Import 2.2.6pre1

[davej-history.git] / 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.Cox@linux.org>, 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/config.h>
#include <linux/module.h>

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/locks.h>
#include <linux/unistd.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/stats.h>
#include <linux/nfs_fs.h>
#include <linux/lockd/bind.h>

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

#define CONFIG_NFS_SNAPSHOT 1
#define NFSDBG_FACILITY         NFSDBG_VFS
#define NFS_PARANOIA 1

static struct inode * __nfs_fhget(struct super_block *, struct nfs_fattr *);

static void nfs_read_inode(struct inode *);
static void nfs_put_inode(struct inode *);
static void nfs_delete_inode(struct inode *);
static int  nfs_notify_change(struct dentry *, struct iattr *);
static void nfs_put_super(struct super_block *);
static void nfs_umount_begin(struct super_block *);
static int  nfs_statfs(struct super_block *, struct statfs *, int);

static struct super_operations nfs_sops = { 
        nfs_read_inode,         /* read inode */
        NULL,                   /* write inode */
        nfs_put_inode,          /* put inode */
        nfs_delete_inode,       /* delete inode */
        nfs_notify_change,      /* notify change */
        nfs_put_super,          /* put superblock */
        NULL,                   /* write superblock */
        nfs_statfs,             /* stat filesystem */
        NULL,                   /* no remount */
        NULL,                   /* no clear inode */
        nfs_umount_begin        /* umount attempt begin */
};

struct rpc_stat                 nfs_rpcstat = { &nfs_program };

/*
 * The "read_inode" function doesn't actually do anything:
 * the real data is filled in later in nfs_fhget. Here we
 * just mark the cache times invalid, and zero out i_mode
 * (the latter makes "nfs_refresh_inode" do the right thing
 * wrt pipe inodes)
 */
static void
nfs_read_inode(struct inode * inode)
{
        inode->i_blksize = inode->i_sb->s_blocksize;
        inode->i_mode = 0;
        inode->i_rdev = 0;
        inode->i_op = NULL;
        NFS_CACHEINV(inode);
        NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
}

static void
nfs_put_inode(struct inode * inode)
{
        dprintk("NFS: put_inode(%x/%ld)\n", inode->i_dev, inode->i_ino);
        /*
         * We want to get rid of unused inodes ...
         */
        if (inode->i_count == 1)
                inode->i_nlink = 0;
}

static void
nfs_delete_inode(struct inode * inode)
{
        int failed;

        dprintk("NFS: delete_inode(%x/%ld)\n", inode->i_dev, inode->i_ino);
        /*
         * Flush out any pending write requests ...
         */
        if (NFS_WRITEBACK(inode) != NULL) {
                unsigned long timeout = jiffies + 5*HZ;
#ifdef NFS_DEBUG_VERBOSE
printk("nfs_delete_inode: inode %ld has pending RPC requests\n", inode->i_ino);
#endif
                nfs_inval(inode);
                while (NFS_WRITEBACK(inode) != NULL &&
                       time_before(jiffies, timeout)) {
                        current->state = TASK_INTERRUPTIBLE;
                        schedule_timeout(HZ/10);
                }
                current->state = TASK_RUNNING;
                if (NFS_WRITEBACK(inode) != NULL)
                        printk("NFS: Arghhh, stuck RPC requests!\n");
        }

        failed = nfs_check_failed_request(inode);
        if (failed)
                printk("NFS: inode %ld had %d failed requests\n",
                        inode->i_ino, failed);
        clear_inode(inode);
}

void
nfs_put_super(struct super_block *sb)
{
        struct nfs_server *server = &sb->u.nfs_sb.s_server;
        struct rpc_clnt *rpc;

        if ((rpc = server->client) != NULL)
                rpc_shutdown_client(rpc);

        if (!(server->flags & NFS_MOUNT_NONLM))
                lockd_down();   /* release rpc.lockd */
        rpciod_down();          /* release rpciod */
        /*
         * Invalidate the dircache for this superblock.
         */
        nfs_invalidate_dircache_sb(sb);

        kfree(server->hostname);

