/*
 *  linux/fs/nfs/inode.c
 *
 *  Copyright (C) 1992  Rick Sladkey
 *
 *  nfs inode and superblock handling functions
 *
 *  Modularised by Alan Cox <alan@lxorguk.ukuu.org.uk>, while hacking some
 *  experimental NFS changes. Modularisation taken straight from SYS5 fs.
 *
 *  Change to nfs_read_super() to permit NFS mounts to multi-homed hosts.
 *  J.S.Peatfield@damtp.cam.ac.uk
 *
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/metrics.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/nfs4_mount.h>
#include <linux/lockd/bind.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/vfs.h>
#include <linux/inet.h>
#include <linux/nfs_xdr.h>
#include <linux/slab.h>
#include <linux/compat.h>
#include <linux/freezer.h>

#include <asm/uaccess.h>

#include "nfs4_fs.h"
#include "callback.h"
#include "delegation.h"
#include "iostat.h"
#include "internal.h"
#include "fscache.h"
#include "pnfs.h"
#include "nfs.h"
#include "netns.h"

#include "nfstrace.h"

#define NFSDBG_FACILITY         NFSDBG_VFS

#define NFS_64_BIT_INODE_NUMBERS_ENABLED        1

/* Default is to see 64-bit inode numbers */
static bool enable_ino64 = NFS_64_BIT_INODE_NUMBERS_ENABLED;

static void nfs_invalidate_inode(struct inode *);
static int nfs_update_inode(struct inode *, struct nfs_fattr *);

static struct kmem_cache * nfs_inode_cachep;

static inline unsigned long
nfs_fattr_to_ino_t(struct nfs_fattr *fattr)
{
        return nfs_fileid_to_ino_t(fattr->fileid);
}

/**
 * nfs_wait_bit_killable - helper for functions that are sleeping on bit locks
 * @word: long word containing the bit lock
 */
int nfs_wait_bit_killable(void *word)
{
        if (fatal_signal_pending(current))
                return -ERESTARTSYS;
        freezable_schedule_unsafe();
        return 0;
}
EXPORT_SYMBOL_GPL(nfs_wait_bit_killable);

/**
 * nfs_compat_user_ino64 - returns the user-visible inode number
 * @fileid: 64-bit fileid
 *
 * This function returns a 32-bit inode number if the boot parameter
 * nfs.enable_ino64 is zero.
 */
u64 nfs_compat_user_ino64(u64 fileid)
{
#ifdef CONFIG_COMPAT
        compat_ulong_t ino;
#else   
        unsigned long ino;
#endif

        if (enable_ino64)
                return fileid;
        ino = fileid;
        if (sizeof(ino) < sizeof(fileid))
                ino ^= fileid >> (sizeof(fileid)-sizeof(ino)) * 8;
        return ino;
}

int nfs_drop_inode(struct inode *inode)
{
        return NFS_STALE(inode) || generic_drop_inode(inode);
}
EXPORT_SYMBOL_GPL(nfs_drop_inode);

void nfs_clear_inode(struct inode *inode)
{
        /*
         * The following should never happen...
         */
        WARN_ON_ONCE(nfs_have_writebacks(inode));
        WARN_ON_ONCE(!list_empty(&NFS_I(inode)->open_files));
        nfs_zap_acl_cache(inode);
        nfs_access_zap_cache(inode);
        nfs_fscache_clear_inode(inode);
}
EXPORT_SYMBOL_GPL(nfs_clear_inode);

void nfs_evict_inode(struct inode *inode)
{
        truncate_inode_pages_final(&inode->i_data);
        clear_inode(inode);
        nfs_clear_inode(inode);
}

/**
 * nfs_sync_mapping - helper to flush all mmapped dirty data to disk
 */
int nfs_sync_mapping(struct address_space *mapping)
{
        int ret = 0;

        if (mapping->nrpages != 0) {
                unmap_mapping_range(mapping, 0, 0, 0);
                ret = nfs_wb_all(mapping->host);
        }
        return ret;
}

/*
 * Invalidate the local caches
 */
static void nfs_zap_caches_locked(struct inode *inode)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        int mode = inode->i_mode;

        nfs_inc_stats(inode, NFSIOS_ATTRINVALIDATE);

        nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
        nfsi->attrtimeo_timestamp = jiffies;

        memset(NFS_I(inode)->cookieverf, 0, sizeof(NFS_I(inode)->cookieverf));
        if (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)) {
                nfs_fscache_invalidate(inode);
                nfsi->cache_validity |= NFS_INO_INVALID_ATTR
                                        | NFS_INO_INVALID_DATA
                                        | NFS_INO_INVALID_ACCESS
                                        | NFS_INO_INVALID_ACL
                                        | NFS_INO_REVAL_PAGECACHE;
        } else
                nfsi->cache_validity |= NFS_INO_INVALID_ATTR
                                        | NFS_INO_INVALID_ACCESS
                                        | NFS_INO_INVALID_ACL
                                        | NFS_INO_REVAL_PAGECACHE;
        nfs_zap_label_cache_locked(nfsi);
}

void nfs_zap_caches(struct inode *inode)
{
        spin_lock(&inode->i_lock);
        nfs_zap_caches_locked(inode);
        spin_unlock(&inode->i_lock);
}

void nfs_zap_mapping(struct inode *inode, struct address_space *mapping)
{
        if (mapping->nrpages != 0) {
                spin_lock(&inode->i_lock);
                NFS_I(inode)->cache_validity |= NFS_INO_INVALID_DATA;
                nfs_fscache_invalidate(inode);
                spin_unlock(&inode->i_lock);
        }
}

void nfs_zap_acl_cache(struct inode *inode)
{
        void (*clear_acl_cache)(struct inode *);

        clear_acl_cache = NFS_PROTO(inode)->clear_acl_cache;
        if (clear_acl_cache != NULL)
                clear_acl_cache(inode);
        spin_lock(&inode->i_lock);
        NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_ACL;
        spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL_GPL(nfs_zap_acl_cache);

void nfs_invalidate_atime(struct inode *inode)
{
        spin_lock(&inode->i_lock);
        NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ATIME;
        spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL_GPL(nfs_invalidate_atime);

/*
 * Invalidate, but do not unhash, the inode.
 * NB: must be called with inode->i_lock held!
 */
static void nfs_invalidate_inode(struct inode *inode)
{
        set_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
        nfs_zap_caches_locked(inode);
}

struct nfs_find_desc {
        struct nfs_fh           *fh;
        struct nfs_fattr        *fattr;
};

/*
 * In NFSv3 we can have 64bit inode numbers. In order to support
 * this, and re-exported directories (also seen in NFSv2)
 * we are forced to allow 2 different inodes to have the same
 * i_ino.
 */
static int
nfs_find_actor(struct inode *inode, void *opaque)
{
        struct nfs_find_desc    *desc = (struct nfs_find_desc *)opaque;
        struct nfs_fh           *fh = desc->fh;
        struct nfs_fattr        *fattr = desc->fattr;

        if (NFS_FILEID(inode) != fattr->fileid)
                return 0;
        if ((S_IFMT & inode->i_mode) != (S_IFMT & fattr->mode))
                return 0;
        if (nfs_compare_fh(NFS_FH(inode), fh))
                return 0;
        if (is_bad_inode(inode) || NFS_STALE(inode))
                return 0;
        return 1;
}

static int
nfs_init_locked(struct inode *inode, void *opaque)
{
        struct nfs_find_desc    *desc = (struct nfs_find_desc *)opaque;
        struct nfs_fattr        *fattr = desc->fattr;

        set_nfs_fileid(inode, fattr->fileid);
        nfs_copy_fh(NFS_FH(inode), desc->fh);
        return 0;
}

