+++ /dev/null
-/*
-** COWLOOP block device driver (2.6 kernel compliant)
-** =======================================================================
-** Read-write loop-driver with copy-on-write functionality.
-**
-** Synopsis:
-**
-** modprobe cowloop [maxcows=..] [rdofile=..... cowfile=.... [option=r]]
-**
-** Definition of number of configured cowdevices:
-** maxcows= number of configured cowdevices (default: 16)
-** (do not confuse this with MAXCOWS: absolute maximum as compiled)
-**
-** One pair of filenames can be supplied during insmod/modprobe to open
-** the first cowdevice:
-** rdofile= read-only file (or filesystem)
-** cowfile= storage-space for modified blocks of read-only file(system)
-** option=r repair cowfile automatically if it appears to be dirty
-**
-** Other cowdevices can be activated via the command "cowdev"
-** whenever the cowloop-driver is loaded.
-**
-** The read-only file may be of type 'regular' or 'block-device'.
-**
-** The cowfile must be of type 'regular'.
-** If an existing regular file is used as cowfile, its contents will be
-** used again for the current read-only file. When the cowfile has not been
-** closed properly during a previous session (i.e. rmmod cowloop), the
-** cowloop-driver refuses to open it unless the parameter "option=r" is
-** specified.
-**
-** Layout of cowfile:
-**
-** +-----------------------------+
-** | cow head block | MAPUNIT bytes
-** |-----------------------------|
-** | | MAPUNIT bytes
-** |--- ---|
-** | | MAPUNIT bytes
-** |--- ---|
-** | used-block bitmap | MAPUNIT bytes
-** |-----------------------------|
-** | gap to align start-offset |
-** | to 4K multiple |
-** |-----------------------------| <---- start-offset cow blocks
-** | |
-** | written cow blocks | MAPUNIT bytes
-** | ..... |
-**
-** cowhead block:
-** - contains general info about the rdofile which is related
-** to this cowfile
-**
-** used-block bitmap:
-** - contains one bit per block with a size of MAPUNIT bytes
-** - bit-value '1' = block has been written on cow
-** '0' = block unused on cow
-** - total bitmap rounded to multiples of MAPUNIT
-**
-** ============================================================================
-** Author: Gerlof Langeveld - AT Computing (March 2003)
-** Current maintainer: Hendrik-Jan Thomassen - AT Computing (Summer 2006)
-** Email: hjt@ATComputing.nl
-** ----------------------------------------------------------------------------
-** Copyright (C) 2003-2009 AT Consultancy
-**
-** 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; either version 2, or (at your option) any
-** later version.
-**
-** This program 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 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 to the Free Software
-** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
-** ----------------------------------------------------------------------------
-**
-** Major modifications:
-**
-** 200405 Ported to kernel-version 2.6 Hendrik-Jan Thomassen
-** 200405 Added cowhead to cowfile to garantee
-** consistency with read-only file Gerlof Langeveld
-** 200405 Postponed flushing of bitmaps to improve
-** performance. Gerlof Langeveld
-** 200405 Inline recovery for dirty cowfiles. Gerlof Langeveld
-** 200502 Redesign to support more cowdevices. Gerlof Langeveld
-** 200502 Support devices/file > 2 Gbytes. Gerlof Langeveld
-** 200507 Check for free space to expand cowfile. Gerlof Langeveld
-** 200902 Upgrade for kernel 2.6.28 Hendrik-Jan Thomassen
-**
-** Inspired by
-** loop.c by Theodore Ts'o and
-** cloop.c by Paul `Rusty' Russell & Klaus Knopper.
-**
-** Design-considerations:
-**
-** For the first experiments with the cowloop-driver, the request-queue
-** made use of the do_generic_file_read() which worked fine except
-** in combination with the cloop-driver; that combination
-** resulted in a non-interruptible hangup of the system during
-** heavy load. Other experiments using the `make_request' interface also
-** resulted in unpredictable system hangups (with proper use of spinlocks).
-**
-** To overcome these problems, the cowloop-driver starts a kernel-thread
-** for every active cowdevice.
-** All read- and write-request on the read-only file and copy-on-write file
-** are handled in the context of that thread.
-** A scheme has been designed to wakeup the kernel-thread as
-** soon as I/O-requests are available in the request-queue; this thread
-** handles the requests one-by-one by calling the proper read- or
-** write-function related to the open read-only file or copy-on-write file.
-** When all pending requests have been handled, the kernel-thread goes
-** back to sleep-state.
-** This approach requires some additional context-switches; however the
-** performance loss during heavy I/O is less than 3%.
-**
-** -------------------------------------------------------------------------*/
-/* The following is the cowloop package version number. It must be
- identical to the content of the include-file "version.h" that is
- used in all supporting utilities: */
-char revision[] = "$Revision: 3.1 $"; /* cowlo_init_module() has
- assumptions about this string's format */
-
-/* Note that the following numbers are *not* the cowloop package version
- numbers, but separate revision history numbers to track the
- modifications of this particular source file: */
-/* $Log: cowloop.c,v $
-**
-** Revision 1.30 2009/02/08 hjt
-** Integrated earlier fixes
-** Upgraded to kernel 2.6.28 (thanks Jerome Poulin)
-**
-** Revision 1.29 2006/12/03 22:12:00 hjt
-** changed 'cowdevlock' from spinlock to semaphore, to avoid
-** "scheduling while atomic". Contributed by Juergen Christ.
-** Added version.h again
-**
-** Revision 1.28 2006/08/16 16:00:00 hjt
-** malloc each individual cowloopdevice struct separately
-**
-** Revision 1.27 2006/03/14 14:57:03 root
-** Removed include version.h
-**
-** Revision 1.26 2005/08/08 11:22:48 root
-** Implement possibility to close a cow file or reopen a cowfile read-only.
-**
-** Revision 1.25 2005/08/03 14:00:39 root
-** Added modinfo info to driver.
-**
-** Revision 1.24 2005/07/21 06:14:53 root
-** Cosmetic changes source code.
-**
-** Revision 1.23 2005/07/20 13:07:32 root
-** Supply ioctl to write watchdog program to react on lack of cowfile space.
-**
-** Revision 1.22 2005/07/20 07:53:34 root
-** Regular verification of free space in filesystem holding the cowfile
-** (give warnings whenever space is almost exhausted).
-** Terminology change: checksum renamed to fingerprint.
-**
-** Revision 1.21 2005/07/19 09:21:52 root
-** Removing maximum limit of 16 Gb per cowdevice.
-**
-** Revision 1.20 2005/07/19 07:50:33 root
-** Minor bugfixes and cosmetic changes.
-**
-** Revision 1.19 2005/06/10 12:29:55 root
-** Removed lock/unlock operation from cowlo_open().
-**
-** Revision 1.18 2005/05/09 12:56:26 root
-** Allow a cowdevice to be open more than once
-** (needed for support of ReiserFS and XFS).
-**
-** Revision 1.17 2005/03/17 14:36:16 root
-** Fixed some license issues.
-**
-** Revision 1.16 2005/03/07 14:42:05 root
-** Only allow one parallel open per cowdevice.
-**
-** Revision 1.15 2005/02/18 11:52:04 gerlof
-** Redesign to support more than one cowdevice > 2 Gb space.
-**
-** Revision 1.14 2004/08/17 14:19:16 gerlof
-** Modified output of /proc/cowloop.
-**
-** Revision 1.13 2004/08/16 07:21:10 gerlof
-** Separate statistical counter for read on rdofile and cowfile.
-**
-** Revision 1.12 2004/08/11 06:52:11 gerlof
-** Modified messages.
-**
-** Revision 1.11 2004/08/11 06:44:11 gerlof
-** Modified log messages.
-**
-** Revision 1.10 2004/08/10 12:27:27 gerlof
-** Cosmetic changes.
-**
-** Revision 1.9 2004/08/09 11:43:37 gerlof
-** Removed double definition of major number (COWMAJOR).
-**
-** Revision 1.8 2004/08/09 08:03:39 gerlof
-** Cleanup of messages.
-**
-** Revision 1.7 2004/05/27 06:37:33 gerlof
-** Modified /proc message.
-**
-** Revision 1.6 2004/05/26 21:23:28 gerlof
-** Modified /proc output.
-**
-** Revision 1.5 2004/05/26 13:23:34 gerlof
-** Support cowsync to force flushing the bitmaps and cowhead.
-**
-** Revision 1.4 2004/05/26 11:11:10 gerlof
-** Updated the comment to the actual situation.
-**
-** Revision 1.3 2004/05/26 10:50:00 gerlof
-** Implemented recovery-option.
-**
-** Revision 1.2 2004/05/25 15:14:41 gerlof
-** Modified bitmap flushing strategy.
-**
-*/
-
-#define COWMAJOR 241
-
-// #define COWDEBUG
-
-#ifdef COWDEBUG
-#define DEBUGP printk
-#define DCOW KERN_ALERT
-#else
-#define DEBUGP(format, x...)
