/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 1995, 1996, 1997 Olaf Kirch <okir@monad.swb.de>
 *
 * This file describes the layout of the file handles as passed
 * over the wire.
 */
#ifndef _LINUX_NFSD_NFSFH_H
#define _LINUX_NFSD_NFSFH_H

#include <linux/crc32.h>
#include <linux/sunrpc/svc.h>
#include <uapi/linux/nfsd/nfsfh.h>
#include <linux/iversion.h>
#include <linux/exportfs.h>

static inline __u32 ino_t_to_u32(ino_t ino)
{
        return (__u32) ino;
}

static inline ino_t u32_to_ino_t(__u32 uino)
{
        return (ino_t) uino;
}

/*
 * This is the internal representation of an NFS handle used in knfsd.
 * pre_mtime/post_version will be used to support wcc_attr's in NFSv3.
 */
typedef struct svc_fh {
        struct knfsd_fh         fh_handle;      /* FH data */
        int                     fh_maxsize;     /* max size for fh_handle */
        struct dentry *         fh_dentry;      /* validated dentry */
        struct svc_export *     fh_export;      /* export pointer */

        bool                    fh_locked;      /* inode locked by us */
        bool                    fh_want_write;  /* remount protection taken */
        bool                    fh_no_wcc;      /* no wcc data needed */
        bool                    fh_no_atomic_attr;
                                                /*
                                                 * wcc data is not atomic with
                                                 * operation
                                                 */
        int                     fh_flags;       /* FH flags */
#ifdef CONFIG_NFSD_V3
        bool                    fh_post_saved;  /* post-op attrs saved */
        bool                    fh_pre_saved;   /* pre-op attrs saved */

        /* Pre-op attributes saved during fh_lock */
        __u64                   fh_pre_size;    /* size before operation */
        struct timespec64       fh_pre_mtime;   /* mtime before oper */
        struct timespec64       fh_pre_ctime;   /* ctime before oper */
        /*
         * pre-op nfsv4 change attr: note must check IS_I_VERSION(inode)
         *  to find out if it is valid.
         */
        u64                     fh_pre_change;

        /* Post-op attributes saved in fh_unlock */
        struct kstat            fh_post_attr;   /* full attrs after operation */
        u64                     fh_post_change; /* nfsv4 change; see above */
#endif /* CONFIG_NFSD_V3 */
} svc_fh;
#define NFSD4_FH_FOREIGN (1<<0)
#define SET_FH_FLAG(c, f) ((c)->fh_flags |= (f))
#define HAS_FH_FLAG(c, f) ((c)->fh_flags & (f))

enum nfsd_fsid {
        FSID_DEV = 0,
        FSID_NUM,
        FSID_MAJOR_MINOR,
        FSID_ENCODE_DEV,
        FSID_UUID4_INUM,
        FSID_UUID8,
        FSID_UUID16,
        FSID_UUID16_INUM,
};

enum fsid_source {
        FSIDSOURCE_DEV,
        FSIDSOURCE_FSID,
        FSIDSOURCE_UUID,
};
extern enum fsid_source fsid_source(const struct svc_fh *fhp);


/*
 * This might look a little large to "inline" but in all calls except
 * one, 'vers' is constant so moste of the function disappears.
 *
 * In some cases the values are considered to be host endian and in
 * others, net endian. fsidv is always considered to be u32 as the
 * callers don't know which it will be. So we must use __force to keep
 * sparse from complaining. Since these values are opaque to the
 * client, that shouldn't be a problem.
 */
static inline void mk_fsid(int vers, u32 *fsidv, dev_t dev, ino_t ino,
                           u32 fsid, unsigned char *uuid)
{
        u32 *up;
        switch(vers) {
        case FSID_DEV:
                fsidv[0] = (__force __u32)htonl((MAJOR(dev)<<16) |
                                 MINOR(dev));
                fsidv[1] = ino_t_to_u32(ino);
                break;
        case FSID_NUM:
                fsidv[0] = fsid;
                break;
        case FSID_MAJOR_MINOR:
                fsidv[0] = (__force __u32)htonl(MAJOR(dev));
                fsidv[1] = (__force __u32)htonl(MINOR(dev));
                fsidv[2] = ino_t_to_u32(ino);
                break;

        case FSID_ENCODE_DEV:
                fsidv[0] = new_encode_dev(dev);
                fsidv[1] = ino_t_to_u32(ino);
                break;

        case FSID_UUID4_INUM:
                /* 4 byte fsid and inode number */
                up = (u32*)uuid;
                fsidv[0] = ino_t_to_u32(ino);
                fsidv[1] = up[0] ^ up[1] ^ up[2] ^ up[3];
                break;

        case FSID_UUID8:
                /* 8 byte fsid  */
                up = (u32*)uuid;
                fsidv[0] = up[0] ^ up[2];
                fsidv[1] = up[1] ^ up[3];
                break;

        case FSID_UUID16:
                /* 16 byte fsid - NFSv3+ only */
                memcpy(fsidv, uuid, 16);
                break;

        case FSID_UUID16_INUM:
                /* 8 byte inode and 16 byte fsid */
                *(u64*)fsidv = (u64)ino;
                memcpy(fsidv+2, uuid, 16);
                break;
        default: BUG();
        }
}

static inline int key_len(int type)
{
        switch(type) {
        case FSID_DEV:          return 8;
        case FSID_NUM:          return 4;
        case FSID_MAJOR_MINOR:  return 12;
        case FSID_ENCODE_DEV:   return 8;
        case FSID_UUID4_INUM:   return 8;
        case FSID_UUID8:        return 8;
        case FSID_UUID16:       return 16;
        case FSID_UUID16_INUM:  return 24;
        default: return 0;
        }
}

