usbfs: fix race between open and unregister

[linux-2.6/mini2440.git] / fs / cifs / readdir.c

/*
 *   fs/cifs/readdir.c
 *
 *   Directory search handling
 *
 *   Copyright (C) International Business Machines  Corp., 2004, 2008
 *   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/pagemap.h>
#include <linux/stat.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_unicode.h"
#include "cifs_debug.h"
#include "cifs_fs_sb.h"
#include "cifsfs.h"

#ifdef CONFIG_CIFS_DEBUG2
static void dump_cifs_file_struct(struct file *file, char *label)
{
        struct cifsFileInfo *cf;

        if (file) {
                cf = file->private_data;
                if (cf == NULL) {
                        cFYI(1, ("empty cifs private file data"));
                        return;
                }
                if (cf->invalidHandle)
                        cFYI(1, ("invalid handle"));
                if (cf->srch_inf.endOfSearch)
                        cFYI(1, ("end of search"));
                if (cf->srch_inf.emptyDir)
                        cFYI(1, ("empty dir"));
        }
}
#else
static inline void dump_cifs_file_struct(struct file *file, char *label)
{
}
#endif /* DEBUG2 */

/* Returns one if new inode created (which therefore needs to be hashed) */
/* Might check in the future if inode number changed so we can rehash inode */
static int construct_dentry(struct qstr *qstring, struct file *file,
        struct inode **ptmp_inode, struct dentry **pnew_dentry)
{
        struct dentry *tmp_dentry;
        struct cifs_sb_info *cifs_sb;
        struct cifsTconInfo *pTcon;
        int rc = 0;

        cFYI(1, ("For %s", qstring->name));
        cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
        pTcon = cifs_sb->tcon;

        qstring->hash = full_name_hash(qstring->name, qstring->len);
        tmp_dentry = d_lookup(file->f_path.dentry, qstring);
        if (tmp_dentry) {
                cFYI(0, ("existing dentry with inode 0x%p",
                         tmp_dentry->d_inode));
                *ptmp_inode = tmp_dentry->d_inode;
/* BB overwrite old name? i.e. tmp_dentry->d_name and tmp_dentry->d_name.len??*/
                if (*ptmp_inode == NULL) {
                        *ptmp_inode = new_inode(file->f_path.dentry->d_sb);
                        if (*ptmp_inode == NULL)
                                return rc;
                        rc = 1;
                }
                if (file->f_path.dentry->d_sb->s_flags & MS_NOATIME)
                        (*ptmp_inode)->i_flags |= S_NOATIME | S_NOCMTIME;
        } else {
                tmp_dentry = d_alloc(file->f_path.dentry, qstring);
                if (tmp_dentry == NULL) {
                        cERROR(1, ("Failed allocating dentry"));
                        *ptmp_inode = NULL;
                        return rc;
                }

                *ptmp_inode = new_inode(file->f_path.dentry->d_sb);
                if (pTcon->nocase)
                        tmp_dentry->d_op = &cifs_ci_dentry_ops;
                else
                        tmp_dentry->d_op = &cifs_dentry_ops;
                if (*ptmp_inode == NULL)
                        return rc;
                if (file->f_path.dentry->d_sb->s_flags & MS_NOATIME)
                        (*ptmp_inode)->i_flags |= S_NOATIME | S_NOCMTIME;
                rc = 2;
        }

        tmp_dentry->d_time = jiffies;
        *pnew_dentry = tmp_dentry;
        return rc;
}

static void AdjustForTZ(struct cifsTconInfo *tcon, struct inode *inode)
{
        if ((tcon) && (tcon->ses) && (tcon->ses->server)) {
                inode->i_ctime.tv_sec += tcon->ses->server->timeAdj;
                inode->i_mtime.tv_sec += tcon->ses->server->timeAdj;
                inode->i_atime.tv_sec += tcon->ses->server->timeAdj;
        }
        return;
}


static void fill_in_inode(struct inode *tmp_inode, int new_buf_type,
                          char *buf, unsigned int *pobject_type, int isNewInode)
{
        loff_t local_size;
        struct timespec local_mtime;

        struct cifsInodeInfo *cifsInfo = CIFS_I(tmp_inode);
        struct cifs_sb_info *cifs_sb = CIFS_SB(tmp_inode->i_sb);
        __u32 attr;
        __u64 allocation_size;
        __u64 end_of_file;
        umode_t default_mode;

        /* save mtime and size */
        local_mtime = tmp_inode->i_mtime;
        local_size  = tmp_inode->i_size;

        if (new_buf_type) {
                FILE_DIRECTORY_INFO *pfindData = (FILE_DIRECTORY_INFO *)buf;

                attr = le32_to_cpu(pfindData->ExtFileAttributes);
                allocation_size = le64_to_cpu(pfindData->AllocationSize);
                end_of_file = le64_to_cpu(pfindData->EndOfFile);
                tmp_inode->i_atime =
                      cifs_NTtimeToUnix(le64_to_cpu(pfindData->LastAccessTime));
                tmp_inode->i_mtime =
                      cifs_NTtimeToUnix(le64_to_cpu(pfindData->LastWriteTime));
                tmp_inode->i_ctime =
                      cifs_NTtimeToUnix(le64_to_cpu(pfindData->ChangeTime));
        } else { /* legacy, OS2 and DOS style */
/*              struct timespec ts;*/
                FIND_FILE_STANDARD_INFO *pfindData =
                        (FIND_FILE_STANDARD_INFO *)buf;

