fs/exofs/dir.c - fp2-dev/kernel/msm - Gitiles

 /*
  * Copyright (C) 2005, 2006
  * Avishay Traeger (avishay@gmail.com)
  * Copyright (C) 2008, 2009
  * Boaz Harrosh <bharrosh@panasas.com>
  *
  * Copyrights for code taken from ext2:
  *     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/inode.c
  *     Copyright (C) 1991, 1992  Linus Torvalds
  *
  * This file is part of exofs.
  *
  * exofs 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.  Since it is based on ext2, and the only
  * valid version of GPL for the Linux kernel is version 2, the only valid
  * version of GPL for exofs is version 2.
  *
  * exofs 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 exofs; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */

 #include "exofs.h"

 static inline unsigned exofs_chunk_size(struct inode *inode)
 {
 	return inode->i_sb->s_blocksize;
 }

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

 /* Accesses dir's inode->i_size must be called under inode lock */
 static inline unsigned long dir_pages(struct inode *inode)
 {
 	return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 }

 static unsigned exofs_last_byte(struct inode *inode, unsigned long page_nr)
 {
 	loff_t 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 exofs_commit_chunk(struct page *page, loff_t pos, unsigned len)
 {
 	struct address_space *mapping = page->mapping;
 	struct inode *dir = mapping->host;
 	int err = 0;

 	dir->i_version++;

 	if (!PageUptodate(page))
 		SetPageUptodate(page);

 	if (pos+len > dir->i_size) {
 		i_size_write(dir, pos+len);
 		mark_inode_dirty(dir);
 	}
 	set_page_dirty(page);

 	if (IS_DIRSYNC(dir))
 		err = write_one_page(page, 1);
 	else
 		unlock_page(page);

 	return err;
 }

 static void exofs_check_page(struct page *page)
 {
 	struct inode *dir = page->mapping->host;
 	unsigned chunk_size = exofs_chunk_size(dir);
 	char *kaddr = page_address(page);
 	unsigned offs, rec_len;
 	unsigned limit = PAGE_CACHE_SIZE;
 	struct exofs_dir_entry *p;
 	char *error;

 	/* if the page is the last one in the directory */
 	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 - EXOFS_DIR_REC_LEN(1); offs += rec_len) {
 		p = (struct exofs_dir_entry *)(kaddr + offs);
 		rec_len = le16_to_cpu(p->rec_len);

 		if (rec_len < EXOFS_DIR_REC_LEN(1))
 			goto Eshort;
 		if (rec_len & 3)
 			goto Ealign;
 		if (rec_len < EXOFS_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;

 Ebadsize:
 	EXOFS_ERR("ERROR [exofs_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";
 	goto bad_entry;
 bad_entry:
 	EXOFS_ERR(
 		"ERROR [exofs_check_page]: bad entry in directory #%lu: %s - "
 		"offset=%lu, inode=%llu, rec_len=%d, name_len=%d",
 		dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
 		_LLU(le64_to_cpu(p->inode_no)),
 		rec_len, p->name_len);
 	goto fail;
 Eend:
 	p = (struct exofs_dir_entry *)(kaddr + offs);
 	EXOFS_ERR("ERROR [exofs_check_page]: "
 		"entry in directory #%lu spans the page boundary"
 		"offset=%lu, inode=%llu",
 		dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
 		_LLU(le64_to_cpu(p->inode_no)));
 fail:
 	SetPageChecked(page);
 	SetPageError(page);
 }

 static struct page *exofs_get_page(struct inode *dir, unsigned long n)
 {
 	struct address_space *mapping = dir->i_mapping;
 	struct page *page = read_mapping_page(mapping, n, NULL);

 	if (!IS_ERR(page)) {
 		kmap(page);
 		if (!PageChecked(page))
 			exofs_check_page(page);
 		if (PageError(page))
 			goto fail;
 	}
 	return page;

 fail:
 	exofs_put_page(page);
 	return ERR_PTR(-EIO);
 }

 static inline int exofs_match(int len, const unsigned char *name,
 					struct exofs_dir_entry *de)
 {
 	if (len != de->name_len)
 		return 0;
 	if (!de->inode_no)
 		return 0;
 	return !memcmp(name, de->name, len);
 }

 static inline
 struct exofs_dir_entry *exofs_next_entry(struct exofs_dir_entry *p)
 {
 	return (struct exofs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));
 }

 static inline unsigned
 exofs_validate_entry(char *base, unsigned offset, unsigned mask)
 {
 	struct exofs_dir_entry *de = (struct exofs_dir_entry *)(base + offset);
 	struct exofs_dir_entry *p =
 			(struct exofs_dir_entry *)(base + (offset&mask));
 	while ((char *)p < (char *)de) {
 		if (p->rec_len == 0)
 			break;
 		p = exofs_next_entry(p);
 	}
 	return (char *)p - base;
 }

 static unsigned char exofs_filetype_table[EXOFS_FT_MAX] = {
 	[EXOFS_FT_UNKNOWN]	= DT_UNKNOWN,
 	[EXOFS_FT_REG_FILE]	= DT_REG,
 	[EXOFS_FT_DIR]		= DT_DIR,
 	[EXOFS_FT_CHRDEV]	= DT_CHR,
 	[EXOFS_FT_BLKDEV]	= DT_BLK,
 	[EXOFS_FT_FIFO]		= DT_FIFO,
 	[EXOFS_FT_SOCK]		= DT_SOCK,
 	[EXOFS_FT_SYMLINK]	= DT_LNK,
 };

