X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=lustre%2Fobdfs%2Fdir.c;h=e5f929b5f7717b41db9ada687746ccad92b0393e;hb=5636243ee47c831bcde68316fa535ea871864c6c;hp=a59ed56a7c9178158a2146026c2c1bf7c3fc9572;hpb=dd8ece265f41df5851d9978de979490e42237666;p=fs%2Flustre-release.git

diff --git a/lustre/obdfs/dir.c b/lustre/obdfs/dir.c
index a59ed56..e5f929b 100644
--- a/lustre/obdfs/dir.c
+++ b/lustre/obdfs/dir.c
@@ -17,177 +17,598 @@
  *  Big-endian to little-endian byte-swapping/bitmaps by
  *        David S. Miller (davem@caip.rutgers.edu), 1995
  *
- *  Changes for use with Object Based Device File System
- *    
- *  Copyright (C) 1999, Seagate Technology Inc. 
- *   (author Peter J. Braam, braam@stelias.com)
- * 
+ * All code that works with directory layout had been switched to pagecache
+ * and moved here. AV
  */
 
-#include <asm/uaccess.h>
-
-#include <asm/uaccess.h>
-
-#include <linux/errno.h>
 #include <linux/fs.h>
 #include <linux/ext2_fs.h>
-#include <linux/fcntl.h>
-#include <linux/sched.h>
-#include <linux/stat.h>
-#include <linux/string.h>
-#include <linux/locks.h>
-#include <linux/quotaops.h>
-#include <linux/iobuf.h>
+#include <linux/pagemap.h>
 #include <linux/obd_support.h>
-#include <linux/obdfs.h>
+#include <linux/locks.h>
+
+typedef struct ext2_dir_entry_2 ext2_dirent;
 
-#if 0
-static ssize_t obdfs_dir_read (struct file * filp, char * buf,
-			      size_t count, loff_t *ppos)
+#define PageChecked(page)        test_bit(PG_checked, &(page)->flags)
+#define SetPageChecked(page)     set_bit(PG_checked, &(page)->flags)
+#define PG_checked               13      /* kill me in 2.5.<early>. */
+
+int waitfor_one_page(struct page *page)
 {
-	return -EISDIR;
+	int error = 0;
+	struct buffer_head *bh, *head = page->buffers;
+
+	bh = head;
+	do {
+		wait_on_buffer(bh);
+		if (buffer_req(bh) && !buffer_uptodate(bh))
+			error = -EIO;
+	} while ((bh = bh->b_this_page) != head);
+	return error;
 }
-#endif
 
-int obdfs_check_dir_entry (const char * function, struct inode * dir,
-			  struct ext2_dir_entry_2 * de,
-			  struct page * page,
-			  unsigned long offset)
+/*
+ * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
+ * more robust, but we have what we have
+ */
+static inline unsigned ext2_chunk_size(struct inode *inode)
 {
-	const char * error_msg = NULL;
-	return 1;
+	//return inode->i_sb->s_blocksize;
+	return PAGE_SIZE;
+}
+
+static inline void ext2_put_page(struct page *page)
+{
+	kunmap(page);
+	page_cache_release(page);
+}
 