                tmp_inode->i_mtime = cnvrtDosUnixTm(
                                le16_to_cpu(pfindData->LastWriteDate),
                                le16_to_cpu(pfindData->LastWriteTime));
                tmp_inode->i_atime = cnvrtDosUnixTm(
                                le16_to_cpu(pfindData->LastAccessDate),
                                le16_to_cpu(pfindData->LastAccessTime));
                tmp_inode->i_ctime = cnvrtDosUnixTm(
                                le16_to_cpu(pfindData->LastWriteDate),
                                le16_to_cpu(pfindData->LastWriteTime));
                AdjustForTZ(cifs_sb->tcon, tmp_inode);
                attr = le16_to_cpu(pfindData->Attributes);
                allocation_size = le32_to_cpu(pfindData->AllocationSize);
                end_of_file = le32_to_cpu(pfindData->DataSize);
        }

        /* Linux can not store file creation time unfortunately so ignore it */

        cifsInfo->cifsAttrs = attr;
#ifdef CONFIG_CIFS_EXPERIMENTAL
        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_CIFS_ACL) {
                /* get more accurate mode via ACL - so force inode refresh */
                cifsInfo->time = 0;
        } else
#endif /* CONFIG_CIFS_EXPERIMENTAL */
                cifsInfo->time = jiffies;

        /* treat dos attribute of read-only as read-only mode bit e.g. 555? */
        /* 2767 perms - indicate mandatory locking */
                /* BB fill in uid and gid here? with help from winbind?
                   or retrieve from NTFS stream extended attribute */
        if (atomic_read(&cifsInfo->inUse) == 0) {
                tmp_inode->i_uid = cifs_sb->mnt_uid;
                tmp_inode->i_gid = cifs_sb->mnt_gid;
        }

        if (attr & ATTR_DIRECTORY)
                default_mode = cifs_sb->mnt_dir_mode;
        else
                default_mode = cifs_sb->mnt_file_mode;

        /* set initial permissions */
        if ((atomic_read(&cifsInfo->inUse) == 0) ||
            (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DYNPERM) == 0)
                tmp_inode->i_mode = default_mode;
        else {
                /* just reenable write bits if !ATTR_READONLY */
                if ((tmp_inode->i_mode & S_IWUGO) == 0 &&
                    (attr & ATTR_READONLY) == 0)
                        tmp_inode->i_mode |= (S_IWUGO & default_mode);

                tmp_inode->i_mode &= ~S_IFMT;
        }

        /* clear write bits if ATTR_READONLY is set */
        if (attr & ATTR_READONLY)
                tmp_inode->i_mode &= ~S_IWUGO;

        /* set inode type */
        if ((attr & ATTR_SYSTEM) &&
            (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL)) {
                if (end_of_file == 0)  {
                        tmp_inode->i_mode |= S_IFIFO;
                        *pobject_type = DT_FIFO;
                } else {
                        /*
                         * trying to get the type can be slow, so just call
                         * this a regular file for now, and mark for reval
                         */
                        tmp_inode->i_mode |= S_IFREG;
                        *pobject_type = DT_REG;
                        cifsInfo->time = 0;
                }
        } else {
                if (attr & ATTR_DIRECTORY) {
                        tmp_inode->i_mode |= S_IFDIR;
                        *pobject_type = DT_DIR;
                } else {
                        tmp_inode->i_mode |= S_IFREG;
                        *pobject_type = DT_REG;
                }
        }

        /* can not fill in nlink here as in qpathinfo version and Unx search */
        if (atomic_read(&cifsInfo->inUse) == 0)
                atomic_set(&cifsInfo->inUse, 1);

        spin_lock(&tmp_inode->i_lock);
        if (is_size_safe_to_change(cifsInfo, end_of_file)) {
                /* can not safely change the file size here if the
                client is writing to it due to potential races */
                i_size_write(tmp_inode, end_of_file);

        /* 512 bytes (2**9) is the fake blocksize that must be used */
        /* for this calculation, even though the reported blocksize is larger */
                tmp_inode->i_blocks = (512 - 1 + allocation_size) >> 9;
        }
        spin_unlock(&tmp_inode->i_lock);

        if (allocation_size < end_of_file)
                cFYI(1, ("May be sparse file, allocation less than file size"));
        cFYI(1, ("File Size %ld and blocks %llu",
                (unsigned long)tmp_inode->i_size,
                (unsigned long long)tmp_inode->i_blocks));
        if (S_ISREG(tmp_inode->i_mode)) {
                cFYI(1, ("File inode"));
                tmp_inode->i_op = &cifs_file_inode_ops;
                if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DIRECT_IO) {
                        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_BRL)
                                tmp_inode->i_fop = &cifs_file_direct_nobrl_ops;
                        else
                                tmp_inode->i_fop = &cifs_file_direct_ops;
                } else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_BRL)
                        tmp_inode->i_fop = &cifs_file_nobrl_ops;
                else
                        tmp_inode->i_fop = &cifs_file_ops;

                if ((cifs_sb->tcon) && (cifs_sb->tcon->ses) &&
                   (cifs_sb->tcon->ses->server->maxBuf <
                        PAGE_CACHE_SIZE + MAX_CIFS_HDR_SIZE))
                        tmp_inode->i_data.a_ops = &cifs_addr_ops_smallbuf;
                else
                        tmp_inode->i_data.a_ops = &cifs_addr_ops;