 #define S_SHIFT 12
 static unsigned char exofs_type_by_mode[S_IFMT >> S_SHIFT] = {
 	[S_IFREG >> S_SHIFT]	= EXOFS_FT_REG_FILE,
 	[S_IFDIR >> S_SHIFT]	= EXOFS_FT_DIR,
 	[S_IFCHR >> S_SHIFT]	= EXOFS_FT_CHRDEV,
 	[S_IFBLK >> S_SHIFT]	= EXOFS_FT_BLKDEV,
 	[S_IFIFO >> S_SHIFT]	= EXOFS_FT_FIFO,
 	[S_IFSOCK >> S_SHIFT]	= EXOFS_FT_SOCK,
 	[S_IFLNK >> S_SHIFT]	= EXOFS_FT_SYMLINK,
 };

 static inline
 void exofs_set_de_type(struct exofs_dir_entry *de, struct inode *inode)
 {
 	mode_t mode = inode->i_mode;
 	de->file_type = exofs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
 }

 static int
 exofs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 {
 	loff_t pos = filp->f_pos;
 	struct inode *inode = filp->f_path.dentry->d_inode;
 	unsigned int offset = pos & ~PAGE_CACHE_MASK;
 	unsigned long n = pos >> PAGE_CACHE_SHIFT;
 	unsigned long npages = dir_pages(inode);
 	unsigned chunk_mask = ~(exofs_chunk_size(inode)-1);
 	unsigned char *types = NULL;
 	int need_revalidate = (filp->f_version != inode->i_version);

 	if (pos > inode->i_size - EXOFS_DIR_REC_LEN(1))
 		return 0;

 	types = exofs_filetype_table;

 	for ( ; n < npages; n++, offset = 0) {
 		char *kaddr, *limit;
 		struct exofs_dir_entry *de;
 		struct page *page = exofs_get_page(inode, n);

 		if (IS_ERR(page)) {
 			EXOFS_ERR("ERROR: "
 				   "bad page in #%lu",
 				   inode->i_ino);
 			filp->f_pos += PAGE_CACHE_SIZE - offset;
 			return PTR_ERR(page);
 		}
 		kaddr = page_address(page);
 		if (unlikely(need_revalidate)) {
 			if (offset) {
 				offset = exofs_validate_entry(kaddr, offset,
 								chunk_mask);
 				filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
 			}
 			filp->f_version = inode->i_version;
 			need_revalidate = 0;
 		}
 		de = (struct exofs_dir_entry *)(kaddr + offset);
 		limit = kaddr + exofs_last_byte(inode, n) -
 							EXOFS_DIR_REC_LEN(1);
 		for (; (char *)de <= limit; de = exofs_next_entry(de)) {
 			if (de->rec_len == 0) {
 				EXOFS_ERR("ERROR: "
 					"zero-length directory entry");
 				exofs_put_page(page);
 				return -EIO;
 			}
 			if (de->inode_no) {
 				int over;
 				unsigned char d_type = DT_UNKNOWN;

 				if (types && de->file_type < EXOFS_FT_MAX)
 					d_type = types[de->file_type];

 				offset = (char *)de - kaddr;
 				over = filldir(dirent, de->name, de->name_len,
 						(n<<PAGE_CACHE_SHIFT) | offset,
 						le64_to_cpu(de->inode_no),
 						d_type);
 				if (over) {
 					exofs_put_page(page);
 					return 0;
 				}
 			}
 			filp->f_pos += le16_to_cpu(de->rec_len);
 		}
 		exofs_put_page(page);
 	}

 	return 0;
 }

 struct exofs_dir_entry *exofs_find_entry(struct inode *dir,
 			struct dentry *dentry, struct page **res_page)
 {
 	const unsigned char *name = dentry->d_name.name;
 	int namelen = dentry->d_name.len;
 	unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
 	unsigned long start, n;
 	unsigned long npages = dir_pages(dir);
 	struct page *page = NULL;
 	struct exofs_i_info *oi = exofs_i(dir);
 	struct exofs_dir_entry *de;

 	if (npages == 0)
 		goto out;

