Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1009 insertions, 0 deletions

diff --git a/fs/affs/file.c b/fs/affs/file.c
new file mode 100644
index 000000000..8daeed31e
--- /dev/null
+++ b/fs/affs/file.c
@@ -0,0 +1,1009 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/affs/file.c
+ *
+ *  (c) 1996  Hans-Joachim Widmaier - Rewritten
+ *
+ *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
+ *
+ *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
+ *
+ *  (C) 1991  Linus Torvalds - minix filesystem
+ *
+ *  affs regular file handling primitives
+ */
+
+#include <linux/uio.h>
+#include <linux/blkdev.h>
+#include "affs.h"
+
+static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
+
+static int
+affs_file_open(struct inode *inode, struct file *filp)
+{
+	pr_debug("open(%lu,%d)\n",
+		 inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
+	atomic_inc(&AFFS_I(inode)->i_opencnt);
+	return 0;
+}
+
+static int
+affs_file_release(struct inode *inode, struct file *filp)
+{
+	pr_debug("release(%lu, %d)\n",
+		 inode->i_ino, atomic_read(&AFFS_I(inode)->i_opencnt));
+
+	if (atomic_dec_and_test(&AFFS_I(inode)->i_opencnt)) {
+		inode_lock(inode);
+		if (inode->i_size != AFFS_I(inode)->mmu_private)
+			affs_truncate(inode);
+		affs_free_prealloc(inode);
+		inode_unlock(inode);
+	}
+
+	return 0;
+}
+
+static int
+affs_grow_extcache(struct inode *inode, u32 lc_idx)
+{
+	struct super_block	*sb = inode->i_sb;
+	struct buffer_head	*bh;
+	u32 lc_max;
+	int i, j, key;
+
+	if (!AFFS_I(inode)->i_lc) {
+		char *ptr = (char *)get_zeroed_page(GFP_NOFS);
+		if (!ptr)
+			return -ENOMEM;
+		AFFS_I(inode)->i_lc = (u32 *)ptr;
+		AFFS_I(inode)->i_ac = (struct affs_ext_key *)(ptr + AFFS_CACHE_SIZE / 2);
+	}
+
+	lc_max = AFFS_LC_SIZE << AFFS_I(inode)->i_lc_shift;
+
+	if (AFFS_I(inode)->i_extcnt > lc_max) {
+		u32 lc_shift, lc_mask, tmp, off;
+
+		/* need to recalculate linear cache, start from old size */
+		lc_shift = AFFS_I(inode)->i_lc_shift;
+		tmp = (AFFS_I(inode)->i_extcnt / AFFS_LC_SIZE) >> lc_shift;
+		for (; tmp; tmp >>= 1)
+			lc_shift++;
+		lc_mask = (1 << lc_shift) - 1;
+
+		/* fix idx and old size to new shift */
+		lc_idx >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
+		AFFS_I(inode)->i_lc_size >>= (lc_shift - AFFS_I(inode)->i_lc_shift);
+
+		/* first shrink old cache to make more space */
+		off = 1 << (lc_shift - AFFS_I(inode)->i_lc_shift);
+		for (i = 1, j = off; j < AFFS_LC_SIZE; i++, j += off)
+			AFFS_I(inode)->i_ac[i] = AFFS_I(inode)->i_ac[j];
+
+		AFFS_I(inode)->i_lc_shift = lc_shift;
+		AFFS_I(inode)->i_lc_mask = lc_mask;
+	}
+
+	/* fill cache to the needed index */
+	i = AFFS_I(inode)->i_lc_size;
+	AFFS_I(inode)->i_lc_size = lc_idx + 1;
+	for (; i <= lc_idx; i++) {
+		if (!i) {
+			AFFS_I(inode)->i_lc[0] = inode->i_ino;
+			continue;
+		}
+		key = AFFS_I(inode)->i_lc[i - 1];
+		j = AFFS_I(inode)->i_lc_mask + 1;
+		// unlock cache
+		for (; j > 0; j--) {
+			bh = affs_bread(sb, key);
+			if (!bh)
+				goto err;
+			key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
+			affs_brelse(bh);
+		}
+		// lock cache
+		AFFS_I(inode)->i_lc[i] = key;
+	}
+
+	return 0;
+
+err:
+	// lock cache
+	return -EIO;
+}
+
+static struct buffer_head *
+affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext)
+{
+	struct super_block *sb = inode->i_sb;
+	struct buffer_head *new_bh;
+	u32 blocknr, tmp;
+
+	blocknr = affs_alloc_block(inode, bh->b_blocknr);
+	if (!blocknr)
+		return ERR_PTR(-ENOSPC);
+
+	new_bh = affs_getzeroblk(sb, blocknr);
+	if (!new_bh) {
+		affs_free_block(sb, blocknr);
+		return ERR_PTR(-EIO);