                if (isNewInode)
                        return; /* No sense invalidating pages for new inode
                                   since have not started caching readahead file
                                   data yet */

                if (timespec_equal(&tmp_inode->i_mtime, &local_mtime) &&
                        (local_size == tmp_inode->i_size)) {
                        cFYI(1, ("inode exists but unchanged"));
                } else {
                        /* file may have changed on server */
                        cFYI(1, ("invalidate inode, readdir detected change"));
                        invalidate_remote_inode(tmp_inode);
                }
        } else if (S_ISDIR(tmp_inode->i_mode)) {
                cFYI(1, ("Directory inode"));
                tmp_inode->i_op = &cifs_dir_inode_ops;
                tmp_inode->i_fop = &cifs_dir_ops;
        } else if (S_ISLNK(tmp_inode->i_mode)) {
                cFYI(1, ("Symbolic Link inode"));
                tmp_inode->i_op = &cifs_symlink_inode_ops;
        } else {
                cFYI(1, ("Init special inode"));
                init_special_inode(tmp_inode, tmp_inode->i_mode,
                                   tmp_inode->i_rdev);
        }
}

static void unix_fill_in_inode(struct inode *tmp_inode,
        FILE_UNIX_INFO *pfindData, unsigned int *pobject_type, int isNewInode)
{
        loff_t local_size;
        struct timespec local_mtime;

        struct cifsInodeInfo *cifsInfo = CIFS_I(tmp_inode);
        struct cifs_sb_info *cifs_sb = CIFS_SB(tmp_inode->i_sb);

        __u32 type = le32_to_cpu(pfindData->Type);
        __u64 num_of_bytes = le64_to_cpu(pfindData->NumOfBytes);
        __u64 end_of_file = le64_to_cpu(pfindData->EndOfFile);
        cifsInfo->time = jiffies;
        atomic_inc(&cifsInfo->inUse);

        /* save mtime and size */
        local_mtime = tmp_inode->i_mtime;
        local_size  = tmp_inode->i_size;

        tmp_inode->i_atime =
            cifs_NTtimeToUnix(le64_to_cpu(pfindData->LastAccessTime));
        tmp_inode->i_mtime =
            cifs_NTtimeToUnix(le64_to_cpu(pfindData->LastModificationTime));
        tmp_inode->i_ctime =
            cifs_NTtimeToUnix(le64_to_cpu(pfindData->LastStatusChange));

        tmp_inode->i_mode = le64_to_cpu(pfindData->Permissions);
        /* since we set the inode type below we need to mask off type
           to avoid strange results if bits above were corrupt */
        tmp_inode->i_mode &= ~S_IFMT;
        if (type == UNIX_FILE) {
                *pobject_type = DT_REG;
                tmp_inode->i_mode |= S_IFREG;
        } else if (type == UNIX_SYMLINK) {
                *pobject_type = DT_LNK;
                tmp_inode->i_mode |= S_IFLNK;
        } else if (type == UNIX_DIR) {
                *pobject_type = DT_DIR;
                tmp_inode->i_mode |= S_IFDIR;
        } else if (type == UNIX_CHARDEV) {
                *pobject_type = DT_CHR;
                tmp_inode->i_mode |= S_IFCHR;
                tmp_inode->i_rdev = MKDEV(le64_to_cpu(pfindData->DevMajor),
                                le64_to_cpu(pfindData->DevMinor) & MINORMASK);
        } else if (type == UNIX_BLOCKDEV) {
                *pobject_type = DT_BLK;
                tmp_inode->i_mode |= S_IFBLK;
                tmp_inode->i_rdev = MKDEV(le64_to_cpu(pfindData->DevMajor),
                                le64_to_cpu(pfindData->DevMinor) & MINORMASK);
        } else if (type == UNIX_FIFO) {
                *pobject_type = DT_FIFO;
                tmp_inode->i_mode |= S_IFIFO;
        } else if (type == UNIX_SOCKET) {
                *pobject_type = DT_SOCK;
                tmp_inode->i_mode |= S_IFSOCK;
        } else {
                /* safest to just call it a file */
                *pobject_type = DT_REG;
                tmp_inode->i_mode |= S_IFREG;
                cFYI(1, ("unknown inode type %d", type));
        }

        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_OVERR_UID)
                tmp_inode->i_uid = cifs_sb->mnt_uid;
        else
                tmp_inode->i_uid = le64_to_cpu(pfindData->Uid);
        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_OVERR_GID)
                tmp_inode->i_gid = cifs_sb->mnt_gid;
        else
                tmp_inode->i_gid = le64_to_cpu(pfindData->Gid);
        tmp_inode->i_nlink = le64_to_cpu(pfindData->Nlinks);

        spin_lock(&tmp_inode->i_lock);
        if (is_size_safe_to_change(cifsInfo, end_of_file)) {
                /* can not safely change the file size here if the
                client is writing to it due to potential races */
                i_size_write(tmp_inode, end_of_file);