-	ENTRY;
-	if ( !de ) {
-		error_msg = "null de passed";
-		return 1;
+static inline unsigned long dir_pages(struct inode *inode)
+{
+	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
+}
+
+static int ext2_commit_chunk(struct page *page, unsigned from, unsigned to)
+{
+	struct inode *dir = page->mapping->host;
+	int err = 0;
+	dir->i_version = ++event;
+	page->mapping->a_ops->commit_write(NULL, page, from, to);
+	if (IS_SYNC(dir))
+		err = waitfor_one_page(page);
+	return err;
+}
+
+static void ext2_check_page(struct page *page)
+{
+	struct inode *dir = page->mapping->host;
+	struct super_block *sb = dir->i_sb;
+	unsigned chunk_size = ext2_chunk_size(dir);
+	char *kaddr = page_address(page);
+	//	u32 max_inumber = le32_to_cpu(sb->u.ext2_sb.s_es->s_inodes_count);
+	unsigned offs, rec_len;
+	unsigned limit = PAGE_CACHE_SIZE;
+	ext2_dirent *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;
+		for (offs = limit; offs<PAGE_CACHE_SIZE; offs += chunk_size) {
+			ext2_dirent *p = (ext2_dirent*)(kaddr + offs);
+			p->rec_len = cpu_to_le16(chunk_size);
+		}
+		if (!limit)
+			goto out;
+	}
+	for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
+		p = (ext2_dirent *)(kaddr + offs);
+		rec_len = le16_to_cpu(p->rec_len);
+
+		if (rec_len < EXT2_DIR_REC_LEN(1))
+			goto Eshort;
+		if (rec_len & 3)
+			goto Ealign;
+		if (rec_len < EXT2_DIR_REC_LEN(p->name_len))
+			goto Enamelen;
+		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
+			goto Espan;
+		//		if (le32_to_cpu(p->inode) > max_inumber)
+		//goto Einumber;
 	}
+	if (offs != limit)
+		goto Eend;
+out:
+	SetPageChecked(page);
+	return;
+
+	/* Too bad, we had an error */
+
+Ebadsize:
+	ext2_error(sb, "ext2_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;
+	//Einumber:
+	// error = "inode out of bounds";
+bad_entry:
+	ext2_error (sb, "ext2_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) le32_to_cpu(p->inode),
+		rec_len, p->name_len);
+	goto fail;
+Eend:
+	p = (ext2_dirent *)(kaddr + offs);
+	ext2_error (sb, "ext2_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) le32_to_cpu(p->inode));
+fail:
+	SetPageChecked(page);
+	SetPageError(page);
+}
 
