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path: root/fs/nilfs2/dir.c

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generated by cgit v1.2.3 (git 2.25.1) at 2024-09-06 00:42:21 +0000

/*
 * dir.c - NILFS directory entry operations
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * 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 the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Modified for NILFS by Amagai Yoshiji <amagai@osrg.net>
 */
/*
 *  linux/fs/ext2/dir.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/dir.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  ext2 directory handling functions
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 *
 * All code that works with directory layout had been switched to pagecache
 * and moved here. AV
 */

#include <linux/pagemap.h>
#include <linux/smp_lock.h>
#include "nilfs.h"
#include "page.h"

/*
 * nilfs uses block-sized chunks. Arguably, sector-sized ones would be
 * more robust, but we have what we have
 */
static inline unsigned nilfs_chunk_size(struct inode *inode)
{
	return inode->i_sb->s_blocksize;
}

static inline void nilfs_put_page(struct page *page)
{
	kunmap(page);
	page_cache_release(page);
}

static inline unsigned long dir_pages(struct inode *inode)
{
	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
}

/*
 * Return the offset into page `page_nr' of the last valid
 * byte in that page, plus one.
 */
static unsigned nilfs_last_byte(struct inode *inode, unsigned long page_nr)
{
	unsigned last_byte = inode->i_size;

	last_byte -= page_nr << PAGE_CACHE_SHIFT;
	if (last_byte > PAGE_CACHE_SIZE)
		last_byte = PAGE_CACHE_SIZE;
	return last_byte;
}

static int nilfs_prepare_chunk_uninterruptible(struct page *page,
					       struct address_space *mapping,
					       unsigned from, unsigned to)
{
	loff_t pos = page_offset(page) + from;
	return block_write_begin(NULL, mapping, pos, to - from,
				 AOP_FLAG_UNINTERRUPTIBLE, &page,
				 NULL, nilfs_get_block);
}

static int nilfs_prepare_chunk(struct page *page,
			       struct address_space *mapping,
			       unsigned from, unsigned to)
{
	loff_t pos = page_offset(page) + from;
	return block_write_begin(NULL, mapping, pos, to - from, 0, &page,
				 NULL, nilfs_get_block);
}

static int nilfs_commit_chunk(struct page *page,
			      struct address_space *mapping,
			      unsigned from, unsigned to)
{
	struct inode *dir = mapping->host;
	struct nilfs_sb_info *sbi = NILFS_SB(dir->i_sb);
	loff_t pos = page_offset(page) + from;
	unsigned len = to - from;
	unsigned nr_dirty, copied;
	int err;

	nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
	copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
	if (pos + copied > dir->i_size) {
		i_size_write(dir, pos + copied);
		mark_inode_dirty(dir);
	}
	if (IS_DIRSYNC(dir))
		nilfs_set_transaction_flag(NILFS_TI_SYNC);
	err = nilfs_set_file_dirty(sbi, dir, nr_dirty);
	unlock_page(page);
	return err;
}

static void nilfs_check_page(struct page *page)
{
	struct inode *dir = page->mapping->host;
	struct super_block *sb = dir->i_sb;
	unsigned chunk_size = nilfs_chunk_size(dir);
	char *kaddr = page_address(page);
	unsigned offs, rec_len;
	unsigned limit = PAGE_CACHE_SIZE;
	struct nilfs_dir_entry *p;
	char *error;

	if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
		limit = dir->i_size & ~PAGE_CACHE_MASK;
		if (limit & (chunk_size - 1))
			goto Ebadsize;
		if (!limit)
			goto out;
	}
	for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {
		p = (struct nilfs_dir_entry *)(kaddr + offs);
		rec_len = le16_to_cpu(p->rec_len);

		if (rec_len < NILFS_DIR_REC_LEN(1))
			goto Eshort;
		if (rec_len & 3)
			goto Ealign;
		if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
			goto Enamelen;
		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
			goto Espan;
	}
	if (offs != limit)
		goto Eend;
out:
	SetPageChecked(page);
	return;

	/* Too bad, we had an error */

Ebadsize:
	nilfs_error(sb, "nilfs_check_page",
		    "size of directory #%lu is not a multiple of chunk size",
		    dir->i_ino
	);
	goto fail;
Eshort:
	error = "rec_len is smaller than minimal";
	goto bad_entry;
Ealign:
	error = "unaligned directory entry";
	goto bad_entry;
Enamelen:
	error = "rec_len is too small for name_len";
	goto bad_entry;
Espan:
	error = "directory entry across blocks";
bad_entry:
	nilfs_error(sb, "nilfs_check_page", "bad entry in directory #%lu: %s - "
		    "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
		    dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
		    (unsigned long) le64_to_cpu(p->inode),
		    rec_len, p->name_len);
	goto fail;
Eend:
	p = (struct nilfs_dir_entry *)(kaddr + offs);
	nilfs_error(sb, "nilfs_check_page",
		    "entry in directory #%lu spans the page boundary"
		    "offset=%lu, inode=%lu",
		    dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
		    (unsigned long) le64_to_cpu(p->inode));
fail:
	SetPageChecked(page);
	SetPageError(page);
}

static struct page *nilfs_get_page(struct inode *dir,