// SPDX-License-Identifier: GPL-2.0-only /* * linux/fs/adfs/inode.c * * Copyright (C) 1997-1999 Russell King */ #include <linux/buffer_head.h> #include <linux/writeback.h> #include "adfs.h" /* * Lookup/Create a block at offset 'block' into 'inode'. We currently do * not support creation of new blocks, so we return -EIO for this case. */ static int adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh, int create) { if (!create) { if (block >= inode->i_blocks) goto abort_toobig; block = __adfs_block_map(inode->i_sb, ADFS_I(inode)->indaddr, block); if (block) map_bh(bh, inode->i_sb, block); return 0; } /* don't support allocation of blocks yet */ return -EIO; abort_toobig: return 0; } static int adfs_writepage(struct page *page, struct writeback_control *wbc) { return block_write_full_page(page, adfs_get_block, wbc); } static int adfs_readpage(struct file *file, struct page *page) { return block_read_full_page(page, adfs_get_block); } static void adfs_write_failed(struct address_space *mapping, loff_t to) { struct inode *inode = mapping->host; if (to > inode->i_size) truncate_pagecache(inode, inode->i_size); } static int adfs_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata) { int ret; *pagep = NULL; ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata, adfs_get_block, &ADFS_I(mapping->host)->mmu_private); if (unlikely(ret)) adfs_write_failed(mapping, pos + len); return ret; } static sector_t _adfs_bmap(struct address_space *mapping, sector_t block) { return generic_block_bmap(mapping, block, adfs_get_block); } static const struct address_space_operations adfs_aops = { .readpage = adfs_readpage, .writepage = adfs_writepage, .write_begin = adfs_write_begin, .write_end = generic_write_end, .bmap = _adfs_bmap }; /* * Convert ADFS attributes and filetype to Linux permission. */ static umode_t adfs_atts2mode(struct super_block *sb, struct inode *inode) { unsigned int attr = ADFS_I(inode)->attr; umode_t mode, rmask; struct adfs_sb_info *asb = ADFS_SB(sb); if (attr & ADFS_NDA_DIRECTORY) { mode = S_IRUGO & asb->s_owner_mask; return S_IFDIR | S_IXUGO | mode; } switch (adfs_filetype(ADFS_I(inode)->loadaddr)) { case 0xfc0: /* LinkFS */ return S_IFLNK|S_IRWXUGO; case 0xfe6: /* UnixExec */ rmask = S_IRUGO | S_IXUGO; break; default: rmask = S_IRUGO; } mode = S_IFREG; if (attr & ADFS_NDA_OWNER_READ) mode |= rmask & asb->s_owner_mask; if (attr & ADFS_NDA_OWNER_WRITE) mode |= S_IWUGO & asb->s_owner_mask; if (attr & ADFS_NDA_PUBLIC_READ) mode |= rmask & asb->s_other_mask; if (attr & ADFS_NDA_PUBLIC_WRITE) mode |= S_IWUGO & asb->s_other_mask; return mode; } /* * Convert Linux permission to ADFS attribute. We try to do the reverse * of atts2mode, but there is not a 1:1 translation. */ static int adfs_mode2atts(struct super_block *sb, struct inode *inode, umode_t ia_mode) { struct adfs_sb_info *asb = ADFS_SB(sb); umode_t mode; int attr; /* FIXME: should we be able to alter a link? */ if (S_ISLNK(inode->i_mode)) return ADFS_I(inode)->attr; /* Directories do not have read/write permissions on the media */ if (S_ISDIR(inode->i_mode)) return ADFS_NDA_DIRECTORY; attr = 0; mode = ia_mode & asb->s_owner_mask; if (mode & S_IRUGO) attr |= ADFS_NDA_OWNER_READ; if (mode & S_IWUGO) attr |= ADFS_NDA_OWNER_WRITE; mode = ia_mode & asb->s_other_mask; mode &= ~asb->s_owner_mask; if (mode & S_IRUGO) attr |= ADFS_NDA_PUBLIC_READ; if (mode & S_IWUGO) attr |= ADFS_NDA_PUBLIC_WRITE; return attr; } static const s64 nsec_unix_epoch_diff_risc_os_epoch = 2208988800000000000LL; /* * Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time * referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds * of time to convert from RISC OS epoch to Unix epoch. */ static void adfs_adfs2unix_time(struct timespec64 *tv, struct inode *inode) { unsigned int high, low; /* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since * 01 Jan 1900 00:00:00 (RISC OS epoch) */ s64 nsec; if (!adfs_inode_is_stamped(inode)) goto cur_time; high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */ low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */ /* convert 40-bit centi-seconds to 32-bit seconds * going via nanoseconds to retain precision */ nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */ /* Files dated pre 01 Jan 1970 00:00:00. */ if (nsec < nsec_unix_epoch_diff_risc_os_epoch) goto too_early; /* convert from RISC OS to Unix epoch */ nsec -= nsec_unix_epoch_diff_risc_os_epoch; *tv = ns_to_timespec64(nsec); return; cur_time: *tv = current_time(inode); return; too_early: tv->tv_sec = tv->tv_nsec = 0; return; } /* Convert an Unix time to ADFS time for an entry that is already stamped. */ static void adfs_unix2adfs_time(struct inode *inode, const struct timespec64 *ts) { s64 cs, nsec = timespec64_to_ns(ts); /* convert from Unix to RISC OS epoch */ nsec += nsec_unix_epoch_diff_risc_os_epoch; /* convert from nanoseconds to centiseconds */ cs = div_s64(nsec, 10000000); cs = clamp_t(s64, cs, 0, 0xffffffffff); ADFS_I(inode)->loadaddr &= ~0xff; ADFS_I(inode)->loadaddr |= (cs >> 32) & 0xff; ADFS_I(inode)->execaddr = cs; } /* * Fill in the inode information from the object information. * * Note that this is an inode-less filesystem, so we can't use the inode * number to reference the metadata on the media. Instead, we use the * inode number to hold the object ID, which in turn will tell us where * the data is held. We also save the parent object ID, and with these * two, we can locate the metadata. * * This does mean that we rely on an objects parent remaining the same at * all times - we cannot cope with a cross-directory rename (yet). */ struct inode * adfs_iget(struct super_block *sb, struct object_info *obj) { struct inode *inode; inode = new_inode(sb); if (!inode) goto out; inode->i_uid = ADFS_SB(sb)->s_uid; inode->i_gid = ADFS_SB(sb)->s_gid; inode->i_ino = obj->indaddr; inode->i_size = obj->size; set_nlink(inode, 2); inode->i_blocks = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits; /* * we need to save the parent directory ID so that * write_inode can update the directory information * for this file. This will need special handling * for cross-directory renames. */ ADFS_I(inode)->parent_id = obj->parent_id; ADFS_I(inode)->indaddr = obj->indaddr; ADFS_I(inode)->loadaddr = obj->loadaddr; ADFS_I(inode)->execaddr = obj->execaddr; ADFS_I(inode)->attr = obj->attr; inode->i_mode = adfs_atts2mode(sb, inode); adfs_adfs2unix_time(&inode->i_mtime, inode); inode->i_atime = inode->i_mtime; inode->i_ctime = inode->i_mtime; if (S_ISDIR(inode->i_mode)) { inode->i_op = &adfs_dir_inode_operations; inode->i_fop = &adfs_dir_operations; } else if (S_ISREG(inode->i_mode)) { inode->i_op = &adfs_file_inode_operations; inode->i_fop = &adfs_file_operations; inode->i_mapping->a_ops = &adfs_aops; ADFS_I(inode)->mmu_private = inode->i_size; } inode_fake_hash(inode); out: return inode; } /* * Validate and convert a changed access mode/time to their ADFS equivalents. * adfs_write_inode will actually write the information back to the directory * later. */ int adfs_notify_change(struct dentry *dentry, struct iattr *attr) { struct inode *inode = d_inode(dentry); struct super_block *sb = inode->i_sb; unsigned int ia_valid = attr->ia_valid; int error; error = setattr_prepare(dentry, attr); /* * we can't change the UID or GID of any file - * we have a global UID/GID in the superblock */ if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) || (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, ADFS_SB(sb)->s_gid))) error = -EPERM; if (error) goto out; /* XXX: this is missing some actual on-disk truncation.. */ if (ia_valid & ATTR_SIZE) truncate_setsize(inode, attr->ia_size); if (ia_valid & ATTR_MTIME && adfs_inode_is_stamped(inode)) { adfs_unix2adfs_time(inode, &attr->ia_mtime); adfs_adfs2unix_time(&inode->i_mtime, inode); } /* * FIXME: should we make these == to i_mtime since we don't * have the ability to represent them in our filesystem? */ if (ia_valid & ATTR_ATIME) inode->i_atime = attr->ia_atime; if (ia_valid & ATTR_CTIME) inode->i_ctime = attr->ia_ctime; if (ia_valid & ATTR_MODE) { ADFS_I(inode)->attr = adfs_mode2atts(sb, inode, attr->ia_mode); inode->i_mode = adfs_atts2mode(sb, inode); } /* * FIXME: should we be marking this inode dirty even if * we don't have any metadata to write back? */ if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE)) mark_inode_dirty(inode); out: return error; } /* * write an existing inode back to the directory, and therefore the disk. * The adfs-specific inode data has already been updated by * adfs_notify_change() */ int adfs_write_inode(struct inode *inode, struct writeback_control *wbc) { struct super_block *sb = inode->i_sb; struct object_info obj; int ret; obj.indaddr = ADFS_I(inode)->indaddr; obj.name_len = 0; obj.parent_id = ADFS_I(inode)->parent_id; obj.loadaddr = ADFS_I(inode)->loadaddr; obj.execaddr = ADFS_I(inode)->execaddr; obj.attr = ADFS_I(inode)->attr; obj.size = inode->i_size; ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL); return ret; }