF_WRITE,            "WRITE" }, \
        { XBF_READ_AHEAD,       "READ_AHEAD" }, \
        { XBF_ASYNC,            "ASYNC" }, \
        { XBF_DONE,             "DONE" }, \
        { XBF_STALE,            "STALE" }, \
        { XBF_WRITE_FAIL,       "WRITE_FAIL" }, \
        { _XBF_LOGRECOVERY,     "LOG_RECOVERY" }, \
        { _XBF_KMEM,            "KMEM" }, \
        { _XBF_DELWRI_Q,        "DELWRI_Q" }, \
        /* The following interface flags should never be set */ \
        { XBF_LIVESCAN,         "LIVESCAN" }, \
        { XBF_INCORE,           "INCORE" }, \
        { XBF_TRYLOCK,          "TRYLOCK" }

/*
 * Internal state flags.
 */
#define XFS_BSTATE_DISPOSE       (1 << 0)       /* buffer being discarded */

struct xfs_buf_cache {
        struct rhashtable       bc_hash;
};

int xfs_buf_cache_init(struct xfs_buf_cache *bch);
void xfs_buf_cache_destroy(struct xfs_buf_cache *bch);

/*
 * 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.
 */
struct xfs_buftarg {
        dev_t                   bt_dev;
        struct block_device     *bt_bdev;
        struct dax_device       *bt_daxdev;
        struct file             *bt_file;
        u64                     bt_dax_part_off;
        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;
        xfs_daddr_t             bt_nr_sectors;

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

        struct percpu_counter   bt_readahead_count;
        struct ratelimit_state  bt_ioerror_rl;

        /* Hardware atomic write unit values, bytes */
        unsigned int            bt_awu_min;
        unsigned int            bt_awu_max;

        /* built-in cache, if we're not using the perag one */
        struct xfs_buf_cache    bt_cache[];
};

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

/*
 * Online fsck is scanning the buffer cache for live buffers.  Do not warn
 * about length mismatches during lookups and do not return stale buffers.
 */
#define XBM_LIVESCAN            (1U << 0)

#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);
};

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_rhash_key;    /* buffer cache index */
        int                     b_length;       /* size of buffer in BBs */
        unsigned int            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 */
        wait_queue_head_t       b_waiters;      /* unpin waiters */
        struct list_head        b_list;
        struct xfs_perag        *b_pag;
        struct xfs_mount        *b_mount;
        struct xfs_buftarg      *b_target;      /* buffer target (device) */
        void                    *b_addr;        /* virtual address of buffer */
        struct work_struct      b_ioend_work;
        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 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 */
        int                     b_error;        /* error code on I/O */
        void                    (*b_iodone)(struct xfs_buf *bp);

        /*
         * 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 jiffy 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;
        struct rcu_head         b_rcu;
};

/* Finding and Reading Buffers */
int xfs_buf_get_map(struct xfs_buftarg *target, struct xfs_buf_map *map,
                int nmaps, xfs_buf_flags_t flags, struct xfs_buf **bpp);
int xfs_buf_read_map(struct xfs_buftarg *target, struct xfs_buf_map *map,
                int nmaps, xfs_buf_flags_t flags, struct xfs_buf **bpp,
                const struct xfs_buf_ops *ops, xfs_failaddr_t fa);
void xfs_buf_readahead_map(struct xfs_buftarg *target,
                               struct xfs_buf_map *map, int nmaps,
                               const struct xfs_buf_ops *ops);

static inline int
xfs_buf_incore(
        struct xfs_buftarg      *target,
        xfs_daddr_t             blkno,
        size_t                  numblks,
        xfs_buf_flags_t         flags,
        struct xfs_buf          **bpp)
{
        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);

        return xfs_buf_get_map(target, &map, 1, XBF_INCORE | flags, bpp);
}

static inline int
xfs_buf_get(
        struct xfs_buftarg      *target,
        xfs_daddr_t             blkno,
        size_t                  numblks,
        struct xfs_buf          **bpp)
{
        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);

        return xfs_buf_get_map(target, &map, 1, 0, bpp);
}

static inline int
xfs_buf_read(
        struct xfs_buftarg      *target,
        xfs_daddr_t             blkno,
        size_t                  numblks,
        xfs_buf_flags_t         flags,
        struct xfs_buf          **bpp,
        const struct xfs_buf_ops *ops)
{
        DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);

        return xfs_buf_read_map(target, &map, 1, flags, bpp, ops,
                        __builtin_return_address(0));
}

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);
}

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

/* Releasing Buffers */
extern void xfs_buf_rele(struct xfs_buf *);

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

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

/* Buffer Read and Write Routines */
extern int xfs_bwrite(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 *bp, xfs_failaddr_t fa);
void xfs_buf_ioend_fail(struct xfs_buf *);
void __xfs_buf_mark_corrupt(struct xfs_buf *bp, xfs_failaddr_t fa);
#define xfs_buf_mark_corrupt(bp) __xfs_buf_mark_corrupt((bp), __this_address)

/* Buffer Utility Routines */
static inline void *xfs_buf_offset(struct xfs_buf *bp, size_t offset)
{
        return bp->b_addr + offset;
}

static inline void xfs_buf_zero(struct xfs_buf *bp, size_t boff, size_t bsize)
{
        memset(bp->b_addr + boff, 0, bsize);
}

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 *);
void xfs_buf_delwri_queue_here(struct xfs_buf *bp, struct list_head *bl);
extern int xfs_buf_delwri_submit(struct list_head *);
extern int xfs_buf_delwri_submit_nowait(struct list_head *);

static inline xfs_daddr_t xfs_buf_daddr(struct xfs_buf *bp)
{
        return bp->b_maps[0].bm_bn;
}

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 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.
 */
struct xfs_buftarg *xfs_alloc_buftarg(struct xfs_mount *mp,
                struct file *bdev_file);
extern void xfs_free_buftarg(struct xfs_buftarg *);
extern void xfs_buftarg_wait(struct xfs_buftarg *);
extern void xfs_buftarg_drain(struct xfs_buftarg *);
int xfs_configure_buftarg(struct xfs_buftarg *btp, unsigned int sectorsize,
                xfs_fsblock_t nr_blocks);

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

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);

/* for xfs_buf_mem.c only: */
int xfs_init_buftarg(struct xfs_buftarg *btp, size_t logical_sectorsize,
                const char *descr);
void xfs_destroy_buftarg(struct xfs_buftarg *btp);

#endif  /* __XFS_BUF_H__ */