Merge tag 'for-linus-5.11-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git...

[mirror_ubuntu-jammy-kernel.git] / fs / cifs / dir.c

/*
 *   fs/cifs/dir.c
 *
 *   vfs operations that deal with dentries
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2009
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#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"

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->treeName, 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->treeName, 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 */
char *
build_path_from_dentry(struct dentry *direntry)
{
        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,
                                                      prefix);
}

char *
build_path_from_dentry_optional_prefix(struct dentry *direntry, bool prefix)
{
        struct dentry *temp;
        int namelen;
        int dfsplen;
        int pplen = 0;
        char *full_path;
        char dirsep;
        struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
        struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
        unsigned seq;

        dirsep = CIFS_DIR_SEP(cifs_sb);
        if (prefix)
                dfsplen = strnlen(tcon->treeName, MAX_TREE_SIZE + 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;

cifs_bp_rename_retry:
        namelen = dfsplen + pplen;
        seq = read_seqbegin(&rename_lock);
        rcu_read_lock();
        for (temp = direntry; !IS_ROOT(temp);) {
                namelen += (1 + temp->d_name.len);
                temp = temp->d_parent;
                if (temp == NULL) {
                        cifs_dbg(VFS, "corrupt dentry\n");
                        rcu_read_unlock();
                        return NULL;
                }
        }
        rcu_read_unlock();

        full_path = kmalloc(namelen+1, GFP_ATOMIC);
        if (full_path == NULL)
                return full_path;
        full_path[namelen] = 0; /* trailing null */
        rcu_read_lock();
        for (temp = direntry; !IS_ROOT(temp);) {
                spin_lock(&temp->d_lock);
                namelen -= 1 + temp->d_name.len;
                if (namelen < 0) {
                        spin_unlock(&temp->d_lock);
                        break;
                } else {
                        full_path[namelen] = dirsep;
                        strncpy(full_path + namelen + 1, temp->d_name.name,
                                temp->d_name.len);
                        cifs_dbg(FYI, "name: %s\n", full_path + namelen);
                }
                spin_unlock(&temp->d_lock);
                temp = temp->d_parent;
                if (temp == NULL) {
                        cifs_dbg(VFS, "corrupt dentry\n");
                        rcu_read_unlock();
                        kfree(full_path);
                        return NULL;
                }
        }
        rcu_read_unlock();
        if (namelen != dfsplen + pplen || read_seqretry(&rename_lock, seq)) {
                cifs_dbg(FYI, "did not end path lookup where expected. namelen=%ddfsplen=%d\n",
                         namelen, dfsplen);
                /* presumably this is only possible if racing with a rename
                of one of the parent directories  (we can not lock the dentries
                above us to prevent this, but retrying should be harmless) */
                kfree(full_path);
                goto cifs_bp_rename_retry;
        }
        /* DIR_SEP already set for byte  0 / vs \ but not for
           subsequent slashes in prepath which currently must
           be entered the right way - not sure if there is an alternative
           since the '\' is a valid posix character so we can not switch
           those safely to '/' if any are found in the middle of the prepath */
        /* BB test paths to Windows with '/' in the midst of prepath */

        if (pplen) {
                int i;

                cifs_dbg(FYI, "using cifs_sb prepath <%s>\n", cifs_sb->prepath);
                memcpy(full_path+dfsplen+1, cifs_sb->prepath, pplen-1);
                full_path[dfsplen] = dirsep;
                for (i = 0; i < pplen-1; i++)
                        if (full_path[dfsplen+1+i] == '/')
                                full_path[dfsplen+1+i] = CIFS_DIR_SEP(cifs_sb);
        }

        if (dfsplen) {
                strncpy(full_path, tcon->treeName, dfsplen);
                if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) {
                        int i;
                        for (i = 0; i < dfsplen; i++) {
                                if (full_path[i] == '\\')
                                        full_path[i] = '/';
                        }
                }
        }
        return full_path;
}

/*
 * 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 oflags, umode_t mode,
               __u32 *oplock, struct cifs_fid *fid)
{
        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);
        char *full_path = NULL;
        FILE_ALL_INFO *buf = NULL;
        struct inode *newinode = NULL;
        int disposition;
        struct TCP_Server_Info *server = tcon->ses->server;
        struct cifs_open_parms oparms;

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

        full_path = build_path_from_dentry(direntry);
        if (!full_path)
                return -ENOMEM;

        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)
                 */
        }

        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;

        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;
        }

        buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
        if (buf == NULL) {
                rc = -ENOMEM;
                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;

        oparms.tcon = tcon;
        oparms.cifs_sb = cifs_sb;
        oparms.desired_access = desired_access;
        oparms.create_options = cifs_create_options(cifs_sb, create_options);
        oparms.disposition = disposition;
        oparms.path = full_path;
        oparms.fid = fid;
        oparms.reconnect = false;
        oparms.mode = mode;
        rc = server->ops->open(xid, &oparms, oplock, buf);
        if (rc) {
                cifs_dbg(FYI, "cifs_create returned 0x%x\n", rc);
                goto out;
        }

        /*
         * 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 {
                /* 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 (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DYNPERM)
                                newinode->i_mode = mode;
                        if ((*oplock & CIFS_CREATE_ACTION) &&
                            (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();
                        }
                }
        }

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

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

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

out:
        kfree(buf);
        kfree(full_path);
        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;

        /*
         * 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);

        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);
        if (file_info == NULL) {
                if (server->ops->close)
                        server->ops->close(xid, tcon, &fid);
                cifs_del_pending_open(&open);
                rc = -ENOMEM;
        }

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

int cifs_create(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;

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

        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);
        if (!rc && server->ops->close)
                server->ops->close(xid, tcon, &fid);

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

int cifs_mknod(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;
        char *full_path = NULL;

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

        cifs_sb = CIFS_SB(inode->i_sb);
        tlink = cifs_sb_tlink(cifs_sb);
        if (IS_ERR(tlink))
                return PTR_ERR(tlink);

        tcon = tlink_tcon(tlink);

        xid = get_xid();

        full_path = build_path_from_dentry(direntry);
        if (full_path == NULL) {
                rc = -ENOMEM;
                goto mknod_out;
        }

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

mknod_out:
        kfree(full_path);
        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;
        char *full_path = NULL;

        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 */
        full_path = build_path_from_dentry(direntry);
        if (full_path == NULL) {
                cifs_put_tlink(tlink);
                free_xid(xid);
                return ERR_PTR(-ENOMEM);
        }

        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));

        if (pTcon->posix_extensions)
                rc = smb311_posix_get_inode_info(&newInode, full_path, 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 == -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);
        }
        kfree(full_path);
        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;

        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 */

                if (cifs_revalidate_dentry(direntry))
                        return 0;
                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_dfs_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_dfs_d_automount,
};