 	*res_page = NULL;

 	start = oi->i_dir_start_lookup;
 	if (start >= npages)
 		start = 0;
 	n = start;
 	do {
 		char *kaddr;
 		page = exofs_get_page(dir, n);
 		if (!IS_ERR(page)) {
 			kaddr = page_address(page);
 			de = (struct exofs_dir_entry *) kaddr;
 			kaddr += exofs_last_byte(dir, n) - reclen;
 			while ((char *) de <= kaddr) {
 				if (de->rec_len == 0) {
 					EXOFS_ERR(
 						"ERROR: exofs_find_entry: "
 						"zero-length directory entry");
 					exofs_put_page(page);
 					goto out;
 				}
 				if (exofs_match(namelen, name, de))
 					goto found;
 				de = exofs_next_entry(de);
 			}
 			exofs_put_page(page);
 		}
 		if (++n >= npages)
 			n = 0;
 	} while (n != start);
 out:
 	return NULL;

 found:
 	*res_page = page;
 	oi->i_dir_start_lookup = n;
 	return de;
 }

 struct exofs_dir_entry *exofs_dotdot(struct inode *dir, struct page **p)
 {
 	struct page *page = exofs_get_page(dir, 0);
 	struct exofs_dir_entry *de = NULL;

 	if (!IS_ERR(page)) {
 		de = exofs_next_entry(
 				(struct exofs_dir_entry *)page_address(page));
 		*p = page;
 	}
 	return de;
 }

 ino_t exofs_parent_ino(struct dentry *child)
 {
 	struct page *page;
 	struct exofs_dir_entry *de;
 	ino_t ino;

 	de = exofs_dotdot(child->d_inode, &page);
 	if (!de)
 		return 0;

 	ino = le64_to_cpu(de->inode_no);
 	exofs_put_page(page);
 	return ino;
 }

 ino_t exofs_inode_by_name(struct inode *dir, struct dentry *dentry)
 {
 	ino_t res = 0;
 	struct exofs_dir_entry *de;
 	struct page *page;

 	de = exofs_find_entry(dir, dentry, &page);
 	if (de) {
 		res = le64_to_cpu(de->inode_no);
 		exofs_put_page(page);
 	}
 	return res;
 }

 int exofs_set_link(struct inode *dir, struct exofs_dir_entry *de,
 			struct page *page, struct inode *inode)
 {
 	loff_t pos = page_offset(page) +
 			(char *) de - (char *) page_address(page);
 	unsigned len = le16_to_cpu(de->rec_len);
 	int err;

 	lock_page(page);
 	err = exofs_write_begin(NULL, page->mapping, pos, len,
 				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
 	if (err)
 		EXOFS_ERR("exofs_set_link: exofs_write_begin FAILED => %d\n",
 			  err);

 	de->inode_no = cpu_to_le64(inode->i_ino);
 	exofs_set_de_type(de, inode);
 	if (likely(!err))
 		err = exofs_commit_chunk(page, pos, len);
 	exofs_put_page(page);
 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 	mark_inode_dirty(dir);
 	return err;
 }

 int exofs_add_link(struct dentry *dentry, struct inode *inode)
 {
 	struct inode *dir = dentry->d_parent->d_inode;
 	const unsigned char *name = dentry->d_name.name;
 	int namelen = dentry->d_name.len;
 	unsigned chunk_size = exofs_chunk_size(dir);
 	unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
 	unsigned short rec_len, name_len;
 	struct page *page = NULL;
 	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
 	struct exofs_dir_entry *de;
 	unsigned long npages = dir_pages(dir);
 	unsigned long n;
 	char *kaddr;
 	loff_t pos;
 	int err;

 	for (n = 0; n <= npages; n++) {
 		char *dir_end;

 		page = exofs_get_page(dir, n);
 		err = PTR_ERR(page);
 		if (IS_ERR(page))
 			goto out;
 		lock_page(page);
 		kaddr = page_address(page);
 		dir_end = kaddr + exofs_last_byte(dir, n);
 		de = (struct exofs_dir_entry *)kaddr;
 		kaddr += PAGE_CACHE_SIZE - reclen;
 		while ((char *)de <= kaddr) {
 			if ((char *)de == dir_end) {
 				name_len = 0;
 				rec_len = chunk_size;
 				de->rec_len = cpu_to_le16(chunk_size);
 				de->inode_no = 0;
 				goto got_it;
 			}
 			if (de->rec_len == 0) {
 				EXOFS_ERR("ERROR: exofs_add_link: "
 					"zero-length directory entry");
 				err = -EIO;
 				goto out_unlock;
 			}
 			err = -EEXIST;
 			if (exofs_match(namelen, name, de))
 				goto out_unlock;
 			name_len = EXOFS_DIR_REC_LEN(de->name_len);
 			rec_len = le16_to_cpu(de->rec_len);
 			if (!de->inode_no && rec_len >= reclen)
 				goto got_it;
 			if (rec_len >= name_len + reclen)
 				goto got_it;
 			de = (struct exofs_dir_entry *) ((char *) de + rec_len);
 		}
 		unlock_page(page);
 		exofs_put_page(page);
 	}

