// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/ext2/dir.c
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card ([email protected])
* Laboratoire MASI - Institut Blaise Pascal
* Universite Pierre et Marie Curie (Paris VI)
*
* from
*
* linux/fs/minix/dir.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* ext2 directory handling functions
*
* Big-endian to little-endian byte-swapping/bitmaps by
* David S. Miller ([email protected]), 1995
*
* All code that works with directory layout had been switched to pagecache
* and moved here. AV
*/
#include "ext2.h"
#include <linux/buffer_head.h>
#include <linux/pagemap.h>
#include <linux/swap.h>
#include <linux/iversion.h>
typedef struct ext2_dir_entry_2 ext2_dirent;
/*
* Tests against MAX_REC_LEN etc were put in place for 64k block
* sizes; if that is not possible on this arch, we can skip
* those tests and speed things up.
*/
static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
{
unsigned len = le16_to_cpu(dlen);
#if (PAGE_SIZE >= 65536)
if (len == EXT2_MAX_REC_LEN)
return 1 << 16;
#endif
return len;
}
static inline __le16 ext2_rec_len_to_disk(unsigned len)
{
#if (PAGE_SIZE >= 65536)
if (len == (1 << 16))
return cpu_to_le16(EXT2_MAX_REC_LEN);
else
BUG_ON(len > (1 << 16));
#endif
return cpu_to_le16(len);
}
/*
* ext2 uses block-sized chunks. Arguably, sector-sized ones would be
* more robust, but we have what we have
*/
static inline unsigned ext2_chunk_size(struct inode *inode)
{
return inode->i_sb->s_blocksize;
}
/*
* Return the offset into page `page_nr' of the last valid
* byte in that page, plus one.
*/
static unsigned
ext2_last_byte(struct inode *inode, unsigned long page_nr)
{
unsigned last_byte = inode->i_size;
last_byte -= page_nr << PAGE_SHIFT;
if (last_byte > PAGE_SIZE)
last_byte = PAGE_SIZE;
return last_byte;
}
static void ext2_commit_chunk(struct folio *folio, loff_t pos, unsigned len)
{
struct address_space *mapping = folio->mapping;
struct inode *dir = mapping->host;
inode_inc_iversion(dir);
block_write_end(NULL, mapping, pos, len, len, folio, NULL);
if (pos+len > dir->i_size) {
i_size_write(dir, pos+len);
mark_inode_dirty(dir);
}
folio_unlock(folio);
}
static bool ext2_check_folio(struct folio *folio, int quiet, char *kaddr)
{
struct inode *dir = folio->mapping->host;
struct super_block *sb = dir->i_sb;
unsigned chunk_size = ext2_chunk_size(dir);
u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
unsigned offs, rec_len;
unsigned limit = folio_size(folio);
ext2_dirent *p;
char *error;
if (dir->i_size < folio_pos(folio) + limit) {
limit = offset_in_folio(folio, dir->i_size);
if (limit & (chunk_size - 1))
goto Ebadsize;
if (!limit)
goto out;
}
for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
p = (ext2_dirent *)(kaddr + offs);
rec_len = ext2_rec_len_from_disk(p->rec_len);
if (unlikely(rec_len < EXT2_DIR_REC_LEN(1)))
goto Eshort;
if (unlikely(rec_len & 3))
goto Ealign;
if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len)))
goto Enamelen;
if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1)))
goto Espan;
if (unlikely(le32_to_cpu(p->inode) > max_inumber))
goto Einumber;
}
if (offs != limit)
goto Eend;
out:
folio_set_checked(folio);
return true;
/* Too bad, we had an error */
Ebadsize:
if (!quiet)
ext2_error(sb, __func__,
"size of directory #%lu is not a multiple "
"of chunk size", dir->i_ino);
goto fail;
Eshort:
error = "rec_len is smaller than minimal";
goto bad_entry;
Ealign:
error = "unaligned directory entry";
goto bad_entry;
Enamelen:
error = "rec_len is too small for name_len";
goto bad_entry;
Espan:
error = "directory entry across blocks";
goto bad_entry;
Einumber:
error = "inode out of bounds";
bad_entry:
if (!quiet)
ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - "
"offset=%llu, inode=%lu, rec_len=%d, name_len=%d",
dir->i_ino, error, folio_pos(folio) + offs,
(unsigned long) le32_to_cpu(p->inode),
rec_len, p->name_len);
goto fail;
Eend:
if (!quiet) {
p = (ext2_dirent *)(kaddr + offs);
ext2_error(sb, "ext2_check_folio",
"entry in directory #%lu spans the page boundary"
"offset=%llu, inode=%lu",
dir->i_ino, folio_pos(folio) + offs,
(unsigned long) le32_to_cpu(p->inode));
}
fail:
return false;
}
/*
* Calls to ext2_get_folio()/folio_release_kmap() must be nested according
* to the rules documented in kmap_local_folio()/kunmap_local().