        /* 512 bytes (2**9) is the fake blocksize that must be used */
        /* for this calculation, not the real blocksize */
                tmp_inode->i_blocks = (512 - 1 + num_of_bytes) >> 9;
        }
        spin_unlock(&tmp_inode->i_lock);

        if (S_ISREG(tmp_inode->i_mode)) {
                cFYI(1, ("File inode"));
                tmp_inode->i_op = &cifs_file_inode_ops;

                if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_DIRECT_IO) {
                        if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_BRL)
                                tmp_inode->i_fop = &cifs_file_direct_nobrl_ops;
                        else
                                tmp_inode->i_fop = &cifs_file_direct_ops;
                } else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_BRL)
                        tmp_inode->i_fop = &cifs_file_nobrl_ops;
                else
                        tmp_inode->i_fop = &cifs_file_ops;

                if ((cifs_sb->tcon) && (cifs_sb->tcon->ses) &&
                   (cifs_sb->tcon->ses->server->maxBuf <
                        PAGE_CACHE_SIZE + MAX_CIFS_HDR_SIZE))
                        tmp_inode->i_data.a_ops = &cifs_addr_ops_smallbuf;
                else
                        tmp_inode->i_data.a_ops = &cifs_addr_ops;

                if (isNewInode)
                        return; /* No sense invalidating pages for new inode
                                   since we have not started caching readahead
                                   file data for it yet */

                if (timespec_equal(&tmp_inode->i_mtime, &local_mtime) &&
                        (local_size == tmp_inode->i_size)) {
                        cFYI(1, ("inode exists but unchanged"));
                } else {
                        /* file may have changed on server */
                        cFYI(1, ("invalidate inode, readdir detected change"));
                        invalidate_remote_inode(tmp_inode);
                }
        } else if (S_ISDIR(tmp_inode->i_mode)) {
                cFYI(1, ("Directory inode"));
                tmp_inode->i_op = &cifs_dir_inode_ops;
                tmp_inode->i_fop = &cifs_dir_ops;
        } else if (S_ISLNK(tmp_inode->i_mode)) {
                cFYI(1, ("Symbolic Link inode"));
                tmp_inode->i_op = &cifs_symlink_inode_ops;
/* tmp_inode->i_fop = *//* do not need to set to anything */
        } else {
                cFYI(1, ("Special inode"));
                init_special_inode(tmp_inode, tmp_inode->i_mode,
                                   tmp_inode->i_rdev);
        }
}

static int initiate_cifs_search(const int xid, struct file *file)
{
        int rc = 0;
        char *full_path;
        struct cifsFileInfo *cifsFile;
        struct cifs_sb_info *cifs_sb;
        struct cifsTconInfo *pTcon;

        if (file->private_data == NULL) {
                file->private_data =
                        kzalloc(sizeof(struct cifsFileInfo), GFP_KERNEL);
        }

        if (file->private_data == NULL)
                return -ENOMEM;
        cifsFile = file->private_data;
        cifsFile->invalidHandle = true;
        cifsFile->srch_inf.endOfSearch = false;

        cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
        if (cifs_sb == NULL)
                return -EINVAL;

        pTcon = cifs_sb->tcon;
        if (pTcon == NULL)
                return -EINVAL;

        full_path = build_path_from_dentry(file->f_path.dentry);

        if (full_path == NULL)
                return -ENOMEM;

        cFYI(1, ("Full path: %s start at: %lld", full_path, file->f_pos));

ffirst_retry:
        /* test for Unix extensions */
        /* but now check for them on the share/mount not on the SMB session */
/*      if (pTcon->ses->capabilities & CAP_UNIX) { */
        if (pTcon->unix_ext)
                cifsFile->srch_inf.info_level = SMB_FIND_FILE_UNIX;
        else if ((pTcon->ses->capabilities &
                        (CAP_NT_SMBS | CAP_NT_FIND)) == 0) {
                cifsFile->srch_inf.info_level = SMB_FIND_FILE_INFO_STANDARD;
        } else if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM) {
                cifsFile->srch_inf.info_level = SMB_FIND_FILE_ID_FULL_DIR_INFO;
        } else /* not srvinos - BB fixme add check for backlevel? */ {
                cifsFile->srch_inf.info_level = SMB_FIND_FILE_DIRECTORY_INFO;
        }

        rc = CIFSFindFirst(xid, pTcon, full_path, cifs_sb->local_nls,
                &cifsFile->netfid, &cifsFile->srch_inf,
                cifs_sb->mnt_cifs_flags &
                        CIFS_MOUNT_MAP_SPECIAL_CHR, CIFS_DIR_SEP(cifs_sb));
        if (rc == 0)
                cifsFile->invalidHandle = false;
        if ((rc == -EOPNOTSUPP) &&
                (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)) {
                cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_SERVER_INUM;
                goto ffirst_retry;
        }
        kfree(full_path);
        return rc;
}

/* return length of unicode string in bytes */
static int cifs_unicode_bytelen(char *str)
{
        int len;
        __le16 *ustr = (__le16 *)str;

        for (len = 0; len <= PATH_MAX; len++) {
                if (ustr[len] == 0)
                        return len << 1;
        }
        cFYI(1, ("Unicode string longer than PATH_MAX found"));
        return len << 1;
}

static char *nxt_dir_entry(char *old_entry, char *end_of_smb, int level)
{
        char *new_entry;
        FILE_DIRECTORY_INFO *pDirInfo = (FILE_DIRECTORY_INFO *)old_entry;

        if (level == SMB_FIND_FILE_INFO_STANDARD) {
                FIND_FILE_STANDARD_INFO *pfData;
                pfData = (FIND_FILE_STANDARD_INFO *)pDirInfo;

                new_entry = old_entry + sizeof(FIND_FILE_STANDARD_INFO) +
                                pfData->FileNameLength;
        } else
                new_entry = old_entry + le32_to_cpu(pDirInfo->NextEntryOffset);
        cFYI(1, ("new entry %p old entry %p", new_entry, old_entry));
        /* validate that new_entry is not past end of SMB */
        if (new_entry >= end_of_smb) {
                cERROR(1,
                      ("search entry %p began after end of SMB %p old entry %p",
                        new_entry, end_of_smb, old_entry));
                return NULL;
        } else if (((level == SMB_FIND_FILE_INFO_STANDARD) &&
                    (new_entry + sizeof(FIND_FILE_STANDARD_INFO) > end_of_smb))
                  || ((level != SMB_FIND_FILE_INFO_STANDARD) &&
                   (new_entry + sizeof(FILE_DIRECTORY_INFO) > end_of_smb)))  {
                cERROR(1, ("search entry %p extends after end of SMB %p",
                        new_entry, end_of_smb));
                return NULL;
        } else
                return new_entry;