-#endif
-
-#include <linux/types.h>
-#include <linux/autoconf.h>
-#ifndef AUTOCONF_INCLUDED
-#include <linux/config.h>
-#endif
-#include <linux/module.h>
-#include <linux/version.h>
-#include <linux/moduleparam.h>
-#include <linux/init.h>
-#include <linux/errno.h>
-#include <linux/kernel.h>
-#include <linux/major.h>
-#include <linux/sched.h>
-#include <linux/fs.h>
-#include <linux/file.h>
-#include <linux/stat.h>
-#include <linux/vmalloc.h>
-#include <linux/slab.h>
-#include <linux/semaphore.h>
-#include <asm/uaccess.h>
-#include <linux/proc_fs.h>
-#include <linux/blkdev.h>
-#include <linux/buffer_head.h>
-#include <linux/hdreg.h>
-#include <linux/genhd.h>
-#include <linux/statfs.h>
-
-#include "cowloop.h"
-
-MODULE_LICENSE("GPL");
-/* MODULE_AUTHOR("Gerlof Langeveld <gerlof@ATComputing.nl>"); obsolete address */
-MODULE_AUTHOR("Hendrik-Jan Thomassen <hjt@ATComputing.nl>"); /* current maintainer */
-MODULE_DESCRIPTION("Copy-on-write loop driver");
-MODULE_PARM_DESC(maxcows, " Number of configured cowdevices (default 16)");
-MODULE_PARM_DESC(rdofile, " Read-only file for /dev/cow/0");
-MODULE_PARM_DESC(cowfile, " Cowfile for /dev/cow/0");
-MODULE_PARM_DESC(option, " Repair cowfile if inconsistent: option=r");
-
-#define DEVICE_NAME "cow"
-
-#define DFLCOWS 16 /* default cowloop devices */
-
-static int maxcows = DFLCOWS;
-module_param(maxcows, int, 0);
-static char *rdofile = "";
-module_param(rdofile, charp, 0);
-static char *cowfile = "";
-module_param(cowfile, charp, 0);
-static char *option = "";
-module_param(option, charp, 0);
-
-/*
-** per cowdevice several bitmap chunks are allowed of MAPCHUNKSZ each
-**
-** each bitmap chunk can describe MAPCHUNKSZ * 8 * MAPUNIT bytes of data
-** suppose:
-** MAPCHUNKSZ 4096 and MAPUNIT 1024 --> 4096 * 8 * 1024 = 32 Mb per chunk
-*/
-#define MAPCHUNKSZ 4096 /* #bytes per bitmap chunk (do not change) */
-
-#define SPCMINBLK 100 /* space threshold to give warning messages */
-#define SPCDFLINTVL 16 /* once every SPCDFLINTVL writes to cowfile, */
- /* available space in filesystem is checked */
-
-#define CALCMAP(x) ((x)/(MAPCHUNKSZ*8))
-#define CALCBYTE(x) (((x)%(MAPCHUNKSZ*8))>>3)
-#define CALCBIT(x) ((x)&7)
-
-#define ALLCOW 1
-#define ALLRDO 2
-#define MIXEDUP 3
-
-static char allzeroes[MAPUNIT];
-
-/*
-** administration per cowdevice (pair of cowfile/rdofile)
-*/
-
-/* bit-values for state */
-#define COWDEVOPEN 0x01 /* cowdevice opened */
-#define COWRWCOWOPEN 0x02 /* cowfile opened read-write */
-#define COWRDCOWOPEN 0x04 /* cowfile opened read-only */
-#define COWWATCHDOG 0x08 /* ioctl for watchdog cowfile space active */
-
-#define COWCOWOPEN (COWRWCOWOPEN|COWRDCOWOPEN)
-
-struct cowloop_device
-{
- /*
- ** current status
- */
- int state; /* bit-values (see above) */
- int opencnt; /* # opens for cowdevice */
-
- /*
- ** open file pointers
- */
- struct file *rdofp, *cowfp; /* open file pointers */
- char *rdoname, *cowname; /* file names */
-
- /*
- ** request queue administration
- */
- struct request_queue *rqueue;
- spinlock_t rqlock;
- struct gendisk *gd;
-
- /*
- ** administration about read-only file
- */
- unsigned int numblocks; /* # blocks input file in MAPUNIT */
- unsigned int blocksz; /* minimum unit to access this dev */
- unsigned long fingerprint; /* fingerprint of current rdofile */
- struct block_device *belowdev; /* block device below us */
- struct gendisk *belowgd; /* gendisk for blk dev below us */
- struct request_queue *belowq; /* req. queue of blk dev below us */
-
- /*
- ** bitmap administration to register which blocks are modified
- */
- long int mapsize; /* total size of bitmap (bytes) */
- long int mapremain; /* remaining bytes in last bitmap */
- int mapcount; /* number of bitmaps in use */
- char **mapcache; /* area with pointers to bitmaps */
-
- char *iobuf; /* databuffer of MAPUNIT bytes */
- struct cowhead *cowhead; /* buffer containing cowhead */
-
- /*
- ** administration for interface with the kernel-thread
- */
- int pid; /* pid==0: no thread available */
- struct request *req; /* request to be handled now */
- wait_queue_head_t waitq; /* wait-Q: thread waits for work */
- char closedown; /* boolean: thread exit required */
- char qfilled; /* boolean: I/O request pending */
- char iobusy; /* boolean: req under treatment */
-
- /*
- ** administration to keep track of free space in cowfile filesystem
- */
- unsigned long blksize; /* block size of fs (bytes) */
- unsigned long blktotal; /* recent total space in fs (blocks) */
- unsigned long blkavail; /* recent free space in fs (blocks) */
-
- wait_queue_head_t watchq; /* wait-Q: watcher awaits threshold */
- unsigned long watchthresh; /* threshold of watcher (blocks) */
-
- /*
- ** statistical counters
- */
- unsigned long rdoreads; /* number of read-actions rdo */
- unsigned long cowreads; /* number of read-actions cow */
- unsigned long cowwrites; /* number of write-actions */
- unsigned long nrcowblocks; /* number of blocks in use on cow */
-};
-
-static struct cowloop_device **cowdevall; /* ptr to ptrs to all cowdevices */
-static struct semaphore cowdevlock; /* generic lock for cowdevs */
-
-static struct gendisk *cowctlgd; /* gendisk control channel */
-static spinlock_t cowctlrqlock; /* for req.q. of ctrl. channel */
-
-/*
-** private directory /proc/cow
-*/
-struct proc_dir_entry *cowlo_procdir;
-
-/*
-** function prototypes
-*/
-static long int cowlo_do_request (struct request *req);
-static void cowlo_sync (void);
-static int cowlo_checkio (struct cowloop_device *, int, loff_t);
-static int cowlo_readmix (struct cowloop_device *, void *, int, loff_t);
-static int cowlo_writemix (struct cowloop_device *, void *, int, loff_t);
-static long int cowlo_readrdo (struct cowloop_device *, void *, int, loff_t);
-static long int cowlo_readcow (struct cowloop_device *, void *, int, loff_t);
-static long int cowlo_readcowraw (struct cowloop_device *, void *, int, loff_t);
-static long int cowlo_writecow (struct cowloop_device *, void *, int, loff_t);
-static long int cowlo_writecowraw(struct cowloop_device *, void *, int, loff_t);
-static int cowlo_ioctl (struct block_device *, fmode_t,
- unsigned int, unsigned long);
-static int cowlo_makepair (struct cowpair __user *);
-static int cowlo_removepair (unsigned long __user *);
-static int cowlo_watch (struct cowpair __user *);
-static int cowlo_cowctl (unsigned long __user *, int);
-static int cowlo_openpair (char *, char *, int, int);
-static int cowlo_closepair (struct cowloop_device *);
-static int cowlo_openrdo (struct cowloop_device *, char *);
-static int cowlo_opencow (struct cowloop_device *, char *, int);
-static void cowlo_undo_openrdo(struct cowloop_device *);
-static void cowlo_undo_opencow(struct cowloop_device *);
-
-/*****************************************************************************/
-/* System call handling */
-/*****************************************************************************/
-
-/*
-** handle system call open()/mount()
-**
-** returns:
-** 0 - okay
-** < 0 - error value
-*/
-static int cowlo_open(struct block_device *bdev, fmode_t mode)
-{
- struct inode *inode = bdev->bd_inode;
-
- if (!inode)
- return -EINVAL;
-
- if (imajor(inode) != COWMAJOR) {
- printk(KERN_WARNING
- "cowloop - unexpected major %d\n", imajor(inode));
- return -ENODEV;
- }
-
- switch (iminor(inode)) {
- case COWCTL:
- DEBUGP(DCOW"cowloop - open %d control\n", COWCTL);
- break;
-
- default:
- DEBUGP(DCOW"cowloop - open minor %d\n", iminor(inode));
-
- if ( iminor(inode) >= maxcows )
- return -ENODEV;
-
- if ( !((cowdevall[iminor(inode)])->state & COWDEVOPEN) )
- return -ENODEV;
-
- (cowdevall[iminor(inode)])->opencnt++;
- }
-
- return 0;
-}
-
-/*
-** handle system call close()/umount()
-**
-** returns:
-** 0 - okay
-*/
-static int cowlo_release(struct gendisk *gd, fmode_t mode)
-{
- struct block_device *bdev;
- struct inode *inode;
-
- bdev = bdget_disk(gd, 0);
- inode = bdev->bd_inode;
- if (!inode)
- return 0;
-
- DEBUGP(DCOW"cowloop - release (close) minor %d\n", iminor(inode));
-
- if ( iminor(inode) != COWCTL)
- (cowdevall[iminor(inode)])->opencnt--;
-
- return 0;
-}
-
-/*
-** handle system call ioctl()
-**
-** returns:
-** 0 - okay
-** < 0 - error value
-*/
-static int cowlo_ioctl(struct block_device *bdev, fmode_t mode,
- unsigned int cmd, unsigned long arg)
-{
- struct hd_geometry geo;
- struct inode *inode = bdev->bd_inode;
-
- DEBUGP(DCOW "cowloop - ioctl cmd %x\n", cmd);
-
- switch ( iminor(inode) ) {
-
- /*
- ** allowed via control device only
- */
- case COWCTL:
- switch (cmd) {
- /*
- ** write all bitmap chunks and cowheaders to cowfiles
- */
- case COWSYNC:
- down(&cowdevlock);
- cowlo_sync();
- up(&cowdevlock);
- return 0;
-
- /*
- ** open a new cowdevice (pair of rdofile/cowfile)
- */
- case COWMKPAIR:
- return cowlo_makepair((void __user *)arg);
-
- /*
- ** close a cowdevice (pair of rdofile/cowfile)
- */
- case COWRMPAIR:
- return cowlo_removepair((void __user *)arg);
-
- /*
- ** watch free space of filesystem containing cowfile
- */
- case COWWATCH:
- return cowlo_watch((void __user *)arg);
-
- /*
- ** close cowfile for active device
- */
- case COWCLOSE:
- return cowlo_cowctl((void __user *)arg, COWCLOSE);
-
- /*
- ** reopen cowfile read-only for active device
- */
- case COWRDOPEN:
- return cowlo_cowctl((void __user *)arg, COWRDOPEN);
-
- default:
- return -EINVAL;
- } /* end of switch on command */
-
- /*
- ** allowed for any other cowdevice
- */
- default:
- switch (cmd) {
- /*
- ** HDIO_GETGEO must be supported for fdisk, etc
- */
- case HDIO_GETGEO:
- geo.cylinders = 0;
- geo.heads = 0;
- geo.sectors = 0;
-
- if (copy_to_user((void __user *)arg, &geo, sizeof geo))
- return -EFAULT;
- return 0;
-
- default:
- return -EINVAL;
- } /* end of switch on ioctl-cmd code parameter */
- } /* end of switch on minor number */
-}
-
-static struct block_device_operations cowlo_fops =
-{
- .owner = THIS_MODULE,
- .open = cowlo_open, /* called upon open */
- .release = cowlo_release, /* called upon close */
- .ioctl = cowlo_ioctl, /* called upon ioctl */
-};
-
-/*
-** handle ioctl-command COWMKPAIR:
-** open a new cowdevice (pair of rdofile/cowfile) on-the-fly
-**
-** returns:
-** 0 - okay
-** < 0 - error value
-*/
-static int
-cowlo_makepair(struct cowpair __user *arg)
-{
- int i, rv=0;
- struct cowpair cowpair;