*
* NOTE: ext2_find_entry() and ext2_dotdot() act as a call
* to folio_release_kmap() and should be treated as a call to
* folio_release_kmap() for nesting purposes.
*/
static void *ext2_get_folio(struct inode *dir, unsigned long n,
int quiet, struct folio **foliop)
{
struct address_space *mapping = dir->i_mapping;
struct folio *folio = read_mapping_folio(mapping, n, NULL);
void *kaddr;
if (IS_ERR(folio))
return ERR_CAST(folio);
kaddr = kmap_local_folio(folio, 0);
if (unlikely(!folio_test_checked(folio))) {
if (!ext2_check_folio(folio, quiet, kaddr))
goto fail;
}
*foliop = folio;
return kaddr;
fail:
folio_release_kmap(folio, kaddr);
return ERR_PTR(-EIO);
}
/*
* NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
*
* len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
*/
static inline int ext2_match (int len, const char * const name,
struct ext2_dir_entry_2 * de)
{
if (len != de->name_len)
return 0;
if (!de->inode)
return 0;
return !memcmp(name, de->name, len);
}
/*
* p is at least 6 bytes before the end of page
*/
static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
{
return (ext2_dirent *)((char *)p +
ext2_rec_len_from_disk(p->rec_len));
}
static inline unsigned
ext2_validate_entry(char *base, unsigned offset, unsigned mask)
{
ext2_dirent *de = (ext2_dirent*)(base + offset);
ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
while ((char*)p < (char*)de) {
if (p->rec_len == 0)
break;
p = ext2_next_entry(p);
}
return offset_in_page(p);
}
static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
{
if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
de->file_type = fs_umode_to_ftype(inode->i_mode);
else
de->file_type = 0;
}
static int
ext2_readdir(struct file *file, struct dir_context *ctx)
{
loff_t pos = ctx->pos;
struct inode *inode = file_inode(file);
struct super_block *sb = inode->i_sb;
unsigned int offset = pos & ~PAGE_MASK;
unsigned long n = pos >> PAGE_SHIFT;
unsigned long npages = dir_pages(inode);
unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
bool need_revalidate = !inode_eq_iversion(inode, *(u64 *)file->private_data);
bool has_filetype;
if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
return 0;
has_filetype =
EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE);
for ( ; n < npages; n++, offset = 0) {
ext2_dirent *de;
struct folio *folio;
char *kaddr = ext2_get_folio(inode, n, 0, &folio);
char *limit;
if (IS_ERR(kaddr)) {
ext2_error(sb, __func__,
"bad page in #%lu",
inode->i_ino);
ctx->pos += PAGE_SIZE - offset;
return PTR_ERR(kaddr);
}
if (unlikely(need_revalidate)) {
if (offset) {
offset = ext2_validate_entry(kaddr, offset, chunk_mask);
ctx->pos = (n<<PAGE_SHIFT) + offset;
}
*(u64 *)file->private_data = inode_query_iversion(inode);
need_revalidate = false;
}
de = (ext2_dirent *)(kaddr+offset);
limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
if (de->rec_len == 0) {
ext2_error(sb, __func__,
"zero-length directory entry");
folio_release_kmap(folio, de);
return -EIO;
}
if (de->inode) {
unsigned char d_type = DT_UNKNOWN;
if (has_filetype)
d_type = fs_ftype_to_dtype(de->file_type);
if (!dir_emit(ctx, de->name, de->name_len,
le32_to_cpu(de->inode),
d_type)) {
folio_release_kmap(folio, de);
return 0;
}
}
ctx->pos += ext2_rec_len_from_disk(de->rec_len);
}
folio_release_kmap(folio, kaddr);
}
return 0;
}
/*
* ext2_find_entry()
*
* finds an entry in the specified directory with the wanted name. It
* returns the page in which the entry was found (as a parameter - res_page),
* and the entry itself. Page is returned mapped and unlocked.