+	}
+
+	AFFS_HEAD(new_bh)->ptype = cpu_to_be32(T_LIST);
+	AFFS_HEAD(new_bh)->key = cpu_to_be32(blocknr);
+	AFFS_TAIL(sb, new_bh)->stype = cpu_to_be32(ST_FILE);
+	AFFS_TAIL(sb, new_bh)->parent = cpu_to_be32(inode->i_ino);
+	affs_fix_checksum(sb, new_bh);
+
+	mark_buffer_dirty_inode(new_bh, inode);
+
+	tmp = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
+	if (tmp)
+		affs_warning(sb, "alloc_ext", "previous extension set (%x)", tmp);
+	AFFS_TAIL(sb, bh)->extension = cpu_to_be32(blocknr);
+	affs_adjust_checksum(bh, blocknr - tmp);
+	mark_buffer_dirty_inode(bh, inode);
+
+	AFFS_I(inode)->i_extcnt++;
+	mark_inode_dirty(inode);
+
+	return new_bh;
+}
+
+static inline struct buffer_head *
+affs_get_extblock(struct inode *inode, u32 ext)
+{
+	/* inline the simplest case: same extended block as last time */
+	struct buffer_head *bh = AFFS_I(inode)->i_ext_bh;
+	if (ext == AFFS_I(inode)->i_ext_last)
+		get_bh(bh);
+	else
+		/* we have to do more (not inlined) */
+		bh = affs_get_extblock_slow(inode, ext);
+
+	return bh;
+}
+
+static struct buffer_head *
+affs_get_extblock_slow(struct inode *inode, u32 ext)
+{
+	struct super_block *sb = inode->i_sb;
+	struct buffer_head *bh;
+	u32 ext_key;
+	u32 lc_idx, lc_off, ac_idx;
+	u32 tmp, idx;
+
+	if (ext == AFFS_I(inode)->i_ext_last + 1) {
+		/* read the next extended block from the current one */
+		bh = AFFS_I(inode)->i_ext_bh;
+		ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
+		if (ext < AFFS_I(inode)->i_extcnt)
+			goto read_ext;
+		BUG_ON(ext > AFFS_I(inode)->i_extcnt);
+		bh = affs_alloc_extblock(inode, bh, ext);
+		if (IS_ERR(bh))
+			return bh;
+		goto store_ext;
+	}
+
+	if (ext == 0) {
+		/* we seek back to the file header block */
+		ext_key = inode->i_ino;
+		goto read_ext;
+	}
+
+	if (ext >= AFFS_I(inode)->i_extcnt) {
+		struct buffer_head *prev_bh;
+
+		/* allocate a new extended block */
+		BUG_ON(ext > AFFS_I(inode)->i_extcnt);
+
+		/* get previous extended block */
+		prev_bh = affs_get_extblock(inode, ext - 1);
+		if (IS_ERR(prev_bh))
+			return prev_bh;
+		bh = affs_alloc_extblock(inode, prev_bh, ext);
+		affs_brelse(prev_bh);
+		if (IS_ERR(bh))
+			return bh;
+		goto store_ext;
+	}
+
+again:
+	/* check if there is an extended cache and whether it's large enough */
+	lc_idx = ext >> AFFS_I(inode)->i_lc_shift;
+	lc_off = ext & AFFS_I(inode)->i_lc_mask;
+
+	if (lc_idx >= AFFS_I(inode)->i_lc_size) {
+		int err;
+
+		err = affs_grow_extcache(inode, lc_idx);
+		if (err)
+			return ERR_PTR(err);
+		goto again;
+	}
+
+	/* every n'th key we find in the linear cache */
+	if (!lc_off) {
+		ext_key = AFFS_I(inode)->i_lc[lc_idx];
+		goto read_ext;
+	}
+
+	/* maybe it's still in the associative cache */
+	ac_idx = (ext - lc_idx - 1) & AFFS_AC_MASK;
+	if (AFFS_I(inode)->i_ac[ac_idx].ext == ext) {
+		ext_key = AFFS_I(inode)->i_ac[ac_idx].key;
+		goto read_ext;
+	}
+
+	/* try to find one of the previous extended blocks */
+	tmp = ext;
+	idx = ac_idx;
+	while (--tmp, --lc_off > 0) {
+		idx = (idx - 1) & AFFS_AC_MASK;
+		if (AFFS_I(inode)->i_ac[idx].ext == tmp) {
+			ext_key = AFFS_I(inode)->i_ac[idx].key;
+			goto find_ext;
+		}
+	}
+
+	/* fall back to the linear cache */
+	ext_key = AFFS_I(inode)->i_lc[lc_idx];
+find_ext:
+	/* read all extended blocks until we find the one we need */
+	//unlock cache
+	do {
+		bh = affs_bread(sb, ext_key);
+		if (!bh)
+			goto err_bread;
+		ext_key = be32_to_cpu(AFFS_TAIL(sb, bh)->extension);
+		affs_brelse(bh);
+		tmp++;
+	} while (tmp < ext);
+	//lock cache
+
+	/* store it in the associative cache */
+	// recalculate ac_idx?