- unsigned char *cowpath;
- unsigned char *rdopath;
-
- /*
- ** retrieve info about pathnames
- */
- if ( copy_from_user(&cowpair, arg, sizeof cowpair) )
- return -EFAULT;
-
- if ( (MAJOR(cowpair.device) != COWMAJOR) && (cowpair.device != ANYDEV) )
- return -EINVAL;
-
- if ( (MINOR(cowpair.device) >= maxcows) && (cowpair.device != ANYDEV) )
- return -EINVAL;
-
- /*
- ** retrieve pathname strings
- */
- if ( (cowpair.cowflen > PATH_MAX) || (cowpair.rdoflen > PATH_MAX) )
- return -ENAMETOOLONG;
-
- if ( !(cowpath = kmalloc(cowpair.cowflen+1, GFP_KERNEL)) )
- return -ENOMEM;
-
- if ( copy_from_user(cowpath, (void __user *)cowpair.cowfile,
- cowpair.cowflen) ) {
- kfree(cowpath);
- return -EFAULT;
- }
- *(cowpath+cowpair.cowflen) = 0;
-
- if ( !(rdopath = kmalloc(cowpair.rdoflen+1, GFP_KERNEL)) ) {
- kfree(cowpath);
- return -ENOMEM;
- }
-
- if ( copy_from_user(rdopath, (void __user *)cowpair.rdofile,
- cowpair.rdoflen) ) {
- kfree(rdopath);
- kfree(cowpath);
- return -EFAULT;
- }
- *(rdopath+cowpair.rdoflen) = 0;
-
- /*
- ** open new cowdevice
- */
- if ( cowpair.device == ANYDEV) {
- /*
- ** search first unused minor
- */
- for (i=0, rv=-EBUSY; i < maxcows; i++) {
- if ( !((cowdevall[i])->state & COWDEVOPEN) ) {
- rv = cowlo_openpair(rdopath, cowpath, 0, i);
- break;
- }
- }
-
- if (rv) { /* open failed? */
- kfree(rdopath);
- kfree(cowpath);
- return rv;
- }
-
- /*
- ** return newly allocated cowdevice to user space
- */
- cowpair.device = MKDEV(COWMAJOR, i);
-
- if ( copy_to_user(arg, &cowpair, sizeof cowpair)) {
- kfree(rdopath);
- kfree(cowpath);
- return -EFAULT;
- }
- } else { /* specific minor requested */
- if ( (rv = cowlo_openpair(rdopath, cowpath, 0,
- MINOR(cowpair.device)))) {
- kfree(rdopath);
- kfree(cowpath);
- return rv;
- }
- }
-
- return 0;
-}
-
-/*
-** handle ioctl-command COWRMPAIR:
-** deactivate an existing cowdevice (pair of rdofile/cowfile) on-the-fly
-**
-** returns:
-** 0 - okay
-** < 0 - error value
-*/
-static int
-cowlo_removepair(unsigned long __user *arg)
-{
- unsigned long cowdevice;
- struct cowloop_device *cowdev;
-
- /*
- ** retrieve info about device to be removed
- */
- if ( copy_from_user(&cowdevice, arg, sizeof cowdevice))
- return -EFAULT;
-
- /*
- ** verify major-minor number
- */
- if ( MAJOR(cowdevice) != COWMAJOR)
- return -EINVAL;
-
- if ( MINOR(cowdevice) >= maxcows)
- return -EINVAL;
-
- cowdev = cowdevall[MINOR(cowdevice)];
-
- if ( !(cowdev->state & COWDEVOPEN) )
- return -ENODEV;
-
- /*
- ** synchronize bitmaps and close cowdevice
- */
- if (cowdev->state & COWRWCOWOPEN) {
- down(&cowdevlock);
- cowlo_sync();
- up(&cowdevlock);
- }
-
- return cowlo_closepair(cowdev);
-}
-
-/*
-** handle ioctl-command COWWATCH:
-** watch the free space of the filesystem containing a cowfile
-** of an open cowdevice
-**
-** returns:
-** 0 - okay
-** < 0 - error value
-*/
-static int
-cowlo_watch(struct cowpair __user *arg)
-{
- struct cowloop_device *cowdev;
- struct cowwatch cowwatch;
-
- /*
- ** retrieve structure holding info
- */
- if ( copy_from_user(&cowwatch, arg, sizeof cowwatch))
- return -EFAULT;
-
- /*
- ** verify if cowdevice exists and is currently open
- */
- if ( MINOR(cowwatch.device) >= maxcows)
- return -EINVAL;
-
- cowdev = cowdevall[MINOR(cowwatch.device)];
-
- if ( !(cowdev->state & COWDEVOPEN) )
- return -ENODEV;
-
- /*
- ** if the WATCHWAIT-option is set, wait until the indicated
- ** threshold is reached (only one waiter allowed)
- */
- if (cowwatch.flags & WATCHWAIT) {
- /*
- ** check if already another waiter active
- ** for this cowdevice
- */
- if (cowdev->state & COWWATCHDOG)
- return -EAGAIN;
-
- cowdev->state |= COWWATCHDOG;
-
- cowdev->watchthresh = (unsigned long long)
- cowwatch.threshold /
- (cowdev->blksize / 1024);
-
- if (wait_event_interruptible(cowdev->watchq,
- cowdev->watchthresh >= cowdev->blkavail)) {
- cowdev->state &= ~COWWATCHDOG;
- return EINTR;
- }
-
- cowdev->state &= ~COWWATCHDOG;
- }
-
- cowwatch.totalkb = (unsigned long long)cowdev->blktotal *
- cowdev->blksize / 1024;
- cowwatch.availkb = (unsigned long long)cowdev->blkavail *
- cowdev->blksize / 1024;
-
- if ( copy_to_user(arg, &cowwatch, sizeof cowwatch))
- return -EFAULT;
-
- return 0;
-}
-
-/*
-** handle ioctl-commands COWCLOSE and COWRDOPEN:
-** COWCLOSE - close the cowfile while the cowdevice remains open;
-** this allows an unmount of the filesystem on which
-** the cowfile resides
-** COWRDOPEN - close the cowfile and reopen it for read-only;
-** this allows a remount read-ony of the filesystem
-** on which the cowfile resides
-**
-** returns:
-** 0 - okay
-** < 0 - error value
-*/
-static int
-cowlo_cowctl(unsigned long __user *arg, int cmd)
-{
- struct cowloop_device *cowdev;
- unsigned long cowdevice;
-
- /*
- ** retrieve info about device to be removed
- */
- if ( copy_from_user(&cowdevice, arg, sizeof cowdevice))
- return -EFAULT;
-
- /*
- ** verify major-minor number
- */
- if ( MAJOR(cowdevice) != COWMAJOR)
- return -EINVAL;
-
- if ( MINOR(cowdevice) >= maxcows)
- return -EINVAL;
-
- cowdev = cowdevall[MINOR(cowdevice)];
-
- if ( !(cowdev->state & COWDEVOPEN) )
- return -ENODEV;
-
- /*
- ** synchronize bitmaps and close cowfile
- */
- if (cowdev->state & COWRWCOWOPEN) {
- down(&cowdevlock);
- cowlo_sync();
- up(&cowdevlock);
- }
-
- /*
- ** handle specific ioctl-command
- */
- switch (cmd) {
- case COWRDOPEN:
- /*
- ** if the cowfile is still opened read-write
- */
- if (cowdev->state & COWRWCOWOPEN) {
- /*
- ** close the cowfile
- */
- if (cowdev->cowfp)
- filp_close(cowdev->cowfp, 0);
-
- cowdev->state &= ~COWRWCOWOPEN;
-
- /*
- ** open again for read-only
- */
- cowdev->cowfp = filp_open(cowdev->cowname,
- O_RDONLY|O_LARGEFILE, 0600);
-
- if ( (cowdev->cowfp == NULL) || IS_ERR(cowdev->cowfp) ) {
- printk(KERN_ERR
- "cowloop - failed to reopen cowfile %s\n",
- cowdev->cowname);
- return -EINVAL;
- }
-
- /*
- ** mark cowfile open for read-only
- */
- cowdev->state |= COWRDCOWOPEN;
- } else {
- return -EINVAL;
- }
- break;
-
- case COWCLOSE:
- /*
- ** if the cowfile is still open
- */
- if (cowdev->state & COWCOWOPEN) {
- /*
- ** close the cowfile
- */
- if (cowdev->cowfp)
- filp_close(cowdev->cowfp, 0);
-
- cowdev->state &= ~COWCOWOPEN;
- }
- }
-
- return 0;
-}
-
-
-/*****************************************************************************/
-/* Handling of I/O-requests for a cowdevice */
-/*****************************************************************************/
-
-/*
-** function to be called by core-kernel to handle the I/O-requests
-** in the queue
-*/
-static void cowlo_request(struct request_queue *q)
-{
- struct request *req;
- struct cowloop_device *cowdev;
-
- DEBUGP(DCOW "cowloop - request function called....\n");
-
- while((req = blk_peek_request(q)) != NULL) {
- DEBUGP(DCOW "cowloop - got next request\n");
-
- if (! blk_fs_request(req)) {
- /* this is not a normal file system request */
- __blk_end_request_cur(req, -EIO);
- continue;
- }
- cowdev = req->rq_disk->private_data;
-
- if (cowdev->iobusy)
- return;
- else
- cowdev->iobusy = 1;
-
- /*
- ** when no kernel-thread is available, the request will
- ** produce an I/O-error
- */
- if (!cowdev->pid) {
- printk(KERN_ERR"cowloop - no thread available\n");
- __blk_end_request_cur(req, -EIO); /* request failed */
- cowdev->iobusy = 0;
- continue;
- }
-
- /*
- ** handle I/O-request in the context of the kernel-thread
- */
- cowdev->req = req;
- cowdev->qfilled = 1;
-
- wake_up_interruptible_sync(&cowdev->waitq);
-
- /*
- ** get out of this function now while the I/O-request is
- ** under treatment of the kernel-thread; this function
- ** will be called again after the current I/O-request has
- ** been finished by the thread
- */
- return;
- }
-}
-
-/*
-** daemon-process (kernel-thread) executes this function
-*/
-static int
-cowlo_daemon(struct cowloop_device *cowdev)
-{
- int rv;
- int minor;
- char myname[16];
-
- for (minor = 0; minor < maxcows; minor++) {
- if (cowdev == cowdevall[minor]) break;
- }
- sprintf(myname, "cowloopd%d", minor);
-
- daemonize(myname);
-
- while (!cowdev->closedown) {
- /*
- ** sleep while waiting for an I/O request;
- ** note that no non-interruptible wait has been used
- ** because the non-interruptible version of
- ** a *synchronous* wake_up does not exist (any more)
- */
- if (wait_event_interruptible(cowdev->waitq, cowdev->qfilled)){
- flush_signals(current); /* ignore signal-based wakeup */
- continue;
- }
-
- if (cowdev->closedown) /* module will be unloaded ? */{
- cowdev->pid = 0;
- return 0;
- }
-
- /*
- ** woken up by the I/O-request handler: treat requested I/O
- */
- cowdev->qfilled = 0;
-
- rv = cowlo_do_request(cowdev->req);
-
- /*
- ** reacquire the queue-spinlock for manipulating
- ** the request-queue and dequeue the request
- */
- spin_lock_irq(&cowdev->rqlock);
-
- __blk_end_request_cur(cowdev->req, rv);
- cowdev->iobusy = 0;
-
- /*
- ** initiate the next request from the queue
- */
- cowlo_request(cowdev->rqueue);
-
- spin_unlock_irq(&cowdev->rqlock);
- }
- return 0;
-}
-
-/*
-** function to be called in the context of the kernel thread
-** to handle the queued I/O-requests
-**
-** returns:
-** 0 - fail
-** 1 - success
-*/
-static long int
-cowlo_do_request(struct request *req)
-{
- unsigned long len;
- long int rv;
- loff_t offset;
- struct cowloop_device *cowdev = req->rq_disk->private_data;
-
- /*
- ** calculate some variables which are needed later on
- */
- len = blk_rq_cur_sectors(req) << 9;
- offset = (loff_t) blk_rq_pos(req) << 9;
-
- DEBUGP(DCOW"cowloop - req cmd=%d offset=%lld len=%lu addr=%p\n",
- *(req->cmd), offset, len, req->buffer);
-
- /*
- ** handle READ- or WRITE-request
- */
- switch (rq_data_dir(req)) {
- /**********************************************************/
- case READ:
- switch ( cowlo_checkio(cowdev, len, offset) ) {
- case ALLCOW:
- rv = cowlo_readcow(cowdev, req->buffer, len, offset);
- break;
-
- case ALLRDO:
- rv = cowlo_readrdo(cowdev, req->buffer, len, offset);
- break;
-
- case MIXEDUP:
- rv = cowlo_readmix(cowdev, req->buffer, len, offset);
- break;
-
- default:
- rv = 0; /* never happens */
- }
- break;
-
- /**********************************************************/
- case WRITE:
- switch ( cowlo_checkio(cowdev, len, offset) ) {
- case ALLCOW:
- /*
- ** straight-forward write will do...
