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![Christian Brauner](/assets/img/avatar_default.png)
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b
("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
359 lines
8.6 KiB
C
359 lines
8.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* fs/bfs/dir.c
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* BFS directory operations.
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* Copyright (C) 1999-2018 Tigran Aivazian <aivazian.tigran@gmail.com>
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* Made endianness-clean by Andrew Stribblehill <ads@wompom.org> 2005
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*/
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#include <linux/time.h>
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#include <linux/string.h>
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#include <linux/fs.h>
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#include <linux/buffer_head.h>
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#include <linux/sched.h>
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#include "bfs.h"
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#undef DEBUG
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#ifdef DEBUG
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#define dprintf(x...) printf(x)
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#else
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#define dprintf(x...)
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#endif
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static int bfs_add_entry(struct inode *dir, const struct qstr *child, int ino);
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static struct buffer_head *bfs_find_entry(struct inode *dir,
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const struct qstr *child,
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struct bfs_dirent **res_dir);
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static int bfs_readdir(struct file *f, struct dir_context *ctx)
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{
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struct inode *dir = file_inode(f);
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struct buffer_head *bh;
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struct bfs_dirent *de;
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unsigned int offset;
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int block;
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if (ctx->pos & (BFS_DIRENT_SIZE - 1)) {
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printf("Bad f_pos=%08lx for %s:%08lx\n",
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(unsigned long)ctx->pos,
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dir->i_sb->s_id, dir->i_ino);
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return -EINVAL;
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}
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while (ctx->pos < dir->i_size) {
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offset = ctx->pos & (BFS_BSIZE - 1);
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block = BFS_I(dir)->i_sblock + (ctx->pos >> BFS_BSIZE_BITS);
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bh = sb_bread(dir->i_sb, block);
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if (!bh) {
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ctx->pos += BFS_BSIZE - offset;
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continue;
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}
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do {
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de = (struct bfs_dirent *)(bh->b_data + offset);
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if (de->ino) {
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int size = strnlen(de->name, BFS_NAMELEN);
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if (!dir_emit(ctx, de->name, size,
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le16_to_cpu(de->ino),
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DT_UNKNOWN)) {
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brelse(bh);
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return 0;
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}
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}
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offset += BFS_DIRENT_SIZE;
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ctx->pos += BFS_DIRENT_SIZE;
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} while ((offset < BFS_BSIZE) && (ctx->pos < dir->i_size));
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brelse(bh);
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}
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return 0;
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}
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const struct file_operations bfs_dir_operations = {
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.read = generic_read_dir,
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.iterate_shared = bfs_readdir,
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.fsync = generic_file_fsync,
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.llseek = generic_file_llseek,
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};
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static int bfs_create(struct mnt_idmap *idmap, struct inode *dir,
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struct dentry *dentry, umode_t mode, bool excl)
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{
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int err;
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struct inode *inode;
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struct super_block *s = dir->i_sb;
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struct bfs_sb_info *info = BFS_SB(s);
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unsigned long ino;
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inode = new_inode(s);
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if (!inode)
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return -ENOMEM;
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mutex_lock(&info->bfs_lock);
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ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1);
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if (ino > info->si_lasti) {
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mutex_unlock(&info->bfs_lock);
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iput(inode);
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return -ENOSPC;
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}
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set_bit(ino, info->si_imap);
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info->si_freei--;
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inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
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inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
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inode->i_blocks = 0;
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inode->i_op = &bfs_file_inops;
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inode->i_fop = &bfs_file_operations;
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inode->i_mapping->a_ops = &bfs_aops;
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inode->i_ino = ino;
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BFS_I(inode)->i_dsk_ino = ino;
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BFS_I(inode)->i_sblock = 0;
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BFS_I(inode)->i_eblock = 0;
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insert_inode_hash(inode);
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mark_inode_dirty(inode);
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bfs_dump_imap("create", s);
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err = bfs_add_entry(dir, &dentry->d_name, inode->i_ino);
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if (err) {
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inode_dec_link_count(inode);
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mutex_unlock(&info->bfs_lock);
