- Andries Brouwer: final isofs pieces.

[davej-history.git] / fs / nfs / dir.c

/*
 *  linux/fs/nfs/dir.c
 *
 *  Copyright (C) 1992  Rick Sladkey
 *
 *  nfs directory handling functions
 *
 * 10 Apr 1996  Added silly rename for unlink   --okir
 * 28 Sep 1996  Improved directory cache --okir
 * 23 Aug 1997  Claus Heine claus@momo.math.rwth-aachen.de 
 *              Re-implemented silly rename for unlink, newly implemented
 *              silly rename for nfs_rename() following the suggestions
 *              of Olaf Kirch (okir) found in this file.
 *              Following Linus comments on my original hack, this version
 *              depends only on the dcache stuff and doesn't touch the inode
 *              layer (iput() and friends).
 *  6 Jun 1999  Cache readdir lookups in the page cache. -DaveM
 */

#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/malloc.h>
#include <linux/mm.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/pagemap.h>
#include <linux/smp_lock.h>

#define NFS_PARANOIA 1
/* #define NFS_DEBUG_VERBOSE 1 */

static int nfs_readdir(struct file *, void *, filldir_t);
static struct dentry *nfs_lookup(struct inode *, struct dentry *);
static int nfs_create(struct inode *, struct dentry *, int);
static int nfs_mkdir(struct inode *, struct dentry *, int);
static int nfs_rmdir(struct inode *, struct dentry *);
static int nfs_unlink(struct inode *, struct dentry *);
static int nfs_symlink(struct inode *, struct dentry *, const char *);
static int nfs_link(struct dentry *, struct inode *, struct dentry *);
static int nfs_mknod(struct inode *, struct dentry *, int, int);
static int nfs_rename(struct inode *, struct dentry *,
                      struct inode *, struct dentry *);

struct file_operations nfs_dir_operations = {
        read:           generic_read_dir,
        readdir:        nfs_readdir,
        open:           nfs_open,
        release:        nfs_release,
};

struct inode_operations nfs_dir_inode_operations = {
        create:         nfs_create,
        lookup:         nfs_lookup,
        link:           nfs_link,
        unlink:         nfs_unlink,
        symlink:        nfs_symlink,
        mkdir:          nfs_mkdir,
        rmdir:          nfs_rmdir,
        mknod:          nfs_mknod,
        rename:         nfs_rename,
        permission:     nfs_permission,
        revalidate:     nfs_revalidate,
        setattr:        nfs_notify_change,
};

typedef u32 * (*decode_dirent_t)(u32 *, struct nfs_entry *, int);
typedef struct {
        struct file     *file;
        struct page     *page;
        unsigned long   page_index;
        unsigned        page_offset;
        u64             target;
        struct nfs_entry *entry;
        decode_dirent_t decode;
        int             plus;
        int             error;
} nfs_readdir_descriptor_t;

/* Now we cache directories properly, by stuffing the dirent
 * data directly in the page cache.
 *
 * Inode invalidation due to refresh etc. takes care of
 * _everything_, no sloppy entry flushing logic, no extraneous
 * copying, network direct to page cache, the way it was meant
 * to be.
 *
 * NOTE: Dirent information verification is done always by the
 *       page-in of the RPC reply, nowhere else, this simplies
 *       things substantially.
 */
static
int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page *page)
{
        struct file     *file = desc->file;
        struct inode    *inode = file->f_dentry->d_inode;
        struct rpc_cred *cred = nfs_file_cred(file);
        void            *buffer = kmap(page);
        int             plus = NFS_USE_READDIRPLUS(inode);
        int             error;

        dfprintk(VFS, "NFS: nfs_readdir_filler() reading cookie %Lu into page %lu.\n", (long long)desc->entry->cookie, page->index);

 again:
        error = NFS_PROTO(inode)->readdir(inode, cred, desc->entry->cookie, buffer,
                                          NFS_SERVER(inode)->dtsize, plus);
        /* We requested READDIRPLUS, but the server doesn't grok it */
        if (desc->plus && error == -ENOTSUPP) {
                NFS_FLAGS(inode) &= ~NFS_INO_ADVISE_RDPLUS;
                plus = 0;
                goto again;
        }
        if (error < 0)
                goto error;
        SetPageUptodate(page);
        kunmap(page);
        /* Ensure consistent page alignment of the data.
         * Note: assumes we have exclusive access to this mapping either
         *       throught inode->i_sem or some other mechanism.
         */
        if (page->index == 0)
                invalidate_inode_pages(inode);
        UnlockPage(page);
        return 0;
 error:
        SetPageError(page);
        kunmap(page);
        UnlockPage(page);
        invalidate_inode_pages(inode);
        desc->error = error;
        return -EIO;
}

