ark1668ed-bsp/linux/fs/smb/client/dir.c

// SPDX-License-Identifier: LGPL-2.1
/*
 *
 *   vfs operations that deal with dentries
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2009
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 */
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/file.h>
#include "cifsfs.h"
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"
#include "cifs_fs_sb.h"
#include "cifs_unicode.h"
#include "fs_context.h"
#include "cifs_ioctl.h"
#include "fscache.h"

static void
renew_parental_timestamps(struct dentry *direntry)
{
	/* BB check if there is a way to get the kernel to do this or if we
	   really need this */
	do {
		cifs_set_time(direntry, jiffies);
		direntry = direntry->d_parent;
	} while (!IS_ROOT(direntry));
}

char *
cifs_build_path_to_root(struct smb3_fs_context *ctx, struct cifs_sb_info *cifs_sb,
			struct cifs_tcon *tcon, int add_treename)
{
	int pplen = ctx->prepath ? strlen(ctx->prepath) + 1 : 0;
	int dfsplen;
	char *full_path = NULL;

	/* if no prefix path, simply set path to the root of share to "" */
	if (pplen == 0) {
		full_path = kzalloc(1, GFP_KERNEL);
		return full_path;
	}

	if (add_treename)
		dfsplen = strnlen(tcon->tree_name, MAX_TREE_SIZE + 1);
	else
		dfsplen = 0;

	full_path = kmalloc(dfsplen + pplen + 1, GFP_KERNEL);
	if (full_path == NULL)
		return full_path;

	if (dfsplen)
		memcpy(full_path, tcon->tree_name, dfsplen);
	full_path[dfsplen] = CIFS_DIR_SEP(cifs_sb);
	memcpy(full_path + dfsplen + 1, ctx->prepath, pplen);
	convert_delimiter(full_path, CIFS_DIR_SEP(cifs_sb));
	return full_path;
}

/* Note: caller must free return buffer */
const char *
build_path_from_dentry(struct dentry *direntry, void *page)
{
	struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
	bool prefix = tcon->Flags & SMB_SHARE_IS_IN_DFS;

	return build_path_from_dentry_optional_prefix(direntry, page,
						      prefix);
}

char *__build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
					       const char *tree, int tree_len,
					       bool prefix)
{
	int dfsplen;
	int pplen = 0;
	struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
	char dirsep = CIFS_DIR_SEP(cifs_sb);
	char *s;

	if (unlikely(!page))
		return ERR_PTR(-ENOMEM);

	if (prefix)
		dfsplen = strnlen(tree, tree_len + 1);
	else
		dfsplen = 0;

	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH)
		pplen = cifs_sb->prepath ? strlen(cifs_sb->prepath) + 1 : 0;

	s = dentry_path_raw(direntry, page, PATH_MAX);
	if (IS_ERR(s))
		return s;
	if (!s[1])	// for root we want "", not "/"
		s++;
	if (s < (char *)page + pplen + dfsplen)
		return ERR_PTR(-ENAMETOOLONG);
	if (pplen) {
		cifs_dbg(FYI, "using cifs_sb prepath <%s>\n", cifs_sb->prepath);
		s -= pplen;
		memcpy(s + 1, cifs_sb->prepath, pplen - 1);
		*s = '/';
	}
	if (dirsep != '/') {
		/* BB test paths to Windows with '/' in the midst of prepath */
		char *p;

		for (p = s; *p; p++)
			if (*p == '/')
				*p = dirsep;
	}
	if (dfsplen) {
		s -= dfsplen;
		memcpy(s, tree, dfsplen);
		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) {
			int i;
			for (i = 0; i < dfsplen; i++) {
				if (s[i] == '\\')
					s[i] = '/';
			}
		}
	}
	return s;
}

char *build_path_from_dentry_optional_prefix(struct dentry *direntry, void *page,
					     bool prefix)
{
	struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);

	return __build_path_from_dentry_optional_prefix(direntry, page, tcon->tree_name,
							MAX_TREE_SIZE, prefix);
}