        MOD_DEC_USE_COUNT;
}

void
nfs_umount_begin(struct super_block *sb)
{
        struct nfs_server *server = &sb->u.nfs_sb.s_server;
        struct rpc_clnt *rpc;

        /* -EIO all pending I/O */
        if ((rpc = server->client) != NULL)
                rpc_killall_tasks(rpc);
}

/*
 * Compute and set NFS server blocksize
 */
static unsigned int
nfs_block_size(unsigned int bsize, unsigned char *nrbitsp)
{
        if (bsize < 1024)
                bsize = NFS_DEF_FILE_IO_BUFFER_SIZE;
        else if (bsize >= NFS_MAX_FILE_IO_BUFFER_SIZE)
                bsize = NFS_MAX_FILE_IO_BUFFER_SIZE;

        /* make sure blocksize is a power of two */
        if ((bsize & (bsize - 1)) || nrbitsp) {
                unsigned int    nrbits;

                for (nrbits = 31; nrbits && !(bsize & (1 << nrbits)); nrbits--)
                        ;
                bsize = 1 << nrbits;
                if (nrbitsp)
                        *nrbitsp = nrbits;
                if (bsize < NFS_DEF_FILE_IO_BUFFER_SIZE)
                        bsize = NFS_DEF_FILE_IO_BUFFER_SIZE;
        }

        return bsize;
}

/*
 * The way this works is that the mount process passes a structure
 * in the data argument which contains the server's IP address
 * and the root file handle obtained from the server's mount
 * daemon. We stash these away in the private superblock fields.
 */
struct super_block *
nfs_read_super(struct super_block *sb, void *raw_data, int silent)
{
        struct nfs_mount_data   *data = (struct nfs_mount_data *) raw_data;
        struct nfs_server       *server;
        struct rpc_xprt         *xprt;
        struct rpc_clnt         *clnt;
        struct nfs_fh           *root_fh;
        struct inode            *root_inode;
        unsigned int            authflavor;
        int                     tcp;
        struct sockaddr_in      srvaddr;
        struct rpc_timeout      timeparms;
        struct nfs_fattr        fattr;

        MOD_INC_USE_COUNT;
        if (!data)
                goto out_miss_args;

        if (data->version != NFS_MOUNT_VERSION) {
                printk("nfs warning: mount version %s than kernel\n",
                        data->version < NFS_MOUNT_VERSION ? "older" : "newer");
                if (data->version < 2)
                        data->namlen = 0;
                if (data->version < 3)
                        data->bsize  = 0;
        }

        /* We now require that the mount process passes the remote address */
        memcpy(&srvaddr, &data->addr, sizeof(srvaddr));
        if (srvaddr.sin_addr.s_addr == INADDR_ANY)
                goto out_no_remote;

        lock_super(sb);

        sb->s_flags |= MS_ODD_RENAME; /* This should go away */

        sb->s_magic      = NFS_SUPER_MAGIC;
        sb->s_op         = &nfs_sops;
        sb->s_blocksize  = nfs_block_size(data->bsize, &sb->s_blocksize_bits);
        sb->u.nfs_sb.s_root = data->root;
        server           = &sb->u.nfs_sb.s_server;
        server->rsize    = nfs_block_size(data->rsize, NULL);
        server->wsize    = nfs_block_size(data->wsize, NULL);
        server->flags    = data->flags;
        server->acregmin = data->acregmin*HZ;
        server->acregmax = data->acregmax*HZ;
        server->acdirmin = data->acdirmin*HZ;
        server->acdirmax = data->acdirmax*HZ;

        server->hostname = kmalloc(strlen(data->hostname) + 1, GFP_KERNEL);
        if (!server->hostname)
                goto out_unlock;
        strcpy(server->hostname, data->hostname);

        /* Which protocol do we use? */
        tcp   = (data->flags & NFS_MOUNT_TCP);

        /* Initialize timeout values */
        timeparms.to_initval = data->timeo * HZ / 10;
        timeparms.to_retries = data->retrans;
        timeparms.to_maxval  = tcp? RPC_MAX_TCP_TIMEOUT : RPC_MAX_UDP_TIMEOUT;
        timeparms.to_exponential = 1;

