readdir.c

Linux内核自带的cifs模块

		/* 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;

#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 20)
	cifs_sb = CIFS_SB(file->f_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_dentry);
#else
	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);
#endif

	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)
{
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 20)
	struct inode *inode = file->f_dentry->d_inode;
#else
	struct inode *inode = file->f_path.dentry->d_inode;
#endif
	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 */

#ifdef CONFIG_CIFS_DEBUG2
	dump_cifs_file_struct(file, "In fce ");
#endif
	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"));
		cifsFile->invalidHandle = TRUE;
		CIFSFindClose(xid, pTcon, cifsFile->netfid);
		kfree(cifsFile->search_resume_name);
		cifsFile->search_resume_name = NULL;
		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 == FALSE)) {
		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;
	}