dir.c

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/*
 * 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);
	if (!error)
		dentry->d_inode->i_nlink = 0;

	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_len(silly, dentry->d_parent, slen);
		/*
		 * 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;
	if (inode)
		inode->i_nlink--;

 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;

	if (error == -EROFS)
		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:
 */