/*
 * Given a pointer to a buffer that has already been filled by a call
 * to readdir, find the next entry.
 *
 * If the end of the buffer has been reached, return -EAGAIN, if not,
 * return the offset within the buffer of the next entry to be
 * read.
 */
static inline
int find_dirent(nfs_readdir_descriptor_t *desc, struct page *page)
{
        struct nfs_entry *entry = desc->entry;
        char            *start = kmap(page),
                        *p = start;
        int             loop_count = 0,
                        status = 0;

        for(;;) {
                p = (char *)desc->decode((u32*)p, entry, desc->plus);
                if (IS_ERR(p)) {
                        status = PTR_ERR(p);
                        break;
                }
                desc->page_offset = p - start;
                dfprintk(VFS, "NFS: found cookie %Lu\n", (long long)entry->cookie);
                if (entry->prev_cookie == desc->target)
                        break;
                if (loop_count++ > 200) {
                        loop_count = 0;
                        schedule();
                }
        }
        kunmap(page);
        dfprintk(VFS, "NFS: find_dirent() returns %d\n", status);
        return status;
}

/*
 * Find the given page, and call find_dirent() in order to try to
 * return the next entry.
 */
static inline
int find_dirent_page(nfs_readdir_descriptor_t *desc)
{
        struct inode    *inode = desc->file->f_dentry->d_inode;
        struct page     *page;
        unsigned long   index = desc->page_index;
        int             status;

        dfprintk(VFS, "NFS: find_dirent_page() searching directory page %ld\n", desc->page_index);

        if (desc->page) {
                page_cache_release(desc->page);
                desc->page = NULL;
        }

        page = read_cache_page(&inode->i_data, index,
                               (filler_t *)nfs_readdir_filler, desc);
        if (IS_ERR(page)) {
                status = PTR_ERR(page);
                goto out;
        }
        if (!Page_Uptodate(page))
                goto read_error;

        /* NOTE: Someone else may have changed the READDIRPLUS flag */
        desc->plus = NFS_USE_READDIRPLUS(inode);
        status = find_dirent(desc, page);
        if (status >= 0)
                desc->page = page;
        else
                page_cache_release(page);
 out:
        dfprintk(VFS, "NFS: find_dirent_page() returns %d\n", status);
        return status;
 read_error:
        page_cache_release(page);
        return -EIO;
}

/*
 * Recurse through the page cache pages, and return a
 * filled nfs_entry structure of the next directory entry if possible.
 *
 * The target for the search is 'desc->target'.
 */
static inline
int readdir_search_pagecache(nfs_readdir_descriptor_t *desc)
{
        int             res = 0;
        int             loop_count = 0;

        dfprintk(VFS, "NFS: readdir_search_pagecache() searching for cookie %Lu\n", (long long)desc->target);
        for (;;) {
                res = find_dirent_page(desc);
                if (res != -EAGAIN)
                        break;
                /* Align to beginning of next page */
                desc->page_offset = 0;
                desc->page_index ++;
                if (loop_count++ > 200) {
                        loop_count = 0;
                        schedule();
                }
        }
        dfprintk(VFS, "NFS: readdir_search_pagecache() returned %d\n", res);
        return res;
}

/*
 * Once we've found the start of the dirent within a page: fill 'er up...
 */
static 
int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent,
                   filldir_t filldir)
{
        struct file     *file = desc->file;
        struct nfs_entry *entry = desc->entry;
        char            *start = kmap(desc->page),
                        *p = start + desc->page_offset;
        unsigned long   fileid;
        int             loop_count = 0,
                        res = 0;

        dfprintk(VFS, "NFS: nfs_do_filldir() filling starting @ cookie %Lu\n", (long long)desc->target);

        for(;;) {
                /* Note: entry->prev_cookie contains the cookie for
                 *       retrieving the current dirent on the server */
                fileid = nfs_fileid_to_ino_t(entry->ino);
                res = filldir(dirent, entry->name, entry->len, 
                              entry->prev_cookie, fileid, DT_UNKNOWN);
                if (res < 0)
                        break;
                file->f_pos = desc->target = entry->cookie;
                p = (char *)desc->decode((u32 *)p, entry, desc->plus);
                if (IS_ERR(p)) {
                        if (PTR_ERR(p) == -EAGAIN) {
                                desc->page_offset = 0;
                                desc->page_index ++;
                        }
                        break;
                }
                desc->page_offset = p - start;
                if (loop_count++ > 200) {
                        loop_count = 0;
                        schedule();
                }
        }
        kunmap(desc->page);
        page_cache_release(desc->page);
        desc->page = NULL;

        dfprintk(VFS, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n", (long long)desc->target, res);
        return res;
}