- */
- DEBUGP(DCOW"cowloop - write straight ");
-
- rv = cowlo_writecow(cowdev, req->buffer, len, offset);
- break; /* from switch */
-
- case ALLRDO:
- if ( (len & MUMASK) == 0) {
- DEBUGP(DCOW"cowloop - write straight ");
-
- rv = cowlo_writecow(cowdev, req->buffer,
- len, offset);
- break;
- }
-
- case MIXEDUP:
- rv = cowlo_writemix(cowdev, req->buffer, len, offset);
- break;
-
- default:
- rv = 0; /* never happens */
- }
- break;
-
- default:
- printk(KERN_ERR
- "cowloop - unrecognized command %d\n", *(req->cmd));
- rv = 0;
- }
-
- return (rv <= 0 ? 0 : 1);
-}
-
-/*
-** check for a given I/O-request if all underlying blocks
-** (with size MAPUNIT) are either in the read-only file or in
-** the cowfile (or a combination of the two)
-**
-** returns:
-** ALLRDO - all underlying blocks in rdofile
-** ALLCOW - all underlying blocks in cowfile
-** MIXEDUP - underlying blocks partly in rdofile and partly in cowfile
-*/
-static int
-cowlo_checkio(struct cowloop_device *cowdev, int len, loff_t offset)
-{
- unsigned long mapnum, bytenum, bitnum, blocknr, partlen;
- long int totcnt, cowcnt;
- char *mc;
-
- /*
- ** notice that the requested block might cross
- ** a blocksize boundary while one of the concerned
- ** blocks resides in the read-only file and another
- ** one in the copy-on-write file; in that case the
- ** request will be broken up into pieces
- */
- if ( (len <= MAPUNIT) &&
- (MAPUNIT - (offset & MUMASK) <= len) ) {
- /*
- ** easy situation:
- ** requested data-block entirely fits within
- ** the mapunit used for the bitmap
- ** check if that block is located in rdofile or
- ** cowfile
- */
- blocknr = offset >> MUSHIFT;
-
- mapnum = CALCMAP (blocknr);
- bytenum = CALCBYTE(blocknr);
- bitnum = CALCBIT (blocknr);
-
- if (*(*(cowdev->mapcache+mapnum)+bytenum)&(1<<bitnum))
- return ALLCOW;
- else
- return ALLRDO;
- }
-
- /*
- ** less easy situation:
- ** the requested data-block does not fit within the mapunit
- ** used for the bitmap
- ** check if *all* underlying blocks involved reside on the rdofile
- ** or the cowfile (so still no breakup required)
- */
- for (cowcnt=totcnt=0; len > 0; len-=partlen, offset+=partlen, totcnt++){
- /*
- ** calculate blocknr of involved block
- */
- blocknr = offset >> MUSHIFT;
-
- /*
- ** calculate partial length for this transfer
- */
- partlen = MAPUNIT - (offset & MUMASK);
- if (partlen > len)
- partlen = len;
-
- /*
- ** is this block located in the cowfile
- */
- mapnum = CALCMAP (blocknr);
- bytenum = CALCBYTE(blocknr);
- bitnum = CALCBIT (blocknr);
-
- mc = *(cowdev->mapcache+mapnum);
-
- if (*(mc+bytenum)&(1<<bitnum))
- cowcnt++;;
-
- DEBUGP(DCOW
- "cowloop - check %lu - map %lu, byte %lu, bit %lu, "
- "cowcnt %ld, totcnt %ld %02x %p\n",
- blocknr, mapnum, bytenum, bitnum, cowcnt, totcnt,
- *(mc+bytenum), mc);
- }
-
- if (cowcnt == 0) /* all involved blocks on rdofile? */
- return ALLRDO;
-
- if (cowcnt == totcnt) /* all involved blocks on cowfile? */
- return ALLCOW;
-
- /*
- ** situation somewhat more complicated:
- ** involved underlying blocks spread over both files
- */
- return MIXEDUP;
-}
-
-/*
-** read requested chunk partly from rdofile and partly from cowfile
-**
-** returns:
-** 0 - fail
-** 1 - success
-*/
-static int
-cowlo_readmix(struct cowloop_device *cowdev, void *buf, int len, loff_t offset)
-{
- unsigned long mapnum, bytenum, bitnum, blocknr, partlen;
- long int rv;
- char *mc;
-
- /*
- ** complicated approach: breakup required of read-request
- */
- for (rv=1; len > 0; len-=partlen, buf+=partlen, offset+=partlen) {
- /*
- ** calculate blocknr of entire block
- */
- blocknr = offset >> MUSHIFT;
-
- /*
- ** calculate partial length for this transfer
- */
- partlen = MAPUNIT - (offset & MUMASK);
- if (partlen > len)
- partlen = len;
-
- /*
- ** is this block located in the cowfile
- */
- mapnum = CALCMAP (blocknr);
- bytenum = CALCBYTE(blocknr);
- bitnum = CALCBIT (blocknr);
- mc = *(cowdev->mapcache+mapnum);
-
- if (*(mc+bytenum)&(1<<bitnum)) {
- /*
- ** read (partial) block from cowfile
- */
- DEBUGP(DCOW"cowloop - split read "
- "cow partlen=%ld off=%lld\n", partlen, offset);
-
- if (cowlo_readcow(cowdev, buf, partlen, offset) <= 0)
- rv = 0;
- } else {
- /*
- ** read (partial) block from rdofile
- */
- DEBUGP(DCOW"cowloop - split read "
- "rdo partlen=%ld off=%lld\n", partlen, offset);
-
- if (cowlo_readrdo(cowdev, buf, partlen, offset) <= 0)
- rv = 0;
- }
- }
-
- return rv;
-}
-
-/*
-** chunk to be written to the cowfile needs pieces to be
-** read from the rdofile
-**
-** returns:
-** 0 - fail
-** 1 - success
-*/
-static int
-cowlo_writemix(struct cowloop_device *cowdev, void *buf, int len, loff_t offset)
-{
- unsigned long mapnum, bytenum, bitnum, blocknr, partlen;
- long int rv;
- char *mc;
-
- /*
- ** somewhat more complicated stuff is required:
- ** if the request is larger than one underlying
- ** block or is spread over two underlying blocks,
- ** split the request into pieces; if a block does not
- ** start at a block boundary, take care that
- ** surrounding data is read first (if needed),
- ** fit the new data in and write it as a full block
- */
- for (rv=1; len > 0; len-=partlen, buf+=partlen, offset+=partlen) {
- /*
- ** calculate partial length for this transfer
- */
- partlen = MAPUNIT - (offset & MUMASK);
- if (partlen > len)
- partlen = len;
-
- /*
- ** calculate blocknr of entire block
- */
- blocknr = offset >> MUSHIFT;
-
- /*
- ** has this block been written before?
