Merge commit 'v2.6.30' into for-2.6.31

[safe/jmp/linux-2.6] / fs / nfs / inode.c

/*
 *  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/smp_lock.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/nfs_idmap.h>
#include <linux/vfs.h>
#include <linux/inet.h>
#include <linux/nfs_xdr.h>

#include <asm/system.h>
#include <asm/uaccess.h>

#include "nfs4_fs.h"
#include "callback.h"
#include "delegation.h"
#include "iostat.h"
#include "internal.h"
#include "fscache.h"

#define NFSDBG_FACILITY         NFSDBG_VFS

#define NFS_64_BIT_INODE_NUMBERS_ENABLED        1

/* Default is to see 64-bit inode numbers */
static int 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;
        schedule();
        return 0;
}

/**
 * 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)
{
        int ino;

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

int nfs_write_inode(struct inode *inode, int sync)
{
        int ret;

        if (sync) {
                ret = filemap_fdatawait(inode->i_mapping);
                if (ret == 0)
                        ret = nfs_commit_inode(inode, FLUSH_SYNC);
        } else
                ret = nfs_commit_inode(inode, 0);
        if (ret >= 0)
                return 0;
        __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
        return ret;
}

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

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

        if (mapping->nrpages == 0)
                return 0;
        unmap_mapping_range(mapping, 0, 0, 0);
        ret = filemap_write_and_wait(mapping);
        if (ret != 0)
                goto out;
        ret = nfs_wb_all(mapping->host);
out:
        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_COOKIEVERF(inode), 0, sizeof(NFS_COOKIEVERF(inode)));
        if (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))
                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;
}

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;
                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);
}

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);
}

/*
 * 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 (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;
}

/* Don't use READDIRPLUS on directories that we believe are too large */
#define NFS_LIMIT_READDIRPLUS (8*PAGE_SIZE)

/*
 * 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 nfs_find_desc desc = {
                .fh     = fh,
                .fattr  = fattr
        };
        struct inode *inode = ERR_PTR(-ENOENT);
        unsigned long hash;

        if ((fattr->valid & NFS_ATTR_FATTR_FILEID) == 0)
                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;
                /* 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_file_operations;
                        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;
                        if (nfs_server_capable(inode, NFS_CAP_READDIRPLUS)
                            && fattr->size <= NFS_LIMIT_READDIRPLUS)
                                set_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(inode)->flags);
                        /* Deal with crossing mountpoints */
                        if ((fattr->valid & NFS_ATTR_FATTR_FSID)
                                        && !nfs_fsid_equal(&NFS_SB(sb)->fsid, &fattr->fsid)) {
                                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;
                                set_bit(NFS_INO_MOUNTPOINT, &nfsi->flags);
                        }
                } 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));
                nfsi->change_attr = 0;
                inode->i_size = 0;
                inode->i_nlink = 0;
                inode->i_uid = -2;
                inode->i_gid = -2;
                inode->i_blocks = 0;
                memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));

                nfsi->read_cache_jiffies = fattr->time_start;
                nfsi->attr_gencount = fattr->gencount;
                if (fattr->valid & NFS_ATTR_FATTR_ATIME)
                        inode->i_atime = fattr->atime;
                if (fattr->valid & NFS_ATTR_FATTR_MTIME)
                        inode->i_mtime = fattr->mtime;
                if (fattr->valid & NFS_ATTR_FATTR_CTIME)
                        inode->i_ctime = fattr->ctime;
                if (fattr->valid & NFS_ATTR_FATTR_CHANGE)
                        nfsi->change_attr = fattr->change_attr;
                if (fattr->valid & NFS_ATTR_FATTR_SIZE)
                        inode->i_size = nfs_size_to_loff_t(fattr->size);
                if (fattr->valid & NFS_ATTR_FATTR_NLINK)
                        inode->i_nlink = fattr->nlink;
                if (fattr->valid & NFS_ATTR_FATTR_OWNER)
                        inode->i_uid = fattr->uid;
                if (fattr->valid & NFS_ATTR_FATTR_GROUP)
                        inode->i_gid = fattr->gid;
                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);
                }
                nfsi->attrtimeo = NFS_MINATTRTIMEO(inode);
                nfsi->attrtimeo_timestamp = now;
                nfsi->access_cache = RB_ROOT;

                nfs_fscache_init_inode_cookie(inode);

                unlock_new_inode(inode);
        } else
                nfs_refresh_inode(inode, fattr);
        dprintk("NFS: nfs_fhget(%s/%Ld ct=%d)\n",
                inode->i_sb->s_id,
                (long long)NFS_FILEID(inode),
                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;
}