/*
 * Shorthand for dprintk()'s
 */
extern char * SVCFH_fmt(struct svc_fh *fhp);

/*
 * Function prototypes
 */
__be32  fh_verify(struct svc_rqst *, struct svc_fh *, umode_t, int);
__be32  fh_compose(struct svc_fh *, struct svc_export *, struct dentry *, struct svc_fh *);
__be32  fh_update(struct svc_fh *);
void    fh_put(struct svc_fh *);

static __inline__ struct svc_fh *
fh_copy(struct svc_fh *dst, struct svc_fh *src)
{
        WARN_ON(src->fh_dentry || src->fh_locked);
                        
        *dst = *src;
        return dst;
}

static inline void
fh_copy_shallow(struct knfsd_fh *dst, struct knfsd_fh *src)
{
        dst->fh_size = src->fh_size;
        memcpy(&dst->fh_base, &src->fh_base, src->fh_size);
}

static __inline__ struct svc_fh *
fh_init(struct svc_fh *fhp, int maxsize)
{
        memset(fhp, 0, sizeof(*fhp));
        fhp->fh_maxsize = maxsize;
        return fhp;
}

static inline bool fh_match(struct knfsd_fh *fh1, struct knfsd_fh *fh2)
{
        if (fh1->fh_size != fh2->fh_size)
                return false;
        if (memcmp(fh1->fh_base.fh_pad, fh2->fh_base.fh_pad, fh1->fh_size) != 0)
                return false;
        return true;
}

static inline bool fh_fsid_match(struct knfsd_fh *fh1, struct knfsd_fh *fh2)
{
        if (fh1->fh_fsid_type != fh2->fh_fsid_type)
                return false;
        if (memcmp(fh1->fh_fsid, fh2->fh_fsid, key_len(fh1->fh_fsid_type)) != 0)
                return false;
        return true;
}

#ifdef CONFIG_CRC32
/**
 * knfsd_fh_hash - calculate the crc32 hash for the filehandle
 * @fh - pointer to filehandle
 *
 * returns a crc32 hash for the filehandle that is compatible with
 * the one displayed by "wireshark".
 */
static inline u32 knfsd_fh_hash(const struct knfsd_fh *fh)
{
        return ~crc32_le(0xFFFFFFFF, (unsigned char *)&fh->fh_base, fh->fh_size);
}
#else
static inline u32 knfsd_fh_hash(const struct knfsd_fh *fh)
{
        return 0;
}
#endif

#ifdef CONFIG_NFSD_V3
/*
 * The wcc data stored in current_fh should be cleared
 * between compound ops.
 */
static inline void
fh_clear_wcc(struct svc_fh *fhp)
{
        fhp->fh_post_saved = false;
        fhp->fh_pre_saved = false;
}

/*
 * We could use i_version alone as the change attribute.  However,
 * i_version can go backwards after a reboot.  On its own that doesn't
 * necessarily cause a problem, but if i_version goes backwards and then
 * is incremented again it could reuse a value that was previously used
 * before boot, and a client who queried the two values might
 * incorrectly assume nothing changed.
 *
 * By using both ctime and the i_version counter we guarantee that as
 * long as time doesn't go backwards we never reuse an old value.
 */
static inline u64 nfsd4_change_attribute(struct kstat *stat,
                                         struct inode *inode)
{
        if (inode->i_sb->s_export_op->fetch_iversion)
                return inode->i_sb->s_export_op->fetch_iversion(inode);
        else if (IS_I_VERSION(inode)) {
                u64 chattr;

                chattr =  stat->ctime.tv_sec;
                chattr <<= 30;
                chattr += stat->ctime.tv_nsec;
                chattr += inode_query_iversion(inode);
                return chattr;
        } else
                return time_to_chattr(&stat->ctime);
}

extern void fill_pre_wcc(struct svc_fh *fhp);
extern void fill_post_wcc(struct svc_fh *fhp);
#else
#define fh_clear_wcc(ignored)
#define fill_pre_wcc(ignored)
#define fill_post_wcc(notused)
#endif /* CONFIG_NFSD_V3 */


/*
 * Lock a file handle/inode
 * NOTE: both fh_lock and fh_unlock are done "by hand" in
 * vfs.c:nfsd_rename as it needs to grab 2 i_mutex's at once
 * so, any changes here should be reflected there.
 */

static inline void
fh_lock_nested(struct svc_fh *fhp, unsigned int subclass)
{
        struct dentry   *dentry = fhp->fh_dentry;
        struct inode    *inode;

        BUG_ON(!dentry);

        if (fhp->fh_locked) {
                printk(KERN_WARNING "fh_lock: %pd2 already locked!\n",
                        dentry);
                return;
        }

        inode = d_inode(dentry);
        inode_lock_nested(inode, subclass);
        fill_pre_wcc(fhp);
        fhp->fh_locked = true;
}

static inline void
fh_lock(struct svc_fh *fhp)
{
        fh_lock_nested(fhp, I_MUTEX_NORMAL);
}

/*
 * Unlock a file handle/inode
 */
static inline void
fh_unlock(struct svc_fh *fhp)
{
        if (fhp->fh_locked) {
                fill_post_wcc(fhp);
                inode_unlock(d_inode(fhp->fh_dentry));
                fhp->fh_locked = false;
        }
}

#endif /* _LINUX_NFSD_NFSFH_H */