- */
- mapnum = CALCMAP (blocknr);
- bytenum = CALCBYTE(blocknr);
- bitnum = CALCBIT (blocknr);
- mc = *(cowdev->mapcache+mapnum);
-
- if (*(mc+bytenum)&(1<<bitnum)) {
- /*
- ** block has been written before;
- ** write transparantly to cowfile
- */
- DEBUGP(DCOW
- "cowloop - splitwr transp\n");
-
- if (cowlo_writecow(cowdev, buf, partlen, offset) <= 0)
- rv = 0;
- } else {
- /*
- ** block has never been written before,
- ** so read entire block from
- ** read-only file first, unless
- ** a full block is requested to
- ** be written
- */
- if (partlen < MAPUNIT) {
- if (cowlo_readrdo(cowdev, cowdev->iobuf,
- MAPUNIT, (loff_t)blocknr << MUSHIFT) <= 0)
- rv = 0;
- }
-
- /*
- ** transfer modified part into
- ** the block just read
- */
- memcpy(cowdev->iobuf + (offset & MUMASK), buf, partlen);
-
- /*
- ** write entire block to cowfile
- */
- DEBUGP(DCOW"cowloop - split "
- "partlen=%ld off=%lld\n",
- partlen, (loff_t)blocknr << MUSHIFT);
-
- if (cowlo_writecow(cowdev, cowdev->iobuf, MAPUNIT,
- (loff_t)blocknr << MUSHIFT) <= 0)
- rv = 0;
- }
- }
-
- return rv;
-}
-
-/*****************************************************************************/
-/* I/O-support for read-only file and copy-on-write file */
-/*****************************************************************************/
-
-/*
-** read data from the read-only file
-**
-** return-value: similar to user-mode read
-*/
-static long int
-cowlo_readrdo(struct cowloop_device *cowdev, void *buf, int len, loff_t offset)
-{
- long int rv;
- mm_segment_t old_fs;
- loff_t saveoffset = offset;
-
- DEBUGP(DCOW"cowloop - readrdo called\n");
-
- old_fs = get_fs();
- set_fs( get_ds() );
- rv = cowdev->rdofp->f_op->read(cowdev->rdofp, buf, len, &offset);
- set_fs(old_fs);
-
- if (rv < len) {
- printk(KERN_WARNING "cowloop - read-failure %ld on rdofile"
- "- offset=%lld len=%d\n",
- rv, saveoffset, len);
- }
-
- cowdev->rdoreads++;
- return rv;
-}
-
-/*
-** read cowfile from a modified offset, i.e. skipping the bitmap and cowhead
-**
-** return-value: similar to user-mode read
-*/
-static long int
-cowlo_readcow(struct cowloop_device *cowdev, void *buf, int len, loff_t offset)
-{
- DEBUGP(DCOW"cowloop - readcow called\n");
-
- offset += cowdev->cowhead->doffset;
-
- return cowlo_readcowraw(cowdev, buf, len, offset);
-}
-
-/*
-** read cowfile from an absolute offset
-**
-** return-value: similar to user-mode read
-*/
-static long int
-cowlo_readcowraw(struct cowloop_device *cowdev,
- void *buf, int len, loff_t offset)
-{
- long int rv;
- mm_segment_t old_fs;
- loff_t saveoffset = offset;
-
- DEBUGP(DCOW"cowloop - readcowraw called\n");
-
- /*
- ** be sure that cowfile is opened for read-write
- */
- if ( !(cowdev->state & COWCOWOPEN) ) {
- printk(KERN_WARNING
- "cowloop - read request from cowfile refused\n");
-
- return -EBADF;
- }
-
- /*
- ** issue low level read
- */
- old_fs = get_fs();
- set_fs( get_ds() );
- rv = cowdev->cowfp->f_op->read(cowdev->cowfp, buf, len, &offset);
- set_fs(old_fs);
-
- if (rv < len) {
- printk(KERN_WARNING
- "cowloop - read-failure %ld on cowfile"
- "- offset=%lld len=%d\n", rv, saveoffset, len);
- }
-
- cowdev->cowreads++;
- return rv;
-}
-
-/*
-** write cowfile from a modified offset, i.e. skipping the bitmap and cowhead
-**
-** if a block is written for the first time while its contents consists
-** of binary zeroes only, the concerning bitmap is flushed to the cowfile
-**
-** return-value: similar to user-mode write
-*/
-static long int
-cowlo_writecow(struct cowloop_device *cowdev, void *buf, int len, loff_t offset)
-{
- long int rv;
- unsigned long mapnum=0, mapbyte=0, mapbit=0, cowblock=0, partlen;
- char *tmpptr, *mapptr = NULL;
- loff_t tmpoffset, mapoffset = 0;
-
- DEBUGP(DCOW"cowloop - writecow called\n");
-
- /*
- ** be sure that cowfile is opened for read-write
- */
- if ( !(cowdev->state & COWRWCOWOPEN) ) {
- printk(KERN_WARNING
- "cowloop - Write request to cowfile refused\n");
-
- return -EBADF;
- }
-
- /*
- ** write the entire block to the cowfile
- */
- tmpoffset = offset + cowdev->cowhead->doffset;
-
- rv = cowlo_writecowraw(cowdev, buf, len, tmpoffset);
-
- /*
- ** verify if enough space available on filesystem holding
- ** the cowfile
- ** - when the last write failed (might be caused by lack of space)
- ** - when a watcher is active (to react adequatly)
- ** - when the previous check indicated fs was almost full
- ** - with regular intervals
- */
- if ( (rv <= 0) ||
- (cowdev->state & COWWATCHDOG) ||
- (cowdev->blkavail / 2 < SPCDFLINTVL) ||
- (cowdev->cowwrites % SPCDFLINTVL == 0) ) {
- struct kstatfs ks;
-
- if (vfs_statfs(cowdev->cowfp->f_dentry, &ks)==0){
- if (ks.f_bavail <= SPCMINBLK) {
- switch (ks.f_bavail) {
- case 0:
- case 1:
- case 2:
- case 3:
- printk(KERN_ALERT
- "cowloop - "
- "ALERT: cowfile full!\n");
- break;
-
- default:
- printk(KERN_WARNING
- "cowloop - cowfile almost "
- "full (only %llu Kb free)\n",
- (unsigned long long)
- ks.f_bsize * ks.f_bavail /1024);
- }
- }
-
- cowdev->blktotal = ks.f_blocks;
- cowdev->blkavail = ks.f_bavail;
-
- /*
- ** wakeup watcher if threshold has been reached
- */
- if ( (cowdev->state & COWWATCHDOG) &&
- (cowdev->watchthresh >= cowdev->blkavail) ) {
- wake_up_interruptible(&cowdev->watchq);
- }
- }
- }
-
- if (rv <= 0)
- return rv;
-
- DEBUGP(DCOW"cowloop - block written\n");
-
- /*
- ** check if block(s) is/are written to the cowfile
- ** for the first time; if so, adapt the bitmap
- */
- for (; len > 0; len-=partlen, offset+=partlen, buf+=partlen) {
- /*
- ** calculate partial length for this transfer
- */
- partlen = MAPUNIT - (offset & MUMASK);
- if (partlen > len)
- partlen = len;
-
- /*
- ** calculate bitnr of written chunk of cowblock
- */
- cowblock = offset >> MUSHIFT;
-
- mapnum = CALCMAP (cowblock);
- mapbyte = CALCBYTE(cowblock);
- mapbit = CALCBIT (cowblock);
-
- if (*(*(cowdev->mapcache+mapnum)+mapbyte) & (1<<mapbit))
- continue; /* already written before */
-
- /*
- ** if the block is written for the first time,
- ** the corresponding bit should be set in the bitmap
- */
- *(*(cowdev->mapcache+mapnum)+mapbyte) |= (1<<mapbit);
-
- cowdev->nrcowblocks++;
-
- DEBUGP(DCOW"cowloop - bitupdate blk=%ld map=%ld "
- "byte=%ld bit=%ld\n",
- cowblock, mapnum, mapbyte, mapbit);
-
- /*
- ** check if the cowhead in the cowfile is currently
- ** marked clean; if so, mark it dirty and flush it
- */
- if ( !(cowdev->cowhead->flags &= COWDIRTY)) {
- cowdev->cowhead->flags |= COWDIRTY;
-
- cowlo_writecowraw(cowdev, cowdev->cowhead,
- MAPUNIT, (loff_t)0);
- }
-
- /*
- ** if the written datablock contained binary zeroes,
- ** the bitmap block should be marked to be flushed to disk
- ** (blocks containing all zeroes cannot be recovered by
- ** the cowrepair-program later on if cowloop is not properly
- ** removed via rmmod)
- */
- if ( memcmp(buf, allzeroes, partlen) ) /* not all zeroes? */
- continue; /* no flush needed */
-
- /*
- ** calculate positions of bitmap block to be flushed
- ** - pointer of bitmap block in memory
- ** - offset of bitmap block in cowfile
- */
- tmpptr = *(cowdev->mapcache+mapnum) + (mapbyte & (~MUMASK));
- tmpoffset = (loff_t) MAPUNIT + mapnum * MAPCHUNKSZ +
- (mapbyte & (~MUMASK));
-
- /*
- ** flush a bitmap block at the moment that all bits have
- ** been set in that block, i.e. at the moment that we
- ** switch to another bitmap block
- */
- if ( (mapoffset != 0) && (mapoffset != tmpoffset) ) {
- if (cowlo_writecowraw(cowdev, mapptr, MAPUNIT,
- mapoffset) < 0) {
- printk(KERN_WARNING
- "cowloop - write-failure on bitmap - "
- "blk=%ld map=%ld byte=%ld bit=%ld\n",
- cowblock, mapnum, mapbyte, mapbit);
- }
-
- DEBUGP(DCOW"cowloop - bitmap blk written %lld\n",
- mapoffset);
- }
-
- /*
- ** remember offset in cowfile and offset in memory
- ** for bitmap to be flushed; flushing will be done
- ** as soon as all updates in this bitmap block have
- ** been done
- */
- mapoffset = tmpoffset;
- mapptr = tmpptr;
- }
-
- /*
- ** any new block written containing binary zeroes?
- */
- if (mapoffset) {
- if (cowlo_writecowraw(cowdev, mapptr, MAPUNIT, mapoffset) < 0) {
- printk(KERN_WARNING
- "cowloop - write-failure on bitmap - "
- "blk=%ld map=%ld byte=%ld bit=%ld\n",
- cowblock, mapnum, mapbyte, mapbit);
- }
-
- DEBUGP(DCOW"cowloop - bitmap block written %lld\n", mapoffset);
- }
-
- return rv;
-}
-
-/*
-** write cowfile from an absolute offset
-**
-** return-value: similar to user-mode write
-*/
-static long int
-cowlo_writecowraw(struct cowloop_device *cowdev,
- void *buf, int len, loff_t offset)
-{
- long int rv;
- mm_segment_t old_fs;
- loff_t saveoffset = offset;
-
- DEBUGP(DCOW"cowloop - writecowraw called\n");
-
- /*
- ** be sure that cowfile is opened for read-write
- */
- if ( !(cowdev->state & COWRWCOWOPEN) ) {
- printk(KERN_WARNING
- "cowloop - write request to cowfile refused\n");
-
- return -EBADF;
- }
-
- /*
- ** issue low level write
- */
- old_fs = get_fs();
- set_fs( get_ds() );
- rv = cowdev->cowfp->f_op->write(cowdev->cowfp, buf, len, &offset);
- set_fs(old_fs);
-
- if (rv < len) {
- printk(KERN_WARNING
- "cowloop - write-failure %ld on cowfile"
- "- offset=%lld len=%d\n", rv, saveoffset, len);
- }
-
- cowdev->cowwrites++;
- return rv;
-}
-
-
-/*
-** readproc-function: called when the corresponding /proc-file is read
-*/
-static int
-cowlo_readproc(char *buf, char **start, off_t pos, int cnt, int *eof, void *p)
-{
- struct cowloop_device *cowdev = p;
-
- revision[sizeof revision - 3] = '\0';
-
- return sprintf(buf,
- " cowloop version: %9s\n\n"
- " device state: %s%s%s%s\n"
- " number of opens: %9d\n"
- " pid of thread: %9d\n\n"
- " read-only file: %9s\n"
- " rdoreads: %9lu\n\n"
- "copy-on-write file: %9s\n"
- " state cowfile: %9s\n"
- " bitmap-blocks: %9lu (of %d bytes)\n"
- " cowblocks in use: %9lu (of %d bytes)\n"
- " cowreads: %9lu\n"
- " cowwrites: %9lu\n",
- &revision[11],
-
- cowdev->state & COWDEVOPEN ? "devopen " : "",
- cowdev->state & COWRWCOWOPEN ? "cowopenrw " : "",
- cowdev->state & COWRDCOWOPEN ? "cowopenro " : "",
- cowdev->state & COWWATCHDOG ? "watchdog " : "",
-
- cowdev->opencnt,
- cowdev->pid,
- cowdev->rdoname,
- cowdev->rdoreads,
- cowdev->cowname,
- cowdev->cowhead->flags & COWDIRTY ? "dirty":"clean",
- cowdev->mapsize >> MUSHIFT, MAPUNIT,
- cowdev->nrcowblocks, MAPUNIT,
- cowdev->cowreads,
- cowdev->cowwrites);
-}
-
-/*****************************************************************************/
-/* Setup and destroy cowdevices */
-/*****************************************************************************/
-
-/*
-** open and prepare a cowdevice (rdofile and cowfile) and allocate bitmaps
-**
-** returns:
-** 0 - okay
-** < 0 - error value
-*/
-static int
-cowlo_openpair(char *rdof, char *cowf, int autorecover, int minor)
-{
- long int rv;
- struct cowloop_device *cowdev = cowdevall[minor];
- struct kstatfs ks;
-
- down(&cowdevlock);
-
- /*
- ** requested device exists?
