/* * inode.c * * Copyright (c) 1999 Al Smith * * Portions derived from work (c) 1995,1996 Christian Vogelgsang, * and from work (c) 1998 Mike Shaver. */ #include <linux/buffer_head.h> #include <linux/module.h> #include <linux/fs.h> #include "efs.h" #include <linux/efs_fs_sb.h> static int efs_readpage(struct file *file, struct page *page) { return block_read_full_page(page,efs_get_block); } static sector_t _efs_bmap(struct address_space *mapping, sector_t block) { return generic_block_bmap(mapping,block,efs_get_block); } static const struct address_space_operations efs_aops = { .readpage = efs_readpage, .bmap = _efs_bmap }; static inline void extent_copy(efs_extent *src, efs_extent *dst) { /* * this is slightly evil. it doesn't just copy * efs_extent from src to dst, it also mangles * the bits so that dst ends up in cpu byte-order. */ dst->cooked.ex_magic = (unsigned int) src->raw[0]; dst->cooked.ex_bn = ((unsigned int) src->raw[1] << 16) | ((unsigned int) src->raw[2] << 8) | ((unsigned int) src->raw[3] << 0); dst->cooked.ex_length = (unsigned int) src->raw[4]; dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) | ((unsigned int) src->raw[6] << 8) | ((unsigned int) src->raw[7] << 0); return; } struct inode *efs_iget(struct super_block *super, unsigned long ino) { int i, inode_index; dev_t device; u32 rdev; struct buffer_head *bh; struct efs_sb_info *sb = SUPER_INFO(super); struct efs_inode_info *in; efs_block_t block, offset; struct efs_dinode *efs_inode; struct inode *inode; inode = iget_locked(super, ino); if (IS_ERR(inode)) return ERR_PTR(-ENOMEM); if (!(inode->i_state & I_NEW)) return inode; in = INODE_INFO(inode); /* ** EFS layout: ** ** | cylinder group | cylinder group | cylinder group ..etc ** |inodes|data |inodes|data |inodes|data ..etc ** ** work out the inode block index, (considering initially that the ** inodes are stored as consecutive blocks). then work out the block ** number of that inode given the above layout, and finally the ** offset of the inode within that block. */ inode_index = inode->i_ino / (EFS_BLOCKSIZE / sizeof(struct efs_dinode)); block = sb->fs_start + sb->first_block + (sb->group_size * (inode_index / sb->inode_blocks)) + (inode_index % sb->inode_blocks); offset = (inode->i_ino % (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) * sizeof(struct efs_dinode); bh = sb_bread(inode->i_sb, block); if (!bh) { printk(KERN_WARNING "EFS: bread() failed at block %d\n", block); goto read_inode_error; } efs_inode = (struct efs_dinode *) (bh->b_data + offset); inode->i_mode = be16_to_cpu(efs_inode->di_mode); inode->i_nlink = be16_to_cpu(efs_inode->di_nlink); inode->i_uid = (uid_t)be16_to_cpu(efs_inode->di_uid); inode->i_gid = (gid_t)be16_to_cpu(efs_inode->di_gid); inode->i_size = be32_to_cpu(efs_inode->di_size); inode->i_atime.tv_sec = be32_to_cpu(efs_inode->di_atime); inode->i_mtime.tv_sec = be32_to_cpu(efs_inode->di_mtime); inode->i_ctime.tv_sec = be32_to_cpu(efs_inode->di_ctime); inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0; /* this is the number of blocks in the file */ if (inode->i_size == 0) { inode->i_blocks = 0; } else { inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1; } rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev); if (rdev == 0xffff) { rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev); if (sysv_major(rdev) > 0xfff) device = 0; else device = MKDEV(sysv_major(rdev), sysv_minor(rdev)); } else device = old_decode_dev(rdev); /* get the number of extents for this object */ in->numextents = be16_to_cpu(efs_inode->di_numextents); in->lastextent = 0; /* copy the extents contained within the inode to memory */ for(i = 0; i < EFS_DIRECTEXTENTS; i++) { extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i])); if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) { printk(KERN_WARNING "EFS: extent %d has bad magic number in inode %lu\n", i, inode->i_ino); brelse(bh); goto read_inode_error; } } brelse(bh); #ifdef DEBUG printk(KERN_DEBUG "EFS: efs_iget(): inode %lu, extents %d, mode %o\n", inode->i_ino, in->numextents, inode->i_mode); #endif