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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * inode.c4 *5 * Copyright (c) 1999 Al Smith6 *7 * Portions derived from work (c) 1995,1996 Christian Vogelgsang,8 * and from work (c) 1998 Mike Shaver.9 */10 11#include <linux/buffer_head.h>12#include <linux/module.h>13#include <linux/fs.h>14#include "efs.h"15#include <linux/efs_fs_sb.h>16 17static int efs_read_folio(struct file *file, struct folio *folio)18{19 return block_read_full_folio(folio, efs_get_block);20}21 22static sector_t _efs_bmap(struct address_space *mapping, sector_t block)23{24 return generic_block_bmap(mapping,block,efs_get_block);25}26 27static const struct address_space_operations efs_aops = {28 .read_folio = efs_read_folio,29 .bmap = _efs_bmap30};31 32static inline void extent_copy(efs_extent *src, efs_extent *dst) {33 /*34 * this is slightly evil. it doesn't just copy35 * efs_extent from src to dst, it also mangles36 * the bits so that dst ends up in cpu byte-order.37 */38 39 dst->cooked.ex_magic = (unsigned int) src->raw[0];40 dst->cooked.ex_bn = ((unsigned int) src->raw[1] << 16) |41 ((unsigned int) src->raw[2] << 8) |42 ((unsigned int) src->raw[3] << 0);43 dst->cooked.ex_length = (unsigned int) src->raw[4];44 dst->cooked.ex_offset = ((unsigned int) src->raw[5] << 16) |45 ((unsigned int) src->raw[6] << 8) |46 ((unsigned int) src->raw[7] << 0);47 return;48}49 50struct inode *efs_iget(struct super_block *super, unsigned long ino)51{52 int i, inode_index;53 dev_t device;54 u32 rdev;55 struct buffer_head *bh;56 struct efs_sb_info *sb = SUPER_INFO(super);57 struct efs_inode_info *in;58 efs_block_t block, offset;59 struct efs_dinode *efs_inode;60 struct inode *inode;61 62 inode = iget_locked(super, ino);63 if (!inode)64 return ERR_PTR(-ENOMEM);65 if (!(inode->i_state & I_NEW))66 return inode;67 68 in = INODE_INFO(inode);69 70 /*71 ** EFS layout:72 **73 ** | cylinder group | cylinder group | cylinder group ..etc74 ** |inodes|data |inodes|data |inodes|data ..etc75 **76 ** work out the inode block index, (considering initially that the77 ** inodes are stored as consecutive blocks). then work out the block78 ** number of that inode given the above layout, and finally the79 ** offset of the inode within that block.80 */81 82 inode_index = inode->i_ino /83 (EFS_BLOCKSIZE / sizeof(struct efs_dinode));84 85 block = sb->fs_start + sb->first_block + 86 (sb->group_size * (inode_index / sb->inode_blocks)) +87 (inode_index % sb->inode_blocks);88 89 offset = (inode->i_ino %90 (EFS_BLOCKSIZE / sizeof(struct efs_dinode))) *91 sizeof(struct efs_dinode);92 93 bh = sb_bread(inode->i_sb, block);94 if (!bh) {95 pr_warn("%s() failed at block %d\n", __func__, block);96 goto read_inode_error;97 }98 99 efs_inode = (struct efs_dinode *) (bh->b_data + offset);100 101 inode->i_mode = be16_to_cpu(efs_inode->di_mode);102 set_nlink(inode, be16_to_cpu(efs_inode->di_nlink));103 i_uid_write(inode, (uid_t)be16_to_cpu(efs_inode->di_uid));104 i_gid_write(inode, (gid_t)be16_to_cpu(efs_inode->di_gid));105 inode->i_size = be32_to_cpu(efs_inode->di_size);106 inode_set_atime(inode, be32_to_cpu(efs_inode->di_atime), 0);107 inode_set_mtime(inode, be32_to_cpu(efs_inode->di_mtime), 0);108 inode_set_ctime(inode, be32_to_cpu(efs_inode->di_ctime), 0);109 110 /* this is the number of blocks in the file */111 if (inode->i_size == 0) {112 inode->i_blocks = 0;113 } else {114 inode->i_blocks = ((inode->i_size - 1) >> EFS_BLOCKSIZE_BITS) + 1;115 }116 117 rdev = be16_to_cpu(efs_inode->di_u.di_dev.odev);118 if (rdev == 0xffff) {119 rdev = be32_to_cpu(efs_inode->di_u.di_dev.ndev);120 if (sysv_major(rdev) > 0xfff)121 device = 0;122 else123 device = MKDEV(sysv_major(rdev), sysv_minor(rdev));124 } else125 device = old_decode_dev(rdev);126 127 /* get the number of extents for this object */128 in->numextents = be16_to_cpu(efs_inode->di_numextents);129 in->lastextent = 0;130 131 /* copy the extents contained within the inode to memory */132 for(i = 0; i < EFS_DIRECTEXTENTS; i++) {133 extent_copy(&(efs_inode->di_u.di_extents[i]), &(in->extents[i]));134 if (i < in->numextents && in->extents[i].cooked.ex_magic != 0) {135 pr_warn("extent %d has bad magic number in inode %lu\n",136 i, inode->i_ino);137 brelse(bh);138 goto read_inode_error;139 }140 }141 142 brelse(bh);143 pr_debug("efs_iget(): inode %lu, extents %d, mode %o\n",144 inode->i_ino, in->numextents, inode->i_mode);145 switch (inode->i_mode & S_IFMT) {146 case