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DEFINITIONS
This source file includes following definitions.
- efs_readpage
- _efs_bmap
- extent_copy
- efs_iget
- efs_extent_check
- efs_map_block
/*
* 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,
.sync_page = block_sync_page,
.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");