/* SPDX-License-Identifier: GPL-2.0 */
/*
 * linux/include/linux/nfs_page.h
 *
 * Copyright (C) 2000 Trond Myklebust
 *
 * NFS page cache wrapper.
 */

#ifndef _LINUX_NFS_PAGE_H
#define _LINUX_NFS_PAGE_H


#include <linux/list.h>
#include <linux/pagemap.h>
#include <linux/wait.h>
#include <linux/sunrpc/auth.h>
#include <linux/nfs_xdr.h>

#include <linux/kref.h>

/*
 * Valid flags for a dirty buffer
 */
enum {
        PG_BUSY = 0,            /* nfs_{un}lock_request */
        PG_MAPPED,              /* page private set for buffered io */
        PG_FOLIO,               /* Tracking a folio (unset for O_DIRECT) */
        PG_CLEAN,               /* write succeeded */
        PG_COMMIT_TO_DS,        /* used by pnfs layouts */
        PG_INODE_REF,           /* extra ref held by inode when in writeback */
        PG_HEADLOCK,            /* page group lock of wb_head */
        PG_TEARDOWN,            /* page group sync for destroy */
        PG_UNLOCKPAGE,          /* page group sync bit in read path */
        PG_UPTODATE,            /* page group sync bit in read path */
        PG_WB_END,              /* page group sync bit in write path */
        PG_REMOVE,              /* page group sync bit in write path */
        PG_CONTENDED1,          /* Is someone waiting for a lock? */
        PG_CONTENDED2,          /* Is someone waiting for a lock? */
};

struct nfs_inode;
struct nfs_page {
        struct list_head        wb_list;        /* Defines state of page: */
        union {
                struct page     *wb_page;       /* page to read in/write out */
                struct folio    *wb_folio;
        };
        struct nfs_lock_context *wb_lock_context;       /* lock context info */
        pgoff_t                 wb_index;       /* Offset >> PAGE_SHIFT */
        unsigned int            wb_offset,      /* Offset & ~PAGE_MASK */
                                wb_pgbase,      /* Start of page data */
                                wb_bytes;       /* Length of request */
        struct kref             wb_kref;        /* reference count */
        unsigned long           wb_flags;
        struct nfs_write_verifier       wb_verf;        /* Commit cookie */
        struct nfs_page         *wb_this_page;  /* list of reqs for this page */
        struct nfs_page         *wb_head;       /* head pointer for req list */
        unsigned short          wb_nio;         /* Number of I/O attempts */
};

struct nfs_pgio_mirror;
struct nfs_pageio_descriptor;
struct nfs_pageio_ops {
        void    (*pg_init)(struct nfs_pageio_descriptor *, struct nfs_page *);
        size_t  (*pg_test)(struct nfs_pageio_descriptor *, struct nfs_page *,
                           struct nfs_page *);
        int     (*pg_doio)(struct nfs_pageio_descriptor *);
        unsigned int    (*pg_get_mirror_count)(struct nfs_pageio_descriptor *,
                                       struct nfs_page *);
        void    (*pg_cleanup)(struct nfs_pageio_descriptor *);
        struct nfs_pgio_mirror *
                (*pg_get_mirror)(struct nfs_pageio_descriptor *, u32);
        u32     (*pg_set_mirror)(struct nfs_pageio_descriptor *, u32);
};

struct nfs_rw_ops {
        struct nfs_pgio_header *(*rw_alloc_header)(void);
        void (*rw_free_header)(struct nfs_pgio_header *);
        int  (*rw_done)(struct rpc_task *, struct nfs_pgio_header *,
                        struct inode *);
        void (*rw_result)(struct rpc_task *, struct nfs_pgio_header *);
        void (*rw_initiate)(struct nfs_pgio_header *, struct rpc_message *,
                            const struct nfs_rpc_ops *,
                            struct rpc_task_setup *, int);
};

struct nfs_pgio_mirror {
        struct list_head        pg_list;
        unsigned long           pg_bytes_written;
        size_t                  pg_count;
        size_t                  pg_bsize;
        unsigned int            pg_base;
        unsigned char           pg_recoalesce : 1;
};

struct nfs_pageio_descriptor {
        struct inode            *pg_inode;
        const struct nfs_pageio_ops *pg_ops;
        const struct nfs_rw_ops *pg_rw_ops;
        int                     pg_ioflags;
        int                     pg_error;
        const struct rpc_call_ops *pg_rpc_callops;
        const struct nfs_pgio_completion_ops *pg_completion_ops;
        struct pnfs_layout_segment *pg_lseg;
        struct nfs_io_completion *pg_io_completion;
        struct nfs_direct_req   *pg_dreq;
#ifdef CONFIG_NFS_FSCACHE
        void                    *pg_netfs;
#endif
        unsigned int            pg_bsize;       /* default bsize for mirrors */

        u32                     pg_mirror_count;
        struct nfs_pgio_mirror  *pg_mirrors;
        struct nfs_pgio_mirror  pg_mirrors_static[1];
        struct nfs_pgio_mirror  *pg_mirrors_dynamic;
        u32                     pg_mirror_idx;  /* current mirror */
        unsigned short          pg_maxretrans;
        unsigned char           pg_moreio : 1;
};