switch (inode->i_mode & S_IFMT) { case S_IFDIR: inode->i_op = &efs_dir_inode_operations; inode->i_fop = &efs_dir_operations; break; case S_IFREG: inode->i_fop = &generic_ro_fops; inode->i_data.a_ops = &efs_aops; break; case S_IFLNK: inode->i_op = &page_symlink_inode_operations; inode->i_data.a_ops = &efs_symlink_aops; break; case S_IFCHR: case S_IFBLK: case S_IFIFO: init_special_inode(inode, inode->i_mode, device); break; default: printk(KERN_WARNING "EFS: unsupported inode mode %o\n", inode->i_mode); goto read_inode_error; break; } unlock_new_inode(inode); return inode; read_inode_error: printk(KERN_WARNING "EFS: failed to read inode %lu\n", inode->i_ino); iget_failed(inode); return ERR_PTR(-EIO); } static inline efs_block_t efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) { efs_block_t start; efs_block_t length; efs_block_t offset; /* * given an extent and a logical block within a file, * can this block be found within this extent ? */ start = ptr->cooked.ex_bn; length = ptr->cooked.ex_length; offset = ptr->cooked.ex_offset; if ((block >= offset) && (block < offset+length)) { return(sb->fs_start + start + block - offset); } else { return 0; } } efs_block_t efs_map_block(struct inode *inode, efs_block_t block) { struct efs_sb_info *sb = SUPER_INFO(inode->i_sb); struct efs_inode_info *in = INODE_INFO(inode); struct buffer_head *bh = NULL; int cur, last, first = 1; int ibase, ioffset, dirext, direxts, indext, indexts; efs_block_t iblock, result = 0, lastblock = 0; efs_extent ext, *exts; last = in->lastextent; if (in->numextents <= EFS_DIRECTEXTENTS) { /* first check the last extent we returned */ if ((result = efs_extent_check(&in->extents[last], block, sb))) return result; /* if we only have one extent then nothing can be found */ if (in->numextents == 1) { printk(KERN_ERR "EFS: map_block() failed to map (1 extent)\n"); return 0; } direxts = in->numextents; /* * check the stored extents in the inode * start with next extent and check forwards */ for(dirext = 1; dirext < direxts; dirext++) { cur = (last + dirext) % in->numextents; if ((result = efs_extent_check(&in->extents[cur], block, sb))) { in->lastextent = cur; return result; } } printk(KERN_ERR "EFS: map_block() failed to map block %u (dir)\n", block); return 0; } #ifdef DEBUG printk(KERN_DEBUG "EFS: map_block(): indirect search for logical block %u\n", block); #endif direxts = in->extents[0].cooked.ex_offset; indexts = in->numextents; for(indext = 0; indext < indexts; indext++) { cur = (last + indext) % indexts; /* * work out which direct extent contains `cur'. * * also compute ibase: i.e. the number of the first * indirect extent contained within direct extent `cur'. * */ ibase = 0; for(dirext = 0; cur < ibase && dirext < direxts; dirext++) { ibase += in->extents[dirext].cooked.ex_length * (EFS_BLOCKSIZE / sizeof(efs_extent)); } if (dirext == direxts) { /* should never happen */ printk(KERN_ERR "EFS: couldn't find direct extent for indirect extent %d (block %u)\n", cur, block); if (bh) brelse(bh); return 0; } /* work out block number and offset of this indirect extent */ iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn + (cur - ibase) / (EFS_BLOCKSIZE / sizeof(efs_extent)); ioffset = (cur - ibase) % (EFS_BLOCKSIZE / sizeof(efs_extent)); if (first || lastblock != iblock) { if (bh) brelse(bh); bh = sb_bread(inode->i_sb, iblock); if (!bh) { printk(KERN_ERR "EFS: bread() failed at block %d\n", iblock); return 0; } #ifdef DEBUG printk(KERN_DEBUG "EFS: map_block(): read indirect extent block %d\n", iblock); #endif first = 0; lastblock = iblock; } exts = (efs_extent *) bh->b_data; extent_copy(&(exts[ioffset]), &ext); if (ext.cooked.ex_magic != 0) { printk(KERN_ERR "EFS: extent %d has bad magic number in block %d\n", cur, iblock); if (bh) brelse(bh); return 0; } if ((result = efs_extent_check(&ext, block, sb))) { if (bh) brelse(bh); in->lastextent = cur; return result; } } if (bh) brelse(bh); printk(KERN_ERR "EFS: map_block() failed to map block %u (indir)\n", block); return 0; } MODULE_LICENSE("GPL");