        /* Now create transport and client */
        xprt = xprt_create_proto(tcp? IPPROTO_TCP : IPPROTO_UDP,
                                                &srvaddr, &timeparms);
        if (xprt == NULL)
                goto out_no_xprt;

        /* Choose authentication flavor */
        authflavor = RPC_AUTH_UNIX;
        if (data->flags & NFS_MOUNT_SECURE)
                authflavor = RPC_AUTH_DES;
        else if (data->flags & NFS_MOUNT_KERBEROS)
                authflavor = RPC_AUTH_KRB;

        clnt = rpc_create_client(xprt, server->hostname, &nfs_program,
                                                NFS_VERSION, authflavor);
        if (clnt == NULL)
                goto out_no_client;

        clnt->cl_intr     = (data->flags & NFS_MOUNT_INTR)? 1 : 0;
        clnt->cl_softrtry = (data->flags & NFS_MOUNT_SOFT)? 1 : 0;
        clnt->cl_chatty   = 1;
        server->client    = clnt;

        /* Fire up rpciod if not yet running */
        if (rpciod_up() != 0)
                goto out_no_iod;

        /*
         * Keep the super block locked while we try to get 
         * the root fh attributes.
         */
        root_fh = kmalloc(sizeof(struct nfs_fh), GFP_KERNEL);
        if (!root_fh)
                goto out_no_fh;
        *root_fh = data->root;

        if (nfs_proc_getattr(server, root_fh, &fattr) != 0)
                goto out_no_fattr;

        root_inode = __nfs_fhget(sb, &fattr);
        if (!root_inode)
                goto out_no_root;
        sb->s_root = d_alloc_root(root_inode, NULL);
        if (!sb->s_root)
                goto out_no_root;
        sb->s_root->d_op = &nfs_dentry_operations;
        sb->s_root->d_fsdata = root_fh;

        /* We're airborne */
        unlock_super(sb);

        /* Check whether to start the lockd process */
        if (!(server->flags & NFS_MOUNT_NONLM))
                lockd_up();
        return sb;

        /* Yargs. It didn't work out. */
out_no_root:
        printk("nfs_read_super: get root inode failed\n");
        iput(root_inode);
        goto out_free_fh;

out_no_fattr:
        printk("nfs_read_super: get root fattr failed\n");
out_free_fh:
        kfree(root_fh);
out_no_fh:
        rpciod_down();
        goto out_shutdown;

out_no_iod:
        printk(KERN_WARNING "NFS: couldn't start rpciod!\n");
out_shutdown:
        rpc_shutdown_client(server->client);
        goto out_free_host;

out_no_client:
        printk(KERN_WARNING "NFS: cannot create RPC client.\n");
        xprt_destroy(xprt);
        goto out_free_host;

out_no_xprt:
        printk(KERN_WARNING "NFS: cannot create RPC transport.\n");

out_free_host:
        kfree(server->hostname);
out_unlock:
        unlock_super(sb);
        goto out_fail;

out_no_remote:
        printk("NFS: mount program didn't pass remote address!\n");
        goto out_fail;

out_miss_args:
        printk("nfs_read_super: missing data argument\n");

out_fail:
        sb->s_dev = 0;
        MOD_DEC_USE_COUNT;
        return NULL;
}

static int
nfs_statfs(struct super_block *sb, struct statfs *buf, int bufsiz)
{
        int error;
        struct nfs_fsinfo res;
        struct statfs tmp;

        error = nfs_proc_statfs(&sb->u.nfs_sb.s_server, &sb->u.nfs_sb.s_root,
                &res);
        if (error) {
                printk("nfs_statfs: statfs error = %d\n", -error);
                res.bsize = res.blocks = res.bfree = res.bavail = 0;
        }
        tmp.f_type = NFS_SUPER_MAGIC;
        tmp.f_bsize = res.bsize;
        tmp.f_blocks = res.blocks;
        tmp.f_bfree = res.bfree;
        tmp.f_bavail = res.bavail;
        tmp.f_files = 0;
        tmp.f_ffree = 0;
        tmp.f_namelen = NAME_MAX;
        return copy_to_user(buf, &tmp, bufsiz) ? -EFAULT : 0;
}