S_IFDIR: 147 inode->i_op = &efs_dir_inode_operations; 148 inode->i_fop = &efs_dir_operations; 149 break;150 case S_IFREG:151 inode->i_fop = &generic_ro_fops;152 inode->i_data.a_ops = &efs_aops;153 break;154 case S_IFLNK:155 inode->i_op = &page_symlink_inode_operations;156 inode_nohighmem(inode);157 inode->i_data.a_ops = &efs_symlink_aops;158 break;159 case S_IFCHR:160 case S_IFBLK:161 case S_IFIFO:162 init_special_inode(inode, inode->i_mode, device);163 break;164 default:165 pr_warn("unsupported inode mode %o\n", inode->i_mode);166 goto read_inode_error;167 break;168 }169 170 unlock_new_inode(inode);171 return inode;172 173read_inode_error:174 pr_warn("failed to read inode %lu\n", inode->i_ino);175 iget_failed(inode);176 return ERR_PTR(-EIO);177}178 179static inline efs_block_t180efs_extent_check(efs_extent *ptr, efs_block_t block, struct efs_sb_info *sb) {181 efs_block_t start;182 efs_block_t length;183 efs_block_t offset;184 185 /*186 * given an extent and a logical block within a file,187 * can this block be found within this extent ?188 */189 start = ptr->cooked.ex_bn;190 length = ptr->cooked.ex_length;191 offset = ptr->cooked.ex_offset;192 193 if ((block >= offset) && (block < offset+length)) {194 return(sb->fs_start + start + block - offset);195 } else {196 return 0;197 }198}199 200efs_block_t efs_map_block(struct inode *inode, efs_block_t block) {201 struct efs_sb_info *sb = SUPER_INFO(inode->i_sb);202 struct efs_inode_info *in = INODE_INFO(inode);203 struct buffer_head *bh = NULL;204 205 int cur, last, first = 1;206 int ibase, ioffset, dirext, direxts, indext, indexts;207 efs_block_t iblock, result = 0, lastblock = 0;208 efs_extent ext, *exts;209 210 last = in->lastextent;211 212 if (in->numextents <= EFS_DIRECTEXTENTS) {213 /* first check the last extent we returned */214 if ((result = efs_extent_check(&in->extents[last], block, sb)))215 return result;216 217 /* if we only have one extent then nothing can be found */218 if (in->numextents == 1) {219 pr_err("%s() failed to map (1 extent)\n", __func__);220 return 0;221 }222 223 direxts = in->numextents;224 225 /*226 * check the stored extents in the inode227 * start with next extent and check forwards228 */229 for(dirext = 1; dirext < direxts; dirext++) {230 cur = (last + dirext) % in->numextents;231 if ((result = efs_extent_check(&in->extents[cur], block, sb))) {232 in->lastextent = cur;233 return result;234 }235 }236 237 pr_err("%s() failed to map block %u (dir)\n", __func__, block);238 return 0;239 }240 241 pr_debug("%s(): indirect search for logical block %u\n",242 __func__, block);243 direxts = in->extents[0].cooked.ex_offset;244 indexts = in->numextents;245 246 for(indext = 0; indext < indexts; indext++) {247 cur = (last + indext) % indexts;248 249 /*250 * work out which direct extent contains `cur'.251 *252 * also compute ibase: i.e. the number of the first253 * indirect extent contained within direct extent `cur'.254 *255 */256 ibase = 0;257 for(dirext = 0; cur < ibase && dirext < direxts; dirext++) {258 ibase += in->extents[dirext].cooked.ex_length *259 (EFS_BLOCKSIZE / sizeof(efs_extent));260 }261 262 if (dirext == direxts) {263 /* should never happen */264 pr_err("couldn't find direct extent for indirect extent %d (block %u)\n",265 cur, block);266 if (bh) brelse(bh);267 return 0;268 }269 270 /* work out block number and offset of this indirect extent */271 iblock = sb->fs_start + in->extents[dirext].cooked.ex_bn +272 (cur - ibase) /273 (EFS_BLOCKSIZE / sizeof(efs_extent));274 ioffset = (cur - ibase) %275 (EFS_BLOCKSIZE / sizeof(efs_extent));276 277 if (first || lastblock != iblock) {278 if (bh) brelse(bh);279 280 bh = sb_bread(inode->i_sb, iblock);281 if (!bh) {282 pr_err("%s() failed at block %d\n",283 __func__, iblock);284 return 0;285 }286 pr_debug("%s(): read indirect extent block %d\n",287 __func__, iblock);288 first = 0;289 lastblock = iblock;290 }291 292 exts = (efs_extent *) bh->b_data;293 294 extent_copy(&(exts[ioffset]), &ext);295 296 if (ext.cooked.ex_magic != 0) {297 pr_err("extent %d has bad magic number in block %d\n",298 cur, iblock);299 if (bh) brelse(bh);300 return 0;301 }302 303 if ((result = efs_extent_check(&ext, block, sb))) {304 if (bh) brelse(bh);305 in->lastextent = cur;306 return result;307 }308 }309 if (bh) brelse(bh);310 pr_err("%s() failed to map block %u (indir)\n", __func__, block);311 return 0;312} 313 314MODULE_DESCRIPTION("Extent File System (efs)");315MODULE_LICENSE("GPL");316