- */
- if (minor >= maxcows) {
- up(&cowdevlock);
- return -ENODEV;
- }
-
- /*
- ** requested device already assigned to cowdevice?
- */
- if (cowdev->state & COWDEVOPEN) {
- up(&cowdevlock);
- return -EBUSY;
- }
-
- /*
- ** initialize administration
- */
- memset(cowdev, 0, sizeof *cowdev);
-
- spin_lock_init (&cowdev->rqlock);
- init_waitqueue_head(&cowdev->waitq);
- init_waitqueue_head(&cowdev->watchq);
-
- /*
- ** open the read-only file
- */
- DEBUGP(DCOW"cowloop - call openrdo....\n");
-
- if ( (rv = cowlo_openrdo(cowdev, rdof)) ) {
- cowlo_undo_openrdo(cowdev);
- up(&cowdevlock);
- return rv;
- }
-
- /*
- ** open the cowfile
- */
- DEBUGP(DCOW"cowloop - call opencow....\n");
-
- if ( (rv = cowlo_opencow(cowdev, cowf, autorecover)) ) {
- cowlo_undo_openrdo(cowdev);
- cowlo_undo_opencow(cowdev);
- up(&cowdevlock);
- return rv;
- }
-
- /*
- ** administer total and available size of filesystem holding cowfile
- */
- if (vfs_statfs(cowdev->cowfp->f_dentry, &ks)==0) {
- cowdev->blksize = ks.f_bsize;
- cowdev->blktotal = ks.f_blocks;
- cowdev->blkavail = ks.f_bavail;
- } else {
- cowdev->blksize = 1024; /* avoid division by zero */
- }
-
- /*
- ** flush the (recovered) bitmaps and cowhead to the cowfile
- */
- DEBUGP(DCOW"cowloop - call cowsync....\n");
-
- cowlo_sync();
-
- /*
- ** allocate gendisk for the cow device
- */
- DEBUGP(DCOW"cowloop - alloc disk....\n");
-
- if ((cowdev->gd = alloc_disk(1)) == NULL) {
- printk(KERN_WARNING
- "cowloop - unable to alloc_disk for cowloop\n");
-
- cowlo_undo_openrdo(cowdev);
- cowlo_undo_opencow(cowdev);
- up(&cowdevlock);
- return -ENOMEM;
- }
-
- cowdev->gd->major = COWMAJOR;
- cowdev->gd->first_minor = minor;
- cowdev->gd->minors = 1;
- cowdev->gd->fops = &cowlo_fops;
- cowdev->gd->private_data = cowdev;
- sprintf(cowdev->gd->disk_name, "%s%d", DEVICE_NAME, minor);
-
- /* in .5 Kb units */
- set_capacity(cowdev->gd, (cowdev->numblocks*(MAPUNIT/512)));
-
- DEBUGP(DCOW"cowloop - init request queue....\n");
-
- if ((cowdev->rqueue = blk_init_queue(cowlo_request, &cowdev->rqlock))
- == NULL) {
- printk(KERN_WARNING
- "cowloop - unable to get request queue for cowloop\n");
-
- del_gendisk(cowdev->gd);
- cowlo_undo_openrdo(cowdev);
- cowlo_undo_opencow(cowdev);
- up(&cowdevlock);
- return -EINVAL;
- }
-
- blk_queue_logical_block_size(cowdev->rqueue, cowdev->blocksz);
- cowdev->gd->queue = cowdev->rqueue;
-
- /*
- ** start kernel thread to handle requests
- */
- DEBUGP(DCOW"cowloop - kickoff daemon....\n");
-
- cowdev->pid = kernel_thread((int (*)(void *))cowlo_daemon, cowdev, 0);
-
- /*
- ** create a file below directory /proc/cow for this new cowdevice
- */
- if (cowlo_procdir) {
- char tmpname[64];
-
- sprintf(tmpname, "%d", minor);
-
- create_proc_read_entry(tmpname, 0 , cowlo_procdir,
- cowlo_readproc, cowdev);
- }
-
- cowdev->state |= COWDEVOPEN;
-
- cowdev->rdoname = rdof;
- cowdev->cowname = cowf;
-
- /*
- ** enable the new disk; this triggers the first request!
- */
- DEBUGP(DCOW"cowloop - call add_disk....\n");
-
- add_disk(cowdev->gd);
-
- up(&cowdevlock);
- return 0;
-}
-
-/*
-** close a cowdevice (pair of rdofile/cowfile) and release memory
-**
-** returns:
-** 0 - okay
-** < 0 - error value
-*/
-static int
-cowlo_closepair(struct cowloop_device *cowdev)
-{
- int minor;
-
- down(&cowdevlock);
-
- /*
- ** if cowdevice is not activated at all, refuse
- */
- if ( !(cowdev->state & COWDEVOPEN) ) {
- up(&cowdevlock);
- return -ENODEV;
- }
-
- /*
- ** if this cowdevice is still open, refuse
- */
- if (cowdev->opencnt > 0) {
- up(&cowdevlock);
- return -EBUSY;
- }
-
- up(&cowdevlock);
-
- /*
- ** wakeup watcher (if any)
- */
- if (cowdev->state & COWWATCHDOG) {
- cowdev->watchthresh = cowdev->blkavail;
- wake_up_interruptible(&cowdev->watchq);
- }
-
- /*
- ** wakeup kernel-thread to be able to exit
- ** and wait until it has exited
- */
- cowdev->closedown = 1;
- cowdev->qfilled = 1;
- wake_up_interruptible(&cowdev->waitq);
-
- while (cowdev->pid)
- schedule();
-
- del_gendisk(cowdev->gd); /* revert the alloc_disk() */
- put_disk(cowdev->gd); /* revert the add_disk() */
-
- if (cowlo_procdir) {
- char tmpname[64];
-
- for (minor = 0; minor < maxcows; minor++) {
- if (cowdev == cowdevall[minor]) break;
- }
- sprintf(tmpname, "%d", minor);
-
- remove_proc_entry(tmpname, cowlo_procdir);
- }
-
- blk_cleanup_queue(cowdev->rqueue);
-
- /*
- ** release memory for filenames if these names have
- ** been allocated dynamically
- */
- if ( (cowdev->cowname) && (cowdev->cowname != cowfile))
- kfree(cowdev->cowname);
-
- if ( (cowdev->rdoname) && (cowdev->rdoname != rdofile))
- kfree(cowdev->rdoname);
-
- cowlo_undo_openrdo(cowdev);
- cowlo_undo_opencow(cowdev);
-
- cowdev->state &= ~COWDEVOPEN;
-
- return 0;
-}
-
-/*
-** open the read-only file
-**
-** returns:
-** 0 - okay
-** < 0 - error value
-*/
-static int
-cowlo_openrdo(struct cowloop_device *cowdev, char *rdof)
-{
- struct file *f;
- struct inode *inode;
- long int i, nrval;
-
- DEBUGP(DCOW"cowloop - openrdo called\n");
-
- /*
- ** open the read-only file
- */
- if(*rdof == '\0') {
- printk(KERN_ERR
- "cowloop - specify name for read-only file\n\n");
- return -EINVAL;
- }
-
- f = filp_open(rdof, O_RDONLY|O_LARGEFILE, 0);
-
- if ( (f == NULL) || IS_ERR(f) ) {
- printk(KERN_ERR
- "cowloop - open of rdofile %s failed\n", rdof);
- return -EINVAL;
- }
-
- cowdev->rdofp = f;
-
- inode = f->f_dentry->d_inode;
-
- if ( !S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode) ) {
- printk(KERN_ERR
- "cowloop - %s not regular file or blockdev\n", rdof);
- return -EINVAL;
- }
-
- DEBUGP(DCOW"cowloop - determine size rdo....\n");
-
- /*
- ** determine block-size and total size of read-only file
- */
- if (S_ISREG(inode->i_mode)) {
- /*
- ** read-only file is a regular file
- */
- cowdev->blocksz = 512; /* other value fails */
- cowdev->numblocks = inode->i_size >> MUSHIFT;
-
- if (inode->i_size & MUMASK) {
- printk(KERN_WARNING
- "cowloop - rdofile %s truncated to multiple "
- "of %d bytes\n", rdof, MAPUNIT);
- }
-
- DEBUGP(DCOW"cowloop - RO=regular: numblocks=%d, blocksz=%d\n",
- cowdev->numblocks, cowdev->blocksz);
- } else {
- /*
- ** read-only file is a block device
- */
- cowdev->belowdev = inode->i_bdev;
- cowdev->belowgd = cowdev->belowdev->bd_disk; /* gendisk */
-
- if (cowdev->belowdev->bd_part) {
- cowdev->numblocks = cowdev->belowdev->bd_part->nr_sects
- / (MAPUNIT/512);
- }
-
- if (cowdev->belowgd) {
- cowdev->belowq = cowdev->belowgd->queue;
-
- if (cowdev->numblocks == 0) {
- cowdev->numblocks = get_capacity(cowdev->belowgd)
- / (MAPUNIT/512);
- }
- }
-
-
- if (cowdev->belowq)
- cowdev->blocksz = queue_logical_block_size(cowdev->belowq);
-
- if (cowdev->blocksz == 0)
- cowdev->blocksz = BLOCK_SIZE; /* default 2^10 */
-
- DEBUGP(DCOW"cowloop - numblocks=%d, "
- "blocksz=%d, belowgd=%p, belowq=%p\n",
- cowdev->numblocks, cowdev->blocksz,
- cowdev->belowgd, cowdev->belowq);
-
- DEBUGP(DCOW"cowloop - belowdev.bd_block_size=%d\n",
- cowdev->belowdev->bd_block_size);
- }
-
- if (cowdev->numblocks == 0) {
- printk(KERN_ERR "cowloop - %s has no contents\n", rdof);
- return -EINVAL;
- }
-
- /*
- ** reserve space in memory as generic I/O buffer
- */
- cowdev->iobuf = kmalloc(MAPUNIT, GFP_KERNEL);
-
- if (!cowdev->iobuf) {
- printk(KERN_ERR
- "cowloop - cannot get space for buffer %d\n", MAPUNIT);
- return -ENOMEM;
- }
-
- DEBUGP(DCOW"cowloop - determine fingerprint rdo....\n");
-
- /*
- ** determine fingerprint for read-only file
- ** calculate fingerprint from first four datablocks
- ** which do not contain binary zeroes
- */
- for (i=0, cowdev->fingerprint=0, nrval=0;
- (nrval < 4)&&(i < cowdev->numblocks); i++) {
- int j;
- unsigned char cs;
-
- /*
- ** read next block
- */
- if (cowlo_readrdo(cowdev, cowdev->iobuf, MAPUNIT,
- (loff_t)i << MUSHIFT) < 1)
- break;
-
- /*
- ** calculate fingerprint by adding all byte-values
- */
- for (j=0, cs=0; j < MAPUNIT; j++)
- cs += *(cowdev->iobuf+j);
-
- if (cs == 0) /* block probably contained zeroes */
- continue;
-
- /*
- ** shift byte-value to proper place in final fingerprint
- */
- cowdev->fingerprint |= cs << (nrval*8);
- nrval++;
- }
-
- return 0;
-}
-
-/*
-** undo memory allocs and file opens issued so far
-** related to the read-only file
-*/
-static void