 	EXOFS_ERR("exofs_add_link: BAD dentry=%p or inode=%p", dentry, inode);
 	return -EINVAL;

 got_it:
 	pos = page_offset(page) +
 		(char *)de - (char *)page_address(page);
 	err = exofs_write_begin(NULL, page->mapping, pos, rec_len, 0,
 							&page, NULL);
 	if (err)
 		goto out_unlock;
 	if (de->inode_no) {
 		struct exofs_dir_entry *de1 =
 			(struct exofs_dir_entry *)((char *)de + name_len);
 		de1->rec_len = cpu_to_le16(rec_len - name_len);
 		de->rec_len = cpu_to_le16(name_len);
 		de = de1;
 	}
 	de->name_len = namelen;
 	memcpy(de->name, name, namelen);
 	de->inode_no = cpu_to_le64(inode->i_ino);
 	exofs_set_de_type(de, inode);
 	err = exofs_commit_chunk(page, pos, rec_len);
 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 	mark_inode_dirty(dir);
 	sbi->s_numfiles++;

 out_put:
 	exofs_put_page(page);
 out:
 	return err;
 out_unlock:
 	unlock_page(page);
 	goto out_put;
 }

 int exofs_delete_entry(struct exofs_dir_entry *dir, struct page *page)
 {
 	struct address_space *mapping = page->mapping;
 	struct inode *inode = mapping->host;
 	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
 	char *kaddr = page_address(page);
 	unsigned from = ((char *)dir - kaddr) & ~(exofs_chunk_size(inode)-1);
 	unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
 	loff_t pos;
 	struct exofs_dir_entry *pde = NULL;
 	struct exofs_dir_entry *de = (struct exofs_dir_entry *) (kaddr + from);
 	int err;

 	while (de < dir) {
 		if (de->rec_len == 0) {
 			EXOFS_ERR("ERROR: exofs_delete_entry:"
 				"zero-length directory entry");
 			err = -EIO;
 			goto out;
 		}
 		pde = de;
 		de = exofs_next_entry(de);
 	}
 	if (pde)
 		from = (char *)pde - (char *)page_address(page);
 	pos = page_offset(page) + from;
 	lock_page(page);
 	err = exofs_write_begin(NULL, page->mapping, pos, to - from, 0,
 							&page, NULL);
 	if (err)
 		EXOFS_ERR("exofs_delete_entry: exofs_write_begin FAILED => %d\n",
 			  err);
 	if (pde)
 		pde->rec_len = cpu_to_le16(to - from);
 	dir->inode_no = 0;
 	if (likely(!err))
 		err = exofs_commit_chunk(page, pos, to - from);
 	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
 	mark_inode_dirty(inode);
 	sbi->s_numfiles--;
 out:
 	exofs_put_page(page);
 	return err;
 }

 /* kept aligned on 4 bytes */
 #define THIS_DIR ".\0\0"
 #define PARENT_DIR "..\0"

 int exofs_make_empty(struct inode *inode, struct inode *parent)
 {
 	struct address_space *mapping = inode->i_mapping;
 	struct page *page = grab_cache_page(mapping, 0);
 	unsigned chunk_size = exofs_chunk_size(inode);
 	struct exofs_dir_entry *de;
 	int err;
 	void *kaddr;

 	if (!page)
 		return -ENOMEM;

 	err = exofs_write_begin(NULL, page->mapping, 0, chunk_size, 0,
 							&page, NULL);
 	if (err) {
 		unlock_page(page);
 		goto fail;
 	}

 	kaddr = kmap_atomic(page, KM_USER0);
 	de = (struct exofs_dir_entry *)kaddr;
 	de->name_len = 1;
 	de->rec_len = cpu_to_le16(EXOFS_DIR_REC_LEN(1));
 	memcpy(de->name, THIS_DIR, sizeof(THIS_DIR));
 	de->inode_no = cpu_to_le64(inode->i_ino);
 	exofs_set_de_type(de, inode);

 	de = (struct exofs_dir_entry *)(kaddr + EXOFS_DIR_REC_LEN(1));
 	de->name_len = 2;
 	de->rec_len = cpu_to_le16(chunk_size - EXOFS_DIR_REC_LEN(1));
 	de->inode_no = cpu_to_le64(parent->i_ino);
 	memcpy(de->name, PARENT_DIR, sizeof(PARENT_DIR));
 	exofs_set_de_type(de, inode);
 	kunmap_atomic(kaddr, KM_USER0);
 	err = exofs_commit_chunk(page, 0, chunk_size);
 fail:
 	page_cache_release(page);
 	return err;
 }

 int exofs_empty_dir(struct inode *inode)
 {
 	struct page *page = NULL;
 	unsigned long i, npages = dir_pages(inode);

 	for (i = 0; i < npages; i++) {
 		char *kaddr;
 		struct exofs_dir_entry *de;
 		page = exofs_get_page(inode, i);

 		if (IS_ERR(page))
 			continue;

 		kaddr = page_address(page);
 		de = (struct exofs_dir_entry *)kaddr;
 		kaddr += exofs_last_byte(inode, i) - EXOFS_DIR_REC_LEN(1);