/* arbitrarily selected limit to number of mirrors */
#define NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX 16

extern struct nfs_page *nfs_page_create_from_page(struct nfs_open_context *ctx,
                                                  struct page *page,
                                                  unsigned int pgbase,
                                                  loff_t offset,
                                                  unsigned int count);
extern struct nfs_page *nfs_page_create_from_folio(struct nfs_open_context *ctx,
                                                   struct folio *folio,
                                                   unsigned int offset,
                                                   unsigned int count);
extern  void nfs_release_request(struct nfs_page *);


extern  void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
                             struct inode *inode,
                             const struct nfs_pageio_ops *pg_ops,
                             const struct nfs_pgio_completion_ops *compl_ops,
                             const struct nfs_rw_ops *rw_ops,
                             size_t bsize,
                             int how);
extern  int nfs_pageio_add_request(struct nfs_pageio_descriptor *,
                                   struct nfs_page *);
extern  int nfs_pageio_resend(struct nfs_pageio_descriptor *,
                              struct nfs_pgio_header *);
extern  void nfs_pageio_complete(struct nfs_pageio_descriptor *desc);
extern  void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *, pgoff_t);
extern size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
                                struct nfs_page *prev,
                                struct nfs_page *req);
extern  void nfs_unlock_request(struct nfs_page *req);
extern  void nfs_unlock_and_release_request(struct nfs_page *);
extern void nfs_join_page_group(struct nfs_page *head,
                                struct nfs_commit_info *cinfo,
                                struct inode *inode);
extern int nfs_page_group_lock(struct nfs_page *);
extern void nfs_page_group_unlock(struct nfs_page *);
extern bool nfs_page_group_sync_on_bit(struct nfs_page *, unsigned int);
extern bool nfs_page_group_sync_on_bit_locked(struct nfs_page *, unsigned int);
extern  int nfs_page_set_headlock(struct nfs_page *req);
extern void nfs_page_clear_headlock(struct nfs_page *req);
extern bool nfs_async_iocounter_wait(struct rpc_task *, struct nfs_lock_context *);

/**
 * nfs_page_to_folio - Retrieve a struct folio for the request
 * @req: pointer to a struct nfs_page
 *
 * If a folio was assigned to @req, then return it, otherwise return NULL.
 */
static inline struct folio *nfs_page_to_folio(const struct nfs_page *req)
{
        if (test_bit(PG_FOLIO, &req->wb_flags))
                return req->wb_folio;
        return NULL;
}

/**
 * nfs_page_to_page - Retrieve a struct page for the request
 * @req: pointer to a struct nfs_page
 * @pgbase: folio byte offset
 *
 * Return the page containing the byte that is at offset @pgbase relative
 * to the start of the folio.
 * Note: The request starts at offset @req->wb_pgbase.
 */
static inline struct page *nfs_page_to_page(const struct nfs_page *req,
                                            size_t pgbase)
{
        struct folio *folio = nfs_page_to_folio(req);

        if (folio == NULL)
                return req->wb_page;
        return folio_page(folio, pgbase >> PAGE_SHIFT);
}

/**
 * nfs_page_to_inode - Retrieve an inode for the request
 * @req: pointer to a struct nfs_page
 */
static inline struct inode *nfs_page_to_inode(const struct nfs_page *req)
{
        struct folio *folio = nfs_page_to_folio(req);

        if (folio == NULL)
                return req->wb_page->mapping->host;
        return folio->mapping->host;
}

/**
 * nfs_page_max_length - Retrieve the maximum possible length for a request
 * @req: pointer to a struct nfs_page
 *
 * Returns the maximum possible length of a request
 */
static inline size_t nfs_page_max_length(const struct nfs_page *req)
{
        struct folio *folio = nfs_page_to_folio(req);

        if (folio == NULL)
                return PAGE_SIZE;
        return folio_size(folio);
}

/*
 * Lock the page of an asynchronous request
 */
static inline int
nfs_lock_request(struct nfs_page *req)
{
        return !test_and_set_bit(PG_BUSY, &req->wb_flags);
}

/**
 * nfs_list_add_request - Insert a request into a list
 * @req: request
 * @head: head of list into which to insert the request.
 */
static inline void
nfs_list_add_request(struct nfs_page *req, struct list_head *head)
{
        list_add_tail(&req->wb_list, head);
}

/**
 * nfs_list_move_request - Move a request to a new list
 * @req: request
 * @head: head of list into which to insert the request.
 */
static inline void
nfs_list_move_request(struct nfs_page *req, struct list_head *head)
{
        list_move_tail(&req->wb_list, head);
}

/**
 * nfs_list_remove_request - Remove a request from its wb_list
 * @req: request
 */
static inline void
nfs_list_remove_request(struct nfs_page *req)
{
        if (list_empty(&req->wb_list))
                return;
        list_del_init(&req->wb_list);
}

static inline struct nfs_page *
nfs_list_entry(struct list_head *head)
{
        return list_entry(head, struct nfs_page, wb_list);
}

static inline loff_t req_offset(const struct nfs_page *req)
{
        return (((loff_t)req->wb_index) << PAGE_SHIFT) + req->wb_offset;
}

static inline struct nfs_open_context *
nfs_req_openctx(struct nfs_page *req)
{
        return req->wb_lock_context->open_context;
}

#endif /* _LINUX_NFS_PAGE_H */