+	AFFS_I(inode)->i_ac[ac_idx].ext = ext;
+	AFFS_I(inode)->i_ac[ac_idx].key = ext_key;
+
+read_ext:
+	/* finally read the right extended block */
+	//unlock cache
+	bh = affs_bread(sb, ext_key);
+	if (!bh)
+		goto err_bread;
+	//lock cache
+
+store_ext:
+	/* release old cached extended block and store the new one */
+	affs_brelse(AFFS_I(inode)->i_ext_bh);
+	AFFS_I(inode)->i_ext_last = ext;
+	AFFS_I(inode)->i_ext_bh = bh;
+	get_bh(bh);
+
+	return bh;
+
+err_bread:
+	affs_brelse(bh);
+	return ERR_PTR(-EIO);
+}
+
+static int
+affs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh_result, int create)
+{
+	struct super_block	*sb = inode->i_sb;
+	struct buffer_head	*ext_bh;
+	u32			 ext;
+
+	pr_debug("%s(%lu, %llu)\n", __func__, inode->i_ino,
+		 (unsigned long long)block);
+
+	BUG_ON(block > (sector_t)0x7fffffffUL);
+
+	if (block >= AFFS_I(inode)->i_blkcnt) {
+		if (block > AFFS_I(inode)->i_blkcnt || !create)
+			goto err_big;
+	} else
+		create = 0;
+
+	//lock cache
+	affs_lock_ext(inode);
+
+	ext = (u32)block / AFFS_SB(sb)->s_hashsize;
+	block -= ext * AFFS_SB(sb)->s_hashsize;
+	ext_bh = affs_get_extblock(inode, ext);
+	if (IS_ERR(ext_bh))
+		goto err_ext;
+	map_bh(bh_result, sb, (sector_t)be32_to_cpu(AFFS_BLOCK(sb, ext_bh, block)));
+
+	if (create) {
+		u32 blocknr = affs_alloc_block(inode, ext_bh->b_blocknr);
+		if (!blocknr)
+			goto err_alloc;
+		set_buffer_new(bh_result);
+		AFFS_I(inode)->mmu_private += AFFS_SB(sb)->s_data_blksize;
+		AFFS_I(inode)->i_blkcnt++;
+
+		/* store new block */
+		if (bh_result->b_blocknr)
+			affs_warning(sb, "get_block",
+				     "block already set (%llx)",
+				     (unsigned long long)bh_result->b_blocknr);
+		AFFS_BLOCK(sb, ext_bh, block) = cpu_to_be32(blocknr);
+		AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(block + 1);
+		affs_adjust_checksum(ext_bh, blocknr - bh_result->b_blocknr + 1);
+		bh_result->b_blocknr = blocknr;
+
+		if (!block) {
+			/* insert first block into header block */
+			u32 tmp = be32_to_cpu(AFFS_HEAD(ext_bh)->first_data);
+			if (tmp)
+				affs_warning(sb, "get_block", "first block already set (%d)", tmp);
+			AFFS_HEAD(ext_bh)->first_data = cpu_to_be32(blocknr);
+			affs_adjust_checksum(ext_bh, blocknr - tmp);
+		}
+	}
+
+	affs_brelse(ext_bh);
+	//unlock cache
+	affs_unlock_ext(inode);
+	return 0;
+
+err_big:
+	affs_error(inode->i_sb, "get_block", "strange block request %llu",
+		   (unsigned long long)block);
+	return -EIO;
+err_ext:
+	// unlock cache
+	affs_unlock_ext(inode);
+	return PTR_ERR(ext_bh);
+err_alloc:
+	brelse(ext_bh);
+	clear_buffer_mapped(bh_result);
+	bh_result->b_bdev = NULL;
+	// unlock cache
+	affs_unlock_ext(inode);
+	return -ENOSPC;
+}
+
+static int affs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	return block_write_full_page(page, affs_get_block, wbc);
+}
+
+static int affs_read_folio(struct file *file, struct folio *folio)
+{
+	return block_read_full_folio(folio, affs_get_block);
+}
+
+static void affs_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);
+		affs_truncate(inode);
+	}
+}
+
+static ssize_t
+affs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
+{
+	struct file *file = iocb->ki_filp;
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
