--- /dev/null
+/*
+ * 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 (!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) {
+ pr_warn("%s() failed at block %d\n", __func__, block);
+ goto read_inode_error;
+ }
+
+ efs_inode = (struct efs_dinode *) (bh->b_data + offset);
+
+ inode->i_mode = be16_to_cpu(efs_inode->di_mode);
+ set_nlink(inode, be16_to_cpu(efs_inode->di_nlink));
+ i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid));
+ i_gid_write(inode, (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) {
+ pr_warn("extent %d has bad magic number in inode %lu\n",
+ i, inode->i_ino);
+ brelse(bh);
+ goto read_inode_error;
+ }
+ }
+
+ brelse(bh);
+ pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n",
+ inode->i_ino, in->numextents, inode->i_mode);
+ 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:
+ pr_warn("unsupported inode mode %o\n", inode->i_mode);
+ goto read_inode_error;
+ break;
+ }
+
+ unlock_new_inode(inode);
+ return inode;
+
+read_inode_error:
+ pr_warn("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) {
+ pr_err("%s() failed to map (1 extent)\n", __func__);
+ 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;
+ }
+ }
+
+ pr_err("%s() failed to map block %u (dir)\n", __func__, block);
+ return 0;
+ }
+
+ pr_debug("%s(): indirect search for logical block %u\n",
+ __func__, block);
+ 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 */
+ pr_err("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) {
+ pr_err("%s() failed at block %d\n",
+ __func__, iblock);
+ return 0;
+ }
+ pr_debug("%s(): read indirect extent block %d\n",
+ __func__, iblock);
+ first = 0;
+ lastblock = iblock;
+ }
+
+ exts = (efs_extent *) bh->b_data;
+
+ extent_copy(&(exts[ioffset]), &ext);
+
+ if (ext.cooked.ex_magic != 0) {
+ pr_err("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);
+ pr_err("%s() failed to map block %u (indir)\n", __func__, block);
+ return 0;
+}
+
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff