fs/9p/vfs_dentry.c


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/*
 *  linux/fs/9p/vfs_dentry.c
 *
 * This file contians vfs dentry ops for the 9P2000 protocol.
 *
 *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
 *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
 *
 *  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 of the License, 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:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/pagemap.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/smp_lock.h>
#include <linux/inet.h>
#include <linux/namei.h>
#include <linux/idr.h>

#include "debug.h"
#include "v9fs.h"
#include "9p.h"
#include "v9fs_vfs.h"
#include "fid.h"

/**
 * v9fs_dentry_validate - VFS dcache hook to validate cache
 * @dentry:  dentry that is being validated
 * @nd: path data
 *
 * dcache really shouldn't be used for 9P2000 as at all due to
 * potential attached semantics to directory traversal (walk).
 *
 * FUTURE: look into how to use dcache to allow multi-stage
 * walks in Plan 9 & potential for better dcache operation which
 * would remain valid for Plan 9 semantics.  Older versions
 * had validation via stat for those interested.  However, since
 * stat has the same approximate overhead as walk there really
 * is no difference.  The only improvement would be from a
 * time-decay cache like NFS has and that undermines the
 * synchronous nature of 9P2000.
 *
 */

static int v9fs_dentry_validate(struct dentry *dentry, struct nameidata *nd)
{
	struct dentry *dc = current->fs->pwd;

	dprintk(DEBUG_VFS, "dentry: %s (%p)\n", dentry->d_iname, dentry);
	if (v9fs_fid_lookup(dentry)) {
		dprintk(DEBUG_VFS, "VALID\n");
		return 1;
	}

	while (dc != NULL) {
		if (dc == dentry) {
			dprintk(DEBUG_VFS, "VALID\n");
			return 1;
		}
		if (dc == dc->d_parent)
			break;

		dc = dc->d_parent;
	}

	dprintk(DEBUG_VFS, "INVALID\n");
	return 0;
}

/**
 * v9fs_dentry_release - called when dentry is going to be freed
 * @dentry:  dentry that is being release
 *
 */

void v9fs_dentry_release(struct dentry *dentry)
{
	int err;

	dprintk(DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);

	if (dentry->d_fsdata != NULL) {
		struct list_head *fid_list = dentry->d_fsdata;
		struct v9fs_fid *temp = NULL;
		struct v9fs_fid *current_fid = NULL;

		list_for_each_entry_safe(current_fid, temp, fid_list, list) {
			err = v9fs_t_clunk(current_fid->v9ses, current_fid->fid);

			if (err < 0)
				dprintk(DEBUG_ERROR, "clunk failed: %d name %s\n",
					err, dentry->d_iname);

			v9fs_fid_destroy(current_fid);
		}

		kfree(dentry->d_fsdata);	/* free the list_head */
	}
}

struct dentry_operations v9fs_dentry_operations = {
	.d_revalidate = v9fs_dentry_validate,
	.d_release = v9fs_dentry_release,
};
/*
 *  linux/fs/ufs/truncate.c
 *
 * Copyright (C) 1998
 * Daniel Pirkl <daniel.pirkl@email.cz>
 * Charles University, Faculty of Mathematics and Physics
 *
 *  from
 *
 *  linux/fs/ext2/truncate.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/truncate.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 */

/*
 * Real random numbers for secure rm added 94/02/18
 * Idea from Pierre del Perugia <delperug@gla.ecoledoc.ibp.fr>
 */

/*
 * Adoptation to use page cache and UFS2 write support by
 * Evgeniy Dushistov <dushistov@mail.ru>, 2006-2007
 */

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/ufs_fs.h>
#include <linux/fcntl.h>
#include <linux/time.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/smp_lock.h>
#include <linux/buffer_head.h>
#include <linux/blkdev.h>
#include <linux/sched.h>

#include "swab.h"
#include "util.h"

/*
 * Secure deletion currently doesn't work. It interacts very badly
 * with buffers shared with memory mappings, and for that reason
 * can't be done in the truncate() routines. It should instead be
 * done separately in "release()" before calling the truncate routines
 * that will release the actual file blocks.
 *
 *		Linus
 */