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

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

        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) == 0)
                return 0;

        /* Write all dirty data */
        if (S_ISREG(inode->i_mode)) {
                filemap_write_and_wait(inode->i_mapping);
                nfs_wb_all(inode);
        }
        /*
         * Return any delegations if we're going to change ACLs
         */
        if ((attr->ia_valid & (ATTR_MODE|ATTR_UID|ATTR_GID)) != 0)
                nfs_inode_return_delegation(inode);
        error = NFS_PROTO(inode)->setattr(dentry, &fattr, attr);
        if (error == 0)
                nfs_refresh_inode(inode, &fattr);
        return error;
}

/**
 * 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)
{
        if (i_size_read(inode) < offset) {
                unsigned long limit;

                limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
                if (limit != RLIM_INFINITY && offset > limit)
                        goto out_sig;
                if (offset > inode->i_sb->s_maxbytes)
                        goto out_big;
                spin_lock(&inode->i_lock);
                i_size_write(inode, offset);
                spin_unlock(&inode->i_lock);
        } else {
                struct address_space *mapping = inode->i_mapping;

                /*
                 * truncation of in-use swapfiles is disallowed - it would
                 * cause subsequent swapout to scribble on the now-freed
                 * blocks.
                 */
                if (IS_SWAPFILE(inode))
                        return -ETXTBSY;
                spin_lock(&inode->i_lock);
                i_size_write(inode, offset);
                spin_unlock(&inode->i_lock);

                /*
                 * unmap_mapping_range is called twice, first simply for
                 * efficiency so that truncate_inode_pages does fewer
                 * single-page unmaps.  However after this first call, and
                 * before truncate_inode_pages finishes, it is possible for
                 * private pages to be COWed, which remain after
                 * truncate_inode_pages finishes, hence the second
                 * unmap_mapping_range call must be made for correctness.
                 */
                unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
                truncate_inode_pages(mapping, offset);
                unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
        }
        return 0;
out_sig:
        send_sig(SIGXFSZ, current, 0);
out_big:
        return -EFBIG;
}

/**
 * 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);
        }
}

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;

        /*
         * Flush out writes to the server in order to update c/mtime.
         *
         * Hold the i_mutex to suspend application writes temporarily;
         * this prevents long-running writing applications from blocking
         * nfs_wb_nocommit.
         */
        if (S_ISREG(inode->i_mode)) {
                mutex_lock(&inode->i_mutex);
                nfs_wb_nocommit(inode);
                mutex_unlock(&inode->i_mutex);
        }

        /*
         * 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)
                err = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
        else
                err = nfs_revalidate_inode(NFS_SERVER(inode), inode);
        if (!err) {
                generic_fillattr(inode, stat);
                stat->ino = nfs_compat_user_ino64(NFS_FILEID(inode));
        }
        return err;
}

/**
 * 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->path.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);
}

static struct nfs_open_context *alloc_nfs_open_context(struct vfsmount *mnt, struct dentry *dentry, struct rpc_cred *cred)
{
        struct nfs_open_context *ctx;

        ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
        if (ctx != NULL) {
                ctx->path.dentry = dget(dentry);
                ctx->path.mnt = mntget(mnt);
                ctx->cred = get_rpccred(cred);
                ctx->state = NULL;
                ctx->lockowner = current->files;
                ctx->flags = 0;
                ctx->error = 0;
                ctx->dir_cookie = 0;
                atomic_set(&ctx->count, 1);
        }
        return ctx;
}

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

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

        if (!atomic_dec_and_lock(&ctx->count, &inode->i_lock))
                return;
        list_del(&ctx->list);
        spin_unlock(&inode->i_lock);
        NFS_PROTO(inode)->close_context(ctx, is_sync);
        if (ctx->cred != NULL)
                put_rpccred(ctx->cred);
        path_put(&ctx->path);
        kfree(ctx);
}

