462 lines
9.9 KiB
C
462 lines
9.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* OMFS (as used by RIO Karma) directory operations.
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* Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
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*/
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#include <linux/fs.h>
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#include <linux/ctype.h>
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#include <linux/buffer_head.h>
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#include "omfs.h"
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static int omfs_hash(const char *name, int namelen, int mod)
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{
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int i, hash = 0;
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for (i = 0; i < namelen; i++)
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hash ^= tolower(name[i]) << (i % 24);
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return hash % mod;
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}
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/*
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* Finds the bucket for a given name and reads the containing block;
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* *ofs is set to the offset of the first list entry.
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*/
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static struct buffer_head *omfs_get_bucket(struct inode *dir,
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const char *name, int namelen, int *ofs)
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{
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int nbuckets = (dir->i_size - OMFS_DIR_START)/8;
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int bucket = omfs_hash(name, namelen, nbuckets);
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*ofs = OMFS_DIR_START + bucket * 8;
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return omfs_bread(dir->i_sb, dir->i_ino);
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}
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static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block,
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const char *name, int namelen,
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u64 *prev_block)
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{
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struct buffer_head *bh;
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struct omfs_inode *oi;
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int err = -ENOENT;
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*prev_block = ~0;
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while (block != ~0) {
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bh = omfs_bread(dir->i_sb, block);
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if (!bh) {
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err = -EIO;
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goto err;
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}
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oi = (struct omfs_inode *) bh->b_data;
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if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) {
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brelse(bh);
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goto err;
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}
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if (strncmp(oi->i_name, name, namelen) == 0)
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return bh;
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*prev_block = block;
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block = be64_to_cpu(oi->i_sibling);
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brelse(bh);
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}
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err:
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return ERR_PTR(err);
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}
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static struct buffer_head *omfs_find_entry(struct inode *dir,
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const char *name, int namelen)
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{
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struct buffer_head *bh;
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int ofs;
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u64 block, dummy;
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bh = omfs_get_bucket(dir, name, namelen, &ofs);
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if (!bh)
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return ERR_PTR(-EIO);
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block = be64_to_cpu(*((__be64 *) &bh->b_data[ofs]));
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brelse(bh);
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return omfs_scan_list(dir, block, name, namelen, &dummy);
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}
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int omfs_make_empty(struct inode *inode, struct super_block *sb)
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{
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struct omfs_sb_info *sbi = OMFS_SB(sb);
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struct buffer_head *bh;
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struct omfs_inode *oi;
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bh = omfs_bread(sb, inode->i_ino);
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if (!bh)
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return -ENOMEM;
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memset(bh->b_data, 0, sizeof(struct omfs_inode));
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if (S_ISDIR(inode->i_mode)) {
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memset(&bh->b_data[OMFS_DIR_START], 0xff,
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sbi->s_sys_blocksize - OMFS_DIR_START);
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} else
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omfs_make_empty_table(bh, OMFS_EXTENT_START);
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oi = (struct omfs_inode *) bh->b_data;
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oi->i_head.h_self = cpu_to_be64(inode->i_ino);
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oi->i_sibling = ~cpu_to_be64(0ULL);
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mark_buffer_dirty(bh);
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brelse(bh);
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return 0;
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}
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static int omfs_add_link(struct dentry *dentry, struct inode *inode)
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{
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struct inode *dir = d_inode(dentry->d_parent);
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const char *name = dentry->d_name.name;
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int namelen = dentry->d_name.len;
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struct omfs_inode *oi;
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struct buffer_head *bh;
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u64 block;
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__be64 *entry;
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int ofs;
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/* just prepend to head of queue in proper bucket */
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bh = omfs_get_bucket(dir, name, namelen, &ofs);
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if (!bh)
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goto out;
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entry = (__be64 *) &bh->b_data[ofs];
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block = be64_to_cpu(*entry);
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*entry = cpu_to_be64(inode->i_ino);
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mark_buffer_dirty(bh);
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brelse(bh);
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/* now set the sibling and parent pointers on the new inode */
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bh = omfs_bread(dir->i_sb, inode->i_ino);
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if (!bh)
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goto out;
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oi = (struct omfs_inode *) bh->b_data;
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memcpy(oi->i_name, name, namelen);
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memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen);
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oi->i_sibling = cpu_to_be64(block);
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oi->i_parent = cpu_to_be64(dir->i_ino);
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mark_buffer_dirty(bh);
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brelse(bh);
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dir->i_ctime = current_time(dir);
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/* mark affected inodes dirty to rebuild checksums */
