// SPDX-License-Identifier: GPL-2.0+
/*
* NILFS directory entry operations
*
* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
*
* Modified for NILFS by Amagai Yoshiji.
*/
/*
* 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 <linux/pagemap.h>
#include "nilfs.h"
#include "page.h"
static inline unsigned int nilfs_rec_len_from_disk(__le16 dlen)
{
unsigned int len = le16_to_cpu(dlen);
#if (PAGE_SIZE >= 65536)
if (len == NILFS_MAX_REC_LEN)
return 1 << 16;
#endif
return len;
}
static inline __le16 nilfs_rec_len_to_disk(unsigned int len)
{
#if (PAGE_SIZE >= 65536)
if (len == (1 << 16))
return cpu_to_le16(NILFS_MAX_REC_LEN);
BUG_ON(len > (1 << 16));
#endif
return cpu_to_le16(len);
}
/*
* nilfs uses block-sized chunks. Arguably, sector-sized ones would be
* more robust, but we have what we have
*/
static inline unsigned int nilfs_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 int nilfs_last_byte(struct inode *inode, unsigned long page_nr)
{
unsigned int last_byte = inode->i_size;
last_byte -= page_nr << PAGE_SHIFT;
if (last_byte > PAGE_SIZE)
last_byte = PAGE_SIZE;
return last_byte;
}
static int nilfs_prepare_chunk(struct folio *folio, unsigned int from,
unsigned int to)
{
loff_t pos = folio_pos(folio) + from;
return __block_write_begin(folio, pos, to - from, nilfs_get_block);
}
static void nilfs_commit_chunk(struct folio *folio,
struct address_space *mapping, size_t from, size_t to)
{
struct inode *dir = mapping->host;
loff_t pos = folio_pos(folio) + from;
size_t copied, len = to - from;
unsigned int nr_dirty;
int err;
nr_dirty = nilfs_page_count_clean_buffers(&folio->page, from, to);
copied = block_write_end(NULL, mapping, pos, len, len, folio, NULL);
if (pos + copied > dir->i_size)
i_size_write(dir, pos + copied);
if (IS_DIRSYNC(dir))
nilfs_set_transaction_flag(NILFS_TI_SYNC);
err = nilfs_set_file_dirty(dir, nr_dirty);
WARN_ON(err); /* do not happen */
folio_unlock(folio);
}
static bool nilfs_check_folio(struct folio *folio, char *kaddr)
{
struct inode *dir = folio->mapping->host;
struct super_block *sb = dir->i_sb;
unsigned int chunk_size = nilfs_chunk_size(dir);
size_t offs, rec_len;
size_t limit = folio_size(folio);
struct nilfs_dir_entry *p;
char *error;
if (dir->i_size < folio_pos(folio) + limit) {
limit = dir->i_size - folio_pos(folio);
if (limit & (chunk_size - 1))
goto Ebadsize;
if (!limit)
goto out;
}
for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {
p = (struct nilfs_dir_entry *)(kaddr + offs);
rec_len = nilfs_rec_len_from_disk(p->rec_len);
if (rec_len < NILFS_DIR_REC_LEN(1))
goto Eshort;
if (rec_len & 3)
goto Ealign;
if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
goto Enamelen;
if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
goto Espan;
if (unlikely(p->inode &&
NILFS_PRIVATE_INODE(le64_to_cpu(p->inode))))
goto Einumber;
}
if (offs != limit)
goto Eend;
out:
folio_set_checked(folio);
return true;
/* Too bad, we had an error */
Ebadsize:
nilfs_error(sb,
"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 = "disallowed inode number";
bad_entry:
nilfs_error(sb,
"bad entry in directory #%lu: %s - offset=%lu, inode=%lu, rec_len=%zd, name_len=%d",
dir->i_ino, error, (folio->index << PAGE_SHIFT) + offs,
(unsigned long)le64_to_cpu(p->inode),
rec_len, p->name_len);
goto fail;
Eend:
p = (struct nilfs_dir_entry *)(kaddr + offs);
nilfs_error(sb,
"entry in directory #%lu spans the page boundary offset=%lu, inode=%lu",
dir->i_ino, (folio->index << PAGE_SHIFT) + offs,
(unsigned long)le64_to_cpu(p->inode));
fail:
return false;
}
static void *nilfs_get_folio(struct inode *dir, unsigned long n,