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

static void put_nfs_open_context_sync(struct nfs_open_context *ctx)
{
        __put_nfs_open_context(ctx, 1);
}

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

        filp->private_data = get_nfs_open_context(ctx);
        spin_lock(&inode->i_lock);
        list_add(&ctx->list, &nfsi->open_files);
        spin_unlock(&inode->i_lock);
}

/*
 * 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 & mode) == mode) {
                        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 inode *inode = filp->f_path.dentry->d_inode;
        struct nfs_open_context *ctx = nfs_file_open_context(filp);

        if (ctx) {
                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_sync(ctx);
        }
}

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

        cred = rpc_lookup_cred();
        if (IS_ERR(cred))
                return PTR_ERR(cred);
        ctx = alloc_nfs_open_context(filp->f_path.mnt, filp->f_path.dentry, cred);
        put_rpccred(cred);
        if (ctx == NULL)
                return -ENOMEM;
        ctx->mode = filp->f_mode;
        nfs_file_set_open_context(filp, ctx);
        put_nfs_open_context(ctx);
        nfs_fscache_set_inode_cookie(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 nfs_fattr fattr;
        struct nfs_inode *nfsi = NFS_I(inode);

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

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

        nfs_inc_stats(inode, NFSIOS_INODEREVALIDATE);
        status = NFS_PROTO(inode)->getattr(server, NFS_FH(inode), &fattr);
        if (status != 0) {
                dfprintk(PAGECACHE, "nfs_revalidate_inode: (%s/%Ld) getattr failed, error=%d\n",
                         inode->i_sb->s_id,
                         (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 out;
        }

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

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

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

 out:
        return status;
}

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

        if (nfs_have_delegation(inode, FMODE_READ))
                return 0;
        return !time_in_range_open(jiffies, nfsi->read_cache_jiffies, nfsi->read_cache_jiffies + nfsi->attrtimeo);
}

/**
 * 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_I(inode)->cache_validity & NFS_INO_INVALID_ATTR)
                        && !nfs_attribute_timeout(inode))
                return NFS_STALE(inode) ? -ESTALE : 0;
        return __nfs_revalidate_inode(server, inode);
}

static int nfs_invalidate_mapping_nolock(struct inode *inode, struct address_space *mapping)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        
        if (mapping->nrpages != 0) {
                int ret = invalidate_inode_pages2(mapping);
                if (ret < 0)
                        return ret;
        }
        spin_lock(&inode->i_lock);
        nfsi->cache_validity &= ~NFS_INO_INVALID_DATA;
        if (S_ISDIR(inode->i_mode))
                memset(nfsi->cookieverf, 0, sizeof(nfsi->cookieverf));
        spin_unlock(&inode->i_lock);
        nfs_inc_stats(inode, NFSIOS_DATAINVALIDATE);
        nfs_fscache_reset_inode_cookie(inode);
        dfprintk(PAGECACHE, "NFS: (%s/%Ld) data cache invalidated\n",
                        inode->i_sb->s_id, (long long)NFS_FILEID(inode));
        return 0;
}

static int nfs_invalidate_mapping(struct inode *inode, struct address_space *mapping)
{
        int ret = 0;

        mutex_lock(&inode->i_mutex);
        if (NFS_I(inode)->cache_validity & NFS_INO_INVALID_DATA) {
                ret = nfs_sync_mapping(mapping);
                if (ret == 0)
                        ret = nfs_invalidate_mapping_nolock(inode, mapping);
        }
        mutex_unlock(&inode->i_mutex);
        return ret;
}

/**
 * nfs_revalidate_mapping_nolock - Revalidate the pagecache
 * @inode - pointer to host inode
 * @mapping - pointer to mapping
 */
int nfs_revalidate_mapping_nolock(struct inode *inode, struct address_space *mapping)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        int ret = 0;

        if ((nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
                        || nfs_attribute_timeout(inode) || NFS_STALE(inode)) {
                ret = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
                if (ret < 0)
                        goto out;
        }
        if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
                ret = nfs_invalidate_mapping_nolock(inode, mapping);
out:
        return ret;
}