* Entry is guaranteed to be valid.
*
* On Success folio_release_kmap() should be called on *foliop.
*
* NOTE: Calls to ext2_get_folio()/folio_release_kmap() must be nested
* according to the rules documented in kmap_local_folio()/kunmap_local().
*
* ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_folio()
* and should be treated as a call to ext2_get_folio() for nesting
* purposes.
*/
struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
const struct qstr *child, struct folio **foliop)
{
const char *name = child->name;
int namelen = child->len;
unsigned reclen = EXT2_DIR_REC_LEN(namelen);
unsigned long start, n;
unsigned long npages = dir_pages(dir);
struct ext2_inode_info *ei = EXT2_I(dir);
ext2_dirent * de;
if (npages == 0)
goto out;
start = ei->i_dir_start_lookup;
if (start >= npages)
start = 0;
n = start;
do {
char *kaddr = ext2_get_folio(dir, n, 0, foliop);
if (IS_ERR(kaddr))
return ERR_CAST(kaddr);
de = (ext2_dirent *) kaddr;
kaddr += ext2_last_byte(dir, n) - reclen;
while ((char *) de <= kaddr) {
if (de->rec_len == 0) {
ext2_error(dir->i_sb, __func__,
"zero-length directory entry");
folio_release_kmap(*foliop, de);
goto out;
}
if (ext2_match(namelen, name, de))
goto found;
de = ext2_next_entry(de);
}
folio_release_kmap(*foliop, kaddr);
if (++n >= npages)
n = 0;
/* next folio is past the blocks we've got */
if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
ext2_error(dir->i_sb, __func__,
"dir %lu size %lld exceeds block count %llu",
dir->i_ino, dir->i_size,
(unsigned long long)dir->i_blocks);
goto out;
}
} while (n != start);
out:
return ERR_PTR(-ENOENT);
found:
ei->i_dir_start_lookup = n;
return de;
}
/*
* Return the '..' directory entry and the page in which the entry was found
* (as a parameter - p).
*
* On Success folio_release_kmap() should be called on *foliop.
*
* NOTE: Calls to ext2_get_folio()/folio_release_kmap() must be nested
* according to the rules documented in kmap_local_folio()/kunmap_local().
*
* ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_folio()
* and should be treated as a call to ext2_get_folio() for nesting
* purposes.
*/
struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct folio **foliop)
{
ext2_dirent *de = ext2_get_folio(dir, 0, 0, foliop);
if (!IS_ERR(de))
return ext2_next_entry(de);
return NULL;
}
int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino)
{
struct ext2_dir_entry_2 *de;
struct folio *folio;
de = ext2_find_entry(dir, child, &folio);
if (IS_ERR(de))
return PTR_ERR(de);
*ino = le32_to_cpu(de->inode);
folio_release_kmap(folio, de);
return 0;
}
static int ext2_prepare_chunk(struct folio *folio, loff_t pos, unsigned len)
{
return __block_write_begin(folio, pos, len, ext2_get_block);
}
static int ext2_handle_dirsync(struct inode *dir)
{
int err;
err = filemap_write_and_wait(dir->i_mapping);
if (!err)
err = sync_inode_metadata(dir, 1);
return err;
}
int ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
struct folio *folio, struct inode *inode, bool update_times)
{
loff_t pos = folio_pos(folio) + offset_in_folio(folio, de);
unsigned len = ext2_rec_len_from_disk(de->rec_len);
int err;
folio_lock(folio);
err = ext2_prepare_chunk(folio, pos, len);
if (err) {
folio_unlock(folio);
return err;
}
de->inode = cpu_to_le32(inode->i_ino);
ext2_set_de_type(de, inode);
ext2_commit_chunk(folio, pos, len);
if (update_times)
inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
mark_inode_dirty(dir);
return ext2_handle_dirsync(dir);
}
/*
* Parent is locked.