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 folio;
kaddr = kmap_local_folio(folio, 0);
if (unlikely(!folio_test_checked(folio))) {
if (!nilfs_check_folio(folio, kaddr))
goto fail;
}
*foliop = folio;
return kaddr;
fail:
folio_release_kmap(folio, kaddr);
return ERR_PTR(-EIO);
}
/*
* NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
*
* len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
*/
static int
nilfs_match(int len, const unsigned char *name, struct nilfs_dir_entry *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 struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)
{
return (struct nilfs_dir_entry *)((char *)p +
nilfs_rec_len_from_disk(p->rec_len));
}
static int nilfs_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);
if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
return 0;
for ( ; n < npages; n++, offset = 0) {
char *kaddr, *limit;
struct nilfs_dir_entry *de;
struct folio *folio;
kaddr = nilfs_get_folio(inode, n, &folio);
if (IS_ERR(kaddr)) {
nilfs_error(sb, "bad page in #%lu", inode->i_ino);
ctx->pos += PAGE_SIZE - offset;
return -EIO;
}
de = (struct nilfs_dir_entry *)(kaddr + offset);
limit = kaddr + nilfs_last_byte(inode, n) -
NILFS_DIR_REC_LEN(1);
for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
if (de->rec_len == 0) {
nilfs_error(sb, "zero-length directory entry");
folio_release_kmap(folio, kaddr);
return -EIO;
}
if (de->inode) {
unsigned char t;
t = fs_ftype_to_dtype(de->file_type);
if (!dir_emit(ctx, de->name, de->name_len,
le64_to_cpu(de->inode), t)) {
folio_release_kmap(folio, kaddr);
return 0;
}
}
ctx->pos += nilfs_rec_len_from_disk(de->rec_len);
}
folio_release_kmap(folio, kaddr);
}
return 0;
}
/*
* nilfs_find_entry()
*
* Finds an entry in the specified directory with the wanted name. It
* returns the folio in which the entry was found, and the entry itself.
* The folio is mapped and unlocked. When the caller is finished with
* the entry, it should call folio_release_kmap().
*
* On failure, returns NULL and the caller should ignore foliop.
*/
struct nilfs_dir_entry *nilfs_find_entry(struct inode *dir,
const struct qstr *qstr, struct folio **foliop)
{
const unsigned char *name = qstr->name;
int namelen = qstr->len;
unsigned int reclen = NILFS_DIR_REC_LEN(namelen);
unsigned long start, n;
unsigned long npages = dir_pages(dir);
struct nilfs_inode_info *ei = NILFS_I(dir);
struct nilfs_dir_entry *de;
if (npages == 0)
goto out;
start = ei->i_dir_start_lookup;
if (start >= npages)
start = 0;
n = start;
do {
char *kaddr = nilfs_get_folio(dir, n, foliop);
if (!IS_ERR(kaddr)) {
de = (struct nilfs_dir_entry *)kaddr;
kaddr += nilfs_last_byte(dir, n) - reclen;
while ((char *) de <= kaddr) {
if (de->rec_len == 0) {
nilfs_error(dir->i_sb,
"zero-length directory entry");
folio_release_kmap(*foliop, kaddr);
goto out;
}
if (nilfs_match(namelen, name, de))
goto found;
de = nilfs_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)))) {
nilfs_error(dir->i_sb,
"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 NULL;
found:
ei->i_dir_start_lookup = n;
return de;
}
struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct folio **foliop)
{
struct folio *folio;
struct nilfs_dir_entry *de, *next_de;
size_t limit;
char *msg;
de = nilfs_get_folio(dir, 0, &folio);
if (IS_ERR(de))
return NULL;
limit = nilfs_last_byte(dir, 0); /* is a multiple of chunk size */
if (unlikely(!limit || le64_to_cpu(de->inode) != dir->i_ino ||
!nilfs_match(1, ".", de))) {
msg = "missing '.'";
goto fail;
}
next_de = nilfs_next_entry(de);
/*
* If "next_de" has not reached the end of the chunk, there is
* at least one more record. Check whether it matches "..".