 		while ((char *)de <= kaddr) {
 			if (de->rec_len == 0) {
 				EXOFS_ERR("ERROR: exofs_empty_dir: "
 					  "zero-length directory entry"
 					  "kaddr=%p, de=%p\n", kaddr, de);
 				goto not_empty;
 			}
 			if (de->inode_no != 0) {
 				/* check for . and .. */
 				if (de->name[0] != '.')
 					goto not_empty;
 				if (de->name_len > 2)
 					goto not_empty;
 				if (de->name_len < 2) {
 					if (le64_to_cpu(de->inode_no) !=
 					    inode->i_ino)
 						goto not_empty;
 				} else if (de->name[1] != '.')
 					goto not_empty;
 			}
 			de = exofs_next_entry(de);
 		}
 		exofs_put_page(page);
 	}
 	return 1;

 not_empty:
 	exofs_put_page(page);
 	return 0;
 }

 const struct file_operations exofs_dir_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= generic_read_dir,
 	.readdir	= exofs_readdir,
 };
	/*
	* Copyright (C) 2005, 2006
	* Avishay Traeger (avishay@gmail.com)
	* Copyright (C) 2008, 2009
	* Boaz Harrosh <bharrosh@panasas.com>
	*
	* Copyrights for code taken from ext2:
	* 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/inode.c
	* Copyright (C) 1991, 1992 Linus Torvalds
	*
	* This file is part of exofs.
	*
	* exofs 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. Since it is based on ext2, and the only
	* valid version of GPL for the Linux kernel is version 2, the only valid
	* version of GPL for exofs is version 2.
	*
	* exofs 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 exofs; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	#include "exofs.h"

	static inline unsigned exofs_chunk_size(struct inode *inode)
	{
	return inode->i_sb->s_blocksize;
	}

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

	/* Accesses dir's inode->i_size must be called under inode lock */
	static inline unsigned long dir_pages(struct inode *inode)
	{
	return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
	}

	static unsigned exofs_last_byte(struct inode *inode, unsigned long page_nr)
	{
	loff_t 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 exofs_commit_chunk(struct page *page, loff_t pos, unsigned len)
	{
	struct address_space *mapping = page->mapping;
	struct inode *dir = mapping->host;
	int err = 0;

	dir->i_version++;

	if (!PageUptodate(page))
	SetPageUptodate(page);

	if (pos+len > dir->i_size) {
	i_size_write(dir, pos+len);
	mark_inode_dirty(dir);
	}
	set_page_dirty(page);

	if (IS_DIRSYNC(dir))
	err = write_one_page(page, 1);
	else
	unlock_page(page);

	return err;
	}

	static void exofs_check_page(struct page *page)
	{
	struct inode *dir = page->mapping->host;
	unsigned chunk_size = exofs_chunk_size(dir);
	char *kaddr = page_address(page);
	unsigned offs, rec_len;
	unsigned limit = PAGE_CACHE_SIZE;
	struct exofs_dir_entry *p;
	char *error;

	/* if the page is the last one in the directory */
	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 - EXOFS_DIR_REC_LEN(1); offs += rec_len) {
	p = (struct exofs_dir_entry *)(kaddr + offs);
	rec_len = le16_to_cpu(p->rec_len);

	if (rec_len < EXOFS_DIR_REC_LEN(1))
	goto Eshort;
	if (rec_len & 3)
	goto Ealign;
	if (rec_len < EXOFS_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;

	Ebadsize:
	EXOFS_ERR("ERROR [exofs_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";
	goto bad_entry;
	bad_entry:
	EXOFS_ERR(
	"ERROR [exofs_check_page]: bad entry in directory #%lu: %s - "
	"offset=%lu, inode=%llu, rec_len=%d, name_len=%d",
	dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
	_LLU(le64_to_cpu(p->inode_no)),
	rec_len, p->name_len);
	goto fail;
	Eend:
	p = (struct exofs_dir_entry *)(kaddr + offs);
	EXOFS_ERR("ERROR [exofs_check_page]: "
	"entry in directory #%lu spans the page boundary"
	"offset=%lu, inode=%llu",
	dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
	_LLU(le64_to_cpu(p->inode_no)));
	fail:
	SetPageChecked(page);
	SetPageError(page);
	}

	static struct page exofs_get_page(struct inode dir, unsigned long n)
	{
	struct address_space *mapping = dir->i_mapping;
	struct page *page = read_mapping_page(mapping, n, NULL);

	if (!IS_ERR(page)) {
	kmap(page);
	if (!PageChecked(page))
	exofs_check_page(page);
	if (PageError(page))
	goto fail;
	}
	return page;

	fail:
	exofs_put_page(page);
	return ERR_PTR(-EIO);
	}

	static inline int exofs_match(int len, const unsigned char *name,
	struct exofs_dir_entry *de)
	{
	if (len != de->name_len)
	return 0;
	if (!de->inode_no)
	return 0;
	return !memcmp(name, de->name, len);
	}

	static inline
	struct exofs_dir_entry exofs_next_entry(struct exofs_dir_entry p)
	{
	return (struct exofs_dir_entry )((char )p + le16_to_cpu(p->rec_len));
	}

	static inline unsigned
	exofs_validate_entry(char *base, unsigned offset, unsigned mask)
	{
	struct exofs_dir_entry de = (struct exofs_dir_entry )(base + offset);
	struct exofs_dir_entry *p =
	(struct exofs_dir_entry *)(base + (offset&mask));
	while ((char )p < (char )de) {
	if (p->rec_len == 0)
	break;
	p = exofs_next_entry(p);
	}
	return (char *)p - base;
	}