/*
 * If we cannot find a cookie in our cache, we suspect that this is
 * because it points to a deleted file, so we ask the server to return
 * whatever it thinks is the next entry. We then feed this to filldir.
 * If all goes well, we should then be able to find our way round the
 * cache on the next call to readdir_search_pagecache();
 *
 * NOTE: we cannot add the anonymous page to the pagecache because
 *       the data it contains might not be page aligned. Besides,
 *       we should already have a complete representation of the
 *       directory in the page cache by the time we get here.
 */
static inline
int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent,
                     filldir_t filldir)
{
        struct file     *file = desc->file;
        struct inode    *inode = file->f_dentry->d_inode;
        struct rpc_cred *cred = nfs_file_cred(file);
        struct page     *page = NULL;
        u32             *p;
        int             status = -EIO;

        dfprintk(VFS, "NFS: uncached_readdir() searching for cookie %Lu\n", (long long)desc->target);
        if (desc->page) {
                page_cache_release(desc->page);
                desc->page = NULL;
        }

        page = page_cache_alloc();
        if (!page) {
                status = -ENOMEM;
                goto out;
        }
        p = kmap(page);
        status = NFS_PROTO(inode)->readdir(inode, cred, desc->target, p,
                                           NFS_SERVER(inode)->dtsize, 0);
        if (status >= 0) {
                p = desc->decode(p, desc->entry, 0);
                if (IS_ERR(p))
                        status = PTR_ERR(p);
                else
                        desc->entry->prev_cookie = desc->target;
        }
        kunmap(page);
        if (status < 0)
                goto out_release;

        desc->page_index = 0;
        desc->page_offset = 0;
        desc->page = page;
        status = nfs_do_filldir(desc, dirent, filldir);

        /* Reset read descriptor so it searches the page cache from
         * the start upon the next call to readdir_search_pagecache() */
        desc->page_index = 0;
        desc->page_offset = 0;
        memset(desc->entry, 0, sizeof(*desc->entry));
 out:
        dfprintk(VFS, "NFS: uncached_readdir() returns %d\n", status);
        return status;
 out_release:
        page_cache_release(page);
        goto out;
}

/* The file offset position is now represented as a true offset into the
 * page cache as is the case in most of the other filesystems.
 */
static int nfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
        struct dentry   *dentry = filp->f_dentry;
        struct inode    *inode = dentry->d_inode;
        nfs_readdir_descriptor_t my_desc,
                        *desc = &my_desc;
        struct nfs_entry my_entry;
        long            res;

        res = nfs_revalidate(dentry);
        if (res < 0)
                return res;

        /*
         * filp->f_pos points to the file offset in the page cache.
         * but if the cache has meanwhile been zapped, we need to
         * read from the last dirent to revalidate f_pos
         * itself.
         */
        memset(desc, 0, sizeof(*desc));
        memset(&my_entry, 0, sizeof(my_entry));

        desc->file = filp;
        desc->target = filp->f_pos;
        desc->entry = &my_entry;
        desc->decode = NFS_PROTO(inode)->decode_dirent;

        while(!desc->entry->eof) {
                res = readdir_search_pagecache(desc);
                if (res == -EBADCOOKIE) {
                        /* This means either end of directory */
                        if (desc->entry->cookie == desc->target) {
                                res = 0;
                                break;
                        }
                        /* Or that the server has 'lost' a cookie */
                        res = uncached_readdir(desc, dirent, filldir);
                        if (res >= 0)
                                continue;
                }
                if (res < 0)
                        break;

                res = nfs_do_filldir(desc, dirent, filldir);
                if (res < 0) {
                        res = 0;
                        break;
                }
        }
        if (desc->page)
                page_cache_release(desc->page);
        if (desc->error < 0)
                return desc->error;
        if (res < 0)
                return res;
        return 0;
}

