/* * 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. * * Modified for NILFS by Amagai Yoshiji. */ /* * 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 "nilfs.h" #include "page.h" static inline unsigned int nilfs_rec_len_from_disk(__le16 dlen) { unsigned int len = le16_to_cpu(dlen); #if (PAGE_SIZE >= 65536) if (len == NILFS_MAX_REC_LEN) return 1 << 16; #endif return len; } static inline __le16 nilfs_rec_len_to_disk(unsigned int len) { #if (PAGE_SIZE >= 65536) if (len == (1 << 16)) return cpu_to_le16(NILFS_MAX_REC_LEN); BUG_ON(len > (1 << 16)); #endif return cpu_to_le16(len); } /* * nilfs uses block-sized chunks. Arguably, sector-sized ones would be * more robust, but we have what we have */ static inline unsigned int nilfs_chunk_size(struct inode *inode) { return inode->i_sb->s_blocksize; } static inline void nilfs_put_page(struct page *page) { kunmap(page); put_page(page); } /* * Return the offset into page `page_nr' of the last valid * byte in that page, plus one. */ static unsigned int nilfs_last_byte(struct inode *inode, unsigned long page_nr) { unsigned int last_byte = inode->i_size; last_byte -= page_nr << PAGE_SHIFT; if (last_byte > PAGE_SIZE) last_byte = PAGE_SIZE; return last_byte; } static int nilfs_prepare_chunk(struct page *page, unsigned int from, unsigned int to) { loff_t pos = page_offset(page) + from; return __block_write_begin(page, pos, to - from, nilfs_get_block); } static void nilfs_commit_chunk(struct page *page, struct address_space *mapping, unsigned int from, unsigned int to) { struct inode *dir = mapping->host; loff_t pos = page_offset(page) + from; unsigned int len = to - from; unsigned int 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); if (IS_DIRSYNC(dir)) nilfs_set_transaction_flag(NILFS_TI_SYNC); err = nilfs_set_file_dirty(dir, nr_dirty); WARN_ON(err); /* do not happen */ unlock_page(page); } static bool nilfs_check_page(struct page *page) { struct inode *dir = page->mapping->host; struct super_block *sb = dir->i_sb; unsigned int chunk_size = nilfs_chunk_size(dir); char *kaddr = page_address(page); unsigned int offs, rec_len; unsigned int limit = PAGE_SIZE; struct nilfs_dir_entry *p; char *error; if ((dir->i_size >> PAGE_SHIFT) == page->index) { limit = dir->i_size & ~PAGE_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 = nilfs_rec_len_from_disk(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 true; /* Too bad, we had an error */ Ebadsize: nilfs_error(sb, "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, "bad entry in directory #%lu: %s - offset=%lu, inode=%lu, rec_len=%d, name_len=%d", dir->i_ino, error, (page->index << PAGE_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, "entry in directory #%lu spans the page boundary offset=%lu, inode=%lu", dir->i_ino, (page->index << PAGE_SHIFT) + offs, (unsigned long)le64_to_cpu(p->inode)); fail: SetPageError(page); return false; } static struct page *nilfs_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 (unlikely(!PageChecked(page))) { if (PageError(page) || !nilfs_check_page(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 unsigned char *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 + nilfs_rec_len_from_disk(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) { umode_t mode = inode->i_mode; de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT]; } static int nilfs_readdir(struct file *file, struct dir_context *ctx) { loff_t pos = ctx->pos; struct inode *inode = file_inode(file); struct super_block *sb = inode->i_sb; unsigned int offset = pos & ~PAGE_MASK; unsigned long n = pos >> PAGE_SHIFT; unsigned long npages = dir_pages(inode); if (pos > inode->i_size - NILFS_DIR_REC_LEN(1)) return 0; 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, "bad page in #%lu", inode->i_ino); ctx->pos += PAGE_SIZE - offset; return -EIO; } 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, "zero-length directory entry"); nilfs_put_page(page); return -EIO; } if (de->inode) { unsigned char t; if (de->file_type < NILFS_FT_MAX) t = nilfs_filetype_table[de->file_type]; else t = DT_UNKNOWN; if (!dir_emit(ctx, de->name, de->name_len, le64_to_cpu(de->inode), t)) { nilfs_put_page(page); return 0; } } ctx->pos += nilfs_rec_len_from_disk(de->rec_len); } nilfs_put_page(page); } return 0; } /* * 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, const struct qstr *qstr, struct page **res_page) { const unsigned char *name = qstr->name; int namelen = qstr->len; unsigned int 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, "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_SHIFT - 9)))) { nilfs_error(dir->i_sb, "dir %lu size %lld exceeds block count %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, const struct qstr *qstr) { ino_t res = 0; struct nilfs_dir_entry *de; struct page *page; de = nilfs_find_entry(dir, qstr, &page); if (de) { res = le64_to_cpu(de->inode); kunmap(page); put_page(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 int from = (char *)de - (char *)page_address(page); unsigned int to = from + nilfs_rec_len_from_disk(de->rec_len); struct address_space *mapping = page->mapping; int err; lock_page(page); err = nilfs_prepare_chunk(page, from, to); BUG_ON(err); de->inode = cpu_to_le64(inode->i_ino); nilfs_set_de_type(de, inode); nilfs_commit_chunk(page, mapping, from, to); nilfs_put_page(page); dir->i_mtime = dir->i_ctime = current_time(dir); } /* * Parent is locked. */ int nilfs_add_link(struct dentry *dentry, struct inode *inode) { struct inode *dir = d_inode(dentry->d_parent); const unsigned char *name = dentry->d_name.name; int namelen = dentry->d_name.len; unsigned int chunk_size = nilfs_chunk_size(dir); unsigned int 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 int 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_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 = nilfs_rec_len_to_disk(chunk_size); de->inode = 0; goto got_it; } if (de->rec_len == 0) { nilfs_error(dir->i_sb, "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 = nilfs_rec_len_from_disk(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, 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 = nilfs_rec_len_to_disk(rec_len - name_len); de->rec_len = nilfs_rec_len_to_disk(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); nilfs_commit_chunk(page, page->mapping, from, to); dir->i_mtime = dir->i_ctime = current_time(dir); nilfs_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 int from, to; struct nilfs_dir_entry *de, *pde = NULL; int err; from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1); to = ((char *)dir - kaddr) + nilfs_rec_len_from_disk(dir->rec_len); de = (struct nilfs_dir_entry *)(kaddr + from); while ((char *)de < (char *)dir) { if (de->rec_len == 0) { nilfs_error(inode->i_sb, "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, from, to); BUG_ON(err); if (pde) pde->rec_len = nilfs_rec_len_to_disk(to - from); dir->inode = 0; nilfs_commit_chunk(page, mapping, from, to); inode->i_ctime = inode->i_mtime = current_time(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 int chunk_size = nilfs_chunk_size(inode); struct nilfs_dir_entry *de; int err; void *kaddr; if (!page) return -ENOMEM; err = nilfs_prepare_chunk(page, 0, chunk_size); if (unlikely(err)) { unlock_page(page); goto fail; } kaddr = kmap_atomic(page); memset(kaddr, 0, chunk_size); de = (struct nilfs_dir_entry *)kaddr; de->name_len = 1; de->rec_len = nilfs_rec_len_to_disk(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 = nilfs_rec_len_to_disk(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); nilfs_commit_chunk(page, mapping, 0, chunk_size); fail: put_page(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, "zero-length directory entry (kaddr=%p, de=%p)", 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; } const struct file_operations nilfs_dir_operations = { .llseek = generic_file_llseek, .read = generic_read_dir, .iterate_shared = nilfs_readdir, .unlocked_ioctl = nilfs_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = nilfs_compat_ioctl, #endif /* CONFIG_COMPAT */ .fsync = nilfs_sync_file, };