#ifdef CONFIG_NFS_V4_SECURITY_LABEL
static void nfs_clear_label_invalid(struct inode *inode)
{
        spin_lock(&inode->i_lock);
        NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_LABEL;
        spin_unlock(&inode->i_lock);
}

void nfs_setsecurity(struct inode *inode, struct nfs_fattr *fattr,
                                        struct nfs4_label *label)
{
        int error;

        if (label == NULL)
                return;

        if ((fattr->valid & NFS_ATTR_FATTR_V4_SECURITY_LABEL) && inode->i_security) {
                error = security_inode_notifysecctx(inode, label->label,
                                label->len);
                if (error)
                        printk(KERN_ERR "%s() %s %d "
                                        "security_inode_notifysecctx() %d\n",
                                        __func__,
                                        (char *)label->label,
                                        label->len, error);
                nfs_clear_label_invalid(inode);
        }
}

struct nfs4_label *nfs4_label_alloc(struct nfs_server *server, gfp_t flags)
{
        struct nfs4_label *label = NULL;
        int minor_version = server->nfs_client->cl_minorversion;

        if (minor_version < 2)
                return label;

        if (!(server->caps & NFS_CAP_SECURITY_LABEL))
                return label;

        label = kzalloc(sizeof(struct nfs4_label), flags);
        if (label == NULL)
                return ERR_PTR(-ENOMEM);

        label->label = kzalloc(NFS4_MAXLABELLEN, flags);
        if (label->label == NULL) {
                kfree(label);
                return ERR_PTR(-ENOMEM);
        }
        label->len = NFS4_MAXLABELLEN;

        return label;
}
EXPORT_SYMBOL_GPL(nfs4_label_alloc);
#else
void nfs_setsecurity(struct inode *inode, struct nfs_fattr *fattr,
                                        struct nfs4_label *label)
{
}
#endif
EXPORT_SYMBOL_GPL(nfs_setsecurity);

/*
 * This is our front-end to iget that looks up inodes by file handle
 * instead of inode number.
 */
struct inode *
nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr, struct nfs4_label *label)
{
        struct nfs_find_desc desc = {
                .fh     = fh,
                .fattr  = fattr
        };
        struct inode *inode = ERR_PTR(-ENOENT);
        unsigned long hash;

        nfs_attr_check_mountpoint(sb, fattr);

        if (((fattr->valid & NFS_ATTR_FATTR_FILEID) == 0) &&
            !nfs_attr_use_mounted_on_fileid(fattr))
                goto out_no_inode;
        if ((fattr->valid & NFS_ATTR_FATTR_TYPE) == 0)
                goto out_no_inode;

        hash = nfs_fattr_to_ino_t(fattr);

        inode = iget5_locked(sb, hash, nfs_find_actor, nfs_init_locked, &desc);
        if (inode == NULL) {
                inode = ERR_PTR(-ENOMEM);
                goto out_no_inode;
        }

        if (inode->i_state & I_NEW) {
                struct nfs_inode *nfsi = NFS_I(inode);
                unsigned long now = jiffies;

                /* We set i_ino for the few things that still rely on it,
                 * such as stat(2) */
                inode->i_ino = hash;

                /* We can't support update_atime(), since the server will reset it */
                inode->i_flags |= S_NOATIME|S_NOCMTIME;
                inode->i_mode = fattr->mode;
                if ((fattr->valid & NFS_ATTR_FATTR_MODE) == 0
                                && nfs_server_capable(inode, NFS_CAP_MODE))
                        nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
                /* Why so? Because we want revalidate for devices/FIFOs, and
                 * that's precisely what we have in nfs_file_inode_operations.
                 */
                inode->i_op = NFS_SB(sb)->nfs_client->rpc_ops->file_inode_ops;
                if (S_ISREG(inode->i_mode)) {
                        inode->i_fop = NFS_SB(sb)->nfs_client->rpc_ops->file_ops;
                        inode->i_data.a_ops = &nfs_file_aops;
                        inode->i_data.backing_dev_info = &NFS_SB(sb)->backing_dev_info;
                } else if (S_ISDIR(inode->i_mode)) {
                        inode->i_op = NFS_SB(sb)->nfs_client->rpc_ops->dir_inode_ops;
                        inode->i_fop = &nfs_dir_operations;
                        inode->i_data.a_ops = &nfs_dir_aops;
                        /* Deal with crossing mountpoints */
                        if (fattr->valid & NFS_ATTR_FATTR_MOUNTPOINT ||
                                        fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
                                if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
                                        inode->i_op = &nfs_referral_inode_operations;
                                else
                                        inode->i_op = &nfs_mountpoint_inode_operations;
                                inode->i_fop = NULL;
                                inode->i_flags |= S_AUTOMOUNT;
                        }
                } else if (S_ISLNK(inode->i_mode))
                        inode->i_op = &nfs_symlink_inode_operations;
                else
                        init_special_inode(inode, inode->i_mode, fattr->rdev);

                memset(&inode->i_atime, 0, sizeof(inode->i_atime));
                memset(&inode->i_mtime, 0, sizeof(inode->i_mtime));
                memset(&inode->i_ctime, 0, sizeof(inode->i_ctime));
                inode->i_version = 0;
                inode->i_size = 0;
                clear_nlink(inode);
                inode->i_uid = make_kuid(&init_user_ns, -2);
                inode->i_gid = make_kgid(&init_user_ns, -2);
                inode->i_blocks = 0;
                memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
                nfsi->write_io = 0;
                nfsi->read_io = 0;

                nfsi->read_cache_jiffies = fattr->time_start;
                nfsi->attr_gencount = fattr->gencount;
                if (fattr->valid & NFS_ATTR_FATTR_ATIME)
                        inode->i_atime = fattr->atime;
                else if (nfs_server_capable(inode, NFS_CAP_ATIME))
                        nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
                if (fattr->valid & NFS_ATTR_FATTR_MTIME)
                        inode->i_mtime = fattr->mtime;
                else if (nfs_server_capable(inode, NFS_CAP_MTIME))
                        nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
                if (fattr->valid & NFS_ATTR_FATTR_CTIME)
                        inode->i_ctime = fattr->ctime;
                else if (nfs_server_capable(inode, NFS_CAP_CTIME))
                        nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
                if (fattr->valid & NFS_ATTR_FATTR_CHANGE)
                        inode->i_version = fattr->change_attr;
                else if (nfs_server_capable(inode, NFS_CAP_CHANGE_ATTR))
                        nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
                if (fattr->valid & NFS_ATTR_FATTR_SIZE)
                        inode->i_size = nfs_size_to_loff_t(fattr->size);
                else
                        nfsi->cache_validity |= NFS_INO_INVALID_ATTR
                                | NFS_INO_REVAL_PAGECACHE;
                if (fattr->valid & NFS_ATTR_FATTR_NLINK)
                        set_nlink(inode, fattr->nlink);
                else if (nfs_server_capable(inode, NFS_CAP_NLINK))
                        nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
                if (fattr->valid & NFS_ATTR_FATTR_OWNER)
                        inode->i_uid = fattr->uid;
                else if (nfs_server_capable(inode, NFS_CAP_OWNER))
                        nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
                if (fattr->valid & NFS_ATTR_FATTR_GROUP)
                        inode->i_gid = fattr->gid;
                else if (nfs_server_capable(inode, NFS_CAP_OWNER_GROUP))
                        nfsi->cache_validity |= NFS_INO_INVALID_ATTR;
                if (fattr->valid & NFS_ATTR_FATTR_BLOCKS_USED)
                        inode->i_blocks = fattr->du.nfs2.blocks;
                if (fattr->valid & NFS_ATTR_FATTR_SPACE_USED) {
                        /*
                         * report the blocks in 512byte units
                         */
                        inode->i_blocks = nfs_calc_block_size(fattr->du.nfs3.used);
                }

                nfs_setsecurity(inode, fattr, label);

                nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
                nfsi->attrtimeo_timestamp = now;
                nfsi->access_cache = RB_ROOT;

                nfs_fscache_init_inode(inode);

                unlock_new_inode(inode);
        } else
                nfs_refresh_inode(inode, fattr);
        dprintk("NFS: nfs_fhget(%s/%Lu fh_crc=0x%08x ct=%d)\n",
                inode->i_sb->s_id,
                (unsigned long long)NFS_FILEID(inode),
                nfs_display_fhandle_hash(fh),
                atomic_read(&inode->i_count));

out:
        return inode;

out_no_inode:
        dprintk("nfs_fhget: iget failed with error %ld\n", PTR_ERR(inode));
        goto out;
}
EXPORT_SYMBOL_GPL(nfs_fhget);

#define NFS_VALID_ATTRS (ATTR_MODE|ATTR_UID|ATTR_GID|ATTR_SIZE|ATTR_ATIME|ATTR_ATIME_SET|ATTR_MTIME|ATTR_MTIME_SET|ATTR_FILE|ATTR_OPEN)

int
nfs_setattr(struct dentry *dentry, struct iattr *attr)
{
        struct inode *inode = dentry->d_inode;
        struct nfs_fattr *fattr;
        int error = -ENOMEM;

        nfs_inc_stats(inode, NFSIOS_VFSSETATTR);

