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WSL2-Linux-Kernel
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WSL2-Linux-Kernel/fs/ufs/dir.c

645 строки
16 KiB
C
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/*
* linux/fs/ufs/ufs_dir.c
*
* Copyright (C) 1996
* Adrian Rodriguez (adrian@franklins-tower.rutgers.edu)
* Laboratory for Computer Science Research Computing Facility
* Rutgers, The State University of New Jersey
*
* swab support by Francois-Rene Rideau <fare@tunes.org> 19970406
*
* 4.4BSD (FreeBSD) support added on February 1st 1998 by
* Niels Kristian Bech Jensen <nkbj@image.dk> partially based
* on code by Martin von Loewis <martin@mira.isdn.cs.tu-berlin.de>.
*
* Migration to usage of "page cache" on May 2006 by
* Evgeniy Dushistov <dushistov@mail.ru> based on ext2 code base.
*/
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/swap.h>
#include "ufs_fs.h"
#include "ufs.h"
#include "swab.h"
#include "util.h"
/*
* NOTE! unlike strncmp, ufs_match returns 1 for success, 0 for failure.
*
* len <= UFS_MAXNAMLEN and de != NULL are guaranteed by caller.
*/
static inline int ufs_match(struct super_block *sb, int len,
const unsigned char *name, struct ufs_dir_entry *de)
{
if (len != ufs_get_de_namlen(sb, de))
return 0;
if (!de->d_ino)
return 0;
return !memcmp(name, de->d_name, len);
}
static int ufs_commit_chunk(struct page *page, loff_t pos, unsigned len)
{
struct address_space *mapping = page->mapping;
struct inode *dir = mapping->host;
int err = 0;
dir->i_version++;
block_write_end(NULL, mapping, pos, len, len, page, NULL);
if (pos+len > dir->i_size) {
i_size_write(dir, pos+len);
mark_inode_dirty(dir);
}
if (IS_DIRSYNC(dir))
err = write_one_page(page, 1);
else
unlock_page(page);
return err;
}
static inline void ufs_put_page(struct page *page)
{
kunmap(page);
put_page(page);
}
ino_t ufs_inode_by_name(struct inode *dir, const struct qstr *qstr)
{
ino_t res = 0;
struct ufs_dir_entry *de;
struct page *page;
de = ufs_find_entry(dir, qstr, &page);
if (de) {
res = fs32_to_cpu(dir->i_sb, de->d_ino);
ufs_put_page(page);
}
return res;
}
/* Releases the page */
void ufs_set_link(struct inode *dir, struct ufs_dir_entry *de,
struct page *page, struct inode *inode,
bool update_times)
{
loff_t pos = page_offset(page) +
(char *) de - (char *) page_address(page);
unsigned len = fs16_to_cpu(dir->i_sb, de->d_reclen);
int err;
lock_page(page);
err = ufs_prepare_chunk(page, pos, len);
BUG_ON(err);
de->d_ino = cpu_to_fs32(dir->i_sb, inode->i_ino);
ufs_set_de_type(dir->i_sb, de, inode->i_mode);
err = ufs_commit_chunk(page, pos, len);
ufs_put_page(page);
if (update_times)
dir->i_mtime = dir->i_ctime = current_time(dir);
mark_inode_dirty(dir);
}
static bool ufs_check_page(struct page *page)
{
struct inode *dir = page->mapping->host;
struct super_block *sb = dir->i_sb;
char *kaddr = page_address(page);
unsigned offs, rec_len;
unsigned limit = PAGE_SIZE;
const unsigned chunk_mask = UFS_SB(sb)->s_uspi->s_dirblksize - 1;
struct ufs_dir_entry *p;
char *error;
if ((dir->i_size >> PAGE_SHIFT) == page->index) {
limit = dir->i_size & ~PAGE_MASK;
if (limit & chunk_mask)
goto Ebadsize;
if (!limit)
goto out;
}
for (offs = 0; offs <= limit - UFS_DIR_REC_LEN(1); offs += rec_len) {
p = (struct ufs_dir_entry *)(kaddr + offs);
rec_len = fs16_to_cpu(sb, p->d_reclen);
if (rec_len < UFS_DIR_REC_LEN(1))
goto Eshort;
if (rec_len & 3)
goto Ealign;
if (rec_len < UFS_DIR_REC_LEN(ufs_get_de_namlen(sb, p)))
goto Enamelen;
if (((offs + rec_len - 1) ^ offs) & ~chunk_mask)
goto Espan;
if (fs32_to_cpu(sb, p->d_ino) > (UFS_SB(sb)->s_uspi->s_ipg *
UFS_SB(sb)->s_uspi->s_ncg))
goto Einumber;
}
if (offs != limit)
goto Eend;
out:
SetPageChecked(page);
return true;
/* Too bad, we had an error */
Ebadsize:
ufs_error(sb, "ufs_check_page",
"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:
ufs_error (sb, "ufs_check_page", "bad entry in directory #%lu: %s - "
"offset=%lu, rec_len=%d, name_len=%d",
dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs,
rec_len, ufs_get_de_namlen(sb, p));
goto fail;
Eend:
p = (struct ufs_dir_entry *)(kaddr + offs);
ufs_error(sb, __func__,
"entry in directory #%lu spans the page boundary"
"offset=%lu",
dir->i_ino, (page->index<<PAGE_SHIFT)+offs);
fail:
SetPageError(page);
return false;
}
static struct page *ufs_get_page(struct inode *dir, unsigned long n)
{
struct address_space *mapping = dir->i_mapping;
struct page *page = read_mapping_page(mapping, n, NULL);
if (!IS_ERR(page)) {
kmap(page);
if (unlikely(!PageChecked(page))) {
if (PageError(page) || !ufs_check_page(page))
goto fail;
}
}
return page;
fail:
ufs_put_page(page);
return ERR_PTR(-EIO);
}
/*
* Return the offset into page `page_nr' of the last valid
* byte in that page, plus one.