	static unsigned char exofs_filetype_table[EXOFS_FT_MAX] = {
	[EXOFS_FT_UNKNOWN] = DT_UNKNOWN,
	[EXOFS_FT_REG_FILE] = DT_REG,
	[EXOFS_FT_DIR] = DT_DIR,
	[EXOFS_FT_CHRDEV] = DT_CHR,
	[EXOFS_FT_BLKDEV] = DT_BLK,
	[EXOFS_FT_FIFO] = DT_FIFO,
	[EXOFS_FT_SOCK] = DT_SOCK,
	[EXOFS_FT_SYMLINK] = DT_LNK,
	};

	#define S_SHIFT 12
	static unsigned char exofs_type_by_mode[S_IFMT >> S_SHIFT] = {
	[S_IFREG >> S_SHIFT] = EXOFS_FT_REG_FILE,
	[S_IFDIR >> S_SHIFT] = EXOFS_FT_DIR,
	[S_IFCHR >> S_SHIFT] = EXOFS_FT_CHRDEV,
	[S_IFBLK >> S_SHIFT] = EXOFS_FT_BLKDEV,
	[S_IFIFO >> S_SHIFT] = EXOFS_FT_FIFO,
	[S_IFSOCK >> S_SHIFT] = EXOFS_FT_SOCK,
	[S_IFLNK >> S_SHIFT] = EXOFS_FT_SYMLINK,
	};

	static inline
	void exofs_set_de_type(struct exofs_dir_entry de, struct inode inode)
	{
	mode_t mode = inode->i_mode;
	de->file_type = exofs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
	}

	static int
	exofs_readdir(struct file filp, void dirent, filldir_t filldir)
	{
	loff_t pos = filp->f_pos;
	struct inode *inode = filp->f_path.dentry->d_inode;
	unsigned int offset = pos & ~PAGE_CACHE_MASK;
	unsigned long n = pos >> PAGE_CACHE_SHIFT;
	unsigned long npages = dir_pages(inode);
	unsigned chunk_mask = ~(exofs_chunk_size(inode)-1);
	unsigned char *types = NULL;
	int need_revalidate = (filp->f_version != inode->i_version);

	if (pos > inode->i_size - EXOFS_DIR_REC_LEN(1))
	return 0;

	types = exofs_filetype_table;

	for ( ; n < npages; n++, offset = 0) {
	char kaddr, limit;
	struct exofs_dir_entry *de;
	struct page *page = exofs_get_page(inode, n);

	if (IS_ERR(page)) {
	EXOFS_ERR("ERROR: "
	"bad page in #%lu",
	inode->i_ino);
	filp->f_pos += PAGE_CACHE_SIZE - offset;
	return PTR_ERR(page);
	}
	kaddr = page_address(page);
	if (unlikely(need_revalidate)) {
	if (offset) {
	offset = exofs_validate_entry(kaddr, offset,
	chunk_mask);
	filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
	}
	filp->f_version = inode->i_version;
	need_revalidate = 0;
	}
	de = (struct exofs_dir_entry *)(kaddr + offset);
	limit = kaddr + exofs_last_byte(inode, n) -
	EXOFS_DIR_REC_LEN(1);
	for (; (char *)de <= limit; de = exofs_next_entry(de)) {
	if (de->rec_len == 0) {
	EXOFS_ERR("ERROR: "
	"zero-length directory entry");
	exofs_put_page(page);
	return -EIO;
	}
	if (de->inode_no) {
	int over;
	unsigned char d_type = DT_UNKNOWN;

	if (types && de->file_type < EXOFS_FT_MAX)
	d_type = types[de->file_type];

	offset = (char *)de - kaddr;
	over = filldir(dirent, de->name, de->name_len,
	(n<<PAGE_CACHE_SHIFT) \| offset,
	le64_to_cpu(de->inode_no),
	d_type);
	if (over) {
	exofs_put_page(page);
	return 0;
	}
	}
	filp->f_pos += le16_to_cpu(de->rec_len);
	}
	exofs_put_page(page);
	}

	return 0;
	}

	struct exofs_dir_entry exofs_find_entry(struct inode dir,
	struct dentry dentry, struct page *res_page)
	{
	const unsigned char *name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
	unsigned long start, n;
	unsigned long npages = dir_pages(dir);
	struct page *page = NULL;
	struct exofs_i_info *oi = exofs_i(dir);
	struct exofs_dir_entry *de;

	if (npages == 0)
	goto out;