/*
 * Free all unused dentries in an inode's alias list.
 *
 * Subtle note: we have to be very careful not to cause
 * any IO operations with the stale dentries, as this
 * could cause file corruption. But since the dentry
 * count is 0 and all pending IO for a dentry has been
 * flushed when the count went to 0, we're safe here.
 */
void nfs_free_dentries(struct inode *inode)
{
        struct list_head *tmp, *head = &inode->i_dentry;

restart:
        tmp = head;
        while ((tmp = tmp->next) != head) {
                struct dentry *dentry = list_entry(tmp, struct dentry, d_alias);
printk("nfs_free_dentries: found %s/%s, d_count=%d, hashed=%d\n",
dentry->d_parent->d_name.name, dentry->d_name.name,
dentry->d_count, !list_empty(&dentry->d_hash));
                if (!dentry->d_count) {
                        dget(dentry);
                        d_drop(dentry);
                        dput(dentry);
                        goto restart;
                }
        }
}

/*
 * Fill in inode information from the fattr.
 */
static void
nfs_fill_inode(struct inode *inode, struct nfs_fattr *fattr)
{
        /*
         * Check whether the mode has been set, as we only want to
         * do this once. (We don't allow inodes to change types.)
         */
        if (inode->i_mode == 0) {
                inode->i_mode = fattr->mode;
                if (S_ISREG(inode->i_mode))
                        inode->i_op = &nfs_file_inode_operations;
                else if (S_ISDIR(inode->i_mode))
                        inode->i_op = &nfs_dir_inode_operations;
                else if (S_ISLNK(inode->i_mode))
                        inode->i_op = &nfs_symlink_inode_operations;
                else if (S_ISCHR(inode->i_mode)) {
                        inode->i_op = &chrdev_inode_operations;
                        inode->i_rdev = to_kdev_t(fattr->rdev);
                } else if (S_ISBLK(inode->i_mode)) {
                        inode->i_op = &blkdev_inode_operations;
                        inode->i_rdev = to_kdev_t(fattr->rdev);
                } else if (S_ISFIFO(inode->i_mode))
                        init_fifo(inode);
                else
                        inode->i_op = NULL;
                /*
                 * Preset the size and mtime, as there's no need
                 * to invalidate the caches.
                 */ 
                inode->i_size  = fattr->size;
                inode->i_mtime = fattr->mtime.seconds;
                NFS_OLDMTIME(inode) = fattr->mtime.seconds;
        }
        nfs_refresh_inode(inode, fattr);
}

/*
 * This is our own version of iget that looks up inodes by file handle
 * instead of inode number.  We use this technique instead of using
 * the vfs read_inode function because there is no way to pass the
 * file handle or current attributes into the read_inode function.
 *
 * We provide a special check for NetApp .snapshot directories to avoid
 * inode aliasing problems. All snapshot inodes are anonymous (unhashed).
 */
struct inode *
nfs_fhget(struct dentry *dentry, struct nfs_fh *fhandle,
                                 struct nfs_fattr *fattr)
{
        struct super_block *sb = dentry->d_sb;

        dprintk("NFS: nfs_fhget(%s/%s fileid=%d)\n",
                dentry->d_parent->d_name.name, dentry->d_name.name,
                fattr->fileid);

        /* Install the file handle in the dentry */
        *((struct nfs_fh *) dentry->d_fsdata) = *fhandle;

#ifdef CONFIG_NFS_SNAPSHOT
        /*
         * Check for NetApp snapshot dentries, and get an 
         * unhashed inode to avoid aliasing problems.
         */
        if ((dentry->d_parent->d_inode->u.nfs_i.flags & NFS_IS_SNAPSHOT) ||
            (dentry->d_name.len == 9 &&
             memcmp(dentry->d_name.name, ".snapshot", 9) == 0)) {
                struct inode *inode = get_empty_inode();
                if (!inode)
                        goto out;       
                inode->i_sb = sb;
                inode->i_dev = sb->s_dev;
                inode->i_flags = 0;
                inode->i_ino = fattr->fileid;
                nfs_read_inode(inode);
                nfs_fill_inode(inode, fattr);
                inode->u.nfs_i.flags |= NFS_IS_SNAPSHOT;
                dprintk("NFS: nfs_fhget(snapshot ino=%ld)\n", inode->i_ino);
        out:
                return inode;
        }
#endif
        return __nfs_fhget(sb, fattr);
}