*/
static unsigned
ufs_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 inline struct ufs_dir_entry *
ufs_next_entry(struct super_block *sb, struct ufs_dir_entry *p)
{
return (struct ufs_dir_entry *)((char *)p +
fs16_to_cpu(sb, p->d_reclen));
}
struct ufs_dir_entry *ufs_dotdot(struct inode *dir, struct page **p)
{
struct page *page = ufs_get_page(dir, 0);
struct ufs_dir_entry *de = NULL;
if (!IS_ERR(page)) {
de = ufs_next_entry(dir->i_sb,
(struct ufs_dir_entry *)page_address(page));
*p = page;
}
return de;
}
/*
* ufs_find_entry()
*
* finds an entry in the specified directory with the wanted name. It
* returns the page in which the entry was found, and the entry itself
* (as a parameter - res_dir). Page is returned mapped and unlocked.
* Entry is guaranteed to be valid.
*/
struct ufs_dir_entry *ufs_find_entry(struct inode *dir, const struct qstr *qstr,
struct page **res_page)
{
struct super_block *sb = dir->i_sb;
const unsigned char *name = qstr->name;
int namelen = qstr->len;
unsigned reclen = UFS_DIR_REC_LEN(namelen);
unsigned long start, n;
unsigned long npages = dir_pages(dir);
struct page *page = NULL;
struct ufs_inode_info *ui = UFS_I(dir);
struct ufs_dir_entry *de;
UFSD("ENTER, dir_ino %lu, name %s, namlen %u\n", dir->i_ino, name, namelen);
if (npages == 0 || namelen > UFS_MAXNAMLEN)
goto out;
/* OFFSET_CACHE */
*res_page = NULL;
start = ui->i_dir_start_lookup;
if (start >= npages)
start = 0;
n = start;
do {
char *kaddr;
page = ufs_get_page(dir, n);
if (!IS_ERR(page)) {
kaddr = page_address(page);
de = (struct ufs_dir_entry *) kaddr;
kaddr += ufs_last_byte(dir, n) - reclen;
while ((char *) de <= kaddr) {
if (ufs_match(sb, namelen, name, de))
goto found;
de = ufs_next_entry(sb, de);
}
ufs_put_page(page);
}
if (++n >= npages)
n = 0;
} while (n != start);
out:
return NULL;
found:
*res_page = page;
ui->i_dir_start_lookup = n;
return de;
}
/*
* Parent is locked.
*/
int ufs_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;
struct super_block *sb = dir->i_sb;
unsigned reclen = UFS_DIR_REC_LEN(namelen);
const unsigned int chunk_size = UFS_SB(sb)->s_uspi->s_dirblksize;
unsigned short rec_len, name_len;
struct page *page = NULL;
struct ufs_dir_entry *de;
unsigned long npages = dir_pages(dir);
unsigned long n;
char *kaddr;
loff_t pos;
int err;
UFSD("ENTER, name %s, namelen %u\n", name, namelen);
/*
* We take care of directory expansion in the same loop.
* This code plays outside i_size, so it locks the page
* to protect that region.
