// SPDX-License-Identifier: GPL-2.0 /* * fs/bfs/dir.c * BFS directory operations. * Copyright (C) 1999-2018 Tigran Aivazian <aivazian.tigran@gmail.com> * Made endianness-clean by Andrew Stribblehill <ads@wompom.org> 2005 */ #include <linux/time.h> #include <linux/string.h> #include <linux/fs.h> #include <linux/buffer_head.h> #include <linux/sched.h> #include "bfs.h" #undef DEBUG #ifdef DEBUG #define dprintf(x...) printf(x) #else #define dprintf(x...) #endif static int bfs_add_entry(struct inode *dir, const struct qstr *child, int ino); static struct buffer_head *bfs_find_entry(struct inode *dir, const struct qstr *child, struct bfs_dirent **res_dir); static int bfs_readdir(struct file *f, struct dir_context *ctx) { struct inode *dir = file_inode(f); struct buffer_head *bh; struct bfs_dirent *de; unsigned int offset; int block; if (ctx->pos & (BFS_DIRENT_SIZE - 1)) { printf("Bad f_pos=%08lx for %s:%08lx\n", (unsigned long)ctx->pos, dir->i_sb->s_id, dir->i_ino); return -EINVAL; } while (ctx->pos < dir->i_size) { offset = ctx->pos & (BFS_BSIZE - 1); block = BFS_I(dir)->i_sblock + (ctx->pos >> BFS_BSIZE_BITS); bh = sb_bread(dir->i_sb, block); if (!bh) { ctx->pos += BFS_BSIZE - offset; continue; } do { de = (struct bfs_dirent *)(bh->b_data + offset); if (de->ino) { int size = strnlen(de->name, BFS_NAMELEN); if (!dir_emit(ctx, de->name, size, le16_to_cpu(de->ino), DT_UNKNOWN)) { brelse(bh); return 0; } } offset += BFS_DIRENT_SIZE; ctx->pos += BFS_DIRENT_SIZE; } while ((offset < BFS_BSIZE) && (ctx->pos < dir->i_size)); brelse(bh); } return 0; } const struct file_operations bfs_dir_operations = { .read = generic_read_dir, .iterate_shared = bfs_readdir, .fsync = generic_file_fsync, .llseek = generic_file_llseek, }; static int bfs_create(struct mnt_idmap *idmap, struct inode *dir, struct dentry *dentry, umode_t mode, bool excl) { int err; struct inode *inode; struct super_block *s = dir->i_sb; struct bfs_sb_info *info = BFS_SB(s); unsigned long ino; inode = new_inode(s); if (!inode) return -ENOMEM; mutex_lock(&info->bfs_lock); ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1); if (ino > info->si_lasti) { mutex_unlock(&info->bfs_lock); iput(inode); return -ENOSPC; } set_bit(ino, info->si_imap); info->si_freei--; inode_init_owner(&nop_mnt_idmap, inode, dir, mode); inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode); inode->i_blocks = 0; inode->i_op = &bfs_file_inops; inode->i_fop = &bfs_file_operations; inode->i_mapping->a_ops = &bfs_aops; inode->i_ino = ino; BFS_I(inode)->i_dsk_ino = ino; BFS_I(inode)->i_sblock = 0; BFS_I(inode)->i_eblock = 0; insert_inode_hash(inode); mark_inode_dirty(inode); bfs_dump_imap("create", s); err = bfs_add_entry(dir, &dentry->d_name, inode->i_ino); if (err) { inode_dec_link_count(inode); mutex_unlock(&info->bfs_lock); iput(inode); return err; } mutex_unlock(&info->bfs_lock); d_instantiate(dentry, inode); return 0; } static struct dentry *bfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) { struct inode *inode = NULL; struct buffer_head *bh; struct bfs_dirent *de; struct bfs_sb_info *info = BFS_SB(dir->i_sb); if (dentry->d_name.len > BFS_NAMELEN) return ERR_PTR(-ENAMETOOLONG); mutex_lock(&info->bfs_lock); bh = bfs_find_entry(dir, &dentry->d_name, &de); if (bh) { unsigned long ino = (unsigned long)le16_to_cpu(de->ino); brelse(bh); inode = bfs_iget(dir->i_sb, ino); } mutex_unlock(&info->bfs_lock); return d_splice_alias(inode, dentry); } static int bfs_link(struct dentry *old, struct inode *dir, struct dentry *new) { struct inode *inode = d_inode(old); struct bfs_sb_info *info = BFS_SB(inode->i_sb); int err; mutex_lock(&info->bfs_lock); err = bfs_add_entry(dir, &new->d_name, inode->i_ino); if (err) { mutex_unlock(&info->bfs_lock); return err; } inc_nlink(inode); inode_set_ctime_current(inode); mark_inode_dirty(inode); ihold(inode); d_instantiate(new, inode); mutex_unlock(&info->bfs_lock); return 0; } static int bfs_unlink(struct inode *dir, struct dentry *dentry) { int error = -ENOENT; struct inode *inode = d_inode(dentry); struct buffer_head *bh; struct bfs_dirent *de; struct bfs_sb_info *info = BFS_SB(inode->i_sb); mutex_lock(&info->bfs_lock); bh = bfs_find_entry(dir, &dentry->d_name, &de); if (!bh || (le16_to_cpu(de->ino) != inode->i_ino)) goto out_brelse; if (!inode->i_nlink) { printf("unlinking non-existent file %s:%lu (nlink=%d)\n", inode->i_sb->s_id, inode->i_ino, inode->i_nlink); set_nlink(inode, 1); } de->ino = 0; mark_buffer_dirty_inode(bh, dir); dir->i_mtime = inode_set_ctime_current(dir); mark_inode_dirty(dir); inode_set_ctime_to_ts(inode, inode_get_ctime(dir)); inode_dec_link_count(inode); error = 0; out_brelse: brelse(bh); mutex_unlock(&info->bfs_lock); return error; } static int bfs_rename(struct mnt_idmap *idmap, struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags) { struct inode *old_inode, *new_inode; struct buffer_head *old_bh, *new_bh; struct bfs_dirent *old_de, *new_de; struct bfs_sb_info *info; int error = -ENOENT; if (flags & ~RENAME_NOREPLACE) return -EINVAL; old_bh = new_bh = NULL; old_inode = d_inode(old_dentry); if (S_ISDIR(old_inode->i_mode)) return -EINVAL; info = BFS_SB(old_inode->i_sb); mutex_lock(&info->bfs_lock); old_bh = bfs_find_entry(old_dir, &old_dentry->d_name, &old_de); if (!old_bh || (le16_to_cpu(old_de->ino) != old_inode->i_ino)) goto end_rename; error = -EPERM; new_inode = d_inode(new_dentry); new_bh = bfs_find_entry(new_dir, &new_dentry->d_name, &new_de); if (new_bh && !new_inode) { brelse(new_bh); new_bh = NULL; } if (!new_bh) { error = bfs_add_entry(new_dir, &new_dentry->d_name, old_inode->i_ino); if (error) goto end_rename; } old_de->ino = 0; old_dir->i_mtime = inode_set_ctime_current(old_dir); mark_inode_dirty(old_dir); if (new_inode) { inode_set_ctime_current(new_inode); inode_dec_link_count(new_inode); } mark_buffer_dirty_inode(old_bh, old_dir); error = 0; end_rename: mutex_unlock(&info->bfs_lock); brelse(old_bh); brelse(new_bh); return error; } const struct inode_operations bfs_dir_inops = { .create = bfs_create, .lookup = bfs_lookup, .link = bfs_link, .unlink = bfs_unlink, .rename = bfs_rename, }; static int bfs_add_entry(struct inode *dir, const struct qstr *child, int ino) { const unsigned char *name = child->name; int namelen = child->len; struct buffer_head *bh; struct bfs_dirent *de; int block, sblock, eblock, off, pos; int i; dprintf("name=%s, namelen=%d\n", name, namelen); if (!namelen) return -ENOENT; if (namelen > BFS_NAMELEN) return -ENAMETOOLONG; sblock = BFS_I(dir)->i_sblock; eblock = BFS_I(dir)->i_eblock; for (block = sblock; block <= eblock; block++) { bh = sb_bread(dir->i_sb, block); if (!bh) return -EIO; for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) { de = (struct bfs_dirent *)(bh->b_data + off); if (!de->ino) { pos = (block - sblock) * BFS_BSIZE + off; if (pos >= dir->i_size) { dir->i_size += BFS_DIRENT_SIZE; inode_set_ctime_current(dir); } dir->i_mtime = inode_set_ctime_current(dir); mark_inode_dirty(dir); de->ino = cpu_to_le16((u16)ino); for (i = 0; i < BFS_NAMELEN; i++) de->name[i] = (i < namelen) ? name[i] : 0; mark_buffer_dirty_inode(bh, dir); brelse(bh); return 0; } } brelse(bh); } return -ENOSPC; } static inline int bfs_namecmp(int len, const unsigned char *name, const char *buffer) { if ((len < BFS_NAMELEN) && buffer[len]) return 0; return !memcmp(name, buffer, len); } static struct buffer_head *bfs_find_entry(struct inode *dir, const struct qstr *child, struct bfs_dirent **res_dir) { unsigned long block = 0, offset = 0; struct buffer_head *bh = NULL; struct bfs_dirent *de; const unsigned char *name = child->name; int namelen = child->len; *res_dir = NULL; if (namelen > BFS_NAMELEN) return NULL; while (block * BFS_BSIZE + offset < dir->i_size) { if (!bh) { bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block); if (!bh) { block++; continue; } } de = (struct bfs_dirent *)(bh->b_data + offset); offset += BFS_DIRENT_SIZE; if (le16_to_cpu(de->ino) && bfs_namecmp(namelen, name, de->name)) { *res_dir = de; return bh; } if (offset < bh->b_size) continue; brelse(bh); bh = NULL; offset = 0; block++; } brelse(bh); return NULL; }