diff options
Diffstat (limited to 'fs/adfs/inode.c')
| -rw-r--r-- | fs/adfs/inode.c | 369 |
1 files changed, 369 insertions, 0 deletions
diff --git a/fs/adfs/inode.c b/fs/adfs/inode.c new file mode 100644 index 000000000..ee22278b0 --- /dev/null +++ b/fs/adfs/inode.c @@ -0,0 +1,369 @@ +// 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_read_folio(struct file *file, struct folio *folio) +{ + return block_read_full_folio(folio, 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, + struct page **pagep, void **fsdata) +{ + int ret; + + *pagep = NULL; + ret = cont_write_begin(file, mapping, pos, len, 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 = { + .dirty_folio = block_dirty_folio, + .invalidate_folio = block_invalidate_folio, + .read_folio = adfs_read_folio, + .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 user_namespace *mnt_userns, 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(&init_user_ns, 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; + + 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; + + return adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL); +} |