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DEFINITIONS
This source file includes following definitions.
- omfs_hash
- omfs_get_bucket
- omfs_scan_list
- omfs_find_entry
- omfs_make_empty
- omfs_add_link
- omfs_delete_entry
- omfs_dir_is_empty
- omfs_unlink
- omfs_rmdir
- omfs_add_node
- omfs_mkdir
- omfs_create
- omfs_lookup
- omfs_is_bad
- omfs_fill_chain
- omfs_rename
- omfs_readdir
/*
* OMFS (as used by RIO Karma) directory operations.
* Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
* Released under GPL v2.
*/
#include <linux/fs.h>
#include <linux/ctype.h>
#include <linux/buffer_head.h>
#include "omfs.h"
static int omfs_hash(const char *name, int namelen, int mod)
{
int i, hash = 0;
for (i = 0; i < namelen; i++)
hash ^= tolower(name[i]) << (i % 24);
return hash % mod;
}
/*
* Finds the bucket for a given name and reads the containing block;
* *ofs is set to the offset of the first list entry.
*/
static struct buffer_head *omfs_get_bucket(struct inode *dir,
const char *name, int namelen, int *ofs)
{
int nbuckets = (dir->i_size - OMFS_DIR_START)/8;
int block = clus_to_blk(OMFS_SB(dir->i_sb), dir->i_ino);
int bucket = omfs_hash(name, namelen, nbuckets);
*ofs = OMFS_DIR_START + bucket * 8;
return sb_bread(dir->i_sb, block);
}
static struct buffer_head *omfs_scan_list(struct inode *dir, u64 block,
const char *name, int namelen,
u64 *prev_block)
{
struct buffer_head *bh;
struct omfs_inode *oi;
int err = -ENOENT;
*prev_block = ~0;
while (block != ~0) {
bh = sb_bread(dir->i_sb,
clus_to_blk(OMFS_SB(dir->i_sb), block));
if (!bh) {
err = -EIO;
goto err;
}
oi = (struct omfs_inode *) bh->b_data;
if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, block)) {
brelse(bh);
goto err;
}
if (strncmp(oi->i_name, name, namelen) == 0)
return bh;
*prev_block = block;
block = be64_to_cpu(oi->i_sibling);
brelse(bh);
}
err:
return ERR_PTR(err);
}
static struct buffer_head *omfs_find_entry(struct inode *dir,
const char *name, int namelen)
{
struct buffer_head *bh;
int ofs;
u64 block, dummy;
bh = omfs_get_bucket(dir, name, namelen, &ofs);
if (!bh)
return ERR_PTR(-EIO);
block = be64_to_cpu(*((__be64 *) &bh->b_data[ofs]));
brelse(bh);
return omfs_scan_list(dir, block, name, namelen, &dummy);
}
int omfs_make_empty(struct inode *inode, struct super_block *sb)
{
struct omfs_sb_info *sbi = OMFS_SB(sb);
int block = clus_to_blk(sbi, inode->i_ino);
struct buffer_head *bh;
struct omfs_inode *oi;
bh = sb_bread(sb, block);
if (!bh)
return -ENOMEM;
memset(bh->b_data, 0, sizeof(struct omfs_inode));
if (inode->i_mode & S_IFDIR) {
memset(&bh->b_data[OMFS_DIR_START], 0xff,
sbi->s_sys_blocksize - OMFS_DIR_START);
} else
omfs_make_empty_table(bh, OMFS_EXTENT_START);
oi = (struct omfs_inode *) bh->b_data;
oi->i_head.h_self = cpu_to_be64(inode->i_ino);
oi->i_sibling = ~cpu_to_be64(0ULL);
mark_buffer_dirty(bh);
brelse(bh);
return 0;
}
static int omfs_add_link(struct dentry *dentry, struct inode *inode)
{
struct inode *dir = dentry->d_parent->d_inode;
const char *name = dentry->d_name.name;
int namelen = dentry->d_name.len;
struct omfs_inode *oi;
struct buffer_head *bh;
u64 block;
__be64 *entry;
int ofs;
/* just prepend to head of queue in proper bucket */
bh = omfs_get_bucket(dir, name, namelen, &ofs);
if (!bh)
goto out;
entry = (__be64 *) &bh->b_data[ofs];
block = be64_to_cpu(*entry);
*entry = cpu_to_be64(inode->i_ino);
mark_buffer_dirty(bh);
brelse(bh);
/* now set the sibling and parent pointers on the new inode */
bh = sb_bread(dir->i_sb, clus_to_blk(OMFS_SB(dir->i_sb), inode->i_ino));
if (!bh)
goto out;
oi = (struct omfs_inode *) bh->b_data;