/*
 * Don't allow path components longer than the server max.
 * Don't allow the separator character in a path component.
 * The VFS will not allow "/", but "\" is allowed by posix.
 */
static int
check_name(struct dentry *direntry, struct cifs_tcon *tcon)
{
	struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
	int i;

	if (unlikely(tcon->fsAttrInfo.MaxPathNameComponentLength &&
		     direntry->d_name.len >
		     le32_to_cpu(tcon->fsAttrInfo.MaxPathNameComponentLength)))
		return -ENAMETOOLONG;

	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)) {
		for (i = 0; i < direntry->d_name.len; i++) {
			if (direntry->d_name.name[i] == '\\') {
				cifs_dbg(FYI, "Invalid file name\n");
				return -EINVAL;
			}
		}
	}
	return 0;
}


/* Inode operations in similar order to how they appear in Linux file fs.h */

static int cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned int xid,
			  struct tcon_link *tlink, unsigned int oflags, umode_t mode, __u32 *oplock,
			  struct cifs_fid *fid, struct cifs_open_info_data *buf)
{
	int rc = -ENOENT;
	int create_options = CREATE_NOT_DIR;
	int desired_access;
	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
	struct cifs_tcon *tcon = tlink_tcon(tlink);
	const char *full_path;
	void *page = alloc_dentry_path();
	struct inode *newinode = NULL;
	int disposition;
	struct TCP_Server_Info *server = tcon->ses->server;
	struct cifs_open_parms oparms;
	int rdwr_for_fscache = 0;

	*oplock = 0;
	if (tcon->ses->server->oplocks)
		*oplock = REQ_OPLOCK;

	full_path = build_path_from_dentry(direntry, page);
	if (IS_ERR(full_path)) {
		free_dentry_path(page);
		return PTR_ERR(full_path);
	}

	/* If we're caching, we need to be able to fill in around partial writes. */
	if (cifs_fscache_enabled(inode) && (oflags & O_ACCMODE) == O_WRONLY)
		rdwr_for_fscache = 1;

#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
	if (tcon->unix_ext && cap_unix(tcon->ses) && !tcon->broken_posix_open &&
	    (CIFS_UNIX_POSIX_PATH_OPS_CAP &
			le64_to_cpu(tcon->fsUnixInfo.Capability))) {
		rc = cifs_posix_open(full_path, &newinode, inode->i_sb, mode,
				     oflags, oplock, &fid->netfid, xid);
		switch (rc) {
		case 0:
			if (newinode == NULL) {
				/* query inode info */
				goto cifs_create_get_file_info;
			}

			if (S_ISDIR(newinode->i_mode)) {
				CIFSSMBClose(xid, tcon, fid->netfid);
				iput(newinode);
				rc = -EISDIR;
				goto out;
			}

			if (!S_ISREG(newinode->i_mode)) {
				/*
				 * The server may allow us to open things like
				 * FIFOs, but the client isn't set up to deal
				 * with that. If it's not a regular file, just
				 * close it and proceed as if it were a normal
				 * lookup.
				 */
				CIFSSMBClose(xid, tcon, fid->netfid);
				goto cifs_create_get_file_info;
			}
			/* success, no need to query */
			goto cifs_create_set_dentry;

		case -ENOENT:
			goto cifs_create_get_file_info;

		case -EIO:
		case -EINVAL:
			/*
			 * EIO could indicate that (posix open) operation is not
			 * supported, despite what server claimed in capability
			 * negotiation.
			 *
			 * POSIX open in samba versions 3.3.1 and earlier could
			 * incorrectly fail with invalid parameter.
			 */
			tcon->broken_posix_open = true;
			break;

		case -EREMOTE:
		case -EOPNOTSUPP:
			/*
			 * EREMOTE indicates DFS junction, which is not handled
			 * in posix open.  If either that or op not supported
			 * returned, follow the normal lookup.
			 */
			break;

