nilfs2: directory entry operations

This adds directory handling functions, most of which comes from the ext2
file system.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Yoshiji Amagai <amagai.yoshiji@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 711 insertions, 0 deletions

diff --git a/fs/nilfs2/dir.c b/fs/nilfs2/dir.c
new file mode 100644
index 000000000000..1b7e6ddabbeb
--- /dev/null
+++ b/fs/nilfs2/dir.c
@@ -0,0 +1,711 @@
+/*
+ * 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, unsigned long n)
+{
+        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_locked(page);
+                kmap(page);
+                if (!PageUptodate(page))
+                        goto fail;
+                if (!PageChecked(page))
+                        nilfs_check_page(page);
+                if (PageError(page))
+                        goto fail;
+        }
+        return page;
+
+fail:
+        nilfs_put_page(page);
+        return ERR_PTR(-EIO);
+}
+
+/*
+ * NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
+ *
+ * len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
+ */
+static int
+nilfs_match(int len, const char * const name, struct nilfs_dir_entry *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 struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)
+{
+        return (struct nilfs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));
+}
+
+static unsigned char
+nilfs_filetype_table[NILFS_FT_MAX] = {
+        [NILFS_FT_UNKNOWN]      = DT_UNKNOWN,
+        [NILFS_FT_REG_FILE]     = DT_REG,
+        [NILFS_FT_DIR]          = DT_DIR,
+        [NILFS_FT_CHRDEV]       = DT_CHR,
+        [NILFS_FT_BLKDEV]       = DT_BLK,
+        [NILFS_FT_FIFO]         = DT_FIFO,
+        [NILFS_FT_SOCK]         = DT_SOCK,
+        [NILFS_FT_SYMLINK]      = DT_LNK,
+};
+
+#define S_SHIFT 12
+static unsigned char
+nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
+        [S_IFREG >> S_SHIFT]    = NILFS_FT_REG_FILE,
+        [S_IFDIR >> S_SHIFT]    = NILFS_FT_DIR,
+        [S_IFCHR >> S_SHIFT]    = NILFS_FT_CHRDEV,
+        [S_IFBLK >> S_SHIFT]    = NILFS_FT_BLKDEV,
+        [S_IFIFO >> S_SHIFT]    = NILFS_FT_FIFO,
+        [S_IFSOCK >> S_SHIFT]   = NILFS_FT_SOCK,
+        [S_IFLNK >> S_SHIFT]    = NILFS_FT_SYMLINK,
+};
+
+static void nilfs_set_de_type(struct nilfs_dir_entry *de, struct inode *inode)
+{
+        mode_t mode = inode->i_mode;
+
+        de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
+}
+
+static int nilfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
+{
+        loff_t pos = filp->f_pos;
+        struct inode *inode = filp->f_dentry->d_inode;
+        struct super_block *sb = inode->i_sb;
+        unsigned int offset = pos & ~PAGE_CACHE_MASK;
+        unsigned long n = pos >> PAGE_CACHE_SHIFT;
+        unsigned long npages = dir_pages(inode);
+/*      unsigned chunk_mask = ~(nilfs_chunk_size(inode)-1); */
+        unsigned char *types = NULL;
+        int ret;
+
+        if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
+                goto success;
+
+        types = nilfs_filetype_table;
+
+        for ( ; n < npages; n++, offset = 0) {
+                char *kaddr, *limit;
+                struct nilfs_dir_entry *de;
+                struct page *page = nilfs_get_page(inode, n);
+
+                if (IS_ERR(page)) {
+                        nilfs_error(sb, __func__, "bad page in #%lu",
+                                    inode->i_ino);
+                        filp->f_pos += PAGE_CACHE_SIZE - offset;
+                        ret = -EIO;
+                        goto done;
+                }
+                kaddr = page_address(page);
+                de = (struct nilfs_dir_entry *)(kaddr + offset);
+                limit = kaddr + nilfs_last_byte(inode, n) -
+                        NILFS_DIR_REC_LEN(1);
+                for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
+                        if (de->rec_len == 0) {
+                                nilfs_error(sb, __func__,
+                                            "zero-length directory entry");
+                                ret = -EIO;
+                                nilfs_put_page(page);
+                                goto done;
+                        }
+                        if (de->inode) {
+                                int over;
+                                unsigned char d_type = DT_UNKNOWN;
+
+                                if (types && de->file_type < NILFS_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), d_type);
+                                if (over) {
+                                        nilfs_put_page(page);
+                                        goto success;
+                                }
+                        }
+                        filp->f_pos += le16_to_cpu(de->rec_len);
+                }
+                nilfs_put_page(page);
+        }
+
+success:
+        ret = 0;
+done:
+        return ret;
+}
+
+/*
+ *      nilfs_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 nilfs_dir_entry *
+nilfs_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 = NILFS_DIR_REC_LEN(namelen);
+        unsigned long start, n;
+        unsigned long npages = dir_pages(dir);
+        struct page *page = NULL;
+        struct nilfs_inode_info *ei = NILFS_I(dir);
+        struct nilfs_dir_entry *de;
+
+        if (npages == 0)
+                goto out;
+
+        /* OFFSET_CACHE */
+        *res_page = NULL;
+
+        start = ei->i_dir_start_lookup;
+        if (start >= npages)
+                start = 0;
+        n = start;
+        do {
+                char *kaddr;
+                page = nilfs_get_page(dir, n);
+                if (!IS_ERR(page)) {
+                        kaddr = page_address(page);
+                        de = (struct nilfs_dir_entry *)kaddr;
+                        kaddr += nilfs_last_byte(dir, n) - reclen;
+                        while ((char *) de <= kaddr) {
