1 files changed, 382 insertions, 0 deletions
diff --git a/fs/omfs/file.c b/fs/omfs/file.c
new file mode 100644
index 000000000..2c7b70ee1
--- /dev/null
+++ b/fs/omfs/file.c
@@ -0,0 +1,382 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * OMFS (as used by RIO Karma) file operations.
+ * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/buffer_head.h>
+#include <linux/mpage.h>
+#include "omfs.h"
+
+static u32 omfs_max_extents(struct omfs_sb_info *sbi, int offset)
+{
+	return (sbi->s_sys_blocksize - offset -
+		sizeof(struct omfs_extent)) /
+		sizeof(struct omfs_extent_entry) + 1;
+}
+
+void omfs_make_empty_table(struct buffer_head *bh, int offset)
+{
+	struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];
+
+	oe->e_next = ~cpu_to_be64(0ULL);
+	oe->e_extent_count = cpu_to_be32(1),
+	oe->e_fill = cpu_to_be32(0x22),
+	oe->e_entry.e_cluster = ~cpu_to_be64(0ULL);
+	oe->e_entry.e_blocks = ~cpu_to_be64(0ULL);
+}
+
+int omfs_shrink_inode(struct inode *inode)
+{
+	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
+	struct omfs_extent *oe;
+	struct omfs_extent_entry *entry;
+	struct buffer_head *bh;
+	u64 next, last;
+	u32 extent_count;
+	u32 max_extents;
+	int ret;
+
+	/* traverse extent table, freeing each entry that is greater
+	 * than inode->i_size;
+	 */
+	next = inode->i_ino;
+
+	/* only support truncate -> 0 for now */
+	ret = -EIO;
+	if (inode->i_size != 0)
+		goto out;
+
+	bh = omfs_bread(inode->i_sb, next);
+	if (!bh)
+		goto out;
+
+	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
+	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
+
+	for (;;) {
+
+		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
+			goto out_brelse;
+
+		extent_count = be32_to_cpu(oe->e_extent_count);
+
+		if (extent_count > max_extents)
+			goto out_brelse;
+
+		last = next;
+		next = be64_to_cpu(oe->e_next);
+		entry = &oe->e_entry;
+
+		/* ignore last entry as it is the terminator */
+		for (; extent_count > 1; extent_count--) {
+			u64 start, count;
+			start = be64_to_cpu(entry->e_cluster);
+			count = be64_to_cpu(entry->e_blocks);
+
+			omfs_clear_range(inode->i_sb, start, (int) count);
+			entry++;
+		}
+		omfs_make_empty_table(bh, (char *) oe - bh->b_data);
+		mark_buffer_dirty(bh);
+		brelse(bh);
+
+		if (last != inode->i_ino)
+			omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);
+
+		if (next == ~0)
+			break;
+
+		bh = omfs_bread(inode->i_sb, next);
+		if (!bh)
+			goto out;
+		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
+		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
+	}
+	ret = 0;
+out:
+	return ret;
+out_brelse:
+	brelse(bh);
+	return ret;
+}
+
+static void omfs_truncate(struct inode *inode)
+{
+	omfs_shrink_inode(inode);
+	mark_inode_dirty(inode);
+}
+
+/*
+ * Add new blocks to the current extent, or create new entries/continuations
+ * as necessary.
+ */
+static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,
+			u64 *ret_block)
+{
+	struct omfs_extent_entry *terminator;
+	struct omfs_extent_entry *entry = &oe->e_entry;
+	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
+	u32 extent_count = be32_to_cpu(oe->e_extent_count);
+	u64 new_block = 0;
+	u32 max_count;
+	int new_count;
+	int ret = 0;
+
+	/* reached the end of the extent table with no blocks mapped.
+	 * there are three possibilities for adding: grow last extent,
+	 * add a new extent to the current extent table, and add a
+	 * continuation inode.  in last two cases need an allocator for
+	 * sbi->s_cluster_size
+	 */
+
+	/* TODO: handle holes */
+
+	/* should always have a terminator */
+	if (extent_count < 1)
+		return -EIO;
+
+	/* trivially grow current extent, if next block is not taken */
+	terminator = entry + extent_count - 1;
+	if (extent_count > 1) {
+		entry = terminator-1;
+		new_block = be64_to_cpu(entry->e_cluster) +
+			be64_to_cpu(entry->e_blocks);
+
+		if (omfs_allocate_block(inode->i_sb, new_block)) {
+			be64_add_cpu(&entry->e_blocks, 1);
+			terminator->e_blocks = ~(cpu_to_be64(
+				be64_to_cpu(~terminator->e_blocks) + 1));
+			goto out;
+		}
+	}
+	max_count = omfs_max_extents(sbi, OMFS_EXTENT_START);
+
+	/* TODO: add a continuation block here */
+	if (be32_to_cpu(oe->e_extent_count) > max_count-1)
+		return -EIO;
+
+	/* try to allocate a new cluster */
+	ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,
+		&new_block, &new_count);
+	if (ret)
+		goto out_fail;
+
+	/* copy terminator down an entry */
+	entry = terminator;
+	terminator++;
+	memcpy(terminator, entry, sizeof(struct omfs_extent_entry));
+
+	entry->e_cluster = cpu_to_be64(new_block);
+	entry->e_blocks = cpu_to_be64((u64) new_count);
+
+	terminator->e_blocks = ~(cpu_to_be64(
+		be64_to_cpu(~terminator->e_blocks) + (u64) new_count));
+
+	/* write in new entry */
+	be32_add_cpu(&oe->e_extent_count, 1);
+
+out:
+	*ret_block = new_block;
+out_fail:
+	return ret;
+}
+
+/*
+ * Scans across the directory table for a given file block number.
