// 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_read_folio(struct file *file, struct folio *folio) { return block_read_full_folio(folio, 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, struct page **pagep, void **fsdata) { int ret; ret = block_write_begin(mapping, pos, len, 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 user_namespace *mnt_userns, struct dentry *dentry, struct iattr *attr) { struct inode *inode = d_inode(dentry); int error; error = setattr_prepare(&init_user_ns, 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(&init_user_ns, 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 = { .dirty_folio = block_dirty_folio, .invalidate_folio = block_invalidate_folio, .read_folio = omfs_read_folio, .readahead = omfs_readahead, .writepage = omfs_writepage, .writepages = omfs_writepages, .write_begin = omfs_write_begin, .write_end = generic_write_end, .bmap = omfs_bmap, };