        /* skip mode change if it's just for clearing setuid/setgid */
        if (attr->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
                attr->ia_valid &= ~ATTR_MODE;

        if (attr->ia_valid & ATTR_SIZE) {
                if (!S_ISREG(inode->i_mode) || attr->ia_size == i_size_read(inode))
                        attr->ia_valid &= ~ATTR_SIZE;
        }

        /* Optimization: if the end result is no change, don't RPC */
        attr->ia_valid &= NFS_VALID_ATTRS;
        if ((attr->ia_valid & ~(ATTR_FILE|ATTR_OPEN)) == 0)
                return 0;

        trace_nfs_setattr_enter(inode);

        /* Write all dirty data */
        if (S_ISREG(inode->i_mode)) {
                nfs_inode_dio_wait(inode);
                nfs_wb_all(inode);
        }

        fattr = nfs_alloc_fattr();
        if (fattr == NULL)
                goto out;
        /*
         * Return any delegations if we're going to change ACLs
         */
        if ((attr->ia_valid & (ATTR_MODE|ATTR_UID|ATTR_GID)) != 0)
                NFS_PROTO(inode)->return_delegation(inode);
        error = NFS_PROTO(inode)->setattr(dentry, fattr, attr);
        if (error == 0)
                error = nfs_refresh_inode(inode, fattr);
        nfs_free_fattr(fattr);
out:
        trace_nfs_setattr_exit(inode, error);
        return error;
}
EXPORT_SYMBOL_GPL(nfs_setattr);

/**
 * nfs_vmtruncate - unmap mappings "freed" by truncate() syscall
 * @inode: inode of the file used
 * @offset: file offset to start truncating
 *
 * This is a copy of the common vmtruncate, but with the locking
 * corrected to take into account the fact that NFS requires
 * inode->i_size to be updated under the inode->i_lock.
 */
static int nfs_vmtruncate(struct inode * inode, loff_t offset)
{
        int err;

        err = inode_newsize_ok(inode, offset);
        if (err)
                goto out;

        spin_lock(&inode->i_lock);
        i_size_write(inode, offset);
        spin_unlock(&inode->i_lock);

        truncate_pagecache(inode, offset);
out:
        return err;
}

/**
 * nfs_setattr_update_inode - Update inode metadata after a setattr call.
 * @inode: pointer to struct inode
 * @attr: pointer to struct iattr
 *
 * Note: we do this in the *proc.c in order to ensure that
 *       it works for things like exclusive creates too.
 */
void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr)
{
        if ((attr->ia_valid & (ATTR_MODE|ATTR_UID|ATTR_GID)) != 0) {
                spin_lock(&inode->i_lock);
                if ((attr->ia_valid & ATTR_MODE) != 0) {
                        int mode = attr->ia_mode & S_IALLUGO;
                        mode |= inode->i_mode & ~S_IALLUGO;
                        inode->i_mode = mode;
                }
                if ((attr->ia_valid & ATTR_UID) != 0)
                        inode->i_uid = attr->ia_uid;
                if ((attr->ia_valid & ATTR_GID) != 0)
                        inode->i_gid = attr->ia_gid;
                NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                spin_unlock(&inode->i_lock);
        }
        if ((attr->ia_valid & ATTR_SIZE) != 0) {
                nfs_inc_stats(inode, NFSIOS_SETATTRTRUNC);
                nfs_vmtruncate(inode, attr->ia_size);
        }
}
EXPORT_SYMBOL_GPL(nfs_setattr_update_inode);

static void nfs_request_parent_use_readdirplus(struct dentry *dentry)
{
        struct dentry *parent;

        parent = dget_parent(dentry);
        nfs_force_use_readdirplus(parent->d_inode);
        dput(parent);
}

static bool nfs_need_revalidate_inode(struct inode *inode)
{
        if (NFS_I(inode)->cache_validity &
                        (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_LABEL))
                return true;
        if (nfs_attribute_cache_expired(inode))
                return true;
        return false;
}

int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
        struct inode *inode = dentry->d_inode;
        int need_atime = NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATIME;
        int err;

        trace_nfs_getattr_enter(inode);
        /* Flush out writes to the server in order to update c/mtime.  */
        if (S_ISREG(inode->i_mode)) {
                nfs_inode_dio_wait(inode);
                err = filemap_write_and_wait(inode->i_mapping);
                if (err)
                        goto out;
        }

        /*
         * We may force a getattr if the user cares about atime.
         *
         * Note that we only have to check the vfsmount flags here:
         *  - NFS always sets S_NOATIME by so checking it would give a
         *    bogus result
         *  - NFS never sets MS_NOATIME or MS_NODIRATIME so there is
         *    no point in checking those.
         */
        if ((mnt->mnt_flags & MNT_NOATIME) ||
            ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode)))
                need_atime = 0;

        if (need_atime || nfs_need_revalidate_inode(inode)) {
                struct nfs_server *server = NFS_SERVER(inode);

                if (server->caps & NFS_CAP_READDIRPLUS)
                        nfs_request_parent_use_readdirplus(dentry);
                err = __nfs_revalidate_inode(server, inode);
        }
        if (!err) {
                generic_fillattr(inode, stat);
                stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));
        }
out:
        trace_nfs_getattr_exit(inode, err);
        return err;
}
EXPORT_SYMBOL_GPL(nfs_getattr);

static void nfs_init_lock_context(struct nfs_lock_context *l_ctx)
{
        atomic_set(&l_ctx->count, 1);
        l_ctx->lockowner.l_owner = current->files;
        l_ctx->lockowner.l_pid = current->tgid;
        INIT_LIST_HEAD(&l_ctx->list);
        nfs_iocounter_init(&l_ctx->io_count);
}

static struct nfs_lock_context *__nfs_find_lock_context(struct nfs_open_context *ctx)
{
        struct nfs_lock_context *head = &ctx->lock_context;
        struct nfs_lock_context *pos = head;

        do {
                if (pos->lockowner.l_owner != current->files)
                        continue;
                if (pos->lockowner.l_pid != current->tgid)
                        continue;
                atomic_inc(&pos->count);
                return pos;
        } while ((pos = list_entry(pos->list.next, typeof(*pos), list)) != head);
        return NULL;
}

struct nfs_lock_context *nfs_get_lock_context(struct nfs_open_context *ctx)
{
        struct nfs_lock_context *res, *new = NULL;
        struct inode *inode = ctx->dentry->d_inode;

        spin_lock(&inode->i_lock);
        res = __nfs_find_lock_context(ctx);
        if (res == NULL) {
                spin_unlock(&inode->i_lock);
                new = kmalloc(sizeof(*new), GFP_KERNEL);
                if (new == NULL)
                        return ERR_PTR(-ENOMEM);
                nfs_init_lock_context(new);
                spin_lock(&inode->i_lock);
                res = __nfs_find_lock_context(ctx);
                if (res == NULL) {
                        list_add_tail(&new->list, &ctx->lock_context.list);
                        new->open_context = ctx;
                        res = new;
                        new = NULL;
                }
        }
        spin_unlock(&inode->i_lock);
        kfree(new);
        return res;
}

void nfs_put_lock_context(struct nfs_lock_context *l_ctx)
{
        struct nfs_open_context *ctx = l_ctx->open_context;
        struct inode *inode = ctx->dentry->d_inode;

        if (!atomic_dec_and_lock(&l_ctx->count, &inode->i_lock))
                return;
        list_del(&l_ctx->list);
        spin_unlock(&inode->i_lock);
        kfree(l_ctx);
}

/**
 * nfs_close_context - Common close_context() routine NFSv2/v3
 * @ctx: pointer to context
 * @is_sync: is this a synchronous close
 *
 * always ensure that the attributes are up to date if we're mounted
 * with close-to-open semantics
 */
void nfs_close_context(struct nfs_open_context *ctx, int is_sync)
{
        struct inode *inode;
        struct nfs_server *server;

        if (!(ctx->mode & FMODE_WRITE))
                return;
        if (!is_sync)
                return;
        inode = ctx->dentry->d_inode;
        if (!list_empty(&NFS_I(inode)->open_files))
                return;
        server = NFS_SERVER(inode);
        if (server->flags & NFS_MOUNT_NOCTO)
                return;
        nfs_revalidate_inode(server, inode);
}
EXPORT_SYMBOL_GPL(nfs_close_context);

struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry, fmode_t f_mode)
{
        struct nfs_open_context *ctx;
        struct rpc_cred *cred = rpc_lookup_cred();
        if (IS_ERR(cred))
                return ERR_CAST(cred);

        ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
        if (!ctx) {
                put_rpccred(cred);
                return ERR_PTR(-ENOMEM);
        }
        nfs_sb_active(dentry->d_sb);
        ctx->dentry = dget(dentry);
        ctx->cred = cred;
        ctx->state = NULL;
        ctx->mode = f_mode;
        ctx->flags = 0;
        ctx->error = 0;
        nfs_init_lock_context(&ctx->lock_context);
        ctx->lock_context.open_context = ctx;
        INIT_LIST_HEAD(&ctx->list);
        ctx->mdsthreshold = NULL;
        return ctx;
}
EXPORT_SYMBOL_GPL(alloc_nfs_open_context);

struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx)
{
        if (ctx != NULL)
                atomic_inc(&ctx->lock_context.count);
        return ctx;
}
EXPORT_SYMBOL_GPL(get_nfs_open_context);

static void __put_nfs_open_context(struct nfs_open_context *ctx, int is_sync)
{
        struct inode *inode = ctx->dentry->d_inode;
        struct super_block *sb = ctx->dentry->d_sb;

        if (!list_empty(&ctx->list)) {
                if (!atomic_dec_and_lock(&ctx->lock_context.count, &inode->i_lock))
                        return;
                list_del(&ctx->list);
                spin_unlock(&inode->i_lock);
        } else if (!atomic_dec_and_test(&ctx->lock_context.count))
                return;
        if (inode != NULL)
                NFS_PROTO(inode)->close_context(ctx, is_sync);
        if (ctx->cred != NULL)
                put_rpccred(ctx->cred);
        dput(ctx->dentry);
        nfs_sb_deactive(sb);
        kfree(ctx->mdsthreshold);
        kfree(ctx);
}

void put_nfs_open_context(struct nfs_open_context *ctx)
{
        __put_nfs_open_context(ctx, 0);
}
EXPORT_SYMBOL_GPL(put_nfs_open_context);

/*
 * Ensure that mmap has a recent RPC credential for use when writing out
 * shared pages
 */
void nfs_inode_attach_open_context(struct nfs_open_context *ctx)
{
        struct inode *inode = ctx->dentry->d_inode;
        struct nfs_inode *nfsi = NFS_I(inode);

        spin_lock(&inode->i_lock);
        list_add(&ctx->list, &nfsi->open_files);
        spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL_GPL(nfs_inode_attach_open_context);

void nfs_file_set_open_context(struct file *filp, struct nfs_open_context *ctx)
{
        filp->private_data = get_nfs_open_context(ctx);
        if (list_empty(&ctx->list))
                nfs_inode_attach_open_context(ctx);
}
EXPORT_SYMBOL_GPL(nfs_file_set_open_context);

/*
 * Given an inode, search for an open context with the desired characteristics
 */
struct nfs_open_context *nfs_find_open_context(struct inode *inode, struct rpc_cred *cred, fmode_t mode)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        struct nfs_open_context *pos, *ctx = NULL;

        spin_lock(&inode->i_lock);
        list_for_each_entry(pos, &nfsi->open_files, list) {
                if (cred != NULL && pos->cred != cred)
                        continue;
                if ((pos->mode & (FMODE_READ|FMODE_WRITE)) != mode)
                        continue;
                ctx = get_nfs_open_context(pos);
                break;
        }
        spin_unlock(&inode->i_lock);
        return ctx;
}

static void nfs_file_clear_open_context(struct file *filp)
{
        struct nfs_open_context *ctx = nfs_file_open_context(filp);

        if (ctx) {
                struct inode *inode = ctx->dentry->d_inode;

                filp->private_data = NULL;
                spin_lock(&inode->i_lock);
                list_move_tail(&ctx->list, &NFS_I(inode)->open_files);
                spin_unlock(&inode->i_lock);
                __put_nfs_open_context(ctx, filp->f_flags & O_DIRECT ? 0 : 1);
        }
}

/*
 * These allocate and release file read/write context information.
 */
int nfs_open(struct inode *inode, struct file *filp)
{
        struct nfs_open_context *ctx;

        ctx = alloc_nfs_open_context(filp->f_path.dentry, filp->f_mode);
        if (IS_ERR(ctx))
                return PTR_ERR(ctx);
        nfs_file_set_open_context(filp, ctx);
        put_nfs_open_context(ctx);
        nfs_fscache_open_file(inode, filp);
        return 0;
}

int nfs_release(struct inode *inode, struct file *filp)
{
        nfs_file_clear_open_context(filp);
        return 0;
}

/*
 * This function is called whenever some part of NFS notices that
 * the cached attributes have to be refreshed.
 */
int
__nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
{
        int              status = -ESTALE;
        struct nfs4_label *label = NULL;
        struct nfs_fattr *fattr = NULL;
        struct nfs_inode *nfsi = NFS_I(inode);

        dfprintk(PAGECACHE, "NFS: revalidating (%s/%Lu)\n",
                inode->i_sb->s_id, (unsigned long long)NFS_FILEID(inode));

        trace_nfs_revalidate_inode_enter(inode);

        if (is_bad_inode(inode))
                goto out;
        if (NFS_STALE(inode))
                goto out;

        status = -ENOMEM;
        fattr = nfs_alloc_fattr();
        if (fattr == NULL)
                goto out;

        nfs_inc_stats(inode, NFSIOS_INODEREVALIDATE);

        label = nfs4_label_alloc(NFS_SERVER(inode), GFP_KERNEL);
        if (IS_ERR(label)) {
                status = PTR_ERR(label);
                goto out;
        }

        status = NFS_PROTO(inode)->getattr(server, NFS_FH(inode), fattr, label);
        if (status != 0) {
                dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Lu) getattr failed, error=%d\n",
                         inode->i_sb->s_id,
                         (unsigned long long)NFS_FILEID(inode), status);
                if (status == -ESTALE) {
                        nfs_zap_caches(inode);
                        if (!S_ISDIR(inode->i_mode))
                                set_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
                }
                goto err_out;
        }

        status = nfs_refresh_inode(inode, fattr);
        if (status) {
                dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Lu) refresh failed, error=%d\n",
                         inode->i_sb->s_id,
                         (unsigned long long)NFS_FILEID(inode), status);
                goto err_out;
        }

        if (nfsi->cache_validity & NFS_INO_INVALID_ACL)
                nfs_zap_acl_cache(inode);

        nfs_setsecurity(inode, fattr, label);

        dfprintk(PAGECACHE, "NFS: (%s/%Lu) revalidation complete\n",
                inode->i_sb->s_id,
                (unsigned long long)NFS_FILEID(inode));

err_out:
        nfs4_label_free(label);
out:
        nfs_free_fattr(fattr);
        trace_nfs_revalidate_inode_exit(inode, status);
        return status;
}

int nfs_attribute_timeout(struct inode *inode)
{
        struct nfs_inode *nfsi = NFS_I(inode);

        return !time_in_range_open(jiffies, nfsi->read_cache_jiffies, nfsi->read_cache_jiffies + nfsi->attrtimeo);
}

int nfs_attribute_cache_expired(struct inode *inode)
{
        if (nfs_have_delegated_attributes(inode))
                return 0;
        return nfs_attribute_timeout(inode);
}

/**
 * nfs_revalidate_inode - Revalidate the inode attributes
 * @server - pointer to nfs_server struct
 * @inode - pointer to inode struct
 *
 * Updates inode attribute information by retrieving the data from the server.
 */
int nfs_revalidate_inode(struct nfs_server *server, struct inode *inode)
{
        if (!nfs_need_revalidate_inode(inode))
                return NFS_STALE(inode) ? -ESTALE : 0;
        return __nfs_revalidate_inode(server, inode);
}
EXPORT_SYMBOL_GPL(nfs_revalidate_inode);

static int nfs_invalidate_mapping(struct inode *inode, struct address_space *mapping)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        int ret;

        if (mapping->nrpages != 0) {
                if (S_ISREG(inode->i_mode)) {
                        ret = nfs_sync_mapping(mapping);
                        if (ret < 0)

                                return ret;
                }
                ret = invalidate_inode_pages2(mapping);
                if (ret < 0)
                        return ret;
        }
        if (S_ISDIR(inode->i_mode)) {
                spin_lock(&inode->i_lock);
                memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
                spin_unlock(&inode->i_lock);
        }
        nfs_inc_stats(inode, NFSIOS_DATAINVALIDATE);
        nfs_fscache_wait_on_invalidate(inode);

        dfprintk(PAGECACHE, "NFS: (%s/%Lu) data cache invalidated\n",
                        inode->i_sb->s_id,
                        (unsigned long long)NFS_FILEID(inode));
        return 0;
}

static bool nfs_mapping_need_revalidate_inode(struct inode *inode)
{
        if (nfs_have_delegated_attributes(inode))
                return false;
        return (NFS_I(inode)->cache_validity & NFS_INO_REVAL_PAGECACHE)
                || nfs_attribute_timeout(inode)
                || NFS_STALE(inode);
}