*/
for (n = 0; n <= npages; n++) {
char *dir_end;
page = ufs_get_page(dir, n);
err = PTR_ERR(page);
if (IS_ERR(page))
goto out;
lock_page(page);
kaddr = page_address(page);
dir_end = kaddr + ufs_last_byte(dir, n);
de = (struct ufs_dir_entry *)kaddr;
kaddr += PAGE_SIZE - reclen;
while ((char *)de <= kaddr) {
if ((char *)de == dir_end) {
/* We hit i_size */
name_len = 0;
rec_len = chunk_size;
de->d_reclen = cpu_to_fs16(sb, chunk_size);
de->d_ino = 0;
goto got_it;
}
if (de->d_reclen == 0) {
ufs_error(dir->i_sb, __func__,
"zero-length directory entry");
err = -EIO;
goto out_unlock;
}
err = -EEXIST;
if (ufs_match(sb, namelen, name, de))
goto out_unlock;
name_len = UFS_DIR_REC_LEN(ufs_get_de_namlen(sb, de));
rec_len = fs16_to_cpu(sb, de->d_reclen);
if (!de->d_ino && rec_len >= reclen)
goto got_it;
if (rec_len >= name_len + reclen)
goto got_it;
de = (struct ufs_dir_entry *) ((char *) de + rec_len);
}
unlock_page(page);
ufs_put_page(page);
}
BUG();
return -EINVAL;
got_it:
pos = page_offset(page) +
(char*)de - (char*)page_address(page);
err = ufs_prepare_chunk(page, pos, rec_len);
if (err)
goto out_unlock;
if (de->d_ino) {
struct ufs_dir_entry *de1 =
(struct ufs_dir_entry *) ((char *) de + name_len);
de1->d_reclen = cpu_to_fs16(sb, rec_len - name_len);
de->d_reclen = cpu_to_fs16(sb, name_len);
de = de1;
}
ufs_set_de_namlen(sb, de, namelen);
memcpy(de->d_name, name, namelen + 1);
de->d_ino = cpu_to_fs32(sb, inode->i_ino);
ufs_set_de_type(sb, de, inode->i_mode);
err = ufs_commit_chunk(page, pos, rec_len);
dir->i_mtime = dir->i_ctime = current_time(dir);
mark_inode_dirty(dir);
/* OFFSET_CACHE */
out_put:
ufs_put_page(page);
out:
return err;
out_unlock:
unlock_page(page);
goto out_put;
}
static inline unsigned
ufs_validate_entry(struct super_block *sb, char *base,
unsigned offset, unsigned mask)
{
struct ufs_dir_entry *de = (struct ufs_dir_entry*)(base + offset);
struct ufs_dir_entry *p = (struct ufs_dir_entry*)(base + (offset&mask));
while ((char*)p < (char*)de)
p = ufs_next_entry(sb, p);
return (char *)p - base;
}
/*
* This is blatantly stolen from ext2fs
*/
static int
ufs_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 = ~(UFS_SB(sb)->s_uspi->s_dirblksize - 1);
int need_revalidate = file->f_version != inode->i_version;
unsigned flags = UFS_SB(sb)->s_flags;
UFSD("BEGIN\n");
if (pos > inode->i_size - UFS_DIR_REC_LEN(1))
return 0;
for ( ; n < npages; n++, offset = 0) {
char *kaddr, *limit;
struct ufs_dir_entry *de;
struct page *page = ufs_get_page(inode, n);
if (IS_ERR(page)) {
ufs_error(sb, __func__,
"bad page in #%lu",
inode->i_ino);
ctx->pos += PAGE_SIZE - offset;
return -EIO;
}
kaddr = page_address(page);
if (unlikely(need_revalidate)) {
if (offset) {
offset = ufs_validate_entry(sb, kaddr, offset, chunk_mask);
ctx->pos = (n<<PAGE_SHIFT) + offset;
}
file->f_version = inode->i_version;
need_revalidate = 0;
}
de = (struct ufs_dir_entry *)(kaddr+offset);
limit = kaddr + ufs_last_byte(inode, n) - UFS_DIR_REC_LEN(1);
for ( ;(char*)de <= limit; de = ufs_next_entry(sb, de)) {
if (de->d_ino) {
unsigned char d_type = DT_UNKNOWN;
UFSD("filldir(%s,%u)\n", de->d_name,
fs32_to_cpu(sb, de->d_ino));
UFSD("namlen %u\n", ufs_get_de_namlen(sb, de));
if ((flags & UFS_DE_MASK) == UFS_DE_44BSD)
d_type = de->d_u.d_44.d_type;
if (!dir_emit(ctx, de->d_name,
ufs_get_de_namlen(sb, de),
fs32_to_cpu(sb, de->d_ino),
d_type)) {
ufs_put_page(page);
return 0;
}
}
ctx->pos += fs16_to_cpu(sb, de->d_reclen);
}
ufs_put_page(page);
}
return 0;
}
/*
* ufs_delete_entry deletes a directory entry by merging it with the
* previous entry.