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mark_inode_dirty(dir);
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mark_inode_dirty(inode);
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return 0;
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out:
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return -ENOMEM;
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}
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static int omfs_delete_entry(struct dentry *dentry)
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{
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struct inode *dir = d_inode(dentry->d_parent);
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struct inode *dirty;
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const char *name = dentry->d_name.name;
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int namelen = dentry->d_name.len;
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struct omfs_inode *oi;
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struct buffer_head *bh, *bh2;
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__be64 *entry, next;
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u64 block, prev;
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int ofs;
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int err = -ENOMEM;
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/* delete the proper node in the bucket's linked list */
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bh = omfs_get_bucket(dir, name, namelen, &ofs);
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if (!bh)
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goto out;
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entry = (__be64 *) &bh->b_data[ofs];
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block = be64_to_cpu(*entry);
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bh2 = omfs_scan_list(dir, block, name, namelen, &prev);
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if (IS_ERR(bh2)) {
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err = PTR_ERR(bh2);
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goto out_free_bh;
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}
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oi = (struct omfs_inode *) bh2->b_data;
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next = oi->i_sibling;
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brelse(bh2);
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if (prev != ~0) {
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/* found in middle of list, get list ptr */
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brelse(bh);
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bh = omfs_bread(dir->i_sb, prev);
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if (!bh)
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goto out;
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oi = (struct omfs_inode *) bh->b_data;
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entry = &oi->i_sibling;
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}
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*entry = next;
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mark_buffer_dirty(bh);
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if (prev != ~0) {
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dirty = omfs_iget(dir->i_sb, prev);
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if (!IS_ERR(dirty)) {
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mark_inode_dirty(dirty);
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iput(dirty);
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}
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}
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err = 0;
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out_free_bh:
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brelse(bh);
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out:
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return err;
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}
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static int omfs_dir_is_empty(struct inode *inode)
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{
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int nbuckets = (inode->i_size - OMFS_DIR_START) / 8;
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struct buffer_head *bh;
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u64 *ptr;
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int i;
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bh = omfs_bread(inode->i_sb, inode->i_ino);
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if (!bh)
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return 0;
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ptr = (u64 *) &bh->b_data[OMFS_DIR_START];
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for (i = 0; i < nbuckets; i++, ptr++)
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if (*ptr != ~0)
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break;
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brelse(bh);
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return *ptr != ~0;
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}
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static int omfs_remove(struct inode *dir, struct dentry *dentry)
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{
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struct inode *inode = d_inode(dentry);
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int ret;
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if (S_ISDIR(inode->i_mode) &&
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!omfs_dir_is_empty(inode))
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return -ENOTEMPTY;
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ret = omfs_delete_entry(dentry);
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if (ret)
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return ret;
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clear_nlink(inode);
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mark_inode_dirty(inode);
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mark_inode_dirty(dir);
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return 0;
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}
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static int omfs_add_node(struct inode *dir, struct dentry *dentry, umode_t mode)
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{
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int err;
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struct inode *inode = omfs_new_inode(dir, mode);
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if (IS_ERR(inode))
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return PTR_ERR(inode);
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err = omfs_make_empty(inode, dir->i_sb);
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if (err)
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goto out_free_inode;
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err = omfs_add_link(dentry, inode);
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if (err)
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goto out_free_inode;
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d_instantiate(dentry, inode);
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return 0;
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out_free_inode:
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iput(inode);
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return err;
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}
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static int omfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
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struct dentry *dentry, umode_t mode)
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{
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return omfs_add_node(dir, dentry, mode | S_IFDIR);
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}
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static int omfs_create(struct user_namespace *mnt_userns, struct inode *dir,
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struct dentry *dentry, umode_t mode, bool excl)
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{
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return omfs_add_node(dir, dentry, mode | S_IFREG);
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}
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static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry,
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unsigned int flags)
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{
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struct buffer_head *bh;
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struct inode *inode = NULL;
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if (dentry->d_name.len > OMFS_NAMELEN)
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return ERR_PTR(-ENAMETOOLONG);
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bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
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if (!IS_ERR(bh)) {
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struct omfs_inode *oi = (struct omfs_inode *)bh->b_data;
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ino_t ino = be64_to_cpu(oi->i_head.h_self);
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brelse(bh);