/**
 * nfs_revalidate_mapping - Revalidate the pagecache
 * @inode - pointer to host inode
 * @mapping - pointer to mapping
 */
int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        unsigned long *bitlock = &nfsi->flags;
        int ret = 0;

        /* swapfiles are not supposed to be shared. */
        if (IS_SWAPFILE(inode))
                goto out;

        if (nfs_mapping_need_revalidate_inode(inode)) {
                ret = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
                if (ret < 0)
                        goto out;
        }

        /*
         * We must clear NFS_INO_INVALID_DATA first to ensure that
         * invalidations that come in while we're shooting down the mappings
         * are respected. But, that leaves a race window where one revalidator
         * can clear the flag, and then another checks it before the mapping
         * gets invalidated. Fix that by serializing access to this part of
         * the function.
         *
         * At the same time, we need to allow other tasks to see whether we
         * might be in the middle of invalidating the pages, so we only set
         * the bit lock here if it looks like we're going to be doing that.
         */
        for (;;) {
                ret = wait_on_bit(bitlock, NFS_INO_INVALIDATING,
                                  nfs_wait_bit_killable, TASK_KILLABLE);
                if (ret)
                        goto out;
                spin_lock(&inode->i_lock);
                if (test_bit(NFS_INO_INVALIDATING, bitlock)) {
                        spin_unlock(&inode->i_lock);
                        continue;
                }
                if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
                        break;
                spin_unlock(&inode->i_lock);
                goto out;
        }

        set_bit(NFS_INO_INVALIDATING, bitlock);
        smp_wmb();
        nfsi->cache_validity &= ~NFS_INO_INVALID_DATA;
        spin_unlock(&inode->i_lock);
        trace_nfs_invalidate_mapping_enter(inode);
        ret = nfs_invalidate_mapping(inode, mapping);
        trace_nfs_invalidate_mapping_exit(inode, ret);

        clear_bit_unlock(NFS_INO_INVALIDATING, bitlock);
        smp_mb__after_clear_bit();
        wake_up_bit(bitlock, NFS_INO_INVALIDATING);
out:
        return ret;
}

static unsigned long nfs_wcc_update_inode(struct inode *inode, struct nfs_fattr *fattr)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        unsigned long ret = 0;

        if ((fattr->valid & NFS_ATTR_FATTR_PRECHANGE)
                        && (fattr->valid & NFS_ATTR_FATTR_CHANGE)
                        && inode->i_version == fattr->pre_change_attr) {
                inode->i_version = fattr->change_attr;
                if (S_ISDIR(inode->i_mode))
                        nfsi->cache_validity |= NFS_INO_INVALID_DATA;
                ret |= NFS_INO_INVALID_ATTR;
        }
        /* If we have atomic WCC data, we may update some attributes */
        if ((fattr->valid & NFS_ATTR_FATTR_PRECTIME)
                        && (fattr->valid & NFS_ATTR_FATTR_CTIME)
                        && timespec_equal(&inode->i_ctime, &fattr->pre_ctime)) {
                memcpy(&inode->i_ctime, &fattr->ctime, sizeof(inode->i_ctime));
                ret |= NFS_INO_INVALID_ATTR;
        }

        if ((fattr->valid & NFS_ATTR_FATTR_PREMTIME)
                        && (fattr->valid & NFS_ATTR_FATTR_MTIME)
                        && timespec_equal(&inode->i_mtime, &fattr->pre_mtime)) {
                memcpy(&inode->i_mtime, &fattr->mtime, sizeof(inode->i_mtime));
                if (S_ISDIR(inode->i_mode))
                        nfsi->cache_validity |= NFS_INO_INVALID_DATA;
                ret |= NFS_INO_INVALID_ATTR;
        }
        if ((fattr->valid & NFS_ATTR_FATTR_PRESIZE)
                        && (fattr->valid & NFS_ATTR_FATTR_SIZE)
                        && i_size_read(inode) == nfs_size_to_loff_t(fattr->pre_size)
                        && nfsi->npages == 0) {
                i_size_write(inode, nfs_size_to_loff_t(fattr->size));
                ret |= NFS_INO_INVALID_ATTR;
        }

        if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
                nfs_fscache_invalidate(inode);

        return ret;
}

/**
 * nfs_check_inode_attributes - verify consistency of the inode attribute cache
 * @inode - pointer to inode
 * @fattr - updated attributes
 *
 * Verifies the attribute cache. If we have just changed the attributes,
 * so that fattr carries weak cache consistency data, then it may
 * also update the ctime/mtime/change_attribute.
 */
static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fattr)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        loff_t cur_size, new_isize;
        unsigned long invalid = 0;


        if (nfs_have_delegated_attributes(inode))
                return 0;
        /* Has the inode gone and changed behind our back? */
        if ((fattr->valid & NFS_ATTR_FATTR_FILEID) && nfsi->fileid != fattr->fileid)
                return -EIO;
        if ((fattr->valid & NFS_ATTR_FATTR_TYPE) && (inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
                return -EIO;

        if ((fattr->valid & NFS_ATTR_FATTR_CHANGE) != 0 &&
                        inode->i_version != fattr->change_attr)
                invalid |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;

        /* Verify a few of the more important attributes */
        if ((fattr->valid & NFS_ATTR_FATTR_MTIME) && !timespec_equal(&inode->i_mtime, &fattr->mtime))
                invalid |= NFS_INO_INVALID_ATTR;

        if (fattr->valid & NFS_ATTR_FATTR_SIZE) {
                cur_size = i_size_read(inode);
                new_isize = nfs_size_to_loff_t(fattr->size);
                if (cur_size != new_isize && nfsi->npages == 0)
                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;
        }

        /* Have any file permissions changed? */
        if ((fattr->valid & NFS_ATTR_FATTR_MODE) && (inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO))
                invalid |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL;
        if ((fattr->valid & NFS_ATTR_FATTR_OWNER) && !uid_eq(inode->i_uid, fattr->uid))
                invalid |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL;
        if ((fattr->valid & NFS_ATTR_FATTR_GROUP) && !gid_eq(inode->i_gid, fattr->gid))
                invalid |= NFS_INO_INVALID_ATTR | NFS_INO_INVALID_ACCESS | NFS_INO_INVALID_ACL;

        /* Has the link count changed? */
        if ((fattr->valid & NFS_ATTR_FATTR_NLINK) && inode->i_nlink != fattr->nlink)
                invalid |= NFS_INO_INVALID_ATTR;

        if ((fattr->valid & NFS_ATTR_FATTR_ATIME) && !timespec_equal(&inode->i_atime, &fattr->atime))
                invalid |= NFS_INO_INVALID_ATIME;

        if (invalid != 0)
                nfsi->cache_validity |= invalid;

        nfsi->read_cache_jiffies = fattr->time_start;
        return 0;
}

static int nfs_ctime_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
{
        if (!(fattr->valid & NFS_ATTR_FATTR_CTIME))
                return 0;
        return timespec_compare(&fattr->ctime, &inode->i_ctime) > 0;
}

static int nfs_size_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
{
        if (!(fattr->valid & NFS_ATTR_FATTR_SIZE))
                return 0;
        return nfs_size_to_loff_t(fattr->size) > i_size_read(inode);
}

static atomic_long_t nfs_attr_generation_counter;

static unsigned long nfs_read_attr_generation_counter(void)
{
        return atomic_long_read(&nfs_attr_generation_counter);
}

unsigned long nfs_inc_attr_generation_counter(void)
{
        return atomic_long_inc_return(&nfs_attr_generation_counter);
}

void nfs_fattr_init(struct nfs_fattr *fattr)
{
        fattr->valid = 0;
        fattr->time_start = jiffies;
        fattr->gencount = nfs_inc_attr_generation_counter();
        fattr->owner_name = NULL;
        fattr->group_name = NULL;
}
EXPORT_SYMBOL_GPL(nfs_fattr_init);

struct nfs_fattr *nfs_alloc_fattr(void)
{
        struct nfs_fattr *fattr;

        fattr = kmalloc(sizeof(*fattr), GFP_NOFS);
        if (fattr != NULL)
                nfs_fattr_init(fattr);
        return fattr;
}
EXPORT_SYMBOL_GPL(nfs_alloc_fattr);

struct nfs_fh *nfs_alloc_fhandle(void)
{
        struct nfs_fh *fh;

        fh = kmalloc(sizeof(struct nfs_fh), GFP_NOFS);
        if (fh != NULL)
                fh->size = 0;
        return fh;
}
EXPORT_SYMBOL_GPL(nfs_alloc_fhandle);