#define DIRECT_BLOCK ((inode->i_size + uspi->s_bsize - 1) >> uspi->s_bshift)
#define DIRECT_FRAGMENT ((inode->i_size + uspi->s_fsize - 1) >> uspi->s_fshift)


static int ufs_trunc_direct(struct inode *inode)
{
	struct ufs_inode_info *ufsi = UFS_I(inode);
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	void *p;
	u64 frag1, frag2, frag3, frag4, block1, block2;
	unsigned frag_to_free, free_count;
	unsigned i, tmp;
	int retry;
	
	UFSD("ENTER: ino %lu\n", inode->i_ino);

	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;
	
	frag_to_free = 0;
	free_count = 0;
	retry = 0;
	
	frag1 = DIRECT_FRAGMENT;
	frag4 = min_t(u32, UFS_NDIR_FRAGMENT, ufsi->i_lastfrag);
	frag2 = ((frag1 & uspi->s_fpbmask) ? ((frag1 | uspi->s_fpbmask) + 1) : frag1);
	frag3 = frag4 & ~uspi->s_fpbmask;
	block1 = block2 = 0;
	if (frag2 > frag3) {
		frag2 = frag4;
		frag3 = frag4 = 0;
	} else if (frag2 < frag3) {
		block1 = ufs_fragstoblks (frag2);
		block2 = ufs_fragstoblks (frag3);
	}

	UFSD("ino %lu, frag1 %llu, frag2 %llu, block1 %llu, block2 %llu,"
	     " frag3 %llu, frag4 %llu\n", inode->i_ino,
	     (unsigned long long)frag1, (unsigned long long)frag2,
	     (unsigned long long)block1, (unsigned long long)block2,
	     (unsigned long long)frag3, (unsigned long long)frag4);

	if (frag1 >= frag2)
		goto next1;		

	/*
	 * Free first free fragments
	 */
	p = ufs_get_direct_data_ptr(uspi, ufsi, ufs_fragstoblks(frag1));
	tmp = ufs_data_ptr_to_cpu(sb, p);
	if (!tmp )
		ufs_panic (sb, "ufs_trunc_direct", "internal error");
	frag2 -= frag1;
	frag1 = ufs_fragnum (frag1);

	ufs_free_fragments(inode, tmp + frag1, frag2);
	mark_inode_dirty(inode);
	frag_to_free = tmp + frag1;

next1:
	/*
	 * Free whole blocks
	 */
	for (i = block1 ; i < block2; i++) {
		p = ufs_get_direct_data_ptr(uspi, ufsi, i);
		tmp = ufs_data_ptr_to_cpu(sb, p);
		if (!tmp)
			continue;
		ufs_data_ptr_clear(uspi, p);

		if (free_count == 0) {
			frag_to_free = tmp;
			free_count = uspi->s_fpb;
		} else if (free_count > 0 && frag_to_free == tmp - free_count)
			free_count += uspi->s_fpb;
		else {
			ufs_free_blocks (inode, frag_to_free, free_count);
			frag_to_free = tmp;
			free_count = uspi->s_fpb;
		}
		mark_inode_dirty(inode);
	}
	
	if (free_count > 0)
		ufs_free_blocks (inode, frag_to_free, free_count);

	if (frag3 >= frag4)
		goto next3;

	/*
	 * Free last free fragments
	 */
	p = ufs_get_direct_data_ptr(uspi, ufsi, ufs_fragstoblks(frag3));
	tmp = ufs_data_ptr_to_cpu(sb, p);
	if (!tmp )
		ufs_panic(sb, "ufs_truncate_direct", "internal error");
	frag4 = ufs_fragnum (frag4);
	ufs_data_ptr_clear(uspi, p);

	ufs_free_fragments (inode, tmp, frag4);
	mark_inode_dirty(inode);
 next3:

	UFSD("EXIT: ino %lu\n", inode->i_ino);
	return retry;
}


static int ufs_trunc_indirect(struct inode *inode, u64 offset, void *p)
{
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	struct ufs_buffer_head * ind_ubh;
	void *ind;
	u64 tmp, indirect_block, i, frag_to_free;
	unsigned free_count;
	int retry;

	UFSD("ENTER: ino %lu, offset %llu, p: %p\n",
	     inode->i_ino, (unsigned long long)offset, p);

	BUG_ON(!p);
		