	*res_page = NULL;

	start = oi->i_dir_start_lookup;
	if (start >= npages)
	start = 0;
	n = start;
	do {
	char *kaddr;
	page = exofs_get_page(dir, n);
	if (!IS_ERR(page)) {
	kaddr = page_address(page);
	de = (struct exofs_dir_entry *) kaddr;
	kaddr += exofs_last_byte(dir, n) - reclen;
	while ((char *) de <= kaddr) {
	if (de->rec_len == 0) {
	EXOFS_ERR(
	"ERROR: exofs_find_entry: "
	"zero-length directory entry");
	exofs_put_page(page);
	goto out;
	}
	if (exofs_match(namelen, name, de))
	goto found;
	de = exofs_next_entry(de);
	}
	exofs_put_page(page);
	}
	if (++n >= npages)
	n = 0;
	} while (n != start);
	out:
	return NULL;

	found:
	*res_page = page;
	oi->i_dir_start_lookup = n;
	return de;
	}

	struct exofs_dir_entry exofs_dotdot(struct inode dir, struct page **p)
	{
	struct page *page = exofs_get_page(dir, 0);
	struct exofs_dir_entry *de = NULL;

	if (!IS_ERR(page)) {
	de = exofs_next_entry(
	(struct exofs_dir_entry *)page_address(page));
	*p = page;
	}
	return de;
	}

	ino_t exofs_parent_ino(struct dentry *child)
	{
	struct page *page;
	struct exofs_dir_entry *de;
	ino_t ino;

	de = exofs_dotdot(child->d_inode, &page);
	if (!de)
	return 0;

	ino = le64_to_cpu(de->inode_no);
	exofs_put_page(page);
	return ino;
	}

	ino_t exofs_inode_by_name(struct inode dir, struct dentry dentry)
	{
	ino_t res = 0;
	struct exofs_dir_entry *de;
	struct page *page;

	de = exofs_find_entry(dir, dentry, &page);
	if (de) {
	res = le64_to_cpu(de->inode_no);
	exofs_put_page(page);
	}
	return res;
	}

	int exofs_set_link(struct inode dir, struct exofs_dir_entry de,
	struct page page, struct inode inode)
	{
	loff_t pos = page_offset(page) +
	(char ) de - (char ) page_address(page);
	unsigned len = le16_to_cpu(de->rec_len);
	int err;

	lock_page(page);
	err = exofs_write_begin(NULL, page->mapping, pos, len,
	AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
	if (err)
	EXOFS_ERR("exofs_set_link: exofs_write_begin FAILED => %d\n",
	err);

	de->inode_no = cpu_to_le64(inode->i_ino);
	exofs_set_de_type(de, inode);
	if (likely(!err))
	err = exofs_commit_chunk(page, pos, len);
	exofs_put_page(page);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
	mark_inode_dirty(dir);
	return err;
	}

	int exofs_add_link(struct dentry dentry, struct inode inode)
	{
	struct inode *dir = dentry->d_parent->d_inode;
	const unsigned char *name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	unsigned chunk_size = exofs_chunk_size(dir);
	unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
	unsigned short rec_len, name_len;
	struct page *page = NULL;
	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
	struct exofs_dir_entry *de;
	unsigned long npages = dir_pages(dir);
	unsigned long n;
	char *kaddr;
	loff_t pos;
	int err;

	for (n = 0; n <= npages; n++) {
	char *dir_end;

	page = exofs_get_page(dir, n);
	err = PTR_ERR(page);
	if (IS_ERR(page))
	goto out;
	lock_page(page);
	kaddr = page_address(page);
	dir_end = kaddr + exofs_last_byte(dir, n);
	de = (struct exofs_dir_entry *)kaddr;
	kaddr += PAGE_CACHE_SIZE - reclen;
	while ((char *)de <= kaddr) {
	if ((char *)de == dir_end) {
	name_len = 0;
	rec_len = chunk_size;
	de->rec_len = cpu_to_le16(chunk_size);
	de->inode_no = 0;
	goto got_it;
	}
	if (de->rec_len == 0) {
	EXOFS_ERR("ERROR: exofs_add_link: "
	"zero-length directory entry");
	err = -EIO;
	goto out_unlock;
	}
	err = -EEXIST;
	if (exofs_match(namelen, name, de))
	goto out_unlock;
	name_len = EXOFS_DIR_REC_LEN(de->name_len);
	rec_len = le16_to_cpu(de->rec_len);
	if (!de->inode_no && rec_len >= reclen)
	goto got_it;
	if (rec_len >= name_len + reclen)
	goto got_it;
	de = (struct exofs_dir_entry ) ((char ) de + rec_len);
	}
	unlock_page(page);
	exofs_put_page(page);
	}

	EXOFS_ERR("exofs_add_link: BAD dentry=%p or inode=%p", dentry, inode);
	return -EINVAL;

	got_it:
	pos = page_offset(page) +
	(char )de - (char )page_address(page);
	err = exofs_write_begin(NULL, page->mapping, pos, rec_len, 0,
	&page, NULL);
	if (err)
	goto out_unlock;
	if (de->inode_no) {
	struct exofs_dir_entry *de1 =
	(struct exofs_dir_entry )((char )de + name_len);
	de1->rec_len = cpu_to_le16(rec_len - name_len);
	de->rec_len = cpu_to_le16(name_len);
	de = de1;
	}
	de->name_len = namelen;
	memcpy(de->name, name, namelen);
	de->inode_no = cpu_to_le64(inode->i_ino);
	exofs_set_de_type(de, inode);
	err = exofs_commit_chunk(page, pos, rec_len);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
	mark_inode_dirty(dir);
	sbi->s_numfiles++;