-	if (le16_to_cpu(de->rec_len) < EXT2_DIR_REC_LEN(1))
-		error_msg = "rec_len is smaller than minimal";
-	else if (le16_to_cpu(de->rec_len) % 4 != 0)
-		error_msg = "rec_len % 4 != 0";
-	else if (le16_to_cpu(de->rec_len) < EXT2_DIR_REC_LEN(de->name_len))
-		error_msg = "rec_len is too small for name_len";
-	else if (dir && ((char *) de - (char *)page_address(page)) + le16_to_cpu(de->rec_len) >
-		 dir->i_sb->s_blocksize)
-		error_msg = "directory entry across blocks";
-#if 0 /* this one doesn't yet work for OBDFS */
-	else 
-
-if (dir && le32_to_cpu(de->inode) > le32_to_cpu(dir->i_sb->u.ext2_sb.s_es->s_inodes_count))
-		error_msg = "inode out of bounds";
-#endif
-	if (error_msg != NULL)
-		ext2_error (dir->i_sb, function, "bad entry in directory #%lu: %s - "
-			    "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
-			    dir->i_ino, error_msg, offset,
-			    (unsigned long) le32_to_cpu(de->inode),
-			    le16_to_cpu(de->rec_len), de->name_len);
-	EXIT;
-	return error_msg == NULL ? 1 : 0;
-}
-
-
-int obdfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
+static struct page * ext2_get_page(struct inode *dir, unsigned long n)
 {
-	int error = 0;
-	unsigned long offset;
-	int stored;
-	struct ext2_dir_entry_2 * de;
-	struct super_block * sb;
-	struct page *page;
+	struct address_space *mapping = dir->i_mapping;
+	struct page *page = read_cache_page(mapping, n,
+				(filler_t*)mapping->a_ops->readpage, NULL);
+	if (!IS_ERR(page)) {
+		wait_on_page(page);
+		kmap(page);
+		if (!Page_Uptodate(page))
+			goto fail;
+		if (!PageChecked(page))
+			ext2_check_page(page);
+		if (PageError(page))
+			goto fail;
+	}
+	return page;
+
+fail:
+	ext2_put_page(page);
+	return ERR_PTR(-EIO);
+}
+
+/*
+ * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
+ *
+ * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
+ */
+static inline int ext2_match (int len, const char * const name,
+					struct ext2_dir_entry_2 * de)
+{
+	if (len != de->name_len)
+		return 0;
+	if (!de->inode)
+		return 0;
+	return !memcmp(name, de->name, len);
+}
+
+/*
+ * p is at least 6 bytes before the end of page
+ */
+static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
+{
+	return (ext2_dirent *)((char*)p + le16_to_cpu(p->rec_len));
+}
+
+static inline unsigned 
+ext2_validate_entry(char *base, unsigned offset, unsigned mask)
+{
+	ext2_dirent *de = (ext2_dirent*)(base + offset);
+	ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
+	while ((char*)p < (char*)de)
+		p = ext2_next_entry(p);
+	return (char *)p - base;
+}
+
+static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
+	[EXT2_FT_UNKNOWN]	DT_UNKNOWN,
+	[EXT2_FT_REG_FILE]	DT_REG,
+	[EXT2_FT_DIR]		DT_DIR,
+	[EXT2_FT_CHRDEV]	DT_CHR,
+	[EXT2_FT_BLKDEV]	DT_BLK,
+	[EXT2_FT_FIFO]		DT_FIFO,
+	[EXT2_FT_SOCK]		DT_SOCK,
+	[EXT2_FT_SYMLINK]	DT_LNK,
+};
+
+#define S_SHIFT 12
+static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
+	[S_IFREG >> S_SHIFT]	EXT2_FT_REG_FILE,
+	[S_IFDIR >> S_SHIFT]	EXT2_FT_DIR,
+	[S_IFCHR >> S_SHIFT]	EXT2_FT_CHRDEV,
+	[S_IFBLK >> S_SHIFT]	EXT2_FT_BLKDEV,
+	[S_IFIFO >> S_SHIFT]	EXT2_FT_FIFO,
+	[S_IFSOCK >> S_SHIFT]	EXT2_FT_SOCK,
+	[S_IFLNK >> S_SHIFT]	EXT2_FT_SYMLINK,
+};
+
+static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
+{
+	/* XXX
+	mode_t mode = inode->i_mode;
+	if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
+		de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
+	else
+		de->file_type = 0;
+	*/
+	de->file_type = 0;
+}
+
+int
+new_obdfs_readdir (struct file * filp, void * dirent, filldir_t filldir)
+{
+	loff_t pos = filp->f_pos;
 	struct inode *inode = filp->f_dentry->d_inode;
+	// XXX struct super_block *sb = inode->i_sb;
+	unsigned offset = pos & ~PAGE_CACHE_MASK;
+	unsigned long n = pos >> PAGE_CACHE_SHIFT;
+	unsigned long npages = dir_pages(inode);
+	unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
+	unsigned char *types = NULL;
+	int need_revalidate = (filp->f_version != inode->i_version);
 
-	ENTRY;
+	if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
+		goto done;
 
-	sb = inode->i_sb;
+	//if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
+	//types = ext2_filetype_table;
 
-	stored = 0;
-	offset = filp->f_pos & (PAGE_SIZE - 1);
+	for ( ; n < npages; n++, offset = 0) {
+		char *kaddr, *limit;
+		ext2_dirent *de;
+		struct page *page = ext2_get_page(inode, n);
 
-	while (!error && !stored && filp->f_pos < inode->i_size) {
-		IDEBUG(inode);
-		page = obdfs_getpage(inode, offset, 0, LOCKED);
-		PDEBUG(page, "readdir");
-		if (!page) {
-			ext2_error (sb, "ext2_readdir",
-				    "directory #%lu contains a hole at offset %lu",
-				    inode->i_ino, (unsigned long)filp->f_pos);
-			filp->f_pos += PAGE_SIZE - offset;
+		if (IS_ERR(page))
 			continue;
+		kaddr = page_address(page);
+		if (need_revalidate) {
+			offset = ext2_validate_entry(kaddr, offset, chunk_mask);
+			need_revalidate = 0;
 		}
+		de = (ext2_dirent *)(kaddr+offset);
+		limit = kaddr + PAGE_CACHE_SIZE - EXT2_DIR_REC_LEN(1);
+		for ( ;(char*)de <= limit; de = ext2_next_entry(de))
+			if (de->inode) {
+				int over;
+				unsigned char d_type = DT_UNKNOWN;
 
