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313 lines
8.4 KiB
313 lines
8.4 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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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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