Return to win.h CVS log

Up to [Development] / xfs-cmds / xfsdump / restore

This mod adds a number of optimizations to increase the
performance of xfsdump and xfsrestore, especially on filesystems
with millions of inodes. Many small changes were made to
minimize the number of system calls required per inode.
Significant changes to xfsdump:
- Cache the gen number of each inode during the initial inode
  scan so that a bulkstat single does not need to be done for
  each inode when dumping directories.
- No longer retrieve the DMF attribute when estimating the dump
  size of a file. Use information from the bulkstat instead.
- Retrieve DMF attribute by handle instead of doing
  open/attr_getf/close.
- In determining where to split multi-stream dumps, take into
  consideration the number of files and not just the file size.
  This allows filesystems with large amounts of inodes but
  relatively little data (DMF filesystem) to be split correctly.
Significant changes to xfsrestore:
- Buffer writes to the namreg file to eliminate 2 very small
  write system calls per directory entry.
- Buffer writes to dirattr file to eliminate a small write system
  call per directory.
- Speedup the check to see if a particular window of the tree
  file is mapped. This allows xfsrestore to use more, smaller
  windows which is beneficial if we can't fit them all in memory
  and have to start unmapping them. This also makes the -w
  option obsolete so that option now has no effect.
- Change the hash function to give a better distribution among
  the hash buckets.
- Do not make an unnecessary unlink call if the file being
  restored does not already exist.

/*
 * Copyright (c) 2000-2001 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef WIN_H
#define WIN_H

/* win.[ch] - windows into a very large file
 */

/* initialize the window abstraction
 */
void win_init( intgen_t fd,
	       off64_t rngoff,		/* offset into file of windowing */
	       size_t winsz,		/* window size */
	       size64_t segtablesz,     /* estimate of segment table size */
	       size_t wincntmax );	/* max number of windows to manage */

/* supply a pointer to the portion of the file identified by off.
 */
void win_map( off64_t off,		/* file offset relative to rngoff */
	      void **pp );		/* returns pointer by reference */

/* invalidate the pointer previously supplied. SIDE-EFFECT: zeros
 * by reference the caller's pointer.
 */
void win_unmap( off64_t off,		/* must match win_map param */
	        void **pp );		/* ptr generated by win_map: ZEROED */

/*
 * Functions used to disable the window locking from happening.
 * This is used in the directory reconstruction phase where only
 * one thread is actually executing this code.
 *
 * Assumes called in region where only 1 thread can execute it.
 */
void win_locks_off(void);
void win_locks_on(void);

/*
 * Find out how many mmap calls were made for windows.
 */
size_t win_getnum_mmaps(void);

#endif /* WIN_H */