/*
 * Whenever an NFS operation succeeds, we know that the dentry
 * is valid, so we update the revalidation timestamp.
 */
static inline void nfs_renew_times(struct dentry * dentry)
{
        dentry->d_time = jiffies;
}

static inline int nfs_dentry_force_reval(struct dentry *dentry, int flags)
{
        struct inode *inode = dentry->d_inode;
        unsigned long timeout = NFS_ATTRTIMEO(inode);

        /*
         * If it's the last lookup in a series, we use a stricter
         * cache consistency check by looking at the parent mtime.
         *
         * If it's been modified in the last hour, be really strict.
         * (This still means that we can avoid doing unnecessary
         * work on directories like /usr/share/bin etc which basically
         * never change).
         */
        if (!(flags & LOOKUP_CONTINUE)) {
                long diff = CURRENT_TIME - dentry->d_parent->d_inode->i_mtime;

                if (diff < 15*60)
                        timeout = 0;
        }
        
        return time_after(jiffies,dentry->d_time + timeout);
}

/*
 * We judge how long we want to trust negative
 * dentries by looking at the parent inode mtime.
 *
 * If mtime is close to present time, we revalidate
 * more often.
 */
#define NFS_REVALIDATE_NEGATIVE (1 * HZ)
static inline int nfs_neg_need_reval(struct dentry *dentry)
{
        struct inode *dir = dentry->d_parent->d_inode;
        unsigned long timeout = NFS_ATTRTIMEO(dir);
        long diff = CURRENT_TIME - dir->i_mtime;

        if (diff < 5*60 && timeout > NFS_REVALIDATE_NEGATIVE)
                timeout = NFS_REVALIDATE_NEGATIVE;

        return time_after(jiffies, dentry->d_time + timeout);
}

/*
 * This is called every time the dcache has a lookup hit,
 * and we should check whether we can really trust that
 * lookup.
 *
 * NOTE! The hit can be a negative hit too, don't assume
 * we have an inode!
 *
 * If the dentry is older than the revalidation interval, 
 * we do a new lookup and verify that the dentry is still
 * correct.
 */
static int nfs_lookup_revalidate(struct dentry * dentry, int flags)
{
        struct inode *dir;
        struct inode *inode;
        int error;
        struct nfs_fh fhandle;
        struct nfs_fattr fattr;

        lock_kernel();
        dir = dentry->d_parent->d_inode;
        inode = dentry->d_inode;
        /*
         * If we don't have an inode, let's look at the parent
         * directory mtime to get a hint about how often we
         * should validate things..
         */
        if (!inode) {
                if (nfs_neg_need_reval(dentry))
                        goto out_bad;
                goto out_valid;
        }

        if (is_bad_inode(inode)) {
                dfprintk(VFS, "nfs_lookup_validate: %s/%s has dud inode\n",
                        dentry->d_parent->d_name.name, dentry->d_name.name);
                goto out_bad;
        }

        if (!nfs_dentry_force_reval(dentry, flags))
                goto out_valid;

        if (IS_ROOT(dentry)) {
                __nfs_revalidate_inode(NFS_SERVER(inode), inode);
                goto out_valid_renew;
        }

        /*
         * Do a new lookup and check the dentry attributes.
         */
        error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, &fhandle, &fattr);
        if (error)
                goto out_bad;

        /* Inode number matches? */
        if (!(fattr.valid & NFS_ATTR_FATTR) ||
            NFS_FSID(inode) != fattr.fsid ||
            NFS_FILEID(inode) != fattr.fileid)
                goto out_bad;

        /* Filehandle matches? */
        if (memcmp(NFS_FH(inode), fhandle.data, sizeof(struct nfs_fh)))
                goto out_bad;

        /* Ok, remember that we successfully checked it.. */
        nfs_refresh_inode(inode, &fattr);

 out_valid_renew:
        nfs_renew_times(dentry);
out_valid:
        unlock_kernel();
        return 1;
out_bad:
        shrink_dcache_parent(dentry);
        /* If we have submounts, don't unhash ! */
        if (have_submounts(dentry))
                goto out_valid;
        d_drop(dentry);
        /* Purge readdir caches. */
        nfs_zap_caches(dir);
        if (inode && S_ISDIR(inode->i_mode))
                nfs_zap_caches(inode);
        unlock_kernel();
        return 0;
}

