0458054c4e
description:
How it works:
--
Basically ifs is a copy of ffs, overriding some vfs/vnops. (Yes, hack.)
I didn't see the need in duplicating all of sys/ufs/ffs to get this
off the ground.
File creation is done through a special file - 'newfile' . When newfile
is called, the system allocates and returns an inode. Note that newfile
is done in a cloning fashion:
fd = open("newfile", O_CREAT|O_RDWR, 0644);
fstat(fd, &st);
printf("new file is %d\n", (int)st.st_ino);
Once you have created a file, you can open() and unlink() it by its returned
inode number retrieved from the stat call, ie:
fd = open("5", O_RDWR);
The creation permissions depend entirely if you have write access to the
root directory of the filesystem.
To get the list of currently allocated inodes, VOP_READDIR has been added
which returns a directory listing of those currently allocated.
--
What this entails:
* patching conf/files and conf/options to include IFS as a new compile
option (and since ifs depends upon FFS, include the FFS routines)
* An entry in i386/conf/NOTES indicating IFS exists and where to go for
an explanation
* Unstaticize a couple of routines in src/sys/ufs/ffs/ which the IFS
routines require (ffs_mount() and ffs_reload())
* a new bunch of routines in src/sys/ufs/ifs/ which implement the IFS
routines. IFS replaces some of the vfsops, and a handful of vnops -
most notably are VFS_VGET(), VOP_LOOKUP(), VOP_UNLINK() and VOP_READDIR().
Any other directory operation is marked as invalid.
What this results in:
* an IFS partition's create permissions are controlled by the perm/ownership of
the root mount point, just like a normal directory
* Each inode has perm and ownership too
* IFS does *NOT* mean an FFS partition can be opened per inode. This is a
completely seperate filesystem here
* Softupdates doesn't work with IFS, and really I don't think it needs it.
Besides, fsck's are FAST. (Try it :-)
* Inodes 0 and 1 aren't allocatable because they are special (dump/swap IIRC).
Inode 2 isn't allocatable since UFS/FFS locks all inodes in the system against
this particular inode, and unravelling THAT code isn't trivial. Therefore,
useful inodes start at 3.
Enjoy, and feedback is definitely appreciated!
121 lines
3.9 KiB
C
121 lines
3.9 KiB
C
/*
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* Copyright (c) 1999, 2000
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* Adrian Chadd <adrian@FreeBSD.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)ffs_vnops.c 8.15 (Berkeley) 5/14/95
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/resourcevar.h>
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#include <sys/signalvar.h>
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#include <sys/kernel.h>
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#include <sys/stat.h>
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#include <sys/bio.h>
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#include <sys/buf.h>
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#include <sys/proc.h>
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#include <sys/mount.h>
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#include <sys/vnode.h>
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#include <sys/conf.h>
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#include <sys/namei.h>
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#include <sys/malloc.h>
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#include <sys/dirent.h>
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#include <machine/limits.h>
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#include <vm/vm.h>
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#include <vm/vm_page.h>
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#include <vm/vm_object.h>
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#include <vm/vm_extern.h>
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#include <vm/vm_zone.h>
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#include <ufs/ufs/dir.h>
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#include <ufs/ufs/quota.h>
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#include <ufs/ufs/inode.h>
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#include <ufs/ufs/ufs_extern.h>
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#include <ufs/ffs/fs.h>
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#include <ufs/ffs/ffs_extern.h>
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#include <ufs/ifs/ifs_extern.h>
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/*
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* Check whether the given inode number is free.
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*
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* This routine is a chunk of ffs_nodealloccg - we aren't
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* allocating here. We also check whether there will be
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* any other inodes in the cylinder group, and if not,
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* we return -1.
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*/
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int
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ifs_isinodealloc(struct inode *ip, ufs_daddr_t ino)
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{
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struct fs *fs;
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struct cg *cgp;
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struct buf *bp;
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int error;
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int cg;
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int retval = 0;
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/* Grab the filesystem info and cylinder group */
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fs = ip->i_fs;
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cg = ino_to_cg(fs, ino);
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/* Read in the cylinder group inode allocation bitmap .. */
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error = bread(ip->i_devvp, fsbtodb(fs, cgtod(fs, cg)),
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(int)fs->fs_cgsize, NOCRED, &bp);
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if (error) {
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retval = IFS_INODE_NOALLOC;
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goto end;
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}
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cgp = (struct cg *)bp->b_data;
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if (!cg_chkmagic(cgp)) {
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retval = IFS_INODE_NOALLOC;
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goto end;
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}
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ino %= fs->fs_ipg;
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/*
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* Check whether we have any inodes in this cg, or whether the
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* inode is allocated
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*/
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if (!isclr(cg_inosused(cgp), ino))
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retval = IFS_INODE_ISALLOC; /* it is allocated */
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else if (cgp->cg_niblk == cgp->cg_cs.cs_nifree)
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retval = IFS_INODE_EMPTYCG; /* empty cg */
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else
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retval = IFS_INODE_NOALLOC; /* its not allocated */
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end:
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/* Close the buffer and return */
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brelse(bp);
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return (retval);
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}
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