		default:
			goto out;
		}
		/*
		 * fallthrough to retry, using older open call, this is case
		 * where server does not support this SMB level, and falsely
		 * claims capability (also get here for DFS case which should be
		 * rare for path not covered on files)
		 */
	}
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */

	desired_access = 0;
	if (OPEN_FMODE(oflags) & FMODE_READ)
		desired_access |= GENERIC_READ; /* is this too little? */
	if (OPEN_FMODE(oflags) & FMODE_WRITE)
		desired_access |= GENERIC_WRITE;
	if (rdwr_for_fscache == 1)
		desired_access |= GENERIC_READ;

	disposition = FILE_OVERWRITE_IF;
	if ((oflags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
		disposition = FILE_CREATE;
	else if ((oflags & (O_CREAT | O_TRUNC)) == (O_CREAT | O_TRUNC))
		disposition = FILE_OVERWRITE_IF;
	else if ((oflags & O_CREAT) == O_CREAT)
		disposition = FILE_OPEN_IF;
	else
		cifs_dbg(FYI, "Create flag not set in create function\n");

	/*
	 * BB add processing to set equivalent of mode - e.g. via CreateX with
	 * ACLs
	 */

	if (!server->ops->open) {
		rc = -ENOSYS;
		goto out;
	}

	/*
	 * if we're not using unix extensions, see if we need to set
	 * ATTR_READONLY on the create call
	 */
	if (!tcon->unix_ext && (mode & S_IWUGO) == 0)
		create_options |= CREATE_OPTION_READONLY;

retry_open:
	oparms = (struct cifs_open_parms) {
		.tcon = tcon,
		.cifs_sb = cifs_sb,
		.desired_access = desired_access,
		.create_options = cifs_create_options(cifs_sb, create_options),
		.disposition = disposition,
		.path = full_path,
		.fid = fid,
		.mode = mode,
	};
	rc = server->ops->open(xid, &oparms, oplock, buf);
	if (rc) {
		cifs_dbg(FYI, "cifs_create returned 0x%x\n", rc);
		if (rc == -EACCES && rdwr_for_fscache == 1) {
			desired_access &= ~GENERIC_READ;
			rdwr_for_fscache = 2;
			goto retry_open;
		}
		goto out;
	}
	if (rdwr_for_fscache == 2)
		cifs_invalidate_cache(inode, FSCACHE_INVAL_DIO_WRITE);

#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
	/*
	 * If Open reported that we actually created a file then we now have to
	 * set the mode if possible.
	 */
	if ((tcon->unix_ext) && (*oplock & CIFS_CREATE_ACTION)) {
		struct cifs_unix_set_info_args args = {
				.mode	= mode,
				.ctime	= NO_CHANGE_64,
				.atime	= NO_CHANGE_64,
				.mtime	= NO_CHANGE_64,
				.device	= 0,
		};

		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID) {
			args.uid = current_fsuid();
			if (inode->i_mode & S_ISGID)
				args.gid = inode->i_gid;
			else
				args.gid = current_fsgid();
		} else {
			args.uid = INVALID_UID; /* no change */
			args.gid = INVALID_GID; /* no change */
		}
		CIFSSMBUnixSetFileInfo(xid, tcon, &args, fid->netfid,
				       current->tgid);
	} else {
		/*
		 * BB implement mode setting via Windows security
		 * descriptors e.g.
		 */
		/* CIFSSMBWinSetPerms(xid,tcon,path,mode,-1,-1,nls);*/

		/* Could set r/o dos attribute if mode & 0222 == 0 */
	}

cifs_create_get_file_info:
	/* server might mask mode so we have to query for it */
	if (tcon->unix_ext)
		rc = cifs_get_inode_info_unix(&newinode, full_path, inode->i_sb,
					      xid);
	else {
#else
	{
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
		/* TODO: Add support for calling POSIX query info here, but passing in fid */
		rc = cifs_get_inode_info(&newinode, full_path, buf, inode->i_sb, xid, fid);
		if (newinode) {
			if (server->ops->set_lease_key)
				server->ops->set_lease_key(newinode, fid);
			if ((*oplock & CIFS_CREATE_ACTION) && S_ISREG(newinode->i_mode)) {
				if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DYNPERM)
					newinode->i_mode = mode;
				if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SET_UID) {
					newinode->i_uid = current_fsuid();
					if (inode->i_mode & S_ISGID)
						newinode->i_gid = inode->i_gid;
					else
						newinode->i_gid = current_fsgid();
				}
			}
		}
	}

#ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
cifs_create_set_dentry:
#endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
	if (rc != 0) {
		cifs_dbg(FYI, "Create worked, get_inode_info failed rc = %d\n",
			 rc);
		goto out_err;
	}

	if (newinode)
		if (S_ISDIR(newinode->i_mode)) {
			rc = -EISDIR;
			goto out_err;
		}

	d_drop(direntry);
	d_add(direntry, newinode);

out:
	free_dentry_path(page);
	return rc;

out_err:
	if (server->ops->close)
		server->ops->close(xid, tcon, fid);
	if (newinode)
		iput(newinode);
	goto out;
}

int
cifs_atomic_open(struct inode *inode, struct dentry *direntry,
		 struct file *file, unsigned oflags, umode_t mode)
{
	int rc;
	unsigned int xid;
	struct tcon_link *tlink;
	struct cifs_tcon *tcon;
	struct TCP_Server_Info *server;
	struct cifs_fid fid = {};
	struct cifs_pending_open open;
	__u32 oplock;
	struct cifsFileInfo *file_info;
	struct cifs_open_info_data buf = {};

	if (unlikely(cifs_forced_shutdown(CIFS_SB(inode->i_sb))))
		return -EIO;

	/*
	 * Posix open is only called (at lookup time) for file create now. For
	 * opens (rather than creates), because we do not know if it is a file
	 * or directory yet, and current Samba no longer allows us to do posix
	 * open on dirs, we could end up wasting an open call on what turns out
	 * to be a dir. For file opens, we wait to call posix open till
	 * cifs_open.  It could be added to atomic_open in the future but the
	 * performance tradeoff of the extra network request when EISDIR or
	 * EACCES is returned would have to be weighed against the 50% reduction
	 * in network traffic in the other paths.
	 */
	if (!(oflags & O_CREAT)) {
		struct dentry *res;

		/*
		 * Check for hashed negative dentry. We have already revalidated
		 * the dentry and it is fine. No need to perform another lookup.
		 */
		if (!d_in_lookup(direntry))
			return -ENOENT;

		res = cifs_lookup(inode, direntry, 0);
		if (IS_ERR(res))
			return PTR_ERR(res);

		return finish_no_open(file, res);
	}

	xid = get_xid();

	cifs_dbg(FYI, "parent inode = 0x%p name is: %pd and dentry = 0x%p\n",
		 inode, direntry, direntry);

	tlink = cifs_sb_tlink(CIFS_SB(inode->i_sb));
	if (IS_ERR(tlink)) {
		rc = PTR_ERR(tlink);
		goto out_free_xid;
	}

	tcon = tlink_tcon(tlink);

	rc = check_name(direntry, tcon);
	if (rc)
		goto out;

	server = tcon->ses->server;

	if (server->ops->new_lease_key)
		server->ops->new_lease_key(&fid);

	cifs_add_pending_open(&fid, tlink, &open);

	rc = cifs_do_create(inode, direntry, xid, tlink, oflags, mode,
			    &oplock, &fid, &buf);
	if (rc) {
		cifs_del_pending_open(&open);
		goto out;
	}

	if ((oflags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
		file->f_mode |= FMODE_CREATED;

	rc = finish_open(file, direntry, generic_file_open);
	if (rc) {
		if (server->ops->close)
			server->ops->close(xid, tcon, &fid);
		cifs_del_pending_open(&open);
		goto out;
	}

	if (file->f_flags & O_DIRECT &&
	    CIFS_SB(inode->i_sb)->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO) {
		if (CIFS_SB(inode->i_sb)->mnt_cifs_flags & CIFS_MOUNT_NO_BRL)
			file->f_op = &cifs_file_direct_nobrl_ops;
		else
			file->f_op = &cifs_file_direct_ops;
		}