+	size_t count = iov_iter_count(iter);
+	loff_t offset = iocb->ki_pos;
+	ssize_t ret;
+
+	if (iov_iter_rw(iter) == WRITE) {
+		loff_t size = offset + count;
+
+		if (AFFS_I(inode)->mmu_private < size)
+			return 0;
+	}
+
+	ret = blockdev_direct_IO(iocb, inode, iter, affs_get_block);
+	if (ret < 0 && iov_iter_rw(iter) == WRITE)
+		affs_write_failed(mapping, offset + count);
+	return ret;
+}
+
+static int affs_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,
+				affs_get_block,
+				&AFFS_I(mapping->host)->mmu_private);
+	if (unlikely(ret))
+		affs_write_failed(mapping, pos + len);
+
+	return ret;
+}
+
+static int affs_write_end(struct file *file, struct address_space *mapping,
+			  loff_t pos, unsigned int len, unsigned int copied,
+			  struct page *page, void *fsdata)
+{
+	struct inode *inode = mapping->host;
+	int ret;
+
+	ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
+
+	/* Clear Archived bit on file writes, as AmigaOS would do */
+	if (AFFS_I(inode)->i_protect & FIBF_ARCHIVED) {
+		AFFS_I(inode)->i_protect &= ~FIBF_ARCHIVED;
+		mark_inode_dirty(inode);
+	}
+
+	return ret;
+}
+
+static sector_t _affs_bmap(struct address_space *mapping, sector_t block)
+{
+	return generic_block_bmap(mapping,block,affs_get_block);
+}
+
+const struct address_space_operations affs_aops = {
+	.dirty_folio	= block_dirty_folio,
+	.invalidate_folio = block_invalidate_folio,
+	.read_folio = affs_read_folio,
+	.writepage = affs_writepage,
+	.write_begin = affs_write_begin,
+	.write_end = affs_write_end,
+	.direct_IO = affs_direct_IO,
+	.bmap = _affs_bmap
+};
+
+static inline struct buffer_head *
+affs_bread_ino(struct inode *inode, int block, int create)
+{
+	struct buffer_head *bh, tmp_bh;
+	int err;
+
+	tmp_bh.b_state = 0;
+	err = affs_get_block(inode, block, &tmp_bh, create);
+	if (!err) {
+		bh = affs_bread(inode->i_sb, tmp_bh.b_blocknr);
+		if (bh) {
+			bh->b_state |= tmp_bh.b_state;
+			return bh;
+		}
+		err = -EIO;
+	}
+	return ERR_PTR(err);
+}
+
+static inline struct buffer_head *
+affs_getzeroblk_ino(struct inode *inode, int block)
+{
+	struct buffer_head *bh, tmp_bh;
+	int err;
+
+	tmp_bh.b_state = 0;
+	err = affs_get_block(inode, block, &tmp_bh, 1);
+	if (!err) {
+		bh = affs_getzeroblk(inode->i_sb, tmp_bh.b_blocknr);
+		if (bh) {
+			bh->b_state |= tmp_bh.b_state;
+			return bh;
+		}
+		err = -EIO;
+	}
+	return ERR_PTR(err);
+}
+
+static inline struct buffer_head *
+affs_getemptyblk_ino(struct inode *inode, int block)
+{
+	struct buffer_head *bh, tmp_bh;
+	int err;
+
+	tmp_bh.b_state = 0;
+	err = affs_get_block(inode, block, &tmp_bh, 1);
+	if (!err) {
+		bh = affs_getemptyblk(inode->i_sb, tmp_bh.b_blocknr);
+		if (bh) {
+			bh->b_state |= tmp_bh.b_state;
+			return bh;
+		}
+		err = -EIO;
+	}
+	return ERR_PTR(err);
+}
+
+static int
+affs_do_readpage_ofs(struct page *page, unsigned to, int create)
+{
+	struct inode *inode = page->mapping->host;
+	struct super_block *sb = inode->i_sb;
+	struct buffer_head *bh;
+	unsigned pos = 0;
+	u32 bidx, boff, bsize;
+	u32 tmp;
+
+	pr_debug("%s(%lu, %ld, 0, %d)\n", __func__, inode->i_ino,
+		 page->index, to);
+	BUG_ON(to > PAGE_SIZE);
+	bsize = AFFS_SB(sb)->s_data_blksize;
+	tmp = page->index << PAGE_SHIFT;
+	bidx = tmp / bsize;
+	boff = tmp % bsize;
+