/*
 * Look up the inode by super block and fattr->fileid.
 *
 * Note carefully the special handling of busy inodes (i_count > 1).
 * With the kernel 2.1.xx dcache all inodes except hard links must
 * have i_count == 1 after iget(). Otherwise, it indicates that the
 * server has reused a fileid (i_ino) and we have a stale inode.
 */
static struct inode *
__nfs_fhget(struct super_block *sb, struct nfs_fattr *fattr)
{
        struct inode *inode;
        int max_count;

retry:
        inode = iget(sb, fattr->fileid);
        if (!inode)
                goto out_no_inode;
        /* N.B. This should be impossible ... */
        if (inode->i_ino != fattr->fileid)
                goto out_bad_id;

        /*
         * Check for busy inodes, and attempt to get rid of any
         * unused local references. If successful, we release the
         * inode and try again.
         *
         * Note that the busy test uses the values in the fattr,
         * as the inode may have become a different object.
         * (We can probably handle modes changes here, too.)
         */
        max_count = S_ISDIR(fattr->mode) ? 1 : fattr->nlink;
        if (inode->i_count > max_count) {
printk("__nfs_fhget: inode %ld busy, i_count=%d, i_nlink=%d\n",
inode->i_ino, inode->i_count, inode->i_nlink);
                nfs_free_dentries(inode);
                if (inode->i_count > max_count) {
printk("__nfs_fhget: inode %ld still busy, i_count=%d\n",
inode->i_ino, inode->i_count);
                        if (!list_empty(&inode->i_dentry)) {
                                struct dentry *dentry;
                                dentry = list_entry(inode->i_dentry.next,
                                                 struct dentry, d_alias);
printk("__nfs_fhget: killing %s/%s filehandle\n",
dentry->d_parent->d_name.name, dentry->d_name.name);
                                memset(dentry->d_fsdata, 0, 
                                        sizeof(struct nfs_fh));
                        } else
                                printk("NFS: inode %ld busy, no aliases?\n",
                                        inode->i_ino);
                        make_bad_inode(inode);
                        remove_inode_hash(inode);
                }
                iput(inode);
                goto retry;
        }
        nfs_fill_inode(inode, fattr);
        dprintk("NFS: __nfs_fhget(%x/%ld ct=%d)\n",
                inode->i_dev, inode->i_ino, inode->i_count);

out:
        return inode;

out_no_inode:
        printk("__nfs_fhget: iget failed\n");
        goto out;
out_bad_id:
        printk("__nfs_fhget: unexpected inode from iget\n");
        goto out;
}

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

        /*
         * Make sure the inode is up-to-date.
         */
        error = nfs_revalidate(dentry);
        if (error) {
#ifdef NFS_PARANOIA
printk("nfs_notify_change: revalidate failed, error=%d\n", error);
#endif
                goto out;
        }

        sattr.mode = (u32) -1;
        if (attr->ia_valid & ATTR_MODE) 
                sattr.mode = attr->ia_mode;

        sattr.uid = (u32) -1;
        if (attr->ia_valid & ATTR_UID)
                sattr.uid = attr->ia_uid;

        sattr.gid = (u32) -1;
        if (attr->ia_valid & ATTR_GID)
                sattr.gid = attr->ia_gid;

        sattr.size = (u32) -1;
        if ((attr->ia_valid & ATTR_SIZE) && S_ISREG(inode->i_mode))
                sattr.size = attr->ia_size;

        sattr.mtime.seconds = sattr.mtime.useconds = (u32) -1;
        if (attr->ia_valid & ATTR_MTIME) {
                sattr.mtime.seconds = attr->ia_mtime;
                sattr.mtime.useconds = 0;
        }