/*
 * This is called from dput() when d_count is going to 0.
 */
static int nfs_dentry_delete(struct dentry *dentry)
{
        dfprintk(VFS, "NFS: dentry_delete(%s/%s, %x)\n",
                dentry->d_parent->d_name.name, dentry->d_name.name,
                dentry->d_flags);

        if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
                /* Unhash it, so that ->d_iput() would be called */
                return 1;
        }
        return 0;

}

/*
 * Called when the dentry loses inode.
 * We use it to clean up silly-renamed files.
 */
static void nfs_dentry_iput(struct dentry *dentry, struct inode *inode)
{
        if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
                lock_kernel();
                nfs_complete_unlink(dentry);
                unlock_kernel();
        }
        iput(inode);
}

struct dentry_operations nfs_dentry_operations = {
        d_revalidate:   nfs_lookup_revalidate,
        d_delete:       nfs_dentry_delete,
        d_iput:         nfs_dentry_iput,
};

static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry)
{
        struct inode *inode;
        int error;
        struct nfs_fh fhandle;
        struct nfs_fattr fattr;

        dfprintk(VFS, "NFS: lookup(%s/%s)\n",
                dentry->d_parent->d_name.name, dentry->d_name.name);

        error = -ENAMETOOLONG;
        if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
                goto out;

        error = -ENOMEM;
        dentry->d_op = &nfs_dentry_operations;

        error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, &fhandle, &fattr);
        inode = NULL;
        if (error == -ENOENT)
                goto no_entry;
        if (!error) {
                error = -EACCES;
                inode = nfs_fhget(dentry, &fhandle, &fattr);
                if (inode) {
            no_entry:
                        d_add(dentry, inode);
                        nfs_renew_times(dentry);
                        error = 0;
                }
        }
out:
        return ERR_PTR(error);
}

/*
 * Code common to create, mkdir, and mknod.
 */
static int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
                                struct nfs_fattr *fattr)
{
        struct inode *inode;
        int error = -EACCES;

        inode = nfs_fhget(dentry, fhandle, fattr);
        if (inode) {
                d_instantiate(dentry, inode);
                nfs_renew_times(dentry);
                error = 0;
        }
        return error;
}

/*
 * Following a failed create operation, we drop the dentry rather
 * than retain a negative dentry. This avoids a problem in the event
 * that the operation succeeded on the server, but an error in the
 * reply path made it appear to have failed.
 */
static int nfs_create(struct inode *dir, struct dentry *dentry, int mode)
{
        struct iattr attr;
        struct nfs_fattr fattr;
        struct nfs_fh fhandle;
        int error;

        dfprintk(VFS, "NFS: create(%x/%ld, %s\n",
                dir->i_dev, dir->i_ino, dentry->d_name.name);

        attr.ia_mode = mode;
        attr.ia_valid = ATTR_MODE;

        /*
         * The 0 argument passed into the create function should one day
         * contain the O_EXCL flag if requested. This allows NFSv3 to
         * select the appropriate create strategy. Currently open_namei
         * does not pass the create flags.
         */
        nfs_zap_caches(dir);
        error = NFS_PROTO(dir)->create(dir, &dentry->d_name,
                                         &attr, 0, &fhandle, &fattr);
        if (!error && fhandle.size != 0)
                error = nfs_instantiate(dentry, &fhandle, &fattr);
        if (error || fhandle.size == 0)
                d_drop(dentry);
        return error;
}

/*
 * See comments for nfs_proc_create regarding failed operations.
 */
static int nfs_mknod(struct inode *dir, struct dentry *dentry, int mode, int rdev)
{
        struct iattr attr;
        struct nfs_fattr fattr;
        struct nfs_fh fhandle;
        int error;

        dfprintk(VFS, "NFS: mknod(%x/%ld, %s\n",
                dir->i_dev, dir->i_ino, dentry->d_name.name);

        attr.ia_mode = mode;
        attr.ia_valid = ATTR_MODE;

        nfs_zap_caches(dir);
        error = NFS_PROTO(dir)->mknod(dir, &dentry->d_name, &attr, rdev,
                                        &fhandle, &fattr);
        if (!error && fhandle.size != 0)
                error = nfs_instantiate(dentry, &fhandle, &fattr);
        if (error || fhandle.size == 0)
                d_drop(dentry);
        return error;
}

/*
 * See comments for nfs_proc_create regarding failed operations.
 */
static int nfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
        struct iattr attr;
        struct nfs_fattr fattr;
        struct nfs_fh fhandle;
        int error;

        dfprintk(VFS, "NFS: mkdir(%x/%ld, %s\n",
                dir->i_dev, dir->i_ino, dentry->d_name.name);

        attr.ia_valid = ATTR_MODE;
        attr.ia_mode = mode | S_IFDIR;