}

#define UNICODE_DOT cpu_to_le16(0x2e)

/* return 0 if no match and 1 for . (current directory) and 2 for .. (parent) */
static int cifs_entry_is_dot(char *current_entry, struct cifsFileInfo *cfile)
{
        int rc = 0;
        char *filename = NULL;
        int len = 0;

        if (cfile->srch_inf.info_level == SMB_FIND_FILE_UNIX) {
                FILE_UNIX_INFO *pFindData = (FILE_UNIX_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                if (cfile->srch_inf.unicode) {
                        len = cifs_unicode_bytelen(filename);
                } else {
                        /* BB should we make this strnlen of PATH_MAX? */
                        len = strnlen(filename, 5);
                }
        } else if (cfile->srch_inf.info_level == SMB_FIND_FILE_DIRECTORY_INFO) {
                FILE_DIRECTORY_INFO *pFindData =
                        (FILE_DIRECTORY_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
        } else if (cfile->srch_inf.info_level ==
                        SMB_FIND_FILE_FULL_DIRECTORY_INFO) {
                FILE_FULL_DIRECTORY_INFO *pFindData =
                        (FILE_FULL_DIRECTORY_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
        } else if (cfile->srch_inf.info_level ==
                        SMB_FIND_FILE_ID_FULL_DIR_INFO) {
                SEARCH_ID_FULL_DIR_INFO *pFindData =
                        (SEARCH_ID_FULL_DIR_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
        } else if (cfile->srch_inf.info_level ==
                        SMB_FIND_FILE_BOTH_DIRECTORY_INFO) {
                FILE_BOTH_DIRECTORY_INFO *pFindData =
                        (FILE_BOTH_DIRECTORY_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
        } else if (cfile->srch_inf.info_level == SMB_FIND_FILE_INFO_STANDARD) {
                FIND_FILE_STANDARD_INFO *pFindData =
                        (FIND_FILE_STANDARD_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = pFindData->FileNameLength;
        } else {
                cFYI(1, ("Unknown findfirst level %d",
                         cfile->srch_inf.info_level));
        }

        if (filename) {
                if (cfile->srch_inf.unicode) {
                        __le16 *ufilename = (__le16 *)filename;
                        if (len == 2) {
                                /* check for . */
                                if (ufilename[0] == UNICODE_DOT)
                                        rc = 1;
                        } else if (len == 4) {
                                /* check for .. */
                                if ((ufilename[0] == UNICODE_DOT)
                                   && (ufilename[1] == UNICODE_DOT))
                                        rc = 2;
                        }
                } else /* ASCII */ {
                        if (len == 1) {
                                if (filename[0] == '.')
                                        rc = 1;
                        } else if (len == 2) {
                                if ((filename[0] == '.') && (filename[1] == '.'))
                                        rc = 2;
                        }
                }
        }

        return rc;
}

/* Check if directory that we are searching has changed so we can decide
   whether we can use the cached search results from the previous search */
static int is_dir_changed(struct file *file)
{
        struct inode *inode = file->f_path.dentry->d_inode;
        struct cifsInodeInfo *cifsInfo = CIFS_I(inode);

        if (cifsInfo->time == 0)
                return 1; /* directory was changed, perhaps due to unlink */
        else
                return 0;

}

/* find the corresponding entry in the search */
/* Note that the SMB server returns search entries for . and .. which
   complicates logic here if we choose to parse for them and we do not
   assume that they are located in the findfirst return buffer.*/
/* We start counting in the buffer with entry 2 and increment for every
   entry (do not increment for . or .. entry) */
static int find_cifs_entry(const int xid, struct cifsTconInfo *pTcon,
        struct file *file, char **ppCurrentEntry, int *num_to_ret)
{
        int rc = 0;
        int pos_in_buf = 0;
        loff_t first_entry_in_buffer;
        loff_t index_to_find = file->f_pos;
        struct cifsFileInfo *cifsFile = file->private_data;
        /* check if index in the buffer */

        if ((cifsFile == NULL) || (ppCurrentEntry == NULL) ||
           (num_to_ret == NULL))
                return -ENOENT;

        *ppCurrentEntry = NULL;
        first_entry_in_buffer =
                cifsFile->srch_inf.index_of_last_entry -
                        cifsFile->srch_inf.entries_in_buffer;