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inode = omfs_iget(dir->i_sb, ino);
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} else if (bh != ERR_PTR(-ENOENT)) {
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inode = ERR_CAST(bh);
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}
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return d_splice_alias(inode, dentry);
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}
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/* sanity check block's self pointer */
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int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
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u64 fsblock)
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{
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int is_bad;
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u64 ino = be64_to_cpu(header->h_self);
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is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) ||
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(ino > sbi->s_num_blocks));
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if (is_bad)
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printk(KERN_WARNING "omfs: bad hash chain detected\n");
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return is_bad;
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}
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static bool omfs_fill_chain(struct inode *dir, struct dir_context *ctx,
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u64 fsblock, int hindex)
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{
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/* follow chain in this bucket */
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while (fsblock != ~0) {
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struct buffer_head *bh = omfs_bread(dir->i_sb, fsblock);
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struct omfs_inode *oi;
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u64 self;
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unsigned char d_type;
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if (!bh)
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return true;
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oi = (struct omfs_inode *) bh->b_data;
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if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
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brelse(bh);
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return true;
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}
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self = fsblock;
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fsblock = be64_to_cpu(oi->i_sibling);
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/* skip visited nodes */
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if (hindex) {
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hindex--;
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brelse(bh);
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continue;
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}
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d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG;
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if (!dir_emit(ctx, oi->i_name,
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strnlen(oi->i_name, OMFS_NAMELEN),
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self, d_type)) {
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brelse(bh);
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return false;
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}
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brelse(bh);
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ctx->pos++;
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}
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return true;
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}
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static int omfs_rename(struct user_namespace *mnt_userns, 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 *new_inode = d_inode(new_dentry);
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struct inode *old_inode = d_inode(old_dentry);
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int err;
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if (flags & ~RENAME_NOREPLACE)
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return -EINVAL;
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if (new_inode) {
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/* overwriting existing file/dir */
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err = omfs_remove(new_dir, new_dentry);
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if (err)
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goto out;
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}
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/* since omfs locates files by name, we need to unlink _before_
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* adding the new link or we won't find the old one */
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err = omfs_delete_entry(old_dentry);
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if (err)
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goto out;
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mark_inode_dirty(old_dir);
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err = omfs_add_link(new_dentry, old_inode);
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if (err)
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goto out;
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old_inode->i_ctime = current_time(old_inode);
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mark_inode_dirty(old_inode);
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out:
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return err;
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}
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static int omfs_readdir(struct file *file, struct dir_context *ctx)
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{
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struct inode *dir = file_inode(file);
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struct buffer_head *bh;
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__be64 *p;
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unsigned int hchain, hindex;
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int nbuckets;
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if (ctx->pos >> 32)
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return -EINVAL;
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if (ctx->pos < 1 << 20) {
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if (!dir_emit_dots(file, ctx))
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return 0;
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ctx->pos = 1 << 20;
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}
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nbuckets = (dir->i_size - OMFS_DIR_START) / 8;
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/* high 12 bits store bucket + 1 and low 20 bits store hash index */
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hchain = (ctx->pos >> 20) - 1;
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hindex = ctx->pos & 0xfffff;
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bh = omfs_bread(dir->i_sb, dir->i_ino);
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if (!bh)
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return -EINVAL;
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p = (__be64 *)(bh->b_data + OMFS_DIR_START) + hchain;
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for (; hchain < nbuckets; hchain++) {
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__u64 fsblock = be64_to_cpu(*p++);
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if (!omfs_fill_chain(dir, ctx, fsblock, hindex))
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break;
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hindex = 0;
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ctx->pos = (hchain+2) << 20;
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}
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brelse(bh);
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return 0;
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}
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const struct inode_operations omfs_dir_inops = {
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.lookup = omfs_lookup,
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.mkdir = omfs_mkdir,
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.rename = omfs_rename,
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.create = omfs_create,
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.unlink = omfs_remove,
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.rmdir = omfs_remove,
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};
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const struct file_operations omfs_dir_operations = {
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.read = generic_read_dir,
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.iterate_shared = omfs_readdir,
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.llseek = generic_file_llseek,
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};
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