#ifdef NFS_DEBUG
/*
 * _nfs_display_fhandle_hash - calculate the crc32 hash for the filehandle
 *                             in the same way that wireshark does
 *
 * @fh: file handle
 *
 * For debugging only.
 */
u32 _nfs_display_fhandle_hash(const struct nfs_fh *fh)
{
        /* wireshark uses 32-bit AUTODIN crc and does a bitwise
         * not on the result */
        return nfs_fhandle_hash(fh);
}
EXPORT_SYMBOL_GPL(_nfs_display_fhandle_hash);

/*
 * _nfs_display_fhandle - display an NFS file handle on the console
 *
 * @fh: file handle to display
 * @caption: display caption
 *
 * For debugging only.
 */
void _nfs_display_fhandle(const struct nfs_fh *fh, const char *caption)
{
        unsigned short i;

        if (fh == NULL || fh->size == 0) {
                printk(KERN_DEFAULT "%s at %p is empty\n", caption, fh);
                return;
        }

        printk(KERN_DEFAULT "%s at %p is %u bytes, crc: 0x%08x:\n",
               caption, fh, fh->size, _nfs_display_fhandle_hash(fh));
        for (i = 0; i < fh->size; i += 16) {
                __be32 *pos = (__be32 *)&fh->data[i];

                switch ((fh->size - i - 1) >> 2) {
                case 0:
                        printk(KERN_DEFAULT " %08x\n",
                                be32_to_cpup(pos));
                        break;
                case 1:
                        printk(KERN_DEFAULT " %08x %08x\n",
                                be32_to_cpup(pos), be32_to_cpup(pos + 1));
                        break;
                case 2:
                        printk(KERN_DEFAULT " %08x %08x %08x\n",
                                be32_to_cpup(pos), be32_to_cpup(pos + 1),
                                be32_to_cpup(pos + 2));
                        break;
                default:
                        printk(KERN_DEFAULT " %08x %08x %08x %08x\n",
                                be32_to_cpup(pos), be32_to_cpup(pos + 1),
                                be32_to_cpup(pos + 2), be32_to_cpup(pos + 3));
                }
        }
}
EXPORT_SYMBOL_GPL(_nfs_display_fhandle);
#endif

/**
 * nfs_inode_attrs_need_update - check if the inode attributes need updating
 * @inode - pointer to inode
 * @fattr - attributes
 *
 * Attempt to divine whether or not an RPC call reply carrying stale
 * attributes got scheduled after another call carrying updated ones.
 *
 * To do so, the function first assumes that a more recent ctime means
 * that the attributes in fattr are newer, however it also attempt to
 * catch the case where ctime either didn't change, or went backwards
 * (if someone reset the clock on the server) by looking at whether
 * or not this RPC call was started after the inode was last updated.
 * Note also the check for wraparound of 'attr_gencount'
 *
 * The function returns 'true' if it thinks the attributes in 'fattr' are
 * more recent than the ones cached in the inode.
 *
 */
static int nfs_inode_attrs_need_update(const struct inode *inode, const struct nfs_fattr *fattr)
{
        const struct nfs_inode *nfsi = NFS_I(inode);

        return ((long)fattr->gencount - (long)nfsi->attr_gencount) > 0 ||
                nfs_ctime_need_update(inode, fattr) ||
                nfs_size_need_update(inode, fattr) ||
                ((long)nfsi->attr_gencount - (long)nfs_read_attr_generation_counter() > 0);
}

/*
 * Don't trust the change_attribute, mtime, ctime or size if
 * a pnfs LAYOUTCOMMIT is outstanding
 */
static void nfs_inode_attrs_handle_layoutcommit(struct inode *inode,
                struct nfs_fattr *fattr)
{
        if (pnfs_layoutcommit_outstanding(inode))
                fattr->valid &= ~(NFS_ATTR_FATTR_CHANGE |
                                NFS_ATTR_FATTR_MTIME |
                                NFS_ATTR_FATTR_CTIME |
                                NFS_ATTR_FATTR_SIZE);
}

static int nfs_refresh_inode_locked(struct inode *inode, struct nfs_fattr *fattr)
{
        int ret;

        trace_nfs_refresh_inode_enter(inode);

        nfs_inode_attrs_handle_layoutcommit(inode, fattr);

        if (nfs_inode_attrs_need_update(inode, fattr))
                ret = nfs_update_inode(inode, fattr);
        else
                ret = nfs_check_inode_attributes(inode, fattr);

        trace_nfs_refresh_inode_exit(inode, ret);
        return ret;
}

/**
 * nfs_refresh_inode - try to update the inode attribute cache
 * @inode - pointer to inode
 * @fattr - updated attributes
 *
 * Check that an RPC call that returned attributes has not overlapped with
 * other recent updates of the inode metadata, then decide whether it is
 * safe to do a full update of the inode attributes, or whether just to
 * call nfs_check_inode_attributes.
 */
int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
{
        int status;

        if ((fattr->valid & NFS_ATTR_FATTR) == 0)
                return 0;
        spin_lock(&inode->i_lock);
        status = nfs_refresh_inode_locked(inode, fattr);
        spin_unlock(&inode->i_lock);

        return status;
}
EXPORT_SYMBOL_GPL(nfs_refresh_inode);

static int nfs_post_op_update_inode_locked(struct inode *inode, struct nfs_fattr *fattr)
{
        struct nfs_inode *nfsi = NFS_I(inode);

        nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;
        if (S_ISDIR(inode->i_mode)) {
                nfsi->cache_validity |= NFS_INO_INVALID_DATA;
                nfs_fscache_invalidate(inode);
        }
        if ((fattr->valid & NFS_ATTR_FATTR) == 0)
                return 0;
        return nfs_refresh_inode_locked(inode, fattr);
}

/**
 * nfs_post_op_update_inode - try to update the inode attribute cache
 * @inode - pointer to inode
 * @fattr - updated attributes
 *
 * After an operation that has changed the inode metadata, mark the
 * attribute cache as being invalid, then try to update it.
 *
 * NB: if the server didn't return any post op attributes, this
 * function will force the retrieval of attributes before the next
 * NFS request.  Thus it should be used only for operations that
 * are expected to change one or more attributes, to avoid
 * unnecessary NFS requests and trips through nfs_update_inode().
 */
int nfs_post_op_update_inode(struct inode *inode, struct nfs_fattr *fattr)
{
        int status;

        spin_lock(&inode->i_lock);
        status = nfs_post_op_update_inode_locked(inode, fattr);
        spin_unlock(&inode->i_lock);

        return status;
}
EXPORT_SYMBOL_GPL(nfs_post_op_update_inode);

/**
 * nfs_post_op_update_inode_force_wcc - try to update the inode attribute cache
 * @inode - pointer to inode
 * @fattr - updated attributes
 *
 * After an operation that has changed the inode metadata, mark the
 * attribute cache as being invalid, then try to update it. Fake up
 * weak cache consistency data, if none exist.
 *
 * This function is mainly designed to be used by the ->write_done() functions.
 */
int nfs_post_op_update_inode_force_wcc(struct inode *inode, struct nfs_fattr *fattr)
{
        int status;

        spin_lock(&inode->i_lock);
        /* Don't do a WCC update if these attributes are already stale */
        if ((fattr->valid & NFS_ATTR_FATTR) == 0 ||
                        !nfs_inode_attrs_need_update(inode, fattr)) {
                fattr->valid &= ~(NFS_ATTR_FATTR_PRECHANGE
                                | NFS_ATTR_FATTR_PRESIZE
                                | NFS_ATTR_FATTR_PREMTIME
                                | NFS_ATTR_FATTR_PRECTIME);
                goto out_noforce;
        }
        if ((fattr->valid & NFS_ATTR_FATTR_CHANGE) != 0 &&
                        (fattr->valid & NFS_ATTR_FATTR_PRECHANGE) == 0) {
                fattr->pre_change_attr = inode->i_version;
                fattr->valid |= NFS_ATTR_FATTR_PRECHANGE;
        }
        if ((fattr->valid & NFS_ATTR_FATTR_CTIME) != 0 &&
                        (fattr->valid & NFS_ATTR_FATTR_PRECTIME) == 0) {
                memcpy(&fattr->pre_ctime, &inode->i_ctime, sizeof(fattr->pre_ctime));
                fattr->valid |= NFS_ATTR_FATTR_PRECTIME;
        }
        if ((fattr->valid & NFS_ATTR_FATTR_MTIME) != 0 &&
                        (fattr->valid & NFS_ATTR_FATTR_PREMTIME) == 0) {
                memcpy(&fattr->pre_mtime, &inode->i_mtime, sizeof(fattr->pre_mtime));
                fattr->valid |= NFS_ATTR_FATTR_PREMTIME;
        }
        if ((fattr->valid & NFS_ATTR_FATTR_SIZE) != 0 &&
                        (fattr->valid & NFS_ATTR_FATTR_PRESIZE) == 0) {
                fattr->pre_size = i_size_read(inode);
                fattr->valid |= NFS_ATTR_FATTR_PRESIZE;
        }
out_noforce:
        status = nfs_post_op_update_inode_locked(inode, fattr);
        spin_unlock(&inode->i_lock);
        return status;
}
EXPORT_SYMBOL_GPL(nfs_post_op_update_inode_force_wcc);