+	while (pos < to) {
+		bh = affs_bread_ino(inode, bidx, create);
+		if (IS_ERR(bh))
+			return PTR_ERR(bh);
+		tmp = min(bsize - boff, to - pos);
+		BUG_ON(pos + tmp > to || tmp > bsize);
+		memcpy_to_page(page, pos, AFFS_DATA(bh) + boff, tmp);
+		affs_brelse(bh);
+		bidx++;
+		pos += tmp;
+		boff = 0;
+	}
+	return 0;
+}
+
+static int
+affs_extent_file_ofs(struct inode *inode, u32 newsize)
+{
+	struct super_block *sb = inode->i_sb;
+	struct buffer_head *bh, *prev_bh;
+	u32 bidx, boff;
+	u32 size, bsize;
+	u32 tmp;
+
+	pr_debug("%s(%lu, %d)\n", __func__, inode->i_ino, newsize);
+	bsize = AFFS_SB(sb)->s_data_blksize;
+	bh = NULL;
+	size = AFFS_I(inode)->mmu_private;
+	bidx = size / bsize;
+	boff = size % bsize;
+	if (boff) {
+		bh = affs_bread_ino(inode, bidx, 0);
+		if (IS_ERR(bh))
+			return PTR_ERR(bh);
+		tmp = min(bsize - boff, newsize - size);
+		BUG_ON(boff + tmp > bsize || tmp > bsize);
+		memset(AFFS_DATA(bh) + boff, 0, tmp);
+		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
+		affs_fix_checksum(sb, bh);
+		mark_buffer_dirty_inode(bh, inode);
+		size += tmp;
+		bidx++;
+	} else if (bidx) {
+		bh = affs_bread_ino(inode, bidx - 1, 0);
+		if (IS_ERR(bh))
+			return PTR_ERR(bh);
+	}
+
+	while (size < newsize) {
+		prev_bh = bh;
+		bh = affs_getzeroblk_ino(inode, bidx);
+		if (IS_ERR(bh))
+			goto out;
+		tmp = min(bsize, newsize - size);
+		BUG_ON(tmp > bsize);
+		AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
+		AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
+		AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
+		AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
+		affs_fix_checksum(sb, bh);
+		bh->b_state &= ~(1UL << BH_New);
+		mark_buffer_dirty_inode(bh, inode);
+		if (prev_bh) {
+			u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
+
+			if (tmp_next)
+				affs_warning(sb, "extent_file_ofs",
+					     "next block already set for %d (%d)",
+					     bidx, tmp_next);
+			AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
+			affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
+			mark_buffer_dirty_inode(prev_bh, inode);
+			affs_brelse(prev_bh);
+		}
+		size += bsize;
+		bidx++;
+	}
+	affs_brelse(bh);
+	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
+	return 0;
+
+out:
+	inode->i_size = AFFS_I(inode)->mmu_private = newsize;
+	return PTR_ERR(bh);
+}
+
+static int
+affs_read_folio_ofs(struct file *file, struct folio *folio)
+{
+	struct page *page = &folio->page;
+	struct inode *inode = page->mapping->host;
+	u32 to;
+	int err;
+
+	pr_debug("%s(%lu, %ld)\n", __func__, inode->i_ino, page->index);
+	to = PAGE_SIZE;
+	if (((page->index + 1) << PAGE_SHIFT) > inode->i_size) {
+		to = inode->i_size & ~PAGE_MASK;
+		memset(page_address(page) + to, 0, PAGE_SIZE - to);
+	}
+
+	err = affs_do_readpage_ofs(page, to, 0);
+	if (!err)
+		SetPageUptodate(page);
+	unlock_page(page);
+	return err;
+}
+
+static int affs_write_begin_ofs(struct file *file, struct address_space *mapping,
+				loff_t pos, unsigned len,
+				struct page **pagep, void **fsdata)
+{
+	struct inode *inode = mapping->host;
+	struct page *page;
+	pgoff_t index;
+	int err = 0;
+
+	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
+		 pos + len);
+	if (pos > AFFS_I(inode)->mmu_private) {