memcpy(oi->i_name, name, namelen);
memset(oi->i_name + namelen, 0, OMFS_NAMELEN - namelen);
oi->i_sibling = cpu_to_be64(block);
oi->i_parent = cpu_to_be64(dir->i_ino);
mark_buffer_dirty(bh);
brelse(bh);
dir->i_ctime = CURRENT_TIME_SEC;
/* mark affected inodes dirty to rebuild checksums */
mark_inode_dirty(dir);
mark_inode_dirty(inode);
return 0;
out:
return -ENOMEM;
}
static int omfs_delete_entry(struct dentry *dentry)
{
struct inode *dir = dentry->d_parent->d_inode;
struct inode *dirty;
const char *name = dentry->d_name.name;
int namelen = dentry->d_name.len;
struct omfs_inode *oi;
struct buffer_head *bh, *bh2;
__be64 *entry, next;
u64 block, prev;
int ofs;
int err = -ENOMEM;
/* delete the proper node in the bucket's linked list */
bh = omfs_get_bucket(dir, name, namelen, &ofs);
if (!bh)
goto out;
entry = (__be64 *) &bh->b_data[ofs];
block = be64_to_cpu(*entry);
bh2 = omfs_scan_list(dir, block, name, namelen, &prev);
if (IS_ERR(bh2)) {
err = PTR_ERR(bh2);
goto out_free_bh;
}
oi = (struct omfs_inode *) bh2->b_data;
next = oi->i_sibling;
brelse(bh2);
if (prev != ~0) {
/* found in middle of list, get list ptr */
brelse(bh);
bh = sb_bread(dir->i_sb,
clus_to_blk(OMFS_SB(dir->i_sb), prev));
if (!bh)
goto out;
oi = (struct omfs_inode *) bh->b_data;
entry = &oi->i_sibling;
}
*entry = next;
mark_buffer_dirty(bh);
if (prev != ~0) {
dirty = omfs_iget(dir->i_sb, prev);
if (!IS_ERR(dirty)) {
mark_inode_dirty(dirty);
iput(dirty);
}
}
err = 0;
out_free_bh:
brelse(bh);
out:
return err;
}
static int omfs_dir_is_empty(struct inode *inode)
{
int nbuckets = (inode->i_size - OMFS_DIR_START) / 8;
struct buffer_head *bh;
u64 *ptr;
int i;
bh = sb_bread(inode->i_sb, clus_to_blk(OMFS_SB(inode->i_sb),
inode->i_ino));
if (!bh)
return 0;
ptr = (u64 *) &bh->b_data[OMFS_DIR_START];
for (i = 0; i < nbuckets; i++, ptr++)
if (*ptr != ~0)
break;
brelse(bh);
return *ptr != ~0;
}
static int omfs_unlink(struct inode *dir, struct dentry *dentry)
{
int ret;
struct inode *inode = dentry->d_inode;
ret = omfs_delete_entry(dentry);
if (ret)
goto end_unlink;
inode_dec_link_count(inode);
mark_inode_dirty(dir);
end_unlink:
return ret;
}
static int omfs_rmdir(struct inode *dir, struct dentry *dentry)
{
int err = -ENOTEMPTY;
struct inode *inode = dentry->d_inode;
if (omfs_dir_is_empty(inode)) {
err = omfs_unlink(dir, dentry);
if (!err)
inode_dec_link_count(inode);
}
return err;
}
static int omfs_add_node(struct inode *dir, struct dentry *dentry, int mode)
{
int err;
struct inode *inode = omfs_new_inode(dir, mode);
if (IS_ERR(inode))
return PTR_ERR(inode);
err = omfs_make_empty(inode, dir->i_sb);
if (err)
goto out_free_inode;
err = omfs_add_link(dentry, inode);
if (err)
goto out_free_inode;
d_instantiate(dentry, inode);
return 0;
out_free_inode:
iput(inode);
return err;
}
static int omfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
return omfs_add_node(dir, dentry, mode | S_IFDIR);
}
static int omfs_create(struct inode *dir, struct dentry *dentry, int mode,
struct nameidata *nd)
{
return omfs_add_node(dir, dentry, mode | S_IFREG);
}
static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry,
struct nameidata *nd)
{
struct buffer_head *bh;
struct inode *inode = NULL;
if (dentry->d_name.len > OMFS_NAMELEN)
return ERR_PTR(-ENAMETOOLONG);
bh = omfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len);
if (!IS_ERR(bh)) {
struct omfs_inode *oi = (struct omfs_inode *)bh->b_data;
ino_t ino = be64_to_cpu(oi->i_head.h_self);
brelse(bh);
inode = omfs_iget(dir->i_sb, ino);
if (IS_ERR(inode))
return ERR_CAST(inode);
}
d_add(dentry, inode);
return NULL;
}
/* sanity check block's self pointer */
int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
u64 fsblock)
{
int is_bad;
u64 ino = be64_to_cpu(header->h_self);
is_bad = ((ino != fsblock) || (ino < sbi->s_root_ino) ||
(ino > sbi->s_num_blocks));
if (is_bad)
printk(KERN_WARNING "omfs: bad hash chain detected\n");
return is_bad;
}
static int omfs_fill_chain(struct file *filp, void *dirent, filldir_t filldir,
u64 fsblock, int hindex)
{
struct inode *dir = filp->f_dentry->d_inode;
struct buffer_head *bh;
struct omfs_inode *oi;
u64 self;
int res = 0;
unsigned char d_type;
/* follow chain in this bucket */
while (fsblock != ~0) {
bh = sb_bread(dir->i_sb, clus_to_blk(OMFS_SB(dir->i_sb),
fsblock));
if (!bh)
goto out;
oi = (struct omfs_inode *) bh->b_data;
if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
brelse(bh);
goto out;
}
self = fsblock;
fsblock = be64_to_cpu(oi->i_sibling);
/* skip visited nodes */
if (hindex) {
hindex--;
brelse(bh);
continue;
}
d_type = (oi->i_type == OMFS_DIR) ? DT_DIR : DT_REG;
res = filldir(dirent, oi->i_name, strnlen(oi->i_name,
OMFS_NAMELEN), filp->f_pos, self, d_type);
if (res == 0)
filp->f_pos++;
brelse(bh);
}
out:
return res;
}
static int omfs_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
struct inode *new_inode = new_dentry->d_inode;
struct inode *old_inode = old_dentry->d_inode;
struct buffer_head *bh;
int is_dir;
int err;
is_dir = S_ISDIR(old_inode->i_mode);
if (new_inode) {
/* overwriting existing file/dir */
err = -ENOTEMPTY;
if (is_dir && !omfs_dir_is_empty(new_inode))
goto out;
err = -ENOENT;
bh = omfs_find_entry(new_dir, new_dentry->d_name.name,
new_dentry->d_name.len);
if (IS_ERR(bh))
goto out;
brelse(bh);
err = omfs_unlink(new_dir, new_dentry);
if (err)
goto out;
}
/* since omfs locates files by name, we need to unlink _before_
* adding the new link or we won't find the old one */
inode_inc_link_count(old_inode);
err = omfs_unlink(old_dir, old_dentry);
if (err) {
inode_dec_link_count(old_inode);
goto out;
}
err = omfs_add_link(new_dentry, old_inode);
if (err)
goto out;
old_inode->i_ctime = CURRENT_TIME_SEC;
out:
return err;
}
static int omfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
struct inode *dir = filp->f_dentry->d_inode;
struct buffer_head *bh;
loff_t offset, res;
unsigned int hchain, hindex;
int nbuckets;
u64 fsblock;
int ret = -EINVAL;
if (filp->f_pos >> 32)
goto success;
switch ((unsigned long) filp->f_pos) {
case 0:
if (filldir(dirent, ".", 1, 0, dir->i_ino, DT_DIR) < 0)
goto success;
filp->f_pos++;
/* fall through */
case 1:
if (filldir(dirent, "..", 2, 1,
parent_ino(filp->f_dentry), DT_DIR) < 0)
goto success;
filp->f_pos = 1 << 20;
/* fall through */
}
nbuckets = (dir->i_size - OMFS_DIR_START) / 8;
/* high 12 bits store bucket + 1 and low 20 bits store hash index */
hchain = (filp->f_pos >> 20) - 1;
hindex = filp->f_pos & 0xfffff;
bh = sb_bread(dir->i_sb, clus_to_blk(OMFS_SB(dir->i_sb), dir->i_ino));
if (!bh)
goto out;
offset = OMFS_DIR_START + hchain * 8;
for (; hchain < nbuckets; hchain++, offset += 8) {
fsblock = be64_to_cpu(*((__be64 *) &bh->b_data[offset]));
res = omfs_fill_chain(filp, dirent, filldir, fsblock, hindex);
hindex = 0;
if (res < 0)
break;
filp->f_pos = (hchain+2) << 20;
}
brelse(bh);
success:
ret = 0;
out:
return ret;
}
struct inode_operations omfs_dir_inops = {
.lookup = omfs_lookup,
.mkdir = omfs_mkdir,
.rename = omfs_rename,
.create = omfs_create,
.unlink = omfs_unlink,
.rmdir = omfs_rmdir,
};
struct file_operations omfs_dir_operations = {
.read = generic_read_dir,
.readdir = omfs_readdir,
};