/*
 * Many nfs protocol calls return the new file attributes after
 * an operation.  Here we update the inode to reflect the state
 * of the server's inode.
 *
 * This is a bit tricky because we have to make sure all dirty pages
 * have been sent off to the server before calling invalidate_inode_pages.
 * To make sure no other process adds more write requests while we try
 * our best to flush them, we make them sleep during the attribute refresh.
 *
 * A very similar scenario holds for the dir cache.
 */
static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
{
        struct nfs_server *server;
        struct nfs_inode *nfsi = NFS_I(inode);
        loff_t cur_isize, new_isize;
        unsigned long invalid = 0;
        unsigned long now = jiffies;
        unsigned long save_cache_validity;

        dfprintk(VFS, "NFS: %s(%s/%lu fh_crc=0x%08x ct=%d info=0x%x)\n",
                        __func__, inode->i_sb->s_id, inode->i_ino,
                        nfs_display_fhandle_hash(NFS_FH(inode)),
                        atomic_read(&inode->i_count), fattr->valid);

        if ((fattr->valid & NFS_ATTR_FATTR_FILEID) && nfsi->fileid != fattr->fileid) {
                printk(KERN_ERR "NFS: server %s error: fileid changed\n"
                        "fsid %s: expected fileid 0x%Lx, got 0x%Lx\n",
                        NFS_SERVER(inode)->nfs_client->cl_hostname,
                        inode->i_sb->s_id, (long long)nfsi->fileid,
                        (long long)fattr->fileid);
                goto out_err;
        }

        /*
         * Make sure the inode's type hasn't changed.
         */
        if ((fattr->valid & NFS_ATTR_FATTR_TYPE) && (inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT)) {
                /*
                * Big trouble! The inode has become a different object.
                */
                printk(KERN_DEBUG "NFS: %s: inode %lu mode changed, %07o to %07o\n",
                                __func__, inode->i_ino, inode->i_mode, fattr->mode);
                goto out_err;
        }

        server = NFS_SERVER(inode);
        /* Update the fsid? */
        if (S_ISDIR(inode->i_mode) && (fattr->valid & NFS_ATTR_FATTR_FSID) &&
                        !nfs_fsid_equal(&server->fsid, &fattr->fsid) &&
                        !IS_AUTOMOUNT(inode))
                server->fsid = fattr->fsid;

        /*
         * Update the read time so we don't revalidate too often.
         */
        nfsi->read_cache_jiffies = fattr->time_start;

        save_cache_validity = nfsi->cache_validity;
        nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR
                        | NFS_INO_INVALID_ATIME
                        | NFS_INO_REVAL_FORCED
                        | NFS_INO_REVAL_PAGECACHE);

        /* Do atomic weak cache consistency updates */
        invalid |= nfs_wcc_update_inode(inode, fattr);

        /* More cache consistency checks */
        if (fattr->valid & NFS_ATTR_FATTR_CHANGE) {
                if (inode->i_version != fattr->change_attr) {
                        dprintk("NFS: change_attr change on server for file %s/%ld\n",
                                        inode->i_sb->s_id, inode->i_ino);
                        invalid |= NFS_INO_INVALID_ATTR
                                | NFS_INO_INVALID_DATA
                                | NFS_INO_INVALID_ACCESS
                                | NFS_INO_INVALID_ACL
                                | NFS_INO_REVAL_PAGECACHE;
                        if (S_ISDIR(inode->i_mode))
                                nfs_force_lookup_revalidate(inode);
                        inode->i_version = fattr->change_attr;
                }
        } else if (server->caps & NFS_CAP_CHANGE_ATTR)
                invalid |= save_cache_validity;

        if (fattr->valid & NFS_ATTR_FATTR_MTIME) {
                memcpy(&inode->i_mtime, &fattr->mtime, sizeof(inode->i_mtime));
        } else if (server->caps & NFS_CAP_MTIME)
                invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
                                | NFS_INO_REVAL_FORCED);

        if (fattr->valid & NFS_ATTR_FATTR_CTIME) {
                memcpy(&inode->i_ctime, &fattr->ctime, sizeof(inode->i_ctime));
        } else if (server->caps & NFS_CAP_CTIME)
                invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
                                | NFS_INO_REVAL_FORCED);

        /* Check if our cached file size is stale */
        if (fattr->valid & NFS_ATTR_FATTR_SIZE) {
                new_isize = nfs_size_to_loff_t(fattr->size);
                cur_isize = i_size_read(inode);
                if (new_isize != cur_isize) {
                        /* Do we perhaps have any outstanding writes, or has
                         * the file grown beyond our last write? */
                        if ((nfsi->npages == 0) || new_isize > cur_isize) {
                                i_size_write(inode, new_isize);
                                invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA;
                        }
                        dprintk("NFS: isize change on server for file %s/%ld "
                                        "(%Ld to %Ld)\n",
                                        inode->i_sb->s_id,
                                        inode->i_ino,
                                        (long long)cur_isize,
                                        (long long)new_isize);
                }
        } else
                invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
                                | NFS_INO_REVAL_PAGECACHE
                                | NFS_INO_REVAL_FORCED);


        if (fattr->valid & NFS_ATTR_FATTR_ATIME)
                memcpy(&inode->i_atime, &fattr->atime, sizeof(inode->i_atime));
        else if (server->caps & NFS_CAP_ATIME)
                invalid |= save_cache_validity & (NFS_INO_INVALID_ATIME
                                | NFS_INO_REVAL_FORCED);

        if (fattr->valid & NFS_ATTR_FATTR_MODE) {
                if ((inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO)) {
                        umode_t newmode = inode->i_mode & S_IFMT;
                        newmode |= fattr->mode & S_IALLUGO;
                        inode->i_mode = newmode;
                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                }
        } else if (server->caps & NFS_CAP_MODE)
                invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
                                | NFS_INO_INVALID_ACCESS
                                | NFS_INO_INVALID_ACL
                                | NFS_INO_REVAL_FORCED);

        if (fattr->valid & NFS_ATTR_FATTR_OWNER) {
                if (!uid_eq(inode->i_uid, fattr->uid)) {
                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                        inode->i_uid = fattr->uid;
                }
        } else if (server->caps & NFS_CAP_OWNER)
                invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
                                | NFS_INO_INVALID_ACCESS
                                | NFS_INO_INVALID_ACL
                                | NFS_INO_REVAL_FORCED);

        if (fattr->valid & NFS_ATTR_FATTR_GROUP) {
                if (!gid_eq(inode->i_gid, fattr->gid)) {
                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                        inode->i_gid = fattr->gid;
                }
        } else if (server->caps & NFS_CAP_OWNER_GROUP)
                invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
                                | NFS_INO_INVALID_ACCESS
                                | NFS_INO_INVALID_ACL
                                | NFS_INO_REVAL_FORCED);

        if (fattr->valid & NFS_ATTR_FATTR_NLINK) {
                if (inode->i_nlink != fattr->nlink) {
                        invalid |= NFS_INO_INVALID_ATTR;
                        if (S_ISDIR(inode->i_mode))
                                invalid |= NFS_INO_INVALID_DATA;
                        set_nlink(inode, fattr->nlink);
                }
        } else if (server->caps & NFS_CAP_NLINK)
                invalid |= save_cache_validity & (NFS_INO_INVALID_ATTR
                                | NFS_INO_REVAL_FORCED);

        if (fattr->valid & NFS_ATTR_FATTR_SPACE_USED) {
                /*
                 * report the blocks in 512byte units
                 */
                inode->i_blocks = nfs_calc_block_size(fattr->du.nfs3.used);
        }
        if (fattr->valid & NFS_ATTR_FATTR_BLOCKS_USED)
                inode->i_blocks = fattr->du.nfs2.blocks;