        sattr.atime.seconds = sattr.atime.useconds = (u32) -1;
        if (attr->ia_valid & ATTR_ATIME) {
                sattr.atime.seconds = attr->ia_atime;
                sattr.atime.useconds = 0;
        }

        error = nfs_wb_all(inode);
        if (error)
                goto out;

        error = nfs_proc_setattr(NFS_DSERVER(dentry), NFS_FH(dentry),
                                &sattr, &fattr);
        if (error)
                goto out;
        /*
         * If we changed the size or mtime, update the inode
         * now to avoid invalidating the page cache.
         */
        if (sattr.size != (u32) -1) {
                if (sattr.size != fattr.size)
                        printk("nfs_notify_change: sattr=%d, fattr=%d??\n",
                                sattr.size, fattr.size);
                inode->i_size  = sattr.size;
                inode->i_mtime = fattr.mtime.seconds;
        }
        if (sattr.mtime.seconds != (u32) -1)
                inode->i_mtime = fattr.mtime.seconds;
        error = nfs_refresh_inode(inode, &fattr);
out:
        return error;
}

/*
 * Externally visible revalidation function
 */
int
nfs_revalidate(struct dentry *dentry)
{
        return nfs_revalidate_inode(NFS_DSERVER(dentry), dentry);
}

/*
 * 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 dentry *dentry)
{
        struct inode    *inode = dentry->d_inode;
        int              status = 0;
        struct nfs_fattr fattr;

        /* Don't bother revalidating if we've done it recently */
        if (jiffies - NFS_READTIME(inode) < NFS_ATTRTIMEO(inode))
                goto out;

        dfprintk(PAGECACHE, "NFS: revalidating %s/%s, ino=%ld\n",
                dentry->d_parent->d_name.name, dentry->d_name.name,
                inode->i_ino);
        status = nfs_proc_getattr(server, NFS_FH(dentry), &fattr);
        if (status) {
                int error;
                u32 *fh;
                struct nfs_fh fhandle;
#ifdef NFS_PARANOIA
printk("nfs_revalidate_inode: %s/%s getattr failed, ino=%ld, error=%d\n",
dentry->d_parent->d_name.name, dentry->d_name.name, inode->i_ino, status);
#endif
                if (status != -ESTALE)
                        goto out;
                /*
                 * A "stale filehandle" error ... show the current fh
                 * and find out what the filehandle should be.
                 */
                fh = (u32 *) NFS_FH(dentry);
                printk("NFS: bad fh %08x%08x%08x%08x%08x%08x%08x%08x\n",
                        fh[0],fh[1],fh[2],fh[3],fh[4],fh[5],fh[6],fh[7]);
                error = nfs_proc_lookup(server, NFS_FH(dentry->d_parent), 
                                        dentry->d_name.name, &fhandle, &fattr);
                if (error) {
                        printk("NFS: lookup failed, error=%d\n", error);
                        goto out;
                }
                fh = (u32 *) &fhandle;
                printk("            %08x%08x%08x%08x%08x%08x%08x%08x\n",
                        fh[0],fh[1],fh[2],fh[3],fh[4],fh[5],fh[6],fh[7]);
                goto out;
        }

        status = nfs_refresh_inode(inode, &fattr);
        if (status) {
#ifdef NFS_PARANOIA
printk("nfs_revalidate_inode: %s/%s refresh failed, ino=%ld, error=%d\n",
dentry->d_parent->d_name.name, dentry->d_name.name, inode->i_ino, status);
#endif
                goto out;
        }
        dfprintk(PAGECACHE, "NFS: %s/%s revalidation complete\n",
                dentry->d_parent->d_name.name, dentry->d_name.name);
out:
        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.
 */
int
nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
{
        int invalid = 0;
        int error = -EIO;

        dfprintk(VFS, "NFS: refresh_inode(%x/%ld ct=%d)\n",
                 inode->i_dev, inode->i_ino, inode->i_count);

        if (!inode || !fattr) {
                printk("nfs_refresh_inode: inode or fattr is NULL\n");
                goto out;
        }
        if (inode->i_ino != fattr->fileid) {
                printk("nfs_refresh_inode: mismatch, ino=%ld, fattr=%d\n",
                        inode->i_ino, fattr->fileid);
                goto out;
        }