	file_info = cifs_new_fileinfo(&fid, file, tlink, oplock, buf.symlink_target);
	if (file_info == NULL) {
		if (server->ops->close)
			server->ops->close(xid, tcon, &fid);
		cifs_del_pending_open(&open);
		rc = -ENOMEM;
		goto out;
	}

	fscache_use_cookie(cifs_inode_cookie(file_inode(file)),
			   file->f_mode & FMODE_WRITE);

out:
	cifs_put_tlink(tlink);
out_free_xid:
	free_xid(xid);
	cifs_free_open_info(&buf);
	return rc;
}

int cifs_create(struct mnt_idmap *idmap, struct inode *inode,
		struct dentry *direntry, umode_t mode, bool excl)
{
	int rc;
	unsigned int xid = get_xid();
	/*
	 * BB below access is probably too much for mknod to request
	 *    but we have to do query and setpathinfo so requesting
	 *    less could fail (unless we want to request getatr and setatr
	 *    permissions (only).  At least for POSIX we do not have to
	 *    request so much.
	 */
	unsigned oflags = O_EXCL | O_CREAT | O_RDWR;
	struct tcon_link *tlink;
	struct cifs_tcon *tcon;
	struct TCP_Server_Info *server;
	struct cifs_fid fid;
	__u32 oplock;
	struct cifs_open_info_data buf = {};

	cifs_dbg(FYI, "cifs_create parent inode = 0x%p name is: %pd and dentry = 0x%p\n",
		 inode, direntry, direntry);

	if (unlikely(cifs_forced_shutdown(CIFS_SB(inode->i_sb)))) {
		rc = -EIO;
		goto out_free_xid;
	}

	tlink = cifs_sb_tlink(CIFS_SB(inode->i_sb));
	rc = PTR_ERR(tlink);
	if (IS_ERR(tlink))
		goto out_free_xid;

	tcon = tlink_tcon(tlink);
	server = tcon->ses->server;

	if (server->ops->new_lease_key)
		server->ops->new_lease_key(&fid);

	rc = cifs_do_create(inode, direntry, xid, tlink, oflags, mode, &oplock, &fid, &buf);
	if (!rc && server->ops->close)
		server->ops->close(xid, tcon, &fid);

	cifs_free_open_info(&buf);
	cifs_put_tlink(tlink);
out_free_xid:
	free_xid(xid);
	return rc;
}

int cifs_mknod(struct mnt_idmap *idmap, struct inode *inode,
	       struct dentry *direntry, umode_t mode, dev_t device_number)
{
	int rc = -EPERM;
	unsigned int xid;
	struct cifs_sb_info *cifs_sb;
	struct tcon_link *tlink;
	struct cifs_tcon *tcon;
	const char *full_path;
	void *page;

	if (!old_valid_dev(device_number))
		return -EINVAL;

	cifs_sb = CIFS_SB(inode->i_sb);
	if (unlikely(cifs_forced_shutdown(cifs_sb)))
		return -EIO;

	tlink = cifs_sb_tlink(cifs_sb);
	if (IS_ERR(tlink))
		return PTR_ERR(tlink);

	page = alloc_dentry_path();
	tcon = tlink_tcon(tlink);
	xid = get_xid();

	full_path = build_path_from_dentry(direntry, page);
	if (IS_ERR(full_path)) {
		rc = PTR_ERR(full_path);
		goto mknod_out;
	}

	trace_smb3_mknod_enter(xid, tcon->tid, tcon->ses->Suid, full_path);

	rc = tcon->ses->server->ops->make_node(xid, inode, direntry, tcon,
					       full_path, mode,
					       device_number);

mknod_out:
	if (rc)
		trace_smb3_mknod_err(xid,  tcon->tid, tcon->ses->Suid, rc);
	else
		trace_smb3_mknod_done(xid, tcon->tid, tcon->ses->Suid);