#if 0
        /*
         * Always drop the dentry, we can't always depend on
         * the fattr returned by the server (AIX seems to be
         * broken). We're better off doing another lookup than
         * depending on potentially bogus information.
         */
        d_drop(dentry);
#endif
        nfs_zap_caches(dir);
        error = NFS_PROTO(dir)->mkdir(dir, &dentry->d_name, &attr, &fhandle,
                                        &fattr);
        if (!error && fhandle.size != 0)
                error = nfs_instantiate(dentry, &fhandle, &fattr);
        if (error || fhandle.size == 0)
                d_drop(dentry);
        return error;
}

static int nfs_rmdir(struct inode *dir, struct dentry *dentry)
{
        int error;

        dfprintk(VFS, "NFS: rmdir(%x/%ld, %s\n",
                dir->i_dev, dir->i_ino, dentry->d_name.name);

        nfs_zap_caches(dir);
        error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);

        return error;
}

static int nfs_sillyrename(struct inode *dir, struct dentry *dentry)
{
        static unsigned int sillycounter;
        const int      i_inosize  = sizeof(dir->i_ino)*2;
        const int      countersize = sizeof(sillycounter)*2;
        const int      slen       = strlen(".nfs") + i_inosize + countersize;
        char           silly[slen+1];
        struct qstr    qsilly;
        struct dentry *sdentry;
        int            error = -EIO;

        dfprintk(VFS, "NFS: silly-rename(%s/%s, ct=%d)\n",
                dentry->d_parent->d_name.name, dentry->d_name.name, 
                atomic_read(&dentry->d_count));

        if (atomic_read(&dentry->d_count) == 1)
                goto out;  /* No need to silly rename. */


#ifdef NFS_PARANOIA
if (!dentry->d_inode)
printk("NFS: silly-renaming %s/%s, negative dentry??\n",
dentry->d_parent->d_name.name, dentry->d_name.name);
#endif
        /*
         * We don't allow a dentry to be silly-renamed twice.
         */
        error = -EBUSY;
        if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
                goto out;

        sprintf(silly, ".nfs%*.*lx",
                i_inosize, i_inosize, dentry->d_inode->i_ino);

        sdentry = NULL;
        do {
                char *suffix = silly + slen - countersize;

                dput(sdentry);
                sillycounter++;
                sprintf(suffix, "%*.*x", countersize, countersize, sillycounter);

                dfprintk(VFS, "trying to rename %s to %s\n",
                         dentry->d_name.name, silly);
                
                sdentry = lookup_one(silly, dentry->d_parent);
                /*
                 * N.B. Better to return EBUSY here ... it could be
                 * dangerous to delete the file while it's in use.
                 */
                if (IS_ERR(sdentry))
                        goto out;
        } while(sdentry->d_inode != NULL); /* need negative lookup */

        nfs_zap_caches(dir);
        qsilly.name = silly;
        qsilly.len  = strlen(silly);
        error = NFS_PROTO(dir)->rename(dir, &dentry->d_name, dir, &qsilly);
        if (!error) {
                nfs_renew_times(dentry);
                d_move(dentry, sdentry);
                error = nfs_async_unlink(dentry);
                /* If we return 0 we don't unlink */
        }
        dput(sdentry);
out:
        return error;
}

/*
 * Remove a file after making sure there are no pending writes,
 * and after checking that the file has only one user. 
 *
 * We invalidate the attribute cache and free the inode prior to the operation
 * to avoid possible races if the server reuses the inode.
 */
static int nfs_safe_remove(struct dentry *dentry)
{
        struct inode *dir = dentry->d_parent->d_inode;
        struct inode *inode = dentry->d_inode;
        int error = -EBUSY, rehash = 0;
                
        dfprintk(VFS, "NFS: safe_remove(%s/%s)\n",
                dentry->d_parent->d_name.name, dentry->d_name.name);

        /*
         * Unhash the dentry while we remove the file ...
         */
        if (!d_unhashed(dentry)) {
                d_drop(dentry);
                rehash = 1;
        }
        if (atomic_read(&dentry->d_count) > 1) {
#ifdef NFS_PARANOIA
                printk("nfs_safe_remove: %s/%s busy, d_count=%d\n",
                        dentry->d_parent->d_name.name, dentry->d_name.name,
                        atomic_read(&dentry->d_count));
#endif
                goto out;
        }