+		/* XXX: this probably leaves a too-big i_size in case of
+		 * failure. Should really be updating i_size at write_end time
+		 */
+		err = affs_extent_file_ofs(inode, pos);
+		if (err)
+			return err;
+	}
+
+	index = pos >> PAGE_SHIFT;
+	page = grab_cache_page_write_begin(mapping, index);
+	if (!page)
+		return -ENOMEM;
+	*pagep = page;
+
+	if (PageUptodate(page))
+		return 0;
+
+	/* XXX: inefficient but safe in the face of short writes */
+	err = affs_do_readpage_ofs(page, PAGE_SIZE, 1);
+	if (err) {
+		unlock_page(page);
+		put_page(page);
+	}
+	return err;
+}
+
+static int affs_write_end_ofs(struct file *file, struct address_space *mapping,
+				loff_t pos, unsigned len, unsigned copied,
+				struct page *page, void *fsdata)
+{
+	struct inode *inode = mapping->host;
+	struct super_block *sb = inode->i_sb;
+	struct buffer_head *bh, *prev_bh;
+	char *data;
+	u32 bidx, boff, bsize;
+	unsigned from, to;
+	u32 tmp;
+	int written;
+
+	from = pos & (PAGE_SIZE - 1);
+	to = from + len;
+	/*
+	 * XXX: not sure if this can handle short copies (len < copied), but
+	 * we don't have to, because the page should always be uptodate here,
+	 * due to write_begin.
+	 */
+
+	pr_debug("%s(%lu, %llu, %llu)\n", __func__, inode->i_ino, pos,
+		 pos + len);
+	bsize = AFFS_SB(sb)->s_data_blksize;
+	data = page_address(page);
+
+	bh = NULL;
+	written = 0;
+	tmp = (page->index << PAGE_SHIFT) + from;
+	bidx = tmp / bsize;
+	boff = tmp % bsize;
+	if (boff) {
+		bh = affs_bread_ino(inode, bidx, 0);
+		if (IS_ERR(bh)) {
+			written = PTR_ERR(bh);
+			goto err_first_bh;
+		}
+		tmp = min(bsize - boff, to - from);
+		BUG_ON(boff + tmp > bsize || tmp > bsize);
+		memcpy(AFFS_DATA(bh) + boff, data + from, tmp);
+		be32_add_cpu(&AFFS_DATA_HEAD(bh)->size, tmp);
+		affs_fix_checksum(sb, bh);
+		mark_buffer_dirty_inode(bh, inode);
+		written += tmp;
+		from += tmp;
+		bidx++;
+	} else if (bidx) {
+		bh = affs_bread_ino(inode, bidx - 1, 0);
+		if (IS_ERR(bh)) {
+			written = PTR_ERR(bh);
+			goto err_first_bh;
+		}
+	}
+	while (from + bsize <= to) {
+		prev_bh = bh;
+		bh = affs_getemptyblk_ino(inode, bidx);
+		if (IS_ERR(bh))
+			goto err_bh;
+		memcpy(AFFS_DATA(bh), data + from, bsize);
+		if (buffer_new(bh)) {
+			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
+			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
+			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
+			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize);
+			AFFS_DATA_HEAD(bh)->next = 0;
+			bh->b_state &= ~(1UL << BH_New);
+			if (prev_bh) {
+				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
+
+				if (tmp_next)
+					affs_warning(sb, "commit_write_ofs",
+						     "next block already set for %d (%d)",
+						     bidx, tmp_next);
+				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
+				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
+				mark_buffer_dirty_inode(prev_bh, inode);
+			}
+		}
+		affs_brelse(prev_bh);
+		affs_fix_checksum(sb, bh);
+		mark_buffer_dirty_inode(bh, inode);
+		written += bsize;
+		from += bsize;
+		bidx++;
+	}
+	if (from < to) {
+		prev_bh = bh;
+		bh = affs_bread_ino(inode, bidx, 1);
+		if (IS_ERR(bh))
+			goto err_bh;
+		tmp = min(bsize, to - from);
+		BUG_ON(tmp > bsize);
+		memcpy(AFFS_DATA(bh), data + from, tmp);
+		if (buffer_new(bh)) {
+			AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA);
+			AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino);
+			AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx);
+			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
+			AFFS_DATA_HEAD(bh)->next = 0;
+			bh->b_state &= ~(1UL << BH_New);
+			if (prev_bh) {
+				u32 tmp_next = be32_to_cpu(AFFS_DATA_HEAD(prev_bh)->next);
+
+				if (tmp_next)
+					affs_warning(sb, "commit_write_ofs",
+						     "next block already set for %d (%d)",
+						     bidx, tmp_next);
+				AFFS_DATA_HEAD(prev_bh)->next = cpu_to_be32(bh->b_blocknr);
+				affs_adjust_checksum(prev_bh, bh->b_blocknr - tmp_next);
+				mark_buffer_dirty_inode(prev_bh, inode);
+			}
+		} else if (be32_to_cpu(AFFS_DATA_HEAD(bh)->size) < tmp)
+			AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp);
+		affs_brelse(prev_bh);
+		affs_fix_checksum(sb, bh);
+		mark_buffer_dirty_inode(bh, inode);
+		written += tmp;
+		from += tmp;
+		bidx++;
+	}
+	SetPageUptodate(page);
+
+done:
+	affs_brelse(bh);
+	tmp = (page->index << PAGE_SHIFT) + from;
+	if (tmp > inode->i_size)
+		inode->i_size = AFFS_I(inode)->mmu_private = tmp;
+
+	/* Clear Archived bit on file writes, as AmigaOS would do */
+	if (AFFS_I(inode)->i_protect & FIBF_ARCHIVED) {
+		AFFS_I(inode)->i_protect &= ~FIBF_ARCHIVED;
+		mark_inode_dirty(inode);
+	}
+
+err_first_bh:
+	unlock_page(page);
+	put_page(page);
+
+	return written;
+
+err_bh:
+	bh = prev_bh;
+	if (!written)
+		written = PTR_ERR(bh);
+	goto done;
+}
+
+const struct address_space_operations affs_aops_ofs = {
+	.dirty_folio	= block_dirty_folio,
+	.invalidate_folio = block_invalidate_folio,
+	.read_folio = affs_read_folio_ofs,
+	//.writepage = affs_writepage_ofs,
+	.write_begin = affs_write_begin_ofs,
+	.write_end = affs_write_end_ofs
+};
+
+/* Free any preallocated blocks. */
+
+void
+affs_free_prealloc(struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+
+	pr_debug("free_prealloc(ino=%lu)\n", inode->i_ino);
+
+	while (AFFS_I(inode)->i_pa_cnt) {
+		AFFS_I(inode)->i_pa_cnt--;
+		affs_free_block(sb, ++AFFS_I(inode)->i_lastalloc);
+	}
+}
+
+/* Truncate (or enlarge) a file to the requested size. */
+
+void
+affs_truncate(struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+	u32 ext, ext_key;
+	u32 last_blk, blkcnt, blk;
+	u32 size;
+	struct buffer_head *ext_bh;
+	int i;
+
+	pr_debug("truncate(inode=%lu, oldsize=%llu, newsize=%llu)\n",
+		 inode->i_ino, AFFS_I(inode)->mmu_private, inode->i_size);
+
+	last_blk = 0;
+	ext = 0;
+	if (inode->i_size) {
+		last_blk = ((u32)inode->i_size - 1) / AFFS_SB(sb)->s_data_blksize;
+		ext = last_blk / AFFS_SB(sb)->s_hashsize;
+	}
+
+	if (inode->i_size > AFFS_I(inode)->mmu_private) {
+		struct address_space *mapping = inode->i_mapping;
+		struct page *page;
+		void *fsdata = NULL;
+		loff_t isize = inode->i_size;
+		int res;
+
+		res = mapping->a_ops->write_begin(NULL, mapping, isize, 0, &page, &fsdata);
+		if (!res)
+			res = mapping->a_ops->write_end(NULL, mapping, isize, 0, 0, page, fsdata);
+		else
+			inode->i_size = AFFS_I(inode)->mmu_private;
+		mark_inode_dirty(inode);
+		return;