	free_dentry_path(page);
	free_xid(xid);
	cifs_put_tlink(tlink);
	return rc;
}

struct dentry *
cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
	    unsigned int flags)
{
	unsigned int xid;
	int rc = 0; /* to get around spurious gcc warning, set to zero here */
	struct cifs_sb_info *cifs_sb;
	struct tcon_link *tlink;
	struct cifs_tcon *pTcon;
	struct inode *newInode = NULL;
	const char *full_path;
	void *page;
	int retry_count = 0;

	xid = get_xid();

	cifs_dbg(FYI, "parent inode = 0x%p name is: %pd and dentry = 0x%p\n",
		 parent_dir_inode, direntry, direntry);

	/* check whether path exists */

	cifs_sb = CIFS_SB(parent_dir_inode->i_sb);
	tlink = cifs_sb_tlink(cifs_sb);
	if (IS_ERR(tlink)) {
		free_xid(xid);
		return ERR_CAST(tlink);
	}
	pTcon = tlink_tcon(tlink);

	rc = check_name(direntry, pTcon);
	if (unlikely(rc)) {
		cifs_put_tlink(tlink);
		free_xid(xid);
		return ERR_PTR(rc);
	}

	/* can not grab the rename sem here since it would
	deadlock in the cases (beginning of sys_rename itself)
	in which we already have the sb rename sem */
	page = alloc_dentry_path();
	full_path = build_path_from_dentry(direntry, page);
	if (IS_ERR(full_path)) {
		cifs_put_tlink(tlink);
		free_xid(xid);
		free_dentry_path(page);
		return ERR_CAST(full_path);
	}

	if (d_really_is_positive(direntry)) {
		cifs_dbg(FYI, "non-NULL inode in lookup\n");
	} else {
		cifs_dbg(FYI, "NULL inode in lookup\n");
	}
	cifs_dbg(FYI, "Full path: %s inode = 0x%p\n",
		 full_path, d_inode(direntry));

again:
	if (pTcon->posix_extensions) {
		rc = smb311_posix_get_inode_info(&newInode, full_path, NULL,
						 parent_dir_inode->i_sb, xid);
	} else if (pTcon->unix_ext) {
		rc = cifs_get_inode_info_unix(&newInode, full_path,
					      parent_dir_inode->i_sb, xid);
	} else {
		rc = cifs_get_inode_info(&newInode, full_path, NULL,
				parent_dir_inode->i_sb, xid, NULL);
	}

	if (rc == 0) {
		/* since paths are not looked up by component - the parent
		   directories are presumed to be good here */
		renew_parental_timestamps(direntry);
	} else if (rc == -EAGAIN && retry_count++ < 10) {
		goto again;
	} else if (rc == -ENOENT) {
		cifs_set_time(direntry, jiffies);
		newInode = NULL;
	} else {
		if (rc != -EACCES) {
			cifs_dbg(FYI, "Unexpected lookup error %d\n", rc);
			/* We special case check for Access Denied - since that
			is a common return code */
		}
		newInode = ERR_PTR(rc);
	}
	free_dentry_path(page);
	cifs_put_tlink(tlink);
	free_xid(xid);
	return d_splice_alias(newInode, direntry);
}

static int
cifs_d_revalidate(struct dentry *direntry, unsigned int flags)
{
	struct inode *inode;
	int rc;

	if (flags & LOOKUP_RCU)
		return -ECHILD;

	if (d_really_is_positive(direntry)) {
		inode = d_inode(direntry);
		if ((flags & LOOKUP_REVAL) && !CIFS_CACHE_READ(CIFS_I(inode)))
			CIFS_I(inode)->time = 0; /* force reval */