-cowlo_undo_openrdo(struct cowloop_device *cowdev)
-{
- if(cowdev->iobuf);
- kfree(cowdev->iobuf);
-
- if (cowdev->rdofp)
- filp_close(cowdev->rdofp, 0);
-}
-
-/*
-** open the cowfile
-**
-** returns:
-** 0 - okay
-** < 0 - error value
-*/
-static int
-cowlo_opencow(struct cowloop_device *cowdev, char *cowf, int autorecover)
-{
- long int i, rv;
- int minor;
- unsigned long nb;
- struct file *f;
- struct inode *inode;
- loff_t offset;
- struct cowloop_device *cowtmp;
-
- DEBUGP(DCOW"cowloop - opencow called\n");
-
- /*
- ** open copy-on-write file (read-write)
- */
- if (cowf[0] == '\0') {
- printk(KERN_ERR
- "cowloop - specify name of copy-on-write file\n\n");
- return -EINVAL;
- }
-
- f = filp_open(cowf, O_RDWR|O_LARGEFILE, 0600);
-
- if ( (f == NULL) || IS_ERR(f) ) {
- /*
- ** non-existing cowfile: try to create
- */
- f = filp_open(cowf, O_RDWR|O_CREAT|O_LARGEFILE, 0600);
-
- if ( (f == NULL) || IS_ERR(f) ) {
- printk(KERN_ERR
- "cowloop - failed to open file %s for read-write\n\n",
- cowf);
- return -EINVAL;
- }
- }
-
- cowdev->cowfp = f;
-
- inode = f->f_dentry->d_inode;
-
- if (!S_ISREG(inode->i_mode)) {
- printk(KERN_ERR "cowloop - %s is not regular file\n", cowf);
- return -EINVAL;
- }
-
- /*
- ** check if this cowfile is already in use for another cowdevice
- */
- for (minor = 0; minor < maxcows; minor++) {
-
- cowtmp = cowdevall[minor];
-
- if ( !(cowtmp->state & COWDEVOPEN) )
- continue;
-
- if (cowtmp == cowdev)
- continue;
-
- if (cowtmp->cowfp->f_dentry->d_inode == f->f_dentry->d_inode) {
- printk(KERN_ERR
- "cowloop - %s: already in use as cow\n", cowf);
- return -EBUSY;
- }
- }
-
- /*
- ** mark cowfile open for read-write
- */
- cowdev->state |= COWRWCOWOPEN;
-
- /*
- ** calculate size (in bytes) for total bitmap in cowfile;
- ** when the size of the cowhead block is added, the start-offset
- ** for the modified data blocks can be found
- */
- nb = cowdev->numblocks;
-
- if (nb%8) /* transform #bits to #bytes */
- nb+=8; /* rounded if necessary */
- nb /= 8;
-
- if (nb & MUMASK) /* round up #bytes to MAPUNIT chunks */
- cowdev->mapsize = ( (nb>>MUSHIFT) +1) << MUSHIFT;
- else
- cowdev->mapsize = nb;
-
- /*
- ** reserve space in memory for the cowhead
- */
- cowdev->cowhead = kmalloc(MAPUNIT, GFP_KERNEL);
-
- if (!cowdev->cowhead) {
- printk(KERN_ERR "cowloop - cannot get space for cowhead %d\n",
- MAPUNIT);
- return -ENOMEM;
- }
-
- memset(cowdev->cowhead, 0, MAPUNIT);
-
- DEBUGP(DCOW"cowloop - prepare cowhead....\n");
-
- /*
- ** check if the cowfile exists or should be created
- */
- if (inode->i_size != 0) {
- /*
- ** existing cowfile: read the cow head
- */
- if (inode->i_size < MAPUNIT) {
- printk(KERN_ERR
- "cowloop - existing cowfile %s too small\n",
- cowf);
- return -EINVAL;
- }
-
- cowlo_readcowraw(cowdev, cowdev->cowhead, MAPUNIT, (loff_t) 0);
-
- /*
- ** verify if the existing file is really a cowfile
- */
- if (cowdev->cowhead->magic != COWMAGIC) {
- printk(KERN_ERR
- "cowloop - cowfile %s has incorrect format\n",
- cowf);
- return -EINVAL;
- }
-
- /*
- ** verify the cowhead version of the cowfile
- */
- if (cowdev->cowhead->version > COWVERSION) {
- printk(KERN_ERR
- "cowloop - cowfile %s newer than this driver\n",
- cowf);
- return -EINVAL;
- }
-
- /*
- ** make sure that this is not a packed cowfile
- */
- if (cowdev->cowhead->flags & COWPACKED) {
- printk(KERN_ERR
- "cowloop - packed cowfile %s not accepted\n", cowf);
- return -EINVAL;
- }
-
- /*
- ** verify if the cowfile has been properly closed
- */
- if (cowdev->cowhead->flags & COWDIRTY) {
- /*
- ** cowfile was not properly closed;
- ** check if automatic recovery is required
- ** (actual recovery will be done later on)
- */
- if (!autorecover) {
- printk(KERN_ERR
- "cowloop - cowfile %s is dirty "
- "(not properly closed by rmmod?)\n",
- cowf);
- printk(KERN_ERR
- "cowloop - run cowrepair or specify "
- "'option=r' to recover\n");
- return -EINVAL;
- }
- }
-
- /*
- ** verify if the cowfile is really related to this rdofile
- */
- if (cowdev->cowhead->rdoblocks != cowdev->numblocks) {
- printk(KERN_ERR
- "cowloop - cowfile %s (size %lld) not related "
- "to rdofile (size %lld)\n",
- cowf,
- (long long)cowdev->cowhead->rdoblocks <<MUSHIFT,
- (long long)cowdev->numblocks <<MUSHIFT);
- return -EINVAL;
- }
-
- if (cowdev->cowhead->rdofingerprint != cowdev->fingerprint) {
- printk(KERN_ERR
- "cowloop - cowfile %s not related to rdofile "
- " (fingerprint err - rdofile modified?)\n", cowf);
- return -EINVAL;
- }
- } else {
- /*
- ** new cowfile: determine the minimal size (cowhead+bitmap)
- */
- offset = (loff_t) MAPUNIT + cowdev->mapsize - 1;
-
- if ( cowlo_writecowraw(cowdev, "", 1, offset) < 1) {
- printk(KERN_ERR
- "cowloop - cannot set cowfile to size %lld\n",
- offset+1);
- return -EINVAL;
- }
-
- /*
- ** prepare new cowhead
- */
- cowdev->cowhead->magic = COWMAGIC;
- cowdev->cowhead->version = COWVERSION;
- cowdev->cowhead->mapunit = MAPUNIT;
- cowdev->cowhead->mapsize = cowdev->mapsize;
- cowdev->cowhead->rdoblocks = cowdev->numblocks;
- cowdev->cowhead->rdofingerprint = cowdev->fingerprint;
- cowdev->cowhead->cowused = 0;
-
- /*
- ** calculate start offset of data in cowfile,
- ** rounded up to multiple of 4K to avoid
- ** unnecessary disk-usage for written datablocks in
- ** the sparsed cowfile on e.g. 4K filesystems
- */
- cowdev->cowhead->doffset =
- ((MAPUNIT+cowdev->mapsize+4095)>>12)<<12;
- }
-
- cowdev->cowhead->flags = 0;
-
- DEBUGP(DCOW"cowloop - reserve space bitmap....\n");
-
- /*
- ** reserve space in memory for the entire bitmap and
- ** fill it with the bitmap-data from disk; the entire
- ** bitmap is allocated in several chunks because kmalloc
- ** has restrictions regarding the allowed size per kmalloc
- */
- cowdev->mapcount = (cowdev->mapsize+MAPCHUNKSZ-1)/MAPCHUNKSZ;
-
- /*
- ** the size of every bitmap chunk will be MAPCHUNKSZ bytes, except for
- ** the last bitmap chunk: calculate remaining size for this chunk
- */
- if (cowdev->mapsize % MAPCHUNKSZ == 0)
- cowdev->mapremain = MAPCHUNKSZ;
- else
- cowdev->mapremain = cowdev->mapsize % MAPCHUNKSZ;
-
- /*
- ** allocate space to store all pointers for the bitmap-chunks
- ** (initialize area with zeroes to allow proper undo)
- */
- cowdev->mapcache = kmalloc(cowdev->mapcount * sizeof(char *),
- GFP_KERNEL);
- if (!cowdev->mapcache) {
- printk(KERN_ERR
- "cowloop - can not allocate space for bitmap ptrs\n");
- return -ENOMEM;
- }
-
- memset(cowdev->mapcache, 0, cowdev->mapcount * sizeof(char *));
-
- /*
- ** allocate space to store the bitmap-chunks themselves
- */
- for (i=0; i < cowdev->mapcount; i++) {
- if (i < (cowdev->mapcount-1))
- *(cowdev->mapcache+i) = kmalloc(MAPCHUNKSZ, GFP_KERNEL);
- else
- *(cowdev->mapcache+i) = kmalloc(cowdev->mapremain,
- GFP_KERNEL);
-
- if (*(cowdev->mapcache+i) == NULL) {
- printk(KERN_ERR "cowloop - no space for bitmapchunk %ld"
- " totmapsz=%ld, mapcnt=%d mapunit=%d\n",
- i, cowdev->mapsize, cowdev->mapcount,
- MAPUNIT);
- return -ENOMEM;
- }
- }
-
- DEBUGP(DCOW"cowloop - read bitmap from cow....\n");
-
- /*
- ** read the entire bitmap from the cowfile into the in-memory cache;
- ** count the number of blocks that are in use already
- ** (statistical purposes)
- */
- for (i=0, offset=MAPUNIT; i < cowdev->mapcount;
- i++, offset+=MAPCHUNKSZ) {
- unsigned long numbytes;
-
- if (i < (cowdev->mapcount-1))
- /*
- ** full bitmap chunk
- */
- numbytes = MAPCHUNKSZ;
- else
- /*
- ** last bitmap chunk: might be partly filled
- */
- numbytes = cowdev->mapremain;
-
- cowlo_readcowraw(cowdev, *(cowdev->mapcache+i),
- numbytes, offset);
- }
-
- /*
- ** if the cowfile was dirty and automatic recovery is required,
- ** reconstruct a proper bitmap in memory now
- */
- if (cowdev->cowhead->flags & COWDIRTY) {
- unsigned long long blocknum;
- char databuf[MAPUNIT];
- unsigned long mapnum, mapbyte, mapbit;
-
- printk(KERN_NOTICE "cowloop - recover dirty cowfile %s....\n",
- cowf);
-
- /*
- ** read all data blocks
- */
- for (blocknum=0, rv=1, offset=0;
- cowlo_readcow(cowdev, databuf, MAPUNIT, offset) > 0;
- blocknum++, offset += MAPUNIT) {
-
- /*
- ** if this datablock contains real data (not binary
- ** zeroes), set the corresponding bit in the bitmap
- */
- if ( memcmp(databuf, allzeroes, MAPUNIT) == 0)
- continue;
-