	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;

	frag_to_free = 0;
	free_count = 0;
	retry = 0;
	
	tmp = ufs_data_ptr_to_cpu(sb, p);
	if (!tmp)
		return 0;
	ind_ubh = ubh_bread(sb, tmp, uspi->s_bsize);
	if (tmp != ufs_data_ptr_to_cpu(sb, p)) {
		ubh_brelse (ind_ubh);
		return 1;
	}
	if (!ind_ubh) {
		ufs_data_ptr_clear(uspi, p);
		return 0;
	}

	indirect_block = (DIRECT_BLOCK > offset) ? (DIRECT_BLOCK - offset) : 0;
	for (i = indirect_block; i < uspi->s_apb; i++) {
		ind = ubh_get_data_ptr(uspi, ind_ubh, i);
		tmp = ufs_data_ptr_to_cpu(sb, ind);
		if (!tmp)
			continue;

		ufs_data_ptr_clear(uspi, ind);
		ubh_mark_buffer_dirty(ind_ubh);
		if (free_count == 0) {
			frag_to_free = tmp;
			free_count = uspi->s_fpb;
		} else if (free_count > 0 && frag_to_free == tmp - free_count)
			free_count += uspi->s_fpb;
		else {
			ufs_free_blocks (inode, frag_to_free, free_count);
			frag_to_free = tmp;
			free_count = uspi->s_fpb;
		}

		mark_inode_dirty(inode);
	}

	if (free_count > 0) {
		ufs_free_blocks (inode, frag_to_free, free_count);
	}
	for (i = 0; i < uspi->s_apb; i++)
		if (!ufs_is_data_ptr_zero(uspi,
					  ubh_get_data_ptr(uspi, ind_ubh, i)))
			break;
	if (i >= uspi->s_apb) {
		tmp = ufs_data_ptr_to_cpu(sb, p);
		ufs_data_ptr_clear(uspi, p);

		ufs_free_blocks (inode, tmp, uspi->s_fpb);
		mark_inode_dirty(inode);
		ubh_bforget(ind_ubh);
		ind_ubh = NULL;
	}
	if (IS_SYNC(inode) && ind_ubh && ubh_buffer_dirty(ind_ubh)) {
		ubh_ll_rw_block(SWRITE, ind_ubh);
		ubh_wait_on_buffer (ind_ubh);
	}
	ubh_brelse (ind_ubh);
	
	UFSD("EXIT: ino %lu\n", inode->i_ino);
	
	return retry;
}

static int ufs_trunc_dindirect(struct inode *inode, u64 offset, void *p)
{
	struct super_block * sb;
	struct ufs_sb_private_info * uspi;
	struct ufs_buffer_head *dind_bh;
	u64 i, tmp, dindirect_block;
	void *dind;
	int retry = 0;
	
	UFSD("ENTER: ino %lu\n", inode->i_ino);
	
	sb = inode->i_sb;
	uspi = UFS_SB(sb)->s_uspi;

	dindirect_block = (DIRECT_BLOCK > offset) 
		? ((DIRECT_BLOCK - offset) >> uspi->s_apbshift) : 0;
	retry = 0;
	
	tmp = ufs_data_ptr_to_cpu(sb, p);
	if (!tmp)
		return 0;
	dind_bh = ubh_bread(sb, tmp, uspi->s_bsize);
	if (tmp != ufs_data_ptr_to_cpu(sb, p)) {
		ubh_brelse (dind_bh);
		return 1;
	}
	if (!dind_bh) {
		ufs_data_ptr_clear(uspi, p);
		return 0;
	}

	for (i = dindirect_block ; i < uspi->s_apb ; i++) {
		dind = ubh_get_data_ptr(uspi, dind_bh, i);
		tmp = ufs_data_ptr_to_cpu(sb, dind);
		if (!tmp)
			continue;
		retry |= ufs_trunc_indirect (inode, offset + (i << uspi->s_apbshift), dind);
		ubh_mark_buffer_dirty(dind_bh);
	}

	for (i = 0; i < uspi->s_apb; i++)
		if (!ufs_is_data_ptr_zero(uspi,
					  ubh_get_data_ptr(uspi, dind_bh, i)))
			break;
	if (i >= uspi->s_apb) {
		tmp = ufs_data_ptr_to_cpu(sb, p);
		ufs_data_ptr_clear(uspi, p);

		ufs_free_blocks(inode, tmp, uspi->s_fpb);