+                                if (de->rec_len == 0) {
+                                        nilfs_error(dir->i_sb, __func__,
+                                                "zero-length directory entry");
+                                        nilfs_put_page(page);
+                                        goto out;
+                                }
+                                if (nilfs_match(namelen, name, de))
+                                        goto found;
+                                de = nilfs_next_entry(de);
+                        }
+                        nilfs_put_page(page);
+                }
+                if (++n >= npages)
+                        n = 0;
+                /* next page is past the blocks we've got */
+                if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
+                        nilfs_error(dir->i_sb, __func__,
+                               "dir %lu size %lld exceeds block cout %llu",
+                               dir->i_ino, dir->i_size,
+                               (unsigned long long)dir->i_blocks);
+                        goto out;
+                }
+        } while (n != start);
+out:
+        return NULL;
+
+found:
+        *res_page = page;
+        ei->i_dir_start_lookup = n;
+        return de;
+}
+
+struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct page **p)
+{
+        struct page *page = nilfs_get_page(dir, 0);
+        struct nilfs_dir_entry *de = NULL;
+
+        if (!IS_ERR(page)) {
+                de = nilfs_next_entry(
+                        (struct nilfs_dir_entry *)page_address(page));
+                *p = page;
+        }
+        return de;
+}
+
+ino_t nilfs_inode_by_name(struct inode *dir, struct dentry *dentry)
+{
+        ino_t res = 0;
+        struct nilfs_dir_entry *de;
+        struct page *page;
+
+        de = nilfs_find_entry(dir, dentry, &page);
+        if (de) {
+                res = le64_to_cpu(de->inode);
+                kunmap(page);
+                page_cache_release(page);
+        }
+        return res;
+}
+
+/* Releases the page */
+void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
+                    struct page *page, struct inode *inode)
+{
+        unsigned from = (char *) de - (char *) page_address(page);
+        unsigned to = from + le16_to_cpu(de->rec_len);
+        struct address_space *mapping = page->mapping;
+        int err;
+
+        lock_page(page);
+        err = nilfs_prepare_chunk_uninterruptible(page, mapping, from, to);
+        BUG_ON(err);
+        de->inode = cpu_to_le64(inode->i_ino);
+        nilfs_set_de_type(de, inode);
+        err = nilfs_commit_chunk(page, mapping, from, to);
+        nilfs_put_page(page);
+        dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+/*      NILFS_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
+        mark_inode_dirty(dir);
+}
+
+/*
+ *      Parent is locked.
+ */
+int nilfs_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 chunk_size = nilfs_chunk_size(dir);
+        unsigned reclen = NILFS_DIR_REC_LEN(namelen);
+        unsigned short rec_len, name_len;
+        struct page *page = NULL;
+        struct nilfs_dir_entry *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.
+         * This code plays outside i_size, so it locks the page
+         * to protect that region.
+         */
+        for (n = 0; n <= npages; n++) {
+                char *dir_end;
+
+                page = nilfs_get_page(dir, n);
+                err = PTR_ERR(page);
+                if (IS_ERR(page))
+                        goto out;
+                lock_page(page);
+                kaddr = page_address(page);
+                dir_end = kaddr + nilfs_last_byte(dir, n);
+                de = (struct nilfs_dir_entry *)kaddr;
+                kaddr += PAGE_CACHE_SIZE - reclen;
+                while ((char *)de <= kaddr) {
+                        if ((char *)de == dir_end) {
+                                /* We hit i_size */
+                                name_len = 0;
+                                rec_len = chunk_size;
+                                de->rec_len = cpu_to_le16(chunk_size);
+                                de->inode = 0;
+                                goto got_it;
+                        }
+                        if (de->rec_len == 0) {
+                                nilfs_error(dir->i_sb, __func__,
+                                            "zero-length directory entry");
+                                err = -EIO;
+                                goto out_unlock;
+                        }
+                        err = -EEXIST;
+                        if (nilfs_match(namelen, name, de))
+                                goto out_unlock;
+                        name_len = NILFS_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 = (struct nilfs_dir_entry *)((char *)de + rec_len);
+                }
+                unlock_page(page);
+                nilfs_put_page(page);
+        }
+        BUG();
+        return -EINVAL;
+
+got_it:
+        from = (char *)de - (char *)page_address(page);
+        to = from + rec_len;
+        err = nilfs_prepare_chunk(page, page->mapping, from, to);
+        if (err)
+                goto out_unlock;
+        if (de->inode) {
+                struct nilfs_dir_entry *de1;
+
+                de1 = (struct nilfs_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 = cpu_to_le64(inode->i_ino);
+        nilfs_set_de_type(de, inode);
+        err = nilfs_commit_chunk(page, page->mapping, from, to);
+        dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+/*      NILFS_I(dir)->i_flags &= ~NILFS_BTREE_FL; */
+        mark_inode_dirty(dir);
+        /* OFFSET_CACHE */
+out_put:
+        nilfs_put_page(page);
+out:
+        return err;
+out_unlock:
+        unlock_page(page);
+        goto out_put;
+}
+
+/*
+ * nilfs_delete_entry deletes a directory entry by merging it with the
+ * previous entry. Page is up-to-date. Releases the page.