*/
int ext2_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;
unsigned chunk_size = ext2_chunk_size(dir);
unsigned reclen = EXT2_DIR_REC_LEN(namelen);
unsigned short rec_len, name_len;
struct folio *folio = NULL;
ext2_dirent * de;
unsigned long npages = dir_pages(dir);
unsigned long n;
loff_t pos;
int err;
/*
* We take care of directory expansion in the same loop.
* This code plays outside i_size, so it locks the folio
* to protect that region.
*/
for (n = 0; n <= npages; n++) {
char *kaddr = ext2_get_folio(dir, n, 0, &folio);
char *dir_end;
if (IS_ERR(kaddr))
return PTR_ERR(kaddr);
folio_lock(folio);
dir_end = kaddr + ext2_last_byte(dir, n);
de = (ext2_dirent *)kaddr;
kaddr += folio_size(folio) - reclen;
while ((char *)de <= kaddr) {
if ((char *)de == dir_end) {
/* We hit i_size */
name_len = 0;
rec_len = chunk_size;
de->rec_len = ext2_rec_len_to_disk(chunk_size);
de->inode = 0;
goto got_it;
}
if (de->rec_len == 0) {
ext2_error(dir->i_sb, __func__,
"zero-length directory entry");
err = -EIO;
goto out_unlock;
}
err = -EEXIST;
if (ext2_match (namelen, name, de))
goto out_unlock;
name_len = EXT2_DIR_REC_LEN(de->name_len);
rec_len = ext2_rec_len_from_disk(de->rec_len);
if (!de->inode && rec_len >= reclen)
goto got_it;
if (rec_len >= name_len + reclen)
goto got_it;
de = (ext2_dirent *) ((char *) de + rec_len);
}
folio_unlock(folio);
folio_release_kmap(folio, kaddr);
}
BUG();
return -EINVAL;
got_it:
pos = folio_pos(folio) + offset_in_folio(folio, de);
err = ext2_prepare_chunk(folio, pos, rec_len);
if (err)
goto out_unlock;
if (de->inode) {
ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
de->rec_len = ext2_rec_len_to_disk(name_len);
de = de1;
}
de->name_len = namelen;
memcpy(de->name, name, namelen);
de->inode = cpu_to_le32(inode->i_ino);
ext2_set_de_type (de, inode);
ext2_commit_chunk(folio, pos, rec_len);
inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
mark_inode_dirty(dir);
err = ext2_handle_dirsync(dir);
/* OFFSET_CACHE */
out_put:
folio_release_kmap(folio, de);
return err;
out_unlock:
folio_unlock(folio);
goto out_put;
}
/*
* ext2_delete_entry deletes a directory entry by merging it with the
* previous entry. Page is up-to-date.