        /* If the dentry was sillyrenamed, we simply call d_delete() */
        if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
                error = 0;
                goto out_delete;
        }

        nfs_zap_caches(dir);
        if (inode)
                NFS_CACHEINV(inode);
        error = NFS_PROTO(dir)->remove(dir, &dentry->d_name);
        if (error < 0)
                goto out;

 out_delete:
        /*
         * Free the inode
         */
        d_delete(dentry);
out:
        if (rehash)
                d_rehash(dentry);
        return error;
}

/*  We do silly rename. In case sillyrename() returns -EBUSY, the inode
 *  belongs to an active ".nfs..." file and we return -EBUSY.
 *
 *  If sillyrename() returns 0, we do nothing, otherwise we unlink.
 */
static int nfs_unlink(struct inode *dir, struct dentry *dentry)
{
        int error;

        dfprintk(VFS, "NFS: unlink(%x/%ld, %s)\n",
                dir->i_dev, dir->i_ino, dentry->d_name.name);

        error = nfs_sillyrename(dir, dentry);
        if (error && error != -EBUSY) {
                error = nfs_safe_remove(dentry);
                if (!error) {
                        nfs_renew_times(dentry);
                }
        }
        return error;
}

static int
nfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
{
        struct iattr attr;
        struct nfs_fattr sym_attr;
        struct nfs_fh sym_fh;
        struct qstr qsymname;
        unsigned int maxlen;
        int error;

        dfprintk(VFS, "NFS: symlink(%x/%ld, %s, %s)\n",
                dir->i_dev, dir->i_ino, dentry->d_name.name, symname);

        error = -ENAMETOOLONG;
        maxlen = (NFS_PROTO(dir)->version==2) ? NFS2_MAXPATHLEN : NFS3_MAXPATHLEN;
        if (strlen(symname) > maxlen)
                goto out;

#ifdef NFS_PARANOIA
if (dentry->d_inode)
printk("nfs_proc_symlink: %s/%s not negative!\n",
dentry->d_parent->d_name.name, dentry->d_name.name);
#endif
        /*
         * Fill in the sattr for the call.
         * Note: SunOS 4.1.2 crashes if the mode isn't initialized!
         */
        attr.ia_valid = ATTR_MODE;
        attr.ia_mode = S_IFLNK | S_IRWXUGO;

        qsymname.name = symname;
        qsymname.len  = strlen(symname);

        nfs_zap_caches(dir);
        error = NFS_PROTO(dir)->symlink(dir, &dentry->d_name, &qsymname,
                                          &attr, &sym_fh, &sym_attr);
        if (!error && sym_fh.size != 0 && (sym_attr.valid & NFS_ATTR_FATTR)) {
                error = nfs_instantiate(dentry, &sym_fh, &sym_attr);
        } else {
                if (error == -EEXIST)
                        printk("nfs_proc_symlink: %s/%s already exists??\n",
                               dentry->d_parent->d_name.name, dentry->d_name.name);
                d_drop(dentry);
        }

out:
        return error;
}

static int 
nfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
{
        struct inode *inode = old_dentry->d_inode;
        int error;

        dfprintk(VFS, "NFS: link(%s/%s -> %s/%s)\n",
                old_dentry->d_parent->d_name.name, old_dentry->d_name.name,
                dentry->d_parent->d_name.name, dentry->d_name.name);

        /*
         * Drop the dentry in advance to force a new lookup.
         * Since nfs_proc_link doesn't return a file handle,
         * we can't use the existing dentry.
         */
        d_drop(dentry);
        nfs_zap_caches(dir);
        NFS_CACHEINV(inode);
        error = NFS_PROTO(dir)->link(inode, dir, &dentry->d_name);
        return error;
}