        /* if first entry in buf is zero then is first buffer
        in search response data which means it is likely . and ..
        will be in this buffer, although some servers do not return
        . and .. for the root of a drive and for those we need
        to start two entries earlier */

        dump_cifs_file_struct(file, "In fce ");
        if (((index_to_find < cifsFile->srch_inf.index_of_last_entry) &&
             is_dir_changed(file)) ||
           (index_to_find < first_entry_in_buffer)) {
                /* close and restart search */
                cFYI(1, ("search backing up - close and restart search"));
                if (!cifsFile->srch_inf.endOfSearch &&
                    !cifsFile->invalidHandle) {
                        cifsFile->invalidHandle = true;
                        CIFSFindClose(xid, pTcon, cifsFile->netfid);
                }
                if (cifsFile->srch_inf.ntwrk_buf_start) {
                        cFYI(1, ("freeing SMB ff cache buf on search rewind"));
                        if (cifsFile->srch_inf.smallBuf)
                                cifs_small_buf_release(cifsFile->srch_inf.
                                                ntwrk_buf_start);
                        else
                                cifs_buf_release(cifsFile->srch_inf.
                                                ntwrk_buf_start);
                }
                rc = initiate_cifs_search(xid, file);
                if (rc) {
                        cFYI(1, ("error %d reinitiating a search on rewind",
                                 rc));
                        return rc;
                }
        }

        while ((index_to_find >= cifsFile->srch_inf.index_of_last_entry) &&
              (rc == 0) && !cifsFile->srch_inf.endOfSearch) {
                cFYI(1, ("calling findnext2"));
                rc = CIFSFindNext(xid, pTcon, cifsFile->netfid,
                                  &cifsFile->srch_inf);
                if (rc)
                        return -ENOENT;
        }
        if (index_to_find < cifsFile->srch_inf.index_of_last_entry) {
                /* we found the buffer that contains the entry */
                /* scan and find it */
                int i;
                char *current_entry;
                char *end_of_smb = cifsFile->srch_inf.ntwrk_buf_start +
                        smbCalcSize((struct smb_hdr *)
                                cifsFile->srch_inf.ntwrk_buf_start);

                current_entry = cifsFile->srch_inf.srch_entries_start;
                first_entry_in_buffer = cifsFile->srch_inf.index_of_last_entry
                                        - cifsFile->srch_inf.entries_in_buffer;
                pos_in_buf = index_to_find - first_entry_in_buffer;
                cFYI(1, ("found entry - pos_in_buf %d", pos_in_buf));

                for (i = 0; (i < (pos_in_buf)) && (current_entry != NULL); i++) {
                        /* go entry by entry figuring out which is first */
                        current_entry = nxt_dir_entry(current_entry, end_of_smb,
                                                cifsFile->srch_inf.info_level);
                }
                if ((current_entry == NULL) && (i < pos_in_buf)) {
                        /* BB fixme - check if we should flag this error */
                        cERROR(1, ("reached end of buf searching for pos in buf"
                          " %d index to find %lld rc %d",
                          pos_in_buf, index_to_find, rc));
                }
                rc = 0;
                *ppCurrentEntry = current_entry;
        } else {
                cFYI(1, ("index not in buffer - could not findnext into it"));
                return 0;
        }

        if (pos_in_buf >= cifsFile->srch_inf.entries_in_buffer) {
                cFYI(1, ("can not return entries pos_in_buf beyond last"));
                *num_to_ret = 0;
        } else
                *num_to_ret = cifsFile->srch_inf.entries_in_buffer - pos_in_buf;

        return rc;
}

/* inode num, inode type and filename returned */
static int cifs_get_name_from_search_buf(struct qstr *pqst,
        char *current_entry, __u16 level, unsigned int unicode,
        struct cifs_sb_info *cifs_sb, int max_len, ino_t *pinum)
{
        int rc = 0;
        unsigned int len = 0;
        char *filename;
        struct nls_table *nlt = cifs_sb->local_nls;

        *pinum = 0;

        if (level == SMB_FIND_FILE_UNIX) {
                FILE_UNIX_INFO *pFindData = (FILE_UNIX_INFO *)current_entry;

                filename = &pFindData->FileName[0];
                if (unicode) {
                        len = cifs_unicode_bytelen(filename);
                } else {
                        /* BB should we make this strnlen of PATH_MAX? */
                        len = strnlen(filename, PATH_MAX);
                }

                /* BB fixme - hash low and high 32 bits if not 64 bit arch BB */
                if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_SERVER_INUM)
                        *pinum = pFindData->UniqueId;
        } else if (level == SMB_FIND_FILE_DIRECTORY_INFO) {
                FILE_DIRECTORY_INFO *pFindData =
                        (FILE_DIRECTORY_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
        } else if (level == SMB_FIND_FILE_FULL_DIRECTORY_INFO) {
                FILE_FULL_DIRECTORY_INFO *pFindData =
                        (FILE_FULL_DIRECTORY_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
        } else if (level == SMB_FIND_FILE_ID_FULL_DIR_INFO) {
                SEARCH_ID_FULL_DIR_INFO *pFindData =
                        (SEARCH_ID_FULL_DIR_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
                *pinum = pFindData->UniqueId;
        } else if (level == SMB_FIND_FILE_BOTH_DIRECTORY_INFO) {
                FILE_BOTH_DIRECTORY_INFO *pFindData =
                        (FILE_BOTH_DIRECTORY_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
        } else if (level == SMB_FIND_FILE_INFO_STANDARD) {
                FIND_FILE_STANDARD_INFO *pFindData =
                        (FIND_FILE_STANDARD_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                /* one byte length, no name conversion */
                len = (unsigned int)pFindData->FileNameLength;
        } else {
                cFYI(1, ("Unknown findfirst level %d", level));
                return -EINVAL;
        }