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iput(inode);
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return err;
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}
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mutex_unlock(&info->bfs_lock);
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d_instantiate(dentry, inode);
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return 0;
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}
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static struct dentry *bfs_lookup(struct inode *dir, struct dentry *dentry,
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unsigned int flags)
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{
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struct inode *inode = NULL;
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struct buffer_head *bh;
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struct bfs_dirent *de;
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struct bfs_sb_info *info = BFS_SB(dir->i_sb);
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if (dentry->d_name.len > BFS_NAMELEN)
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return ERR_PTR(-ENAMETOOLONG);
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mutex_lock(&info->bfs_lock);
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bh = bfs_find_entry(dir, &dentry->d_name, &de);
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if (bh) {
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unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
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brelse(bh);
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inode = bfs_iget(dir->i_sb, ino);
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}
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mutex_unlock(&info->bfs_lock);
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return d_splice_alias(inode, dentry);
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}
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static int bfs_link(struct dentry *old, struct inode *dir,
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struct dentry *new)
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{
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struct inode *inode = d_inode(old);
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struct bfs_sb_info *info = BFS_SB(inode->i_sb);
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int err;
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mutex_lock(&info->bfs_lock);
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err = bfs_add_entry(dir, &new->d_name, inode->i_ino);
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if (err) {
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mutex_unlock(&info->bfs_lock);
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return err;
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}
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inc_nlink(inode);
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inode->i_ctime = current_time(inode);
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mark_inode_dirty(inode);
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ihold(inode);
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d_instantiate(new, inode);
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mutex_unlock(&info->bfs_lock);
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return 0;
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}
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static int bfs_unlink(struct inode *dir, struct dentry *dentry)
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{
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int error = -ENOENT;
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struct inode *inode = d_inode(dentry);
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struct buffer_head *bh;
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struct bfs_dirent *de;
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struct bfs_sb_info *info = BFS_SB(inode->i_sb);
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mutex_lock(&info->bfs_lock);
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bh = bfs_find_entry(dir, &dentry->d_name, &de);
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if (!bh || (le16_to_cpu(de->ino) != inode->i_ino))
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goto out_brelse;
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if (!inode->i_nlink) {
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printf("unlinking non-existent file %s:%lu (nlink=%d)\n",
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inode->i_sb->s_id, inode->i_ino,
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inode->i_nlink);
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set_nlink(inode, 1);
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}
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de->ino = 0;
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mark_buffer_dirty_inode(bh, dir);
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dir->i_ctime = dir->i_mtime = current_time(dir);
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mark_inode_dirty(dir);
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inode->i_ctime = dir->i_ctime;
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inode_dec_link_count(inode);
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error = 0;
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out_brelse:
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brelse(bh);
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mutex_unlock(&info->bfs_lock);
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return error;
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}
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static int bfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
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struct dentry *old_dentry, struct inode *new_dir,
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struct dentry *new_dentry, unsigned int flags)
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{
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struct inode *old_inode, *new_inode;
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struct buffer_head *old_bh, *new_bh;
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struct bfs_dirent *old_de, *new_de;
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struct bfs_sb_info *info;
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int error = -ENOENT;
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if (flags & ~RENAME_NOREPLACE)
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return -EINVAL;
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old_bh = new_bh = NULL;
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old_inode = d_inode(old_dentry);
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if (S_ISDIR(old_inode->i_mode))
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return -EINVAL;
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info = BFS_SB(old_inode->i_sb);
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mutex_lock(&info->bfs_lock);
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old_bh = bfs_find_entry(old_dir, &old_dentry->d_name, &old_de);
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if (!old_bh || (le16_to_cpu(old_de->ino) != old_inode->i_ino))
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goto end_rename;
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error = -EPERM;
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new_inode = d_inode(new_dentry);
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new_bh = bfs_find_entry(new_dir, &new_dentry->d_name, &new_de);
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if (new_bh && !new_inode) {
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brelse(new_bh);
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new_bh = NULL;
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}
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if (!new_bh) {
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error = bfs_add_entry(new_dir, &new_dentry->d_name,
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old_inode->i_ino);
