From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001 From: root Date: Fri, 25 Dec 2015 04:40:36 +0000 Subject: initial_commit --- fs/efs/inode.c | 313 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 313 insertions(+) create mode 100644 fs/efs/inode.c (limited to 'fs/efs/inode.c') diff --git a/fs/efs/inode.c b/fs/efs/inode.c new file mode 100644 index 00000000..9c13412e --- /dev/null +++ b/fs/efs/inode.c @@ -0,0 +1,313 @@ +/* + * inode.c + * + * Copyright (c) 1999 Al Smith + * + * Portions derived from work (c) 1995,1996 Christian Vogelgsang, + * and from work (c) 1998 Mike Shaver. + */ + +#include +#include +#include +#include "efs.h" +#include + +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"); -- cgit v1.2.3