*/
if (unlikely((char *)next_de == (char *)de + nilfs_chunk_size(dir) ||
!nilfs_match(2, "..", next_de))) {
msg = "missing '..'";
goto fail;
}
*foliop = folio;
return next_de;
fail:
nilfs_error(dir->i_sb, "directory #%lu %s", dir->i_ino, msg);
folio_release_kmap(folio, de);
return NULL;
}
ino_t nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr)
{
ino_t res = 0;
struct nilfs_dir_entry *de;
struct folio *folio;
de = nilfs_find_entry(dir, qstr, &folio);
if (de) {
res = le64_to_cpu(de->inode);
folio_release_kmap(folio, de);
}
return res;
}
void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
struct folio *folio, struct inode *inode)
{
size_t from = offset_in_folio(folio, de);
size_t to = from + nilfs_rec_len_from_disk(de->rec_len);
struct address_space *mapping = folio->mapping;
int err;
folio_lock(folio);
err = nilfs_prepare_chunk(folio, from, to);
BUG_ON(err);
de->inode = cpu_to_le64(inode->i_ino);
de->file_type = fs_umode_to_ftype(inode->i_mode);
nilfs_commit_chunk(folio, mapping, from, to);
inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
}
/*
* Parent is locked.
*/
int nilfs_add_link(struct dentry *dentry, struct inode *inode)
{
struct inode *dir = d_inode(dentry->d_parent);
const unsigned char *name = dentry->d_name.name;
int namelen = dentry->d_name.len;
unsigned int chunk_size = nilfs_chunk_size(dir);
unsigned int reclen = NILFS_DIR_REC_LEN(namelen);
unsigned short rec_len, name_len;
struct folio *folio = NULL;
struct nilfs_dir_entry *de;
unsigned long npages = dir_pages(dir);
unsigned long n;
size_t from, to;
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 = nilfs_get_folio(dir, n, &folio);
char *dir_end;
if (IS_ERR(kaddr))
return PTR_ERR(kaddr);
folio_lock(folio);
dir_end = kaddr + nilfs_last_byte(dir, n);
de = (struct nilfs_dir_entry *)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 = nilfs_rec_len_to_disk(chunk_size);
de->inode = 0;
goto got_it;
}
if (de->rec_len == 0) {
nilfs_error(dir->i_sb,
"zero-length directory entry");
err = -EIO;
goto out_unlock;
}
err = -EEXIST;
if (nilfs_match(namelen, name, de))
goto out_unlock;
name_len = NILFS_DIR_REC_LEN(de->name_len);
rec_len = nilfs_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 = (struct nilfs_dir_entry *)((char *)de + rec_len);
}
folio_unlock(folio);
folio_release_kmap(folio, kaddr);
}
BUG();
return -EINVAL;
got_it:
from = offset_in_folio(folio, de);
to = from + rec_len;
err = nilfs_prepare_chunk(folio, from, to);
if (err)
goto out_unlock;
if (de->inode) {
struct nilfs_dir_entry *de1;
de1 = (struct nilfs_dir_entry *)((char *)de + name_len);
de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);
de->rec_len = nilfs_rec_len_to_disk(name_len);
de = de1;
}
de->name_len = namelen;
memcpy(de->name, name, namelen);
de->inode = cpu_to_le64(inode->i_ino);
de->file_type = fs_umode_to_ftype(inode->i_mode);
nilfs_commit_chunk(folio, folio->mapping, from, to);
inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
nilfs_mark_inode_dirty(dir);
/* OFFSET_CACHE */
out_put:
folio_release_kmap(folio, de);
return err;
out_unlock:
folio_unlock(folio);
goto out_put;
}
/*
* nilfs_delete_entry deletes a directory entry by merging it with the
* previous entry. Folio is up-to-date.