        if (len > max_len) {
                cERROR(1, ("bad search response length %d past smb end", len));
                return -EINVAL;
        }

        if (unicode) {
                /* BB fixme - test with long names */
                /* Note converted filename can be longer than in unicode */
                if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR)
                        pqst->len = cifs_convertUCSpath((char *)pqst->name,
                                        (__le16 *)filename, len/2, nlt);
                else
                        pqst->len = cifs_strfromUCS_le((char *)pqst->name,
                                        (__le16 *)filename, len/2, nlt);
        } else {
                pqst->name = filename;
                pqst->len = len;
        }
        pqst->hash = full_name_hash(pqst->name, pqst->len);
/*      cFYI(1, ("filldir on %s",pqst->name));  */
        return rc;
}

static int cifs_filldir(char *pfindEntry, struct file *file,
        filldir_t filldir, void *direntry, char *scratch_buf, int max_len)
{
        int rc = 0;
        struct qstr qstring;
        struct cifsFileInfo *pCifsF;
        unsigned int obj_type;
        ino_t  inum;
        struct cifs_sb_info *cifs_sb;
        struct inode *tmp_inode;
        struct dentry *tmp_dentry;

        /* get filename and len into qstring */
        /* get dentry */
        /* decide whether to create and populate ionde */
        if ((direntry == NULL) || (file == NULL))
                return -EINVAL;

        pCifsF = file->private_data;

        if ((scratch_buf == NULL) || (pfindEntry == NULL) || (pCifsF == NULL))
                return -ENOENT;

        rc = cifs_entry_is_dot(pfindEntry, pCifsF);
        /* skip . and .. since we added them first */
        if (rc != 0)
                return 0;

        cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);

        qstring.name = scratch_buf;
        rc = cifs_get_name_from_search_buf(&qstring, pfindEntry,
                        pCifsF->srch_inf.info_level,
                        pCifsF->srch_inf.unicode, cifs_sb,
                        max_len,
                        &inum /* returned */);

        if (rc)
                return rc;

        rc = construct_dentry(&qstring, file, &tmp_inode, &tmp_dentry);
        if ((tmp_inode == NULL) || (tmp_dentry == NULL))
                return -ENOMEM;

        if (rc) {
                /* inode created, we need to hash it with right inode number */
                if (inum != 0) {
                        /* BB fixme - hash the 2 32 quantities bits together if
                         *  necessary BB */
                        tmp_inode->i_ino = inum;
                }
                insert_inode_hash(tmp_inode);
        }

        /* we pass in rc below, indicating whether it is a new inode,
           so we can figure out whether to invalidate the inode cached
           data if the file has changed */
        if (pCifsF->srch_inf.info_level == SMB_FIND_FILE_UNIX)
                unix_fill_in_inode(tmp_inode,
                                   (FILE_UNIX_INFO *)pfindEntry,
                                   &obj_type, rc);
        else if (pCifsF->srch_inf.info_level == SMB_FIND_FILE_INFO_STANDARD)
                fill_in_inode(tmp_inode, 0 /* old level 1 buffer type */,
                                pfindEntry, &obj_type, rc);
        else
                fill_in_inode(tmp_inode, 1 /* NT */, pfindEntry, &obj_type, rc);

        if (rc) /* new inode - needs to be tied to dentry */ {
                d_instantiate(tmp_dentry, tmp_inode);
                if (rc == 2)
                        d_rehash(tmp_dentry);
        }


        rc = filldir(direntry, qstring.name, qstring.len, file->f_pos,
                     tmp_inode->i_ino, obj_type);
        if (rc) {
                cFYI(1, ("filldir rc = %d", rc));
                /* we can not return filldir errors to the caller
                since they are "normal" when the stat blocksize
                is too small - we return remapped error instead */
                rc = -EOVERFLOW;
        }

        dput(tmp_dentry);
        return rc;
}

static int cifs_save_resume_key(const char *current_entry,
        struct cifsFileInfo *cifsFile)
{
        int rc = 0;
        unsigned int len = 0;
        __u16 level;
        char *filename;

        if ((cifsFile == NULL) || (current_entry == NULL))
                return -EINVAL;

        level = cifsFile->srch_inf.info_level;

        if (level == SMB_FIND_FILE_UNIX) {
                FILE_UNIX_INFO *pFindData = (FILE_UNIX_INFO *)current_entry;

                filename = &pFindData->FileName[0];
                if (cifsFile->srch_inf.unicode) {
                        len = cifs_unicode_bytelen(filename);
                } else {
                        /* BB should we make this strnlen of PATH_MAX? */
                        len = strnlen(filename, PATH_MAX);
                }
                cifsFile->srch_inf.resume_key = pFindData->ResumeKey;
        } else if (level == SMB_FIND_FILE_DIRECTORY_INFO) {
                FILE_DIRECTORY_INFO *pFindData =
                        (FILE_DIRECTORY_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
                cifsFile->srch_inf.resume_key = pFindData->FileIndex;
        } else if (level == SMB_FIND_FILE_FULL_DIRECTORY_INFO) {
                FILE_FULL_DIRECTORY_INFO *pFindData =
                        (FILE_FULL_DIRECTORY_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
                cifsFile->srch_inf.resume_key = pFindData->FileIndex;
        } else if (level == SMB_FIND_FILE_ID_FULL_DIR_INFO) {
                SEARCH_ID_FULL_DIR_INFO *pFindData =
                        (SEARCH_ID_FULL_DIR_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
                cifsFile->srch_inf.resume_key = pFindData->FileIndex;
        } else if (level == SMB_FIND_FILE_BOTH_DIRECTORY_INFO) {
                FILE_BOTH_DIRECTORY_INFO *pFindData =
                        (FILE_BOTH_DIRECTORY_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                len = le32_to_cpu(pFindData->FileNameLength);
                cifsFile->srch_inf.resume_key = pFindData->FileIndex;
        } else if (level == SMB_FIND_FILE_INFO_STANDARD) {
                FIND_FILE_STANDARD_INFO *pFindData =
                        (FIND_FILE_STANDARD_INFO *)current_entry;
                filename = &pFindData->FileName[0];
                /* one byte length, no name conversion */
                len = (unsigned int)pFindData->FileNameLength;
                cifsFile->srch_inf.resume_key = pFindData->ResumeKey;
        } else {
                cFYI(1, ("Unknown findfirst level %d", level));
                return -EINVAL;
        }
        cifsFile->srch_inf.resume_name_len = len;
        cifsFile->srch_inf.presume_name = filename;
        return rc;
}

