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