+ * If block not found, return 0.
+ */
+static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,
+			sector_t block, int count, int *left)
+{
+	/* count > 1 because of terminator */
+	sector_t searched = 0;
+	for (; count > 1; count--) {
+		int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),
+			be64_to_cpu(ent->e_blocks));
+
+		if (block >= searched  &&
+		    block < searched + numblocks) {
+			/*
+			 * found it at cluster + (block - searched)
+			 * numblocks - (block - searched) is remainder
+			 */
+			*left = numblocks - (block - searched);
+			return clus_to_blk(OMFS_SB(inode->i_sb),
+				be64_to_cpu(ent->e_cluster)) +
+				block - searched;
+		}
+		searched += numblocks;
+		ent++;
+	}
+	return 0;
+}
+
+static int omfs_get_block(struct inode *inode, sector_t block,
+			  struct buffer_head *bh_result, int create)
+{
+	struct buffer_head *bh;
+	sector_t next, offset;
+	int ret;
+	u64 new_block;
+	u32 max_extents;
+	int extent_count;
+	struct omfs_extent *oe;
+	struct omfs_extent_entry *entry;
+	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
+	int max_blocks = bh_result->b_size >> inode->i_blkbits;
+	int remain;
+
+	ret = -EIO;
+	bh = omfs_bread(inode->i_sb, inode->i_ino);
+	if (!bh)
+		goto out;
+
+	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);
+	max_extents = omfs_max_extents(sbi, OMFS_EXTENT_START);
+	next = inode->i_ino;
+
+	for (;;) {
+
+		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))
+			goto out_brelse;
+
+		extent_count = be32_to_cpu(oe->e_extent_count);
+		next = be64_to_cpu(oe->e_next);
+		entry = &oe->e_entry;
+
+		if (extent_count > max_extents)
+			goto out_brelse;
+
+		offset = find_block(inode, entry, block, extent_count, &remain);
+		if (offset > 0) {
+			ret = 0;
+			map_bh(bh_result, inode->i_sb, offset);
+			if (remain > max_blocks)
+				remain = max_blocks;
+			bh_result->b_size = (remain << inode->i_blkbits);
+			goto out_brelse;
+		}
+		if (next == ~0)
+			break;
+
+		brelse(bh);
+		bh = omfs_bread(inode->i_sb, next);
+		if (!bh)
+			goto out;
+		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);
+		max_extents = omfs_max_extents(sbi, OMFS_EXTENT_CONT);
+	}
+	if (create) {
+		ret = omfs_grow_extent(inode, oe, &new_block);
+		if (ret == 0) {
+			mark_buffer_dirty(bh);
+			mark_inode_dirty(inode);
+			map_bh(bh_result, inode->i_sb,
+					clus_to_blk(sbi, new_block));
+		}
+	}
+out_brelse:
+	brelse(bh);
+out:
+	return ret;
+}
+
+static int omfs_readpage(struct file *file, struct page *page)
+{
+	return block_read_full_page(page, omfs_get_block);
+}
+
+static void omfs_readahead(struct readahead_control *rac)
+{
+	mpage_readahead(rac, omfs_get_block);
+}
+
+static int omfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	return block_write_full_page(page, omfs_get_block, wbc);
+}
+
+static int
+omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
+{
+	return mpage_writepages(mapping, wbc, omfs_get_block);
+}
+
+static void omfs_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);
+		omfs_truncate(inode);
+	}
+}
+
+static int omfs_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata)
+{
+	int ret;
+
+	ret = block_write_begin(mapping, pos, len, flags, pagep,
+				omfs_get_block);
+	if (unlikely(ret))
+		omfs_write_failed(mapping, pos + len);
+
+	return ret;
+}
+
+static sector_t omfs_bmap(struct address_space *mapping, sector_t block)
+{
+	return generic_block_bmap(mapping, block, omfs_get_block);
+}
+
+const struct file_operations omfs_file_operations = {
+	.llseek = generic_file_llseek,
+	.read_iter = generic_file_read_iter,
+	.write_iter = generic_file_write_iter,
+	.mmap = generic_file_mmap,
+	.fsync = generic_file_fsync,
+	.splice_read = generic_file_splice_read,
+};
+
+static int omfs_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	struct inode *inode = d_inode(dentry);
+	int error;
+
+	error = setattr_prepare(dentry, attr);
+	if (error)
+		return error;
+
+	if ((attr->ia_valid & ATTR_SIZE) &&
+	    attr->ia_size != i_size_read(inode)) {
+		error = inode_newsize_ok(inode, attr->ia_size);
+		if (error)
+			return error;
+		truncate_setsize(inode, attr->ia_size);
+		omfs_truncate(inode);
+	}
+
+	setattr_copy(inode, attr);
+	mark_inode_dirty(inode);
+	return 0;
+}
+
+const struct inode_operations omfs_file_inops = {
+	.setattr = omfs_setattr,
+};
+
+const struct address_space_operations omfs_aops = {
+	.readpage = omfs_readpage,
+	.readahead = omfs_readahead,
+	.writepage = omfs_writepage,
+	.writepages = omfs_writepages,
+	.write_begin = omfs_write_begin,
+	.write_end = generic_write_end,
+	.bmap = omfs_bmap,
+};
+