linux/fs/omfs/dir.c
Christian Brauner e18275ae55
fs: port ->rename() to pass mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:26 +01:00

462 lines
9.8 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* OMFS (as used by RIO Karma) directory operations.
* Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>
*/
#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 bucket = omfs_hash(name, namelen, nbuckets);
*ofs = OMFS_DIR_START + bucket * 8;
return omfs_bread(dir->i_sb, dir->i_ino);
}
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 = omfs_bread(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);
struct buffer_head *bh;
struct omfs_inode *oi;
bh = omfs_bread(sb, inode->i_ino);
if (!bh)
return -ENOMEM;
memset(bh->b_data, 0, sizeof(struct omfs_inode));
if (S_ISDIR(inode->i_mode)) {
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 = d_inode(dentry->d_parent);
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 = omfs_bread(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(dir);
/* 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 = d_inode(dentry->d_parent);
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 = omfs_bread(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 = omfs_bread(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_remove(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
int ret;
if (S_ISDIR(inode->i_mode) &&
!omfs_dir_is_empty(inode))
return -ENOTEMPTY;
ret = omfs_delete_entry(dentry);
if (ret)
return ret;
clear_nlink(inode);
mark_inode_dirty(inode);
mark_inode_dirty(dir);
return 0;
}
static int omfs_add_node(struct inode *dir, struct dentry *dentry, umode_t 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 mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode)
{
return omfs_add_node(dir, dentry, mode | S_IFDIR);
}
static int omfs_create(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode, bool excl)
{
return omfs_add_node(dir, dentry, mode | S_IFREG);
}
static struct dentry *omfs_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
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);
} else if (bh != ERR_PTR(-ENOENT)) {
inode = ERR_CAST(bh);
}
return d_splice_alias(inode, dentry);
}
/* 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 bool omfs_fill_chain(struct inode *dir, struct dir_context *ctx,
u64 fsblock, int hindex)
{
/* follow chain in this bucket */
while (fsblock != ~0) {
struct buffer_head *bh = omfs_bread(dir->i_sb, fsblock);
struct omfs_inode *oi;
u64 self;
unsigned char d_type;
if (!bh)
return true;
oi = (struct omfs_inode *) bh->b_data;
if (omfs_is_bad(OMFS_SB(dir->i_sb), &oi->i_head, fsblock)) {
brelse(bh);
return true;
}
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;
if (!dir_emit(ctx, oi->i_name,
strnlen(oi->i_name, OMFS_NAMELEN),
self, d_type)) {
brelse(bh);
return false;
}
brelse(bh);
ctx->pos++;
}
return true;
}
static int omfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
struct dentry *old_dentry, struct inode *new_dir,
struct dentry *new_dentry, unsigned int flags)
{
struct inode *new_inode = d_inode(new_dentry);
struct inode *old_inode = d_inode(old_dentry);
int err;
if (flags & ~RENAME_NOREPLACE)
return -EINVAL;
if (new_inode) {
/* overwriting existing file/dir */
err = omfs_remove(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 */
err = omfs_delete_entry(old_dentry);
if (err)
goto out;
mark_inode_dirty(old_dir);
err = omfs_add_link(new_dentry, old_inode);
if (err)
goto out;
old_inode->i_ctime = current_time(old_inode);
mark_inode_dirty(old_inode);
out:
return err;
}
static int omfs_readdir(struct file *file, struct dir_context *ctx)
{
struct inode *dir = file_inode(file);
struct buffer_head *bh;
__be64 *p;
unsigned int hchain, hindex;
int nbuckets;
if (ctx->pos >> 32)
return -EINVAL;
if (ctx->pos < 1 << 20) {
if (!dir_emit_dots(file, ctx))
return 0;
ctx->pos = 1 << 20;
}
nbuckets = (dir->i_size - OMFS_DIR_START) / 8;
/* high 12 bits store bucket + 1 and low 20 bits store hash index */
hchain = (ctx->pos >> 20) - 1;
hindex = ctx->pos & 0xfffff;
bh = omfs_bread(dir->i_sb, dir->i_ino);
if (!bh)
return -EINVAL;
p = (__be64 *)(bh->b_data + OMFS_DIR_START) + hchain;
for (; hchain < nbuckets; hchain++) {
__u64 fsblock = be64_to_cpu(*p++);
if (!omfs_fill_chain(dir, ctx, fsblock, hindex))
break;
hindex = 0;
ctx->pos = (hchain+2) << 20;
}
brelse(bh);
return 0;
}
const struct inode_operations omfs_dir_inops = {
.lookup = omfs_lookup,
.mkdir = omfs_mkdir,
.rename = omfs_rename,
.create = omfs_create,
.unlink = omfs_remove,
.rmdir = omfs_remove,
};
const struct file_operations omfs_dir_operations = {
.read = generic_read_dir,
.iterate_shared = omfs_readdir,
.llseek = generic_file_llseek,
};