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if (error)
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goto end_rename;
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}
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old_de->ino = 0;
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old_dir->i_ctime = old_dir->i_mtime = current_time(old_dir);
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mark_inode_dirty(old_dir);
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if (new_inode) {
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new_inode->i_ctime = current_time(new_inode);
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inode_dec_link_count(new_inode);
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}
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mark_buffer_dirty_inode(old_bh, old_dir);
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error = 0;
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end_rename:
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mutex_unlock(&info->bfs_lock);
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brelse(old_bh);
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brelse(new_bh);
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return error;
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}
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const struct inode_operations bfs_dir_inops = {
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.create = bfs_create,
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.lookup = bfs_lookup,
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.link = bfs_link,
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.unlink = bfs_unlink,
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.rename = bfs_rename,
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};
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static int bfs_add_entry(struct inode *dir, const struct qstr *child, int ino)
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{
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const unsigned char *name = child->name;
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int namelen = child->len;
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struct buffer_head *bh;
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struct bfs_dirent *de;
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int block, sblock, eblock, off, pos;
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int i;
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dprintf("name=%s, namelen=%d\n", name, namelen);
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if (!namelen)
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return -ENOENT;
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if (namelen > BFS_NAMELEN)
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return -ENAMETOOLONG;
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sblock = BFS_I(dir)->i_sblock;
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eblock = BFS_I(dir)->i_eblock;
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for (block = sblock; block <= eblock; block++) {
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bh = sb_bread(dir->i_sb, block);
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if (!bh)
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return -EIO;
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for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) {
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de = (struct bfs_dirent *)(bh->b_data + off);
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if (!de->ino) {
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pos = (block - sblock) * BFS_BSIZE + off;
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if (pos >= dir->i_size) {
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dir->i_size += BFS_DIRENT_SIZE;
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dir->i_ctime = current_time(dir);
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}
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dir->i_mtime = current_time(dir);
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mark_inode_dirty(dir);
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de->ino = cpu_to_le16((u16)ino);
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for (i = 0; i < BFS_NAMELEN; i++)
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de->name[i] =
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(i < namelen) ? name[i] : 0;
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mark_buffer_dirty_inode(bh, dir);
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brelse(bh);
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return 0;
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}
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}
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brelse(bh);
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}
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return -ENOSPC;
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}
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static inline int bfs_namecmp(int len, const unsigned char *name,
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const char *buffer)
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{
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if ((len < BFS_NAMELEN) && buffer[len])
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return 0;
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return !memcmp(name, buffer, len);
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}
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static struct buffer_head *bfs_find_entry(struct inode *dir,
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const struct qstr *child,
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struct bfs_dirent **res_dir)
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{
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unsigned long block = 0, offset = 0;
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struct buffer_head *bh = NULL;
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struct bfs_dirent *de;
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const unsigned char *name = child->name;
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int namelen = child->len;
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*res_dir = NULL;
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if (namelen > BFS_NAMELEN)
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return NULL;
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while (block * BFS_BSIZE + offset < dir->i_size) {
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if (!bh) {
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bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
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if (!bh) {
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block++;
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continue;
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}
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}
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de = (struct bfs_dirent *)(bh->b_data + offset);
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offset += BFS_DIRENT_SIZE;
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if (le16_to_cpu(de->ino) &&
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bfs_namecmp(namelen, name, de->name)) {
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*res_dir = de;
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return bh;
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}
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if (offset < bh->b_size)
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continue;
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brelse(bh);
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bh = NULL;
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offset = 0;
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block++;
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}
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brelse(bh);
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return NULL;
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}
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