	out_put:
	exofs_put_page(page);
	out:
	return err;
	out_unlock:
	unlock_page(page);
	goto out_put;
	}

	int exofs_delete_entry(struct exofs_dir_entry dir, struct page page)
	{
	struct address_space *mapping = page->mapping;
	struct inode *inode = mapping->host;
	struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
	char *kaddr = page_address(page);
	unsigned from = ((char *)dir - kaddr) & ~(exofs_chunk_size(inode)-1);
	unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
	loff_t pos;
	struct exofs_dir_entry *pde = NULL;
	struct exofs_dir_entry de = (struct exofs_dir_entry ) (kaddr + from);
	int err;

	while (de < dir) {
	if (de->rec_len == 0) {
	EXOFS_ERR("ERROR: exofs_delete_entry:"
	"zero-length directory entry");
	err = -EIO;
	goto out;
	}
	pde = de;
	de = exofs_next_entry(de);
	}
	if (pde)
	from = (char )pde - (char )page_address(page);
	pos = page_offset(page) + from;
	lock_page(page);
	err = exofs_write_begin(NULL, page->mapping, pos, to - from, 0,
	&page, NULL);
	if (err)
	EXOFS_ERR("exofs_delete_entry: exofs_write_begin FAILED => %d\n",
	err);
	if (pde)
	pde->rec_len = cpu_to_le16(to - from);
	dir->inode_no = 0;
	if (likely(!err))
	err = exofs_commit_chunk(page, pos, to - from);
	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
	mark_inode_dirty(inode);
	sbi->s_numfiles--;
	out:
	exofs_put_page(page);
	return err;
	}

	/* kept aligned on 4 bytes */
	#define THIS_DIR ".\0\0"
	#define PARENT_DIR "..\0"

	int exofs_make_empty(struct inode inode, struct inode parent)
	{
	struct address_space *mapping = inode->i_mapping;
	struct page *page = grab_cache_page(mapping, 0);
	unsigned chunk_size = exofs_chunk_size(inode);
	struct exofs_dir_entry *de;
	int err;
	void *kaddr;

	if (!page)
	return -ENOMEM;

	err = exofs_write_begin(NULL, page->mapping, 0, chunk_size, 0,
	&page, NULL);
	if (err) {
	unlock_page(page);
	goto fail;
	}

	kaddr = kmap_atomic(page, KM_USER0);
	de = (struct exofs_dir_entry *)kaddr;
	de->name_len = 1;
	de->rec_len = cpu_to_le16(EXOFS_DIR_REC_LEN(1));
	memcpy(de->name, THIS_DIR, sizeof(THIS_DIR));
	de->inode_no = cpu_to_le64(inode->i_ino);
	exofs_set_de_type(de, inode);

	de = (struct exofs_dir_entry *)(kaddr + EXOFS_DIR_REC_LEN(1));
	de->name_len = 2;
	de->rec_len = cpu_to_le16(chunk_size - EXOFS_DIR_REC_LEN(1));
	de->inode_no = cpu_to_le64(parent->i_ino);
	memcpy(de->name, PARENT_DIR, sizeof(PARENT_DIR));
	exofs_set_de_type(de, inode);
	kunmap_atomic(kaddr, KM_USER0);
	err = exofs_commit_chunk(page, 0, chunk_size);
	fail:
	page_cache_release(page);
	return err;
	}

	int exofs_empty_dir(struct inode *inode)
	{
	struct page *page = NULL;
	unsigned long i, npages = dir_pages(inode);

	for (i = 0; i < npages; i++) {
	char *kaddr;
	struct exofs_dir_entry *de;
	page = exofs_get_page(inode, i);

	if (IS_ERR(page))
	continue;

	kaddr = page_address(page);
	de = (struct exofs_dir_entry *)kaddr;
	kaddr += exofs_last_byte(inode, i) - EXOFS_DIR_REC_LEN(1);

	while ((char *)de <= kaddr) {
	if (de->rec_len == 0) {
	EXOFS_ERR("ERROR: exofs_empty_dir: "
	"zero-length directory entry"
	"kaddr=%p, de=%p\n", kaddr, de);
	goto not_empty;
	}
	if (de->inode_no != 0) {
	/* check for . and .. */
	if (de->name[0] != '.')
	goto not_empty;
	if (de->name_len > 2)
	goto not_empty;
	if (de->name_len < 2) {
	if (le64_to_cpu(de->inode_no) !=
	inode->i_ino)
	goto not_empty;
	} else if (de->name[1] != '.')
	goto not_empty;
	}
	de = exofs_next_entry(de);
	}
	exofs_put_page(page);
	}
	return 1;

	not_empty:
	exofs_put_page(page);
	return 0;
	}

	const struct file_operations exofs_dir_operations = {
	.llseek = generic_file_llseek,
	.read = generic_read_dir,
	.readdir = exofs_readdir,
	};