		rc = cifs_revalidate_dentry(direntry);
		if (rc) {
			cifs_dbg(FYI, "cifs_revalidate_dentry failed with rc=%d", rc);
			switch (rc) {
			case -ENOENT:
			case -ESTALE:
				/*
				 * Those errors mean the dentry is invalid
				 * (file was deleted or recreated)
				 */
				return 0;
			default:
				/*
				 * Otherwise some unexpected error happened
				 * report it as-is to VFS layer
				 */
				return rc;
			}
		}
		else {
			/*
			 * If the inode wasn't known to be a dfs entry when
			 * the dentry was instantiated, such as when created
			 * via ->readdir(), it needs to be set now since the
			 * attributes will have been updated by
			 * cifs_revalidate_dentry().
			 */
			if (IS_AUTOMOUNT(inode) &&
			   !(direntry->d_flags & DCACHE_NEED_AUTOMOUNT)) {
				spin_lock(&direntry->d_lock);
				direntry->d_flags |= DCACHE_NEED_AUTOMOUNT;
				spin_unlock(&direntry->d_lock);
			}

			return 1;
		}
	}

	/*
	 * This may be nfsd (or something), anyway, we can't see the
	 * intent of this. So, since this can be for creation, drop it.
	 */
	if (!flags)
		return 0;

	/*
	 * Drop the negative dentry, in order to make sure to use the
	 * case sensitive name which is specified by user if this is
	 * for creation.
	 */
	if (flags & (LOOKUP_CREATE | LOOKUP_RENAME_TARGET))
		return 0;

	if (time_after(jiffies, cifs_get_time(direntry) + HZ) || !lookupCacheEnabled)
		return 0;

	return 1;
}

/* static int cifs_d_delete(struct dentry *direntry)
{
	int rc = 0;

	cifs_dbg(FYI, "In cifs d_delete, name = %pd\n", direntry);

	return rc;
}     */

const struct dentry_operations cifs_dentry_ops = {
	.d_revalidate = cifs_d_revalidate,
	.d_automount = cifs_d_automount,
/* d_delete:       cifs_d_delete,      */ /* not needed except for debugging */
};

static int cifs_ci_hash(const struct dentry *dentry, struct qstr *q)
{
	struct nls_table *codepage = CIFS_SB(dentry->d_sb)->local_nls;
	unsigned long hash;
	wchar_t c;
	int i, charlen;

	hash = init_name_hash(dentry);
	for (i = 0; i < q->len; i += charlen) {
		charlen = codepage->char2uni(&q->name[i], q->len - i, &c);
		/* error out if we can't convert the character */
		if (unlikely(charlen < 0))
			return charlen;
		hash = partial_name_hash(cifs_toupper(c), hash);
	}
	q->hash = end_name_hash(hash);

	return 0;
}

static int cifs_ci_compare(const struct dentry *dentry,
		unsigned int len, const char *str, const struct qstr *name)
{
	struct nls_table *codepage = CIFS_SB(dentry->d_sb)->local_nls;
	wchar_t c1, c2;
	int i, l1, l2;

	/*
	 * We make the assumption here that uppercase characters in the local
	 * codepage are always the same length as their lowercase counterparts.
	 *
	 * If that's ever not the case, then this will fail to match it.
	 */
	if (name->len != len)
		return 1;

	for (i = 0; i < len; i += l1) {
		/* Convert characters in both strings to UTF-16. */
		l1 = codepage->char2uni(&str[i], len - i, &c1);
		l2 = codepage->char2uni(&name->name[i], name->len - i, &c2);

		/*
		 * If we can't convert either character, just declare it to
		 * be 1 byte long and compare the original byte.
		 */
		if (unlikely(l1 < 0 && l2 < 0)) {
			if (str[i] != name->name[i])
				return 1;
			l1 = 1;
			continue;
		}

		/*
		 * Here, we again ass|u|me that upper/lowercase versions of
		 * a character are the same length in the local NLS.
		 */
		if (l1 != l2)
			return 1;

		/* Now compare uppercase versions of these characters */
		if (cifs_toupper(c1) != cifs_toupper(c2))
			return 1;
	}

	return 0;
}

const struct dentry_operations cifs_ci_dentry_ops = {
	.d_revalidate = cifs_d_revalidate,
	.d_hash = cifs_ci_hash,
	.d_compare = cifs_ci_compare,
	.d_automount = cifs_d_automount,
};