-#if 0
-		/* XXX need to do read ahead and support stuff below */
-revalidate:
-		/* If the dir block has changed since the last call to
-		 * readdir(2), then we might be pointing to an invalid
-		 * dirent right now.  Scan from the start of the block
-		 * to make sure. */
-		if (filp->f_version != inode->i_version) {
-			for (i = 0; i < sb->s_blocksize && i < offset; ) {
-				de = (struct ext2_dir_entry_2 *) 
-					(bh->b_data + i);
-				/* It's too expensive to do a full
-				 * dirent test each time round this
-				 * loop, but we do have to test at
-				 * least that it is non-zero.  A
-				 * failure will be detected in the
-				 * dirent test below. */
-				if (le16_to_cpu(de->rec_len) < EXT2_DIR_REC_LEN(1))
-					break;
-				i += le16_to_cpu(de->rec_len);
-			}
-			offset = i;
-			filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
-				| offset;
-			filp->f_version = inode->i_version;
-		}
-#endif		
-		while (!error && filp->f_pos < inode->i_size 
-		       && offset < PAGE_SIZE) {
-			de = (struct ext2_dir_entry_2 *) ((char *)page_address(page) + offset);
-#if 0
-			if (!obdfs_check_dir_entry ("ext2_readdir", inode, de,
-						   bh, offset)) {
-				/* On error, skip the f_pos to the
-                                   next block. */
-				filp->f_pos = (filp->f_pos & (sb->s_blocksize - 1))
-					      + sb->s_blocksize;
-				brelse (bh);
-				return stored;
+				if (types && de->file_type < EXT2_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,
+						le32_to_cpu(de->inode), d_type);
+				if (over) {
+					ext2_put_page(page);
+					goto done;
+				}
 			}
-#endif
-			offset += le16_to_cpu(de->rec_len);
-			if (le32_to_cpu(de->inode)) {
-				/* We might block in the next section
-				 * if the data destination is
-				 * currently swapped out.  So, use a
-				 * version stamp to detect whether or
-				 * not the directory has been modified
-				 * during the copy operation.
-				 */
-				/* XXX				unsigned long version = inode->i_version;
-				 */
-				error = filldir(dirent, de->name,
-						de->name_len,
-						filp->f_pos, le32_to_cpu(de->inode));
-				if (error)
-					break;
-#if 0
-				if (version != inode->i_version)
-					goto revalidate;
-#endif
-				stored ++;
+		ext2_put_page(page);
+	}
+
+done:
+	filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset;
+	filp->f_version = inode->i_version;
+	UPDATE_ATIME(inode);
+	return 0;
+}
+
+/*
+ *	ext2_find_entry()
+ *
+ * finds an entry in the specified directory with the wanted name. It
+ * returns the page in which the entry was found, and the entry itself
+ * (as a parameter - res_dir). Page is returned mapped and unlocked.
+ * Entry is guaranteed to be valid.
+ */
+struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
+			struct dentry *dentry, struct page ** res_page)
+{
+	const char *name = dentry->d_name.name;
+	int namelen = dentry->d_name.len;
+	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
+	unsigned long start, n;
+	unsigned long npages = dir_pages(dir);
+	struct page *page = NULL;
+	ext2_dirent * de;
+
+	/* OFFSET_CACHE */
+	*res_page = NULL;
+
+	//	start = dir->u.ext2_i.i_dir_start_lookup;
+	start = 0;
+	if (start >= npages)
+		start = 0;
+	n = start;
+	do {
+		char *kaddr;