*/
int ufs_delete_entry(struct inode *inode, struct ufs_dir_entry *dir,
struct page * page)
{
struct super_block *sb = inode->i_sb;
char *kaddr = page_address(page);
unsigned from = ((char*)dir - kaddr) & ~(UFS_SB(sb)->s_uspi->s_dirblksize - 1);
unsigned to = ((char*)dir - kaddr) + fs16_to_cpu(sb, dir->d_reclen);
loff_t pos;
struct ufs_dir_entry *pde = NULL;
struct ufs_dir_entry *de = (struct ufs_dir_entry *) (kaddr + from);
int err;
UFSD("ENTER\n");
UFSD("ino %u, reclen %u, namlen %u, name %s\n",
fs32_to_cpu(sb, de->d_ino),
fs16_to_cpu(sb, de->d_reclen),
ufs_get_de_namlen(sb, de), de->d_name);
while ((char*)de < (char*)dir) {
if (de->d_reclen == 0) {
ufs_error(inode->i_sb, __func__,
"zero-length directory entry");
err = -EIO;
goto out;
}
pde = de;
de = ufs_next_entry(sb, de);
}
if (pde)
from = (char*)pde - (char*)page_address(page);
pos = page_offset(page) + from;
lock_page(page);
err = ufs_prepare_chunk(page, pos, to - from);
BUG_ON(err);
if (pde)
pde->d_reclen = cpu_to_fs16(sb, to - from);
dir->d_ino = 0;
err = ufs_commit_chunk(page, pos, to - from);
inode->i_ctime = inode->i_mtime = current_time(inode);
mark_inode_dirty(inode);
out:
ufs_put_page(page);
UFSD("EXIT\n");
return err;
}
int ufs_make_empty(struct inode * inode, struct inode *dir)
{
struct super_block * sb = dir->i_sb;
struct address_space *mapping = inode->i_mapping;
struct page *page = grab_cache_page(mapping, 0);
const unsigned int chunk_size = UFS_SB(sb)->s_uspi->s_dirblksize;
struct ufs_dir_entry * de;
char *base;
int err;
if (!page)
return -ENOMEM;
err = ufs_prepare_chunk(page, 0, chunk_size);
if (err) {
unlock_page(page);
goto fail;
}
kmap(page);
base = (char*)page_address(page);
memset(base, 0, PAGE_SIZE);
de = (struct ufs_dir_entry *) base;
de->d_ino = cpu_to_fs32(sb, inode->i_ino);
ufs_set_de_type(sb, de, inode->i_mode);
ufs_set_de_namlen(sb, de, 1);
de->d_reclen = cpu_to_fs16(sb, UFS_DIR_REC_LEN(1));
strcpy (de->d_name, ".");
de = (struct ufs_dir_entry *)
((char *)de + fs16_to_cpu(sb, de->d_reclen));
de->d_ino = cpu_to_fs32(sb, dir->i_ino);
ufs_set_de_type(sb, de, dir->i_mode);
de->d_reclen = cpu_to_fs16(sb, chunk_size - UFS_DIR_REC_LEN(1));
ufs_set_de_namlen(sb, de, 2);
strcpy (de->d_name, "..");
kunmap(page);
err = ufs_commit_chunk(page, 0, chunk_size);
fail:
put_page(page);
return err;
}
/*
* routine to check that the specified directory is empty (for rmdir)
*/
int ufs_empty_dir(struct inode * inode)
{
struct super_block *sb = inode->i_sb;
struct page *page = NULL;
unsigned long i, npages = dir_pages(inode);
for (i = 0; i < npages; i++) {
char *kaddr;
struct ufs_dir_entry *de;
page = ufs_get_page(inode, i);
if (IS_ERR(page))
continue;
kaddr = page_address(page);
de = (struct ufs_dir_entry *)kaddr;
kaddr += ufs_last_byte(inode, i) - UFS_DIR_REC_LEN(1);
while ((char *)de <= kaddr) {
if (de->d_reclen == 0) {
ufs_error(inode->i_sb, __func__,
"zero-length directory entry: "
"kaddr=%p, de=%p\n", kaddr, de);
goto not_empty;
}
if (de->d_ino) {
u16 namelen=ufs_get_de_namlen(sb, de);
/* check for . and .. */
if (de->d_name[0] != '.')
goto not_empty;
if (namelen > 2)
goto not_empty;
if (namelen < 2) {
if (inode->i_ino !=
fs32_to_cpu(sb, de->d_ino))
goto not_empty;
} else if (de->d_name[1] != '.')
goto not_empty;
}
de = ufs_next_entry(sb, de);
}
ufs_put_page(page);
}
return 1;
not_empty:
ufs_put_page(page);
return 0;
}
const struct file_operations ufs_dir_operations = {
.read = generic_read_dir,
.iterate_shared = ufs_readdir,
.fsync = generic_file_fsync,
.llseek = generic_file_llseek,
};
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