*/
int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct folio *folio)
{
struct address_space *mapping = folio->mapping;
struct inode *inode = mapping->host;
char *kaddr = (char *)((unsigned long)dir & ~(folio_size(folio) - 1));
size_t from, to;
struct nilfs_dir_entry *de, *pde = NULL;
int err;
from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
to = ((char *)dir - kaddr) + nilfs_rec_len_from_disk(dir->rec_len);
de = (struct nilfs_dir_entry *)(kaddr + from);
while ((char *)de < (char *)dir) {
if (de->rec_len == 0) {
nilfs_error(inode->i_sb,
"zero-length directory entry");
err = -EIO;
goto out;
}
pde = de;
de = nilfs_next_entry(de);
}
if (pde)
from = (char *)pde - kaddr;
folio_lock(folio);
err = nilfs_prepare_chunk(folio, from, to);
BUG_ON(err);
if (pde)
pde->rec_len = nilfs_rec_len_to_disk(to - from);
dir->inode = 0;
nilfs_commit_chunk(folio, mapping, from, to);
inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
out:
return err;
}
/*
* Set the first fragment of directory.
*/
int nilfs_make_empty(struct inode *inode, struct inode *parent)
{
struct address_space *mapping = inode->i_mapping;
struct folio *folio = filemap_grab_folio(mapping, 0);
unsigned int chunk_size = nilfs_chunk_size(inode);
struct nilfs_dir_entry *de;
int err;
void *kaddr;
if (IS_ERR(folio))
return PTR_ERR(folio);
err = nilfs_prepare_chunk(folio, 0, chunk_size);
if (unlikely(err)) {
folio_unlock(folio);
goto fail;
}
kaddr = kmap_local_folio(folio, 0);
memset(kaddr, 0, chunk_size);
de = (struct nilfs_dir_entry *)kaddr;
de->name_len = 1;
de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));
memcpy(de->name, ".\0\0", 4);
de->inode = cpu_to_le64(inode->i_ino);
de->file_type = fs_umode_to_ftype(inode->i_mode);
de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
de->name_len = 2;
de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));
de->inode = cpu_to_le64(parent->i_ino);
memcpy(de->name, "..\0", 4);
de->file_type = fs_umode_to_ftype(inode->i_mode);
kunmap_local(kaddr);
nilfs_commit_chunk(folio, mapping, 0, chunk_size);
fail:
folio_put(folio);
return err;
}
/*
* routine to check that the specified directory is empty (for rmdir)
*/
int nilfs_empty_dir(struct inode *inode)
{
struct folio *folio = NULL;
char *kaddr;
unsigned long i, npages = dir_pages(inode);
for (i = 0; i < npages; i++) {
struct nilfs_dir_entry *de;
kaddr = nilfs_get_folio(inode, i, &folio);
if (IS_ERR(kaddr))
return 0;
de = (struct nilfs_dir_entry *)kaddr;
kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
while ((char *)de <= kaddr) {
if (de->rec_len == 0) {
nilfs_error(inode->i_sb,
"zero-length directory entry (kaddr=%p, de=%p)",
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_le64(inode->i_ino))
goto not_empty;
} else if (de->name[1] != '.')
goto not_empty;
}
de = nilfs_next_entry(de);
}
folio_release_kmap(folio, kaddr);
}
return 1;
not_empty:
folio_release_kmap(folio, kaddr);
return 0;
}
const struct file_operations nilfs_dir_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate_shared = nilfs_readdir,
.unlocked_ioctl = nilfs_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = nilfs_compat_ioctl,
#endif /* CONFIG_COMPAT */
.fsync = nilfs_sync_file,
};
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