*/
int ext2_delete_entry(struct ext2_dir_entry_2 *dir, struct folio *folio)
{
struct inode *inode = folio->mapping->host;
size_t from, to;
char *kaddr;
loff_t pos;
ext2_dirent *de, *pde = NULL;
int err;
from = offset_in_folio(folio, dir);
to = from + ext2_rec_len_from_disk(dir->rec_len);
kaddr = (char *)dir - from;
from &= ~(ext2_chunk_size(inode)-1);
de = (ext2_dirent *)(kaddr + from);
while ((char*)de < (char*)dir) {
if (de->rec_len == 0) {
ext2_error(inode->i_sb, __func__,
"zero-length directory entry");
return -EIO;
}
pde = de;
de = ext2_next_entry(de);
}
if (pde)
from = offset_in_folio(folio, pde);
pos = folio_pos(folio) + from;
folio_lock(folio);
err = ext2_prepare_chunk(folio, pos, to - from);
if (err) {
folio_unlock(folio);
return err;
}
if (pde)
pde->rec_len = ext2_rec_len_to_disk(to - from);
dir->inode = 0;
ext2_commit_chunk(folio, pos, to - from);
inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
mark_inode_dirty(inode);
return ext2_handle_dirsync(inode);
}
/*
* Set the first fragment of directory.
*/
int ext2_make_empty(struct inode *inode, struct inode *parent)
{
struct folio *folio = filemap_grab_folio(inode->i_mapping, 0);
unsigned chunk_size = ext2_chunk_size(inode);
struct ext2_dir_entry_2 * de;
int err;
void *kaddr;
if (IS_ERR(folio))
return PTR_ERR(folio);
err = ext2_prepare_chunk(folio, 0, chunk_size);
if (err) {
folio_unlock(folio);
goto fail;
}
kaddr = kmap_local_folio(folio, 0);
memset(kaddr, 0, chunk_size);
de = (struct ext2_dir_entry_2 *)kaddr;
de->name_len = 1;
de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
memcpy (de->name, ".\0\0", 4);
de->inode = cpu_to_le32(inode->i_ino);
ext2_set_de_type (de, inode);
de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
de->name_len = 2;
de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
de->inode = cpu_to_le32(parent->i_ino);
memcpy (de->name, "..\0", 4);
ext2_set_de_type (de, inode);
kunmap_local(kaddr);
ext2_commit_chunk(folio, 0, chunk_size);
err = ext2_handle_dirsync(inode);
fail:
folio_put(folio);
return err;
}
/*
* routine to check that the specified directory is empty (for rmdir)
*/
int ext2_empty_dir(struct inode *inode)
{
struct folio *folio;
char *kaddr;
unsigned long i, npages = dir_pages(inode);
for (i = 0; i < npages; i++) {
ext2_dirent *de;
kaddr = ext2_get_folio(inode, i, 0, &folio);
if (IS_ERR(kaddr))
return 0;
de = (ext2_dirent *)kaddr;
kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
while ((char *)de <= kaddr) {
if (de->rec_len == 0) {
ext2_error(inode->i_sb, __func__,
"zero-length directory entry");
printk("kaddr=%p, de=%p\n", kaddr, de);
goto not_empty;
}
if (de->inode != 0) {
/* check for . and .. */
if (de->name[0] != '.')
goto not_empty;
if (de->name_len > 2)
goto not_empty;
if (de->name_len < 2) {
if (de->inode !=
cpu_to_le32(inode->i_ino))
goto not_empty;
} else if (de->name[1] != '.')
goto not_empty;
}
de = ext2_next_entry(de);
}
folio_release_kmap(folio, kaddr);
}
return 1;
not_empty:
folio_release_kmap(folio, kaddr);
return 0;
}
static int ext2_dir_open(struct inode *inode, struct file *file)
{
file->private_data = kzalloc(sizeof(u64), GFP_KERNEL);
if (!file->private_data)
return -ENOMEM;
return 0;
}
static int ext2_dir_release(struct inode *inode, struct file *file)
{
kfree(file->private_data);
return 0;
}
static loff_t ext2_dir_llseek(struct file *file, loff_t offset, int whence)
{
return generic_llseek_cookie(file, offset, whence,
(u64 *)file->private_data);
}
const struct file_operations ext2_dir_operations = {
.open = ext2_dir_open,
.release = ext2_dir_release,
.llseek = ext2_dir_llseek,
.read = generic_read_dir,
.iterate_shared = ext2_readdir,
.unlocked_ioctl = ext2_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ext2_compat_ioctl,
#endif
.fsync = ext2_fsync,
};
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