+ */
+int nilfs_delete_entry(struct nilfs_dir_entry *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) & ~(nilfs_chunk_size(inode) - 1);
+        unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
+        struct nilfs_dir_entry *pde = NULL;
+        struct nilfs_dir_entry *de = (struct nilfs_dir_entry *)(kaddr + from);
+        int err;
+
+        while ((char *)de < (char *)dir) {
+                if (de->rec_len == 0) {
+                        nilfs_error(inode->i_sb, __func__,
+                                    "zero-length directory entry");
+                        err = -EIO;
+                        goto out;
+                }
+                pde = de;
+                de = nilfs_next_entry(de);
+        }
+        if (pde)
+                from = (char *)pde - (char *)page_address(page);
+        lock_page(page);
+        err = nilfs_prepare_chunk(page, mapping, from, to);
+        BUG_ON(err);
+        if (pde)
+                pde->rec_len = cpu_to_le16(to - from);
+        dir->inode = 0;
+        err = nilfs_commit_chunk(page, mapping, from, to);
+        inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+/*      NILFS_I(inode)->i_flags &= ~NILFS_BTREE_FL; */
+        mark_inode_dirty(inode);
+out:
+        nilfs_put_page(page);
+        return err;
+}
+
+/*
+ * Set the first fragment of directory.
+ */
+int nilfs_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 = nilfs_chunk_size(inode);
+        struct nilfs_dir_entry *de;
+        int err;
+        void *kaddr;
+
+        if (!page)
+                return -ENOMEM;
+
+        err = nilfs_prepare_chunk(page, mapping, 0, chunk_size);
+        if (unlikely(err)) {
+                unlock_page(page);
+                goto fail;
+        }
+        kaddr = kmap_atomic(page, KM_USER0);
+        memset(kaddr, 0, chunk_size);
+        de = (struct nilfs_dir_entry *)kaddr;
+        de->name_len = 1;
+        de->rec_len = cpu_to_le16(NILFS_DIR_REC_LEN(1));
+        memcpy(de->name, ".\0\0", 4);
+        de->inode = cpu_to_le64(inode->i_ino);
+        nilfs_set_de_type(de, inode);
+
+        de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
+        de->name_len = 2;
+        de->rec_len = cpu_to_le16(chunk_size - NILFS_DIR_REC_LEN(1));
+        de->inode = cpu_to_le64(parent->i_ino);
+        memcpy(de->name, "..\0", 4);
+        nilfs_set_de_type(de, inode);
+        kunmap_atomic(kaddr, KM_USER0);
+        err = nilfs_commit_chunk(page, mapping, 0, chunk_size);
+fail:
+        page_cache_release(page);
+        return err;
+}
+
+/*
+ * routine to check that the specified directory is empty (for rmdir)
+ */
+int nilfs_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 nilfs_dir_entry *de;
+
+                page = nilfs_get_page(inode, i);
+                if (IS_ERR(page))
+                        continue;
+
+                kaddr = page_address(page);
+                de = (struct nilfs_dir_entry *)kaddr;
+                kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
+
+                while ((char *)de <= kaddr) {
+                        if (de->rec_len == 0) {
+                                nilfs_error(inode->i_sb, __func__,
+                                            "zero-length directory entry "
+                                            "(kaddr=%p, de=%p)\n", kaddr, de);
+                                goto not_empty;
+                        }
+                        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_le64(inode->i_ino))
+                                                goto not_empty;
+                                } else if (de->name[1] != '.')
+                                        goto not_empty;
+                        }
+                        de = nilfs_next_entry(de);
+                }
+                nilfs_put_page(page);
+        }
+        return 1;
+
+not_empty:
+        nilfs_put_page(page);
+        return 0;
+}
+
+struct file_operations nilfs_dir_operations = {
+        .llseek         = generic_file_llseek,
+        .read           = generic_read_dir,
+        .readdir        = nilfs_readdir,
+        .ioctl          = nilfs_ioctl,
+#ifdef CONFIG_COMPAT
+        .compat_ioctl   = nilfs_compat_ioctl,
+#endif  /* CONFIG_COMPAT */
+        .fsync          = nilfs_sync_file,
+
+};