+		page = ext2_get_page(dir, n);
+		if (!IS_ERR(page)) {
+			kaddr = page_address(page);
+			de = (ext2_dirent *) kaddr;
+			kaddr += PAGE_CACHE_SIZE - reclen;
+			while ((char *) de <= kaddr) {
+				if (ext2_match (namelen, name, de))
+					goto found;
+				de = ext2_next_entry(de);
 			}
-			filp->f_pos += le16_to_cpu(de->rec_len);
+			ext2_put_page(page);
 		}
-		offset = 0;
-		UnlockPage(page);
+		if (++n >= npages)
+			n = 0;
+	} while (n != start);
+	return NULL;
+
+found:
+	*res_page = page;
+	//	dir->u.ext2_i.i_dir_start_lookup = n;
+	return de;
+}
+
+struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
+{
+	struct page *page = ext2_get_page(dir, 0);
+	ext2_dirent *de = NULL;
+
+	if (!IS_ERR(page)) {
+		de = ext2_next_entry((ext2_dirent *) page_address(page));
+		*p = page;
+	}
+	return de;
+}
+
+ino_t ext2_inode_by_name(struct inode * dir, struct dentry *dentry)
+{
+	ino_t res = 0;
+	struct ext2_dir_entry_2 * de;
+	struct page *page;
+	
+	de = ext2_find_entry (dir, dentry, &page);
+	if (de) {
+		res = le32_to_cpu(de->inode);
+		kunmap(page);
 		page_cache_release(page);
 	}
-	UPDATE_ATIME(inode);
-	EXIT;
+	return res;
+}
+
+/* Releases the page */
+void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
+			struct page *page, struct inode *inode)
+{
+	unsigned from = (char *) de - (char *) page_address(page);
+	unsigned to = from + le16_to_cpu(de->rec_len);
+	int err;
+
+	lock_page(page);
+	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
+	if (err)
+		BUG();
+	de->inode = cpu_to_le32(inode->i_ino);
+	ext2_set_de_type (de, inode);
+	err = ext2_commit_chunk(page, from, to);
+	UnlockPage(page);
+	ext2_put_page(page);
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+	mark_inode_dirty(dir);
+}
+
+/*
+ *	Parent is locked.
+ */
+int ext2_add_link (struct dentry *dentry, struct inode *inode)
+{
+	struct inode *dir = dentry->d_parent->d_inode;
+	const char *name = dentry->d_name.name;
+	int namelen = dentry->d_name.len;
+	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
+	unsigned short rec_len, name_len;
+	struct page *page = NULL;
+	ext2_dirent * de;
+	unsigned long npages = dir_pages(dir);
+	unsigned long n;
+	char *kaddr;
+	unsigned from, to;
+	int err;
+
+	/* We take care of directory expansion in the same loop */
+	for (n = 0; n <= npages; n++) {
+		page = ext2_get_page(dir, n);
+		err = PTR_ERR(page);
+		if (IS_ERR(page))
+			goto out;
+		kaddr = page_address(page);
+		de = (ext2_dirent *)kaddr;
+		kaddr += PAGE_CACHE_SIZE - reclen;
+		while ((char *)de <= kaddr) {
+			err = -EEXIST;
+			if (ext2_match (namelen, name, de))
+				goto out_page;
+			name_len = EXT2_DIR_REC_LEN(de->name_len);
+			rec_len = le16_to_cpu(de->rec_len);
+			if (!de->inode && rec_len >= reclen)
+				goto got_it;
+			if (rec_len >= name_len + reclen)
+				goto got_it;
+			de = (ext2_dirent *) ((char *) de + rec_len);
+		}
+		ext2_put_page(page);
+	}
+	BUG();
+	return -EINVAL;
+
+got_it:
+	from = (char*)de - (char*)page_address(page);
+	to = from + rec_len;
+	lock_page(page);
+	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
+	if (err)
+		goto out_unlock;
+	if (de->inode) {
+		ext2_dirent *de1 = (ext2_dirent *) ((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 = cpu_to_le32(inode->i_ino);