+	} else if (inode->i_size == AFFS_I(inode)->mmu_private)
+		return;
+
+	// lock cache
+	ext_bh = affs_get_extblock(inode, ext);
+	if (IS_ERR(ext_bh)) {
+		affs_warning(sb, "truncate",
+			     "unexpected read error for ext block %u (%ld)",
+			     ext, PTR_ERR(ext_bh));
+		return;
+	}
+	if (AFFS_I(inode)->i_lc) {
+		/* clear linear cache */
+		i = (ext + 1) >> AFFS_I(inode)->i_lc_shift;
+		if (AFFS_I(inode)->i_lc_size > i) {
+			AFFS_I(inode)->i_lc_size = i;
+			for (; i < AFFS_LC_SIZE; i++)
+				AFFS_I(inode)->i_lc[i] = 0;
+		}
+		/* clear associative cache */
+		for (i = 0; i < AFFS_AC_SIZE; i++)
+			if (AFFS_I(inode)->i_ac[i].ext >= ext)
+				AFFS_I(inode)->i_ac[i].ext = 0;
+	}
+	ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
+
+	blkcnt = AFFS_I(inode)->i_blkcnt;
+	i = 0;
+	blk = last_blk;
+	if (inode->i_size) {
+		i = last_blk % AFFS_SB(sb)->s_hashsize + 1;
+		blk++;
+	} else
+		AFFS_HEAD(ext_bh)->first_data = 0;
+	AFFS_HEAD(ext_bh)->block_count = cpu_to_be32(i);
+	size = AFFS_SB(sb)->s_hashsize;
+	if (size > blkcnt - blk + i)
+		size = blkcnt - blk + i;
+	for (; i < size; i++, blk++) {
+		affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
+		AFFS_BLOCK(sb, ext_bh, i) = 0;
+	}
+	AFFS_TAIL(sb, ext_bh)->extension = 0;
+	affs_fix_checksum(sb, ext_bh);
+	mark_buffer_dirty_inode(ext_bh, inode);
+	affs_brelse(ext_bh);
+
+	if (inode->i_size) {
+		AFFS_I(inode)->i_blkcnt = last_blk + 1;
+		AFFS_I(inode)->i_extcnt = ext + 1;
+		if (affs_test_opt(AFFS_SB(sb)->s_flags, SF_OFS)) {
+			struct buffer_head *bh = affs_bread_ino(inode, last_blk, 0);
+			u32 tmp;
+			if (IS_ERR(bh)) {
+				affs_warning(sb, "truncate",
+					     "unexpected read error for last block %u (%ld)",
+					     ext, PTR_ERR(bh));
+				return;
+			}
+			tmp = be32_to_cpu(AFFS_DATA_HEAD(bh)->next);
+			AFFS_DATA_HEAD(bh)->next = 0;
+			affs_adjust_checksum(bh, -tmp);
+			affs_brelse(bh);
+		}
+	} else {
+		AFFS_I(inode)->i_blkcnt = 0;
+		AFFS_I(inode)->i_extcnt = 1;
+	}
+	AFFS_I(inode)->mmu_private = inode->i_size;
+	// unlock cache
+
+	while (ext_key) {
+		ext_bh = affs_bread(sb, ext_key);
+		size = AFFS_SB(sb)->s_hashsize;
+		if (size > blkcnt - blk)
+			size = blkcnt - blk;
+		for (i = 0; i < size; i++, blk++)
+			affs_free_block(sb, be32_to_cpu(AFFS_BLOCK(sb, ext_bh, i)));
+		affs_free_block(sb, ext_key);
+		ext_key = be32_to_cpu(AFFS_TAIL(sb, ext_bh)->extension);
+		affs_brelse(ext_bh);
+	}
+	affs_free_prealloc(inode);
+}
+
+int affs_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
+{
+	struct inode *inode = filp->f_mapping->host;
+	int ret, err;
+
+	err = file_write_and_wait_range(filp, start, end);
+	if (err)
+		return err;
+
+	inode_lock(inode);
+	ret = write_inode_now(inode, 0);
+	err = sync_blockdev(inode->i_sb->s_bdev);
+	if (!ret)
+		ret = err;
+	inode_unlock(inode);
+	return ret;
+}
+const struct file_operations affs_file_operations = {
+	.llseek		= generic_file_llseek,
+	.read_iter	= generic_file_read_iter,
+	.write_iter	= generic_file_write_iter,
+	.mmap		= generic_file_mmap,
+	.open		= affs_file_open,
+	.release	= affs_file_release,
+	.fsync		= affs_file_fsync,
+	.splice_read	= generic_file_splice_read,
+};
+
+const struct inode_operations affs_file_inode_operations = {
+	.setattr	= affs_notify_change,
+};