int cifs_readdir(struct file *file, void *direntry, filldir_t filldir)
{
        int rc = 0;
        int xid, i;
        struct cifs_sb_info *cifs_sb;
        struct cifsTconInfo *pTcon;
        struct cifsFileInfo *cifsFile = NULL;
        char *current_entry;
        int num_to_fill = 0;
        char *tmp_buf = NULL;
        char *end_of_smb;
        int max_len;

        xid = GetXid();

        cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
        pTcon = cifs_sb->tcon;
        if (pTcon == NULL)
                return -EINVAL;

        switch ((int) file->f_pos) {
        case 0:
                if (filldir(direntry, ".", 1, file->f_pos,
                     file->f_path.dentry->d_inode->i_ino, DT_DIR) < 0) {
                        cERROR(1, ("Filldir for current dir failed"));
                        rc = -ENOMEM;
                        break;
                }
                file->f_pos++;
        case 1:
                if (filldir(direntry, "..", 2, file->f_pos,
                     file->f_path.dentry->d_parent->d_inode->i_ino, DT_DIR) < 0) {
                        cERROR(1, ("Filldir for parent dir failed"));
                        rc = -ENOMEM;
                        break;
                }
                file->f_pos++;
        default:
                /* 1) If search is active,
                        is in current search buffer?
                        if it before then restart search
                        if after then keep searching till find it */

                if (file->private_data == NULL) {
                        rc = initiate_cifs_search(xid, file);
                        cFYI(1, ("initiate cifs search rc %d", rc));
                        if (rc) {
                                FreeXid(xid);
                                return rc;
                        }
                }
                if (file->private_data == NULL) {
                        rc = -EINVAL;
                        FreeXid(xid);
                        return rc;
                }
                cifsFile = file->private_data;
                if (cifsFile->srch_inf.endOfSearch) {
                        if (cifsFile->srch_inf.emptyDir) {
                                cFYI(1, ("End of search, empty dir"));
                                rc = 0;
                                break;
                        }
                } /* else {
                        cifsFile->invalidHandle = true;
                        CIFSFindClose(xid, pTcon, cifsFile->netfid);
                } */

                rc = find_cifs_entry(xid, pTcon, file,
                                &current_entry, &num_to_fill);
                if (rc) {
                        cFYI(1, ("fce error %d", rc));
                        goto rddir2_exit;
                } else if (current_entry != NULL) {
                        cFYI(1, ("entry %lld found", file->f_pos));
                } else {
                        cFYI(1, ("could not find entry"));
                        goto rddir2_exit;
                }
                cFYI(1, ("loop through %d times filling dir for net buf %p",
                        num_to_fill, cifsFile->srch_inf.ntwrk_buf_start));
                max_len = smbCalcSize((struct smb_hdr *)
                                cifsFile->srch_inf.ntwrk_buf_start);
                end_of_smb = cifsFile->srch_inf.ntwrk_buf_start + max_len;

                /* To be safe - for UCS to UTF-8 with strings loaded
                with the rare long characters alloc more to account for
                such multibyte target UTF-8 characters. cifs_unicode.c,
                which actually does the conversion, has the same limit */
                tmp_buf = kmalloc((2 * NAME_MAX) + 4, GFP_KERNEL);
                for (i = 0; (i < num_to_fill) && (rc == 0); i++) {
                        if (current_entry == NULL) {
                                /* evaluate whether this case is an error */
                                cERROR(1, ("past SMB end,  num to fill %d i %d",
                                          num_to_fill, i));
                                break;
                        }
                        /* if buggy server returns . and .. late do
                        we want to check for that here? */
                        rc = cifs_filldir(current_entry, file,
                                        filldir, direntry, tmp_buf, max_len);
                        if (rc == -EOVERFLOW) {
                                rc = 0;
                                break;
                        }

                        file->f_pos++;
                        if (file->f_pos ==
                                cifsFile->srch_inf.index_of_last_entry) {
                                cFYI(1, ("last entry in buf at pos %lld %s",
                                        file->f_pos, tmp_buf));
                                cifs_save_resume_key(current_entry, cifsFile);
                                break;
                        } else
                                current_entry =
                                        nxt_dir_entry(current_entry, end_of_smb,
                                                cifsFile->srch_inf.info_level);
                }
                kfree(tmp_buf);
                break;
        } /* end switch */

rddir2_exit:
        FreeXid(xid);
        return rc;
}