        /* Update attrtimeo value if we're out of the unstable period */
        if (invalid & NFS_INO_INVALID_ATTR) {
                nfs_inc_stats(inode, NFSIOS_ATTRINVALIDATE);
                nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
                nfsi->attrtimeo_timestamp = now;
                nfsi->attr_gencount = nfs_inc_attr_generation_counter();
        } else {
                if (!time_in_range_open(now, nfsi->attrtimeo_timestamp, nfsi->attrtimeo_timestamp + nfsi->attrtimeo)) {
                        if ((nfsi->attrtimeo <<= 1) > NFS_MAXATTRTIMEO(inode))
                                nfsi->attrtimeo = NFS_MAXATTRTIMEO(inode);
                        nfsi->attrtimeo_timestamp = now;
                }
        }
        invalid &= ~NFS_INO_INVALID_ATTR;
        /* Don't invalidate the data if we were to blame */
        if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)
                                || S_ISLNK(inode->i_mode)))
                invalid &= ~NFS_INO_INVALID_DATA;
        if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ) ||
                        (save_cache_validity & NFS_INO_REVAL_FORCED))
                nfsi->cache_validity |= invalid;

        if (invalid & NFS_INO_INVALID_DATA)
                nfs_fscache_invalidate(inode);

        return 0;
 out_err:
        /*
         * No need to worry about unhashing the dentry, as the
         * lookup validation will know that the inode is bad.
         * (But we fall through to invalidate the caches.)
         */
        nfs_invalidate_inode(inode);
        return -ESTALE;
}

struct inode *nfs_alloc_inode(struct super_block *sb)
{
        struct nfs_inode *nfsi;
        nfsi = (struct nfs_inode *)kmem_cache_alloc(nfs_inode_cachep, GFP_KERNEL);
        if (!nfsi)
                return NULL;
        nfsi->flags = 0UL;
        nfsi->cache_validity = 0UL;
#if IS_ENABLED(CONFIG_NFS_V4)
        nfsi->nfs4_acl = NULL;
#endif /* CONFIG_NFS_V4 */
        return &nfsi->vfs_inode;
}
EXPORT_SYMBOL_GPL(nfs_alloc_inode);

static void nfs_i_callback(struct rcu_head *head)
{
        struct inode *inode = container_of(head, struct inode, i_rcu);
        kmem_cache_free(nfs_inode_cachep, NFS_I(inode));
}

void nfs_destroy_inode(struct inode *inode)
{
        call_rcu(&inode->i_rcu, nfs_i_callback);
}
EXPORT_SYMBOL_GPL(nfs_destroy_inode);

static inline void nfs4_init_once(struct nfs_inode *nfsi)
{
#if IS_ENABLED(CONFIG_NFS_V4)
        INIT_LIST_HEAD(&nfsi->open_states);
        nfsi->delegation = NULL;
        nfsi->delegation_state = 0;
        init_rwsem(&nfsi->rwsem);
        nfsi->layout = NULL;
#endif
}

static void init_once(void *foo)
{
        struct nfs_inode *nfsi = (struct nfs_inode *) foo;

        inode_init_once(&nfsi->vfs_inode);
        INIT_LIST_HEAD(&nfsi->open_files);
        INIT_LIST_HEAD(&nfsi->access_cache_entry_lru);
        INIT_LIST_HEAD(&nfsi->access_cache_inode_lru);
        INIT_LIST_HEAD(&nfsi->commit_info.list);
        nfsi->npages = 0;
        nfsi->commit_info.ncommit = 0;
        atomic_set(&nfsi->commit_info.rpcs_out, 0);
        atomic_set(&nfsi->silly_count, 1);
        INIT_HLIST_HEAD(&nfsi->silly_list);
        init_waitqueue_head(&nfsi->waitqueue);
        nfs4_init_once(nfsi);
}

static int __init nfs_init_inodecache(void)
{
        nfs_inode_cachep = kmem_cache_create("nfs_inode_cache",
                                             sizeof(struct nfs_inode),
                                             0, (SLAB_RECLAIM_ACCOUNT|
                                                SLAB_MEM_SPREAD),
                                             init_once);
        if (nfs_inode_cachep == NULL)
                return -ENOMEM;

        return 0;
}

static void nfs_destroy_inodecache(void)
{
        /*
         * Make sure all delayed rcu free inodes are flushed before we
         * destroy cache.
         */
        rcu_barrier();
        kmem_cache_destroy(nfs_inode_cachep);
}

struct workqueue_struct *nfsiod_workqueue;
EXPORT_SYMBOL_GPL(nfsiod_workqueue);

/*
 * start up the nfsiod workqueue
 */
static int nfsiod_start(void)
{
        struct workqueue_struct *wq;
        dprintk("RPC:       creating workqueue nfsiod\n");
        wq = alloc_workqueue("nfsiod", WQ_MEM_RECLAIM, 0);
        if (wq == NULL)
                return -ENOMEM;
        nfsiod_workqueue = wq;
        return 0;
}

/*
 * Destroy the nfsiod workqueue
 */
static void nfsiod_stop(void)
{
        struct workqueue_struct *wq;

        wq = nfsiod_workqueue;
        if (wq == NULL)
                return;
        nfsiod_workqueue = NULL;
        destroy_workqueue(wq);
}

int nfs_net_id;
EXPORT_SYMBOL_GPL(nfs_net_id);

static int nfs_net_init(struct net *net)
{
        nfs_clients_init(net);
        return 0;
}

static void nfs_net_exit(struct net *net)
{
        nfs_cleanup_cb_ident_idr(net);
}

static struct pernet_operations nfs_net_ops = {
        .init = nfs_net_init,
        .exit = nfs_net_exit,
        .id   = &nfs_net_id,
        .size = sizeof(struct nfs_net),
};

/*
 * Initialize NFS
 */
static int __init init_nfs_fs(void)
{
        int err;

        err = register_pernet_subsys(&nfs_net_ops);
        if (err < 0)
                goto out9;

        err = nfs_fscache_register();
        if (err < 0)
                goto out8;

        err = nfsiod_start();
        if (err)
                goto out7;

        err = nfs_fs_proc_init();
        if (err)
                goto out6;

        err = nfs_init_nfspagecache();
        if (err)
                goto out5;

        err = nfs_init_inodecache();
        if (err)
                goto out4;

        err = nfs_init_readpagecache();
        if (err)
                goto out3;

        err = nfs_init_writepagecache();
        if (err)
                goto out2;

        err = nfs_init_directcache();
        if (err)
                goto out1;

#ifdef CONFIG_PROC_FS
        rpc_proc_register(&init_net, &nfs_rpcstat);
#endif
        if ((err = register_nfs_fs()) != 0)
                goto out0;

        return 0;
out0:
#ifdef CONFIG_PROC_FS
        rpc_proc_unregister(&init_net, "nfs");
#endif
        nfs_destroy_directcache();
out1:
        nfs_destroy_writepagecache();
out2:
        nfs_destroy_readpagecache();
out3:
        nfs_destroy_inodecache();
out4:
        nfs_destroy_nfspagecache();
out5:
        nfs_fs_proc_exit();
out6:
        nfsiod_stop();
out7:
        nfs_fscache_unregister();
out8:
        unregister_pernet_subsys(&nfs_net_ops);
out9:
        return err;
}

static void __exit exit_nfs_fs(void)
{
        nfs_destroy_directcache();
        nfs_destroy_writepagecache();
        nfs_destroy_readpagecache();
        nfs_destroy_inodecache();
        nfs_destroy_nfspagecache();
        nfs_fscache_unregister();
        unregister_pernet_subsys(&nfs_net_ops);
#ifdef CONFIG_PROC_FS
        rpc_proc_unregister(&init_net, "nfs");
#endif
        unregister_nfs_fs();
        nfs_fs_proc_exit();
        nfsiod_stop();
}

/* Not quite true; I just maintain it */
MODULE_AUTHOR("Olaf Kirch <okir@monad.swb.de>");
MODULE_LICENSE("GPL");
module_param(enable_ino64, bool, 0644);

module_init(init_nfs_fs)
module_exit(exit_nfs_fs)