        /*
         * Make sure the inode's type hasn't changed.
         */
        if ((inode->i_mode & S_IFMT) != (fattr->mode & S_IFMT))
                goto out_changed;

        inode->i_mode = fattr->mode;
        inode->i_nlink = fattr->nlink;
        inode->i_uid = fattr->uid;
        inode->i_gid = fattr->gid;

        inode->i_blocks = fattr->blocks;
        inode->i_atime = fattr->atime.seconds;
        inode->i_ctime = fattr->ctime.seconds;

        /*
         * Update the read time so we don't revalidate too often.
         */
        NFS_READTIME(inode) = jiffies;
        error = 0;

        /*
         * If we have pending write-back entries, we don't want
         * to look at the size or the mtime the server sends us
         * too closely, as we're in the middle of modifying them.
         */
        if (NFS_WRITEBACK(inode))
                goto out;

        if (inode->i_size != fattr->size) {
#ifdef NFS_DEBUG_VERBOSE
printk("NFS: size change on %x/%ld\n", inode->i_dev, inode->i_ino);
#endif
                inode->i_size = fattr->size;
                invalid = 1;
        }

        if (inode->i_mtime != fattr->mtime.seconds) {
#ifdef NFS_DEBUG_VERBOSE
printk("NFS: mtime change on %x/%ld\n", inode->i_dev, inode->i_ino);
#endif
                inode->i_mtime = fattr->mtime.seconds;
                invalid = 1;
        }

        if (invalid)
                goto out_invalid;

        /* Update attrtimeo value */
        if (fattr->mtime.seconds == NFS_OLDMTIME(inode)) {
                if ((NFS_ATTRTIMEO(inode) <<= 1) > NFS_MAXATTRTIMEO(inode))
                        NFS_ATTRTIMEO(inode) = NFS_MAXATTRTIMEO(inode);
        }
        NFS_OLDMTIME(inode) = fattr->mtime.seconds;

out:
        return error;

out_changed:
        /*
         * Big trouble! The inode has become a different object.
         */
#ifdef NFS_PARANOIA
printk("nfs_refresh_inode: inode %ld mode changed, %07o to %07o\n",
inode->i_ino, inode->i_mode, fattr->mode);
#endif
        fattr->mode = inode->i_mode; /* save mode */
        make_bad_inode(inode);
        nfs_inval(inode);
        inode->i_mode = fattr->mode; /* restore mode */
        /*
         * 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.)
         */

out_invalid:
        /*
         * Invalidate the local caches
         */
#ifdef NFS_DEBUG_VERBOSE
printk("nfs_refresh_inode: invalidating %ld pages\n", inode->i_nrpages);
#endif
        if (!S_ISDIR(inode->i_mode))
                invalidate_inode_pages(inode);
        else
                nfs_invalidate_dircache(inode);
        NFS_CACHEINV(inode);
        NFS_ATTRTIMEO(inode) = NFS_MINATTRTIMEO(inode);
        goto out;
}

/*
 * File system information
 */
static struct file_system_type nfs_fs_type = {
        "nfs",
        0 /* FS_NO_DCACHE - this doesn't work right now*/,
        nfs_read_super,
        NULL
};

/*
 * Initialize NFS
 */
int
init_nfs_fs(void)
{
#ifdef CONFIG_PROC_FS
        rpc_register_sysctl();
        rpc_proc_init();
        rpc_proc_register(&nfs_rpcstat);
#endif
        return register_filesystem(&nfs_fs_type);
}

/*
 * Every kernel module contains stuff like this.
 */
#ifdef MODULE

EXPORT_NO_SYMBOLS;
/* Not quite true; I just maintain it */
MODULE_AUTHOR("Olaf Kirch <okir@monad.swb.de>");

int
init_module(void)
{
        return init_nfs_fs();
}

void
cleanup_module(void)
{
#ifdef CONFIG_PROC_FS
        rpc_proc_unregister("nfs");
#endif
        unregister_filesystem(&nfs_fs_type);
        nfs_free_dircache();
}
#endif