+	ext2_set_de_type (de, inode);
+	err = ext2_commit_chunk(page, from, to);
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+	mark_inode_dirty(dir);
+	/* OFFSET_CACHE */
+out_unlock:
+	UnlockPage(page);
+out_page:
+	ext2_put_page(page);
+out:
+	return err;
+}
+
+/*
+ * ext2_delete_entry deletes a directory entry by merging it with the
+ * previous entry. Page is up-to-date. Releases the page.
+ */
+int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
+{
+	struct address_space *mapping = page->mapping;
+	struct inode *inode = mapping->host;
+	char *kaddr = page_address(page);
+	unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
+	unsigned to = ((char*)dir - kaddr) + le16_to_cpu(dir->rec_len);
+	ext2_dirent * pde = NULL;
+	ext2_dirent * de = (ext2_dirent *) (kaddr + from);
+	int err;
+
+	while ((char*)de < (char*)dir) {
+		pde = de;
+		de = ext2_next_entry(de);
+	}
+	if (pde)
+		from = (char*)pde - (char*)page_address(page);
+	lock_page(page);
+	err = mapping->a_ops->prepare_write(NULL, page, from, to);
+	if (err)
+		BUG();
+	if (pde)
+		pde->rec_len = cpu_to_le16(to-from);
+	dir->inode = 0;
+	err = ext2_commit_chunk(page, from, to);
+	UnlockPage(page);
+	ext2_put_page(page);
+	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+	mark_inode_dirty(inode);
+	return err;
+}
+
+/*
+ * Set the first fragment of directory.
+ */
+int ext2_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 = ext2_chunk_size(inode);
+	struct ext2_dir_entry_2 * de;
+	char *base;
+	int err;
+
+	if (!page)
+		return -ENOMEM;
+	err = mapping->a_ops->prepare_write(NULL, page, 0, chunk_size);
+	if (err)
+		goto fail;
+
+	base = page_address(page);
+
+	de = (struct ext2_dir_entry_2 *) base;
+	de->name_len = 1;
+	de->rec_len = cpu_to_le16(EXT2_DIR_REC_LEN(1));
+	memcpy (de->name, ".\0\0", 4);
+	de->inode = cpu_to_le32(inode->i_ino);
+	ext2_set_de_type (de, inode);
+
+	de = (struct ext2_dir_entry_2 *) (base + EXT2_DIR_REC_LEN(1));
+	de->name_len = 2;
+	de->rec_len = cpu_to_le16(chunk_size - EXT2_DIR_REC_LEN(1));
+	de->inode = cpu_to_le32(parent->i_ino);
+	memcpy (de->name, "..\0", 4);
+	ext2_set_de_type (de, inode);
+
+	err = ext2_commit_chunk(page, 0, chunk_size);
+fail:
+	UnlockPage(page);
+	page_cache_release(page);
+	return err;
+}
+
+/*
+ * routine to check that the specified directory is empty (for rmdir)
+ */
+int ext2_empty_dir (struct inode * inode)
+{
+	struct page *page = NULL;
+	unsigned long i, npages = dir_pages(inode);
+	
+	for (i = 0; i < npages; i++) {
+		char *kaddr;
+		ext2_dirent * de;
+		page = ext2_get_page(inode, i);
+
+		if (IS_ERR(page))
+			continue;
+
+		kaddr = page_address(page);
+		de = (ext2_dirent *)kaddr;
+		kaddr += PAGE_CACHE_SIZE-EXT2_DIR_REC_LEN(1);
+
+		while ((char *)de <= kaddr) {
+			if (de->inode != 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 (de->inode !=
+					    cpu_to_le32(inode->i_ino))
+						goto not_empty;
+				} else if (de->name[1] != '.')
+					goto not_empty;
+			}
+			de = ext2_next_entry(de);
+		}
+		ext2_put_page(page);
+	}
+	return 1;
+
+not_empty:
+	ext2_put_page(page);
 	return 0;
 }
+
+struct file_operations obdfs_dir_operations = {
+        read: generic_read_dir,
+        readdir: new_obdfs_readdir
+};