/*
 * RENAME
 * FIXME: Some nfsds, like the Linux user space nfsd, may generate a
 * different file handle for the same inode after a rename (e.g. when
 * moving to a different directory). A fail-safe method to do so would
 * be to look up old_dir/old_name, create a link to new_dir/new_name and
 * rename the old file using the sillyrename stuff. This way, the original
 * file in old_dir will go away when the last process iput()s the inode.
 *
 * FIXED.
 * 
 * It actually works quite well. One needs to have the possibility for
 * at least one ".nfs..." file in each directory the file ever gets
 * moved or linked to which happens automagically with the new
 * implementation that only depends on the dcache stuff instead of
 * using the inode layer
 *
 * Unfortunately, things are a little more complicated than indicated
 * above. For a cross-directory move, we want to make sure we can get
 * rid of the old inode after the operation.  This means there must be
 * no pending writes (if it's a file), and the use count must be 1.
 * If these conditions are met, we can drop the dentries before doing
 * the rename.
 */
static int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
                      struct inode *new_dir, struct dentry *new_dentry)
{
        struct inode *old_inode = old_dentry->d_inode;
        struct inode *new_inode = new_dentry->d_inode;
        struct dentry *dentry = NULL, *rehash = NULL;
        int error = -EBUSY;

        /*
         * To prevent any new references to the target during the rename,
         * we unhash the dentry and free the inode in advance.
         */
        if (!d_unhashed(new_dentry)) {
                d_drop(new_dentry);
                rehash = new_dentry;
        }

        dfprintk(VFS, "NFS: rename(%s/%s -> %s/%s, ct=%d)\n",
                 old_dentry->d_parent->d_name.name, old_dentry->d_name.name,
                 new_dentry->d_parent->d_name.name, new_dentry->d_name.name,
                 atomic_read(&new_dentry->d_count));

        /*
         * First check whether the target is busy ... we can't
         * safely do _any_ rename if the target is in use.
         *
         * For files, make a copy of the dentry and then do a 
         * silly-rename. If the silly-rename succeeds, the
         * copied dentry is hashed and becomes the new target.
         */
        if (!new_inode)
                goto go_ahead;
        if (S_ISDIR(new_inode->i_mode))
                goto out;
        else if (atomic_read(&new_dentry->d_count) > 1) {
                int err;
                /* copy the target dentry's name */
                dentry = d_alloc(new_dentry->d_parent,
                                 &new_dentry->d_name);
                if (!dentry)
                        goto out;

                /* silly-rename the existing target ... */
                err = nfs_sillyrename(new_dir, new_dentry);
                if (!err) {
                        new_dentry = rehash = dentry;
                        new_inode = NULL;
                        /* instantiate the replacement target */
                        d_instantiate(new_dentry, NULL);
                }

                /* dentry still busy? */
                if (atomic_read(&new_dentry->d_count) > 1) {
#ifdef NFS_PARANOIA
                        printk("nfs_rename: target %s/%s busy, d_count=%d\n",
                               new_dentry->d_parent->d_name.name,
                               new_dentry->d_name.name,
                               atomic_read(&new_dentry->d_count));
#endif
                        goto out;
                }
        }

go_ahead:
        /*
         * ... prune child dentries and writebacks if needed.
         */
        if (atomic_read(&old_dentry->d_count) > 1) {
                nfs_wb_all(old_inode);
                shrink_dcache_parent(old_dentry);
        }

        if (new_inode)
                d_delete(new_dentry);

        nfs_zap_caches(new_dir);
        nfs_zap_caches(old_dir);
        error = NFS_PROTO(old_dir)->rename(old_dir, &old_dentry->d_name,
                                           new_dir, &new_dentry->d_name);
out:
        if (rehash)
                d_rehash(rehash);
        if (!error && !S_ISDIR(old_inode->i_mode))
                d_move(old_dentry, new_dentry);

        /* new dentry created? */
        if (dentry)
                dput(dentry);
        return error;
}

int
nfs_permission(struct inode *inode, int mask)
{
        int                     error = vfs_permission(inode, mask);

        if (!NFS_PROTO(inode)->access)
                goto out;
        /*
         * Trust UNIX mode bits except:
         *
         * 1) When override capabilities may have been invoked
         * 2) When root squashing may be involved
         * 3) When ACLs may overturn a negative answer */
        if (!capable(CAP_DAC_OVERRIDE) && !capable(CAP_DAC_READ_SEARCH)
            && (current->fsuid != 0) && (current->fsgid != 0)
            && error != -EACCES)
                goto out;

        error = NFS_PROTO(inode)->access(inode, mask, 0);

        if (error == -EACCES && NFS_CLIENT(inode)->cl_droppriv &&
            current->uid != 0 && current->gid != 0 &&
            (current->fsuid != current->uid || current->fsgid != current->gid))
                error = NFS_PROTO(inode)->access(inode, mask, 1);

 out:
        return error;
}

/*
 * Local variables:
 *  version-control: t
 *  kept-new-versions: 5
 * End:
 */