1 files changed, 369 insertions, 0 deletions
diff --git a/fs/adfs/inode.c b/fs/adfs/inode.c
new file mode 100644
index 0000000000..2096300257
--- /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_set_ctime_to_ts(inode, 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 mnt_idmap *idmap, 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(&nop_mnt_idmap, 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_set_ctime_to_ts(inode, 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);
+}