- mapnum = CALCMAP (blocknum);
- mapbyte = CALCBYTE(blocknum);
- mapbit = CALCBIT (blocknum);
-
- *(*(cowdev->mapcache+mapnum)+mapbyte) |= (1<<mapbit);
- }
-
- printk(KERN_NOTICE "cowloop - cowfile recovery completed\n");
- }
-
- /*
- ** count all bits set in the bitmaps for statistical purposes
- */
- for (i=0, cowdev->nrcowblocks = 0; i < cowdev->mapcount; i++) {
- long numbytes;
- char *p;
-
- if (i < (cowdev->mapcount-1))
- numbytes = MAPCHUNKSZ;
- else
- numbytes = cowdev->mapremain;
-
- p = *(cowdev->mapcache+i);
-
- for (numbytes--; numbytes >= 0; numbytes--, p++) {
- /*
- ** for only eight checks the following construction
- ** is faster than a loop-construction
- */
- if ((*p) & 0x01) cowdev->nrcowblocks++;
- if ((*p) & 0x02) cowdev->nrcowblocks++;
- if ((*p) & 0x04) cowdev->nrcowblocks++;
- if ((*p) & 0x08) cowdev->nrcowblocks++;
- if ((*p) & 0x10) cowdev->nrcowblocks++;
- if ((*p) & 0x20) cowdev->nrcowblocks++;
- if ((*p) & 0x40) cowdev->nrcowblocks++;
- if ((*p) & 0x80) cowdev->nrcowblocks++;
- }
- }
-
- /*
- ** consistency-check for number of bits set in bitmap
- */
- if ( !(cowdev->cowhead->flags & COWDIRTY) &&
- (cowdev->cowhead->cowused != cowdev->nrcowblocks) ) {
- printk(KERN_ERR "cowloop - inconsistent cowfile admi\n");
- return -EINVAL;
- }
-
- return 0;
-}
-
-/*
-** undo memory allocs and file opens issued so far
-** related to the cowfile
-*/
-static void
-cowlo_undo_opencow(struct cowloop_device *cowdev)
-{
- int i;
-
- if (cowdev->mapcache) {
- for (i=0; i < cowdev->mapcount; i++) {
- if (*(cowdev->mapcache+i) != NULL)
- kfree( *(cowdev->mapcache+i) );
- }
-
- kfree(cowdev->mapcache);
- }
-
- if (cowdev->cowhead)
- kfree(cowdev->cowhead);
-
- if ( (cowdev->state & COWCOWOPEN) && (cowdev->cowfp) )
- filp_close(cowdev->cowfp, 0);
-
- /*
- ** mark cowfile closed
- */
- cowdev->state &= ~COWCOWOPEN;
-}
-
-/*
-** flush the entire bitmap and the cowhead (clean) to the cowfile
-**
-** must be called with the cowdevices-lock set
-*/
-static void
-cowlo_sync(void)
-{
- int i, minor;
- loff_t offset;
- struct cowloop_device *cowdev;
-
- for (minor=0; minor < maxcows; minor++) {
- cowdev = cowdevall[minor];
- if ( ! (cowdev->state & COWRWCOWOPEN) )
- continue;
-
- for (i=0, offset=MAPUNIT; i < cowdev->mapcount;
- i++, offset += MAPCHUNKSZ) {
- unsigned long numbytes;
-
- if (i < (cowdev->mapcount-1))
- /*
- ** full bitmap chunk
- */
- numbytes = MAPCHUNKSZ;
- else
- /*
- ** last bitmap chunk: might be partly filled
- */
- numbytes = cowdev->mapremain;
-
- DEBUGP(DCOW
- "cowloop - flushing bitmap %2d (%3ld Kb)\n",
- i, numbytes/1024);
-
- if (cowlo_writecowraw(cowdev, *(cowdev->mapcache+i),
- numbytes, offset) < numbytes) {
- break;
- }
- }
-
- /*
- ** flush clean up-to-date cowhead to cowfile
- */
- cowdev->cowhead->cowused = cowdev->nrcowblocks;
- cowdev->cowhead->flags &= ~COWDIRTY;
-
- DEBUGP(DCOW "cowloop - flushing cowhead (%3d Kb)\n",
- MAPUNIT/1024);
-
- cowlo_writecowraw(cowdev, cowdev->cowhead, MAPUNIT, (loff_t) 0);
- }
-}
-
-/*****************************************************************************/
-/* Module loading/unloading */
-/*****************************************************************************/
-
-/*
-** called during insmod/modprobe
-*/
-static int __init
-cowlo_init_module(void)
-{
- int rv;
- int minor, uptocows;
-
- revision[sizeof revision - 3] = '\0';
-
- printk(KERN_NOTICE "cowloop - (C) 2009 ATComputing.nl - version: %s\n", &revision[11]);
- printk(KERN_NOTICE "cowloop - info: www.ATComputing.nl/cowloop\n");
-
- memset(allzeroes, 0, MAPUNIT);
-
- /*
- ** Setup administration for all possible cowdevices.
- ** Note that their minor numbers go from 0 to MAXCOWS-1 inclusive
- ** and minor == MAXCOWS-1 is reserved for the control device.
- */
- if ((maxcows < 1) || (maxcows > MAXCOWS)) {
- printk(KERN_WARNING
- "cowloop - maxcows exceeds maximum of %d\n", MAXCOWS);
-
- maxcows = DFLCOWS;
- }
-
- /* allocate room for a table with a pointer to each cowloop_device: */
- if ( (cowdevall = kmalloc(maxcows * sizeof(struct cowloop_device *),
- GFP_KERNEL)) == NULL) {
- printk(KERN_WARNING
- "cowloop - can not alloc table for %d devs\n", maxcows);
- uptocows = 0;
- rv = -ENOMEM;
- goto error_out;
- }
- memset(cowdevall, 0, maxcows * sizeof(struct cowloop_device *));
- /* then hook an actual cowloop_device struct to each pointer: */
- for (minor=0; minor < maxcows; minor++) {
- if ((cowdevall[minor] = kmalloc(sizeof(struct cowloop_device),
- GFP_KERNEL)) == NULL) {
- printk(KERN_WARNING
- "cowloop - can not alloc admin-struct for dev no %d\n", minor);
-
- uptocows = minor; /* this is how far we got.... */
- rv = -ENOMEM;
- goto error_out;
- }
- memset(cowdevall[minor], 0, sizeof(struct cowloop_device));
- }
- uptocows = maxcows; /* we got all devices */
-
- sema_init(&cowdevlock, 1);
-
- /*
- ** register cowloop module
- */
- if ( register_blkdev(COWMAJOR, DEVICE_NAME) < 0) {
- printk(KERN_WARNING
- "cowloop - unable to get major %d for cowloop\n", COWMAJOR);
- rv = -EIO;
- goto error_out;
- }
-
- /*
- ** create a directory below /proc to allocate a file
- ** for each cowdevice that is allocated later on
- */
- cowlo_procdir = proc_mkdir("cow", NULL);
-
- /*
- ** check if a cowdevice has to be opened during insmod/modprobe;
- ** two parameters should be specified then: rdofile= and cowfile=
- */
- if( (rdofile[0] != '\0') && (cowfile[0] != '\0') ) {
- char *po = option;
- int wantrecover = 0;
-
- /*
- ** check if automatic recovery is wanted
- */
- while (*po) {
- if (*po == 'r') {
- wantrecover = 1;
- break;
- }
- po++;
- }
-
- /*
- ** open new cowdevice with minor number 0
- */
- if ( (rv = cowlo_openpair(rdofile, cowfile, wantrecover, 0))) {
- remove_proc_entry("cow", NULL);
- unregister_blkdev(COWMAJOR, DEVICE_NAME);
- goto error_out;
- }
- } else {
- /*
- ** check if only one parameter has been specified
- */
- if( (rdofile[0] != '\0') || (cowfile[0] != '\0') ) {
- printk(KERN_ERR
- "cowloop - only one filename specified\n");
- remove_proc_entry("cow", NULL);
- unregister_blkdev(COWMAJOR, DEVICE_NAME);
- rv = -EINVAL;
- goto error_out;
- }
- }
-
- /*
- ** allocate fake disk as control channel to handle the requests
- ** to activate and deactivate cowdevices dynamically
- */
- if (!(cowctlgd = alloc_disk(1))) {
- printk(KERN_WARNING
- "cowloop - unable to alloc_disk for cowctl\n");
-
- remove_proc_entry("cow", NULL);
- (void) cowlo_closepair(cowdevall[0]);
- unregister_blkdev(COWMAJOR, DEVICE_NAME);
- rv = -ENOMEM;
- goto error_out;
- }
-
- spin_lock_init(&cowctlrqlock);
- cowctlgd->major = COWMAJOR;
- cowctlgd->first_minor = COWCTL;
- cowctlgd->minors = 1;
- cowctlgd->fops = &cowlo_fops;
- cowctlgd->private_data = NULL;
- /* the device has capacity 0, so there will be no q-requests */
- cowctlgd->queue = blk_init_queue(NULL, &cowctlrqlock);
- sprintf(cowctlgd->disk_name, "cowctl");
- set_capacity(cowctlgd, 0);
-
- add_disk(cowctlgd);
-
- printk(KERN_NOTICE "cowloop - number of configured cowdevices: %d\n",
- maxcows);
- if (rdofile[0] != '\0') {
- printk(KERN_NOTICE "cowloop - initialized on rdofile=%s\n",
- rdofile);
- } else {
- printk(KERN_NOTICE "cowloop - initialized without rdofile yet\n");
- }
- return 0;
-
-error_out:
- for (minor=0; minor < uptocows ; minor++) {
- kfree(cowdevall[minor]);
- }
- kfree(cowdevall);
- return rv;
-}
-
-/*
-** called during rmmod
-*/
-static void __exit
-cowlo_cleanup_module(void)
-{
- int minor;
-
- /*
- ** flush bitmaps and cowheads to the cowfiles
- */
- down(&cowdevlock);
- cowlo_sync();
- up(&cowdevlock);
-
- /*
- ** close all cowdevices
- */
- for (minor=0; minor < maxcows; minor++)
- (void) cowlo_closepair(cowdevall[minor]);
-
- unregister_blkdev(COWMAJOR, DEVICE_NAME);
-
- /*
- ** get rid of /proc/cow and unregister the driver
- */
- remove_proc_entry("cow", NULL);
-
- for (minor = 0; minor < maxcows; minor++) {
- kfree(cowdevall[minor]);
- }
- kfree(cowdevall);
-
- del_gendisk(cowctlgd); /* revert the alloc_disk() */
- put_disk (cowctlgd); /* revert the add_disk() */
- blk_cleanup_queue(cowctlgd->queue); /* cleanup the empty queue */
-
- printk(KERN_NOTICE "cowloop - unloaded\n");
-}
-
-module_init(cowlo_init_module);
-module_exit(cowlo_cleanup_module);
projects / profile / common / kernel-common.git / commitdiff