/**
 * nfs_revalidate_mapping - Revalidate the pagecache
 * @inode - pointer to host inode
 * @mapping - pointer to mapping
 *
 * This version of the function will take the inode->i_mutex and attempt to
 * flush out all dirty data if it needs to invalidate the page cache.
 */
int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
{
        struct nfs_inode *nfsi = NFS_I(inode);
        int ret = 0;

        if ((nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
                        || nfs_attribute_timeout(inode) || NFS_STALE(inode)) {
                ret = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
                if (ret < 0)
                        goto out;
        }
        if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
                ret = nfs_invalidate_mapping(inode, mapping);
out:
        return ret;
}

static void nfs_wcc_update_inode(struct inode *inode, struct nfs_fattr *fattr)
{
        struct nfs_inode *nfsi = NFS_I(inode);

        if ((fattr->valid & NFS_ATTR_FATTR_PRECHANGE)
                        && (fattr->valid & NFS_ATTR_FATTR_CHANGE)
                        && nfsi->change_attr == fattr->pre_change_attr) {
                nfsi->change_attr = fattr->change_attr;
                if (S_ISDIR(inode->i_mode))
                        nfsi->cache_validity |= NFS_INO_INVALID_DATA;
        }
        /* 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));

        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;
        }
        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));
}

/**
 * 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;


        /* 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 &&
                        nfsi->change_attr != 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|NFS_INO_REVAL_PAGECACHE;

        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) && 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) && 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();
}

/**
 * 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);
}

static int nfs_refresh_inode_locked(struct inode *inode, struct nfs_fattr *fattr)
{
        if (nfs_inode_attrs_need_update(inode, fattr))
                return nfs_update_inode(inode, fattr);
        return nfs_check_inode_attributes(inode, fattr);
}

/**
 * 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;
}

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;
        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;
}

/**
 * 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 = NFS_I(inode)->change_attr;
                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;
}

/*
 * 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;

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

        if ((fattr->valid & NFS_ATTR_FATTR_FILEID) && nfsi->fileid != fattr->fileid)
                goto out_fileid;

        /*
         * 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))
                goto out_changed;

        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) &&
                        !test_bit(NFS_INO_MOUNTPOINT, &nfsi->flags))
                server->fsid = fattr->fsid;

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

        if ((fattr->valid & NFS_ATTR_FATTR_CHANGE) || (fattr->valid & (NFS_ATTR_FATTR_MTIME|NFS_ATTR_FATTR_CTIME)))
            nfsi->cache_validity &= ~(NFS_INO_INVALID_ATTR
                    | NFS_INO_INVALID_ATIME
                    | NFS_INO_REVAL_PAGECACHE);

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

        /* More cache consistency checks */
        if (fattr->valid & NFS_ATTR_FATTR_CHANGE) {
                if (nfsi->change_attr != 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;
                        if (S_ISDIR(inode->i_mode))
                                nfs_force_lookup_revalidate(inode);
                        nfsi->change_attr = fattr->change_attr;
                }
        }

        if (fattr->valid & NFS_ATTR_FATTR_MTIME) {
                /* NFSv2/v3: Check if the mtime agrees */
                if (!timespec_equal(&inode->i_mtime, &fattr->mtime)) {
                        dprintk("NFS: mtime 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;
                        if (S_ISDIR(inode->i_mode))
                                nfs_force_lookup_revalidate(inode);
                        memcpy(&inode->i_mtime, &fattr->mtime, sizeof(inode->i_mtime));
                }
        }
        if (fattr->valid & NFS_ATTR_FATTR_CTIME) {
                /* If ctime has changed we should definitely clear access+acl caches */
                if (!timespec_equal(&inode->i_ctime, &fattr->ctime)) {
                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                        /* and probably clear data for a directory too as utimes can cause
                         * havoc with our cache.
                         */
                        if (S_ISDIR(inode->i_mode)) {
                                invalid |= NFS_INO_INVALID_DATA;
                                nfs_force_lookup_revalidate(inode);
                        }
                        memcpy(&inode->i_ctime, &fattr->ctime, sizeof(inode->i_ctime));
                }
        }

        /* 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\n",
                                        inode->i_sb->s_id, inode->i_ino);
                }
        }


        if (fattr->valid & NFS_ATTR_FATTR_ATIME)
                memcpy(&inode->i_atime, &fattr->atime, sizeof(inode->i_atime));

        if (fattr->valid & NFS_ATTR_FATTR_MODE) {
                if ((inode->i_mode & S_IALLUGO) != (fattr->mode & S_IALLUGO)) {
                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                        inode->i_mode = fattr->mode;
                }
        }
        if (fattr->valid & NFS_ATTR_FATTR_OWNER) {
                if (inode->i_uid != fattr->uid) {
                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                        inode->i_uid = fattr->uid;
                }
        }
        if (fattr->valid & NFS_ATTR_FATTR_GROUP) {
                if (inode->i_gid != fattr->gid) {
                        invalid |= NFS_INO_INVALID_ATTR|NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
                        inode->i_gid = fattr->gid;
                }
        }

        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;
                        inode->i_nlink = fattr->nlink;
                }
        }

        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_have_delegation(inode, FMODE_READ) ||
                        (nfsi->cache_validity & NFS_INO_REVAL_FORCED))
                nfsi->cache_validity |= invalid;
        nfsi->cache_validity &= ~NFS_INO_REVAL_FORCED;

        return 0;
 out_changed:
        /*
         * Big trouble! The inode has become a different object.
         */
        printk(KERN_DEBUG "%s: inode %ld mode changed, %07o to %07o\n",
                        __func__, inode->i_ino, inode->i_mode, fattr->mode);
 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;

 out_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;
}


#ifdef CONFIG_NFS_V4

/*
 * Clean out any remaining NFSv4 state that might be left over due
 * to open() calls that passed nfs_atomic_lookup, but failed to call
 * nfs_open().
 */
void nfs4_clear_inode(struct inode *inode)
{
        /* If we are holding a delegation, return it! */
        nfs_inode_return_delegation_noreclaim(inode);
        /* First call standard NFS clear_inode() code */
        nfs_clear_inode(inode);
}
#endif

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;
#ifdef CONFIG_NFS_V3_ACL
        nfsi->acl_access = ERR_PTR(-EAGAIN);
        nfsi->acl_default = ERR_PTR(-EAGAIN);
#endif
#ifdef CONFIG_NFS_V4
        nfsi->nfs4_acl = NULL;
#endif /* CONFIG_NFS_V4 */
        return &nfsi->vfs_inode;
}

void nfs_destroy_inode(struct inode *inode)
{
        kmem_cache_free(nfs_inode_cachep, NFS_I(inode));
}

static inline void nfs4_init_once(struct nfs_inode *nfsi)
{
#ifdef CONFIG_NFS_V4
        INIT_LIST_HEAD(&nfsi->open_states);
        nfsi->delegation = NULL;
        nfsi->delegation_state = 0;
        init_rwsem(&nfsi->rwsem);
#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_RADIX_TREE(&nfsi->nfs_page_tree, GFP_ATOMIC);
        nfsi->npages = 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)
{
        kmem_cache_destroy(nfs_inode_cachep);
}

struct workqueue_struct *nfsiod_workqueue;

/*
 * start up the nfsiod workqueue
 */
static int nfsiod_start(void)
{
        struct workqueue_struct *wq;
        dprintk("RPC:       creating workqueue nfsiod\n");
        wq = create_singlethread_workqueue("nfsiod");
        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);
}

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

        err = nfs_fscache_register();
        if (err < 0)
                goto out7;

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

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

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

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

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

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

        err = nfs_init_directcache();
        if (err)
                goto out0;

#ifdef CONFIG_PROC_FS
        rpc_proc_register(&nfs_rpcstat);
#endif
        if ((err = register_nfs_fs()) != 0)
                goto out;
        return 0;
out:
#ifdef CONFIG_PROC_FS
        rpc_proc_unregister("nfs");
#endif
        nfs_destroy_directcache();
out0:
        nfs_destroy_writepagecache();
out1:
        nfs_destroy_readpagecache();
out2:
        nfs_destroy_inodecache();
out3:
        nfs_destroy_nfspagecache();
out4:
        nfs_fs_proc_exit();
out5:
        nfsiod_stop();
out6:
        nfs_fscache_unregister();
out7:
        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();
#ifdef CONFIG_PROC_FS
        rpc_proc_unregister("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)