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linux-sg2042/fs/ext2/dir.c

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/*
* linux/fs/ext2/dir.c
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card (card@masi.ibp.fr)
* 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 (davem@caip.rutgers.edu), 1995
*
* All code that works with directory layout had been switched to pagecache
* and moved here. AV
*/
#include "ext2.h"
#include <linux/pagemap.h>
#include <linux/smp_lock.h>
typedef struct ext2_dir_entry_2 ext2_dirent;
/*
* 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;
}
static inline void ext2_put_page(struct page *page)
{
kunmap(page);
page_cache_release(page);
}
static inline unsigned long dir_pages(struct inode *inode)
{
return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
}
/*
* 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_CACHE_SHIFT;
if (last_byte > PAGE_CACHE_SIZE)
last_byte = PAGE_CACHE_SIZE;
return last_byte;
}
static int ext2_commit_chunk(struct page *page, unsigned from, unsigned to)
{
struct inode *dir = page->mapping->host;
int err = 0;
dir->i_version++;
page->mapping->a_ops->commit_write(NULL, page, from, to);
if (IS_DIRSYNC(dir))
err = write_one_page(page, 1);
else
unlock_page(page);
return err;
}
static void ext2_check_page(struct page *page)
{
struct inode *dir = page->mapping->host;
struct super_block *sb = dir->i_sb;
unsigned chunk_size = ext2_chunk_size(dir);
char *kaddr = page_address(page);
u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
unsigned offs, rec_len;
unsigned limit = PAGE_CACHE_SIZE;
ext2_dirent *p;
char *error;
if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
limit = dir->i_size & ~PAGE_CACHE_MASK;
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 = le16_to_cpu(p->rec_len);
if (rec_len < EXT2_DIR_REC_LEN(1))
goto Eshort;
if (rec_len & 3)
goto Ealign;
if (rec_len < EXT2_DIR_REC_LEN(p->name_len))
goto Enamelen;
if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
goto Espan;
if (le32_to_cpu(p->inode) > max_inumber)
goto Einumber;
}
if (offs != limit)
goto Eend;
out:
SetPageChecked(page);
return;
/* Too bad, we had an error */
Ebadsize:
ext2_error(sb, "ext2_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:
ext2_error (sb, "ext2_check_page", "bad entry in directory #%lu: %s - "
"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
(unsigned long) le32_to_cpu(p->inode),
rec_len, p->name_len);
goto fail;
Eend:
p = (ext2_dirent *)(kaddr + offs);
ext2_error (sb, "ext2_check_page",
"entry in directory #%lu spans the page boundary"
"offset=%lu, inode=%lu",
dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
(unsigned long) le32_to_cpu(p->inode));
fail:
SetPageChecked(page);
SetPageError(page);
}
static struct page * ext2_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 (!PageChecked(page))
ext2_check_page(page);
if (PageError(page))
goto fail;
}
return page;
fail:
ext2_put_page(page);
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 + le16_to_cpu(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 (char *)p - base;
}
static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
[EXT2_FT_UNKNOWN] = DT_UNKNOWN,
[EXT2_FT_REG_FILE] = DT_REG,
[EXT2_FT_DIR] = DT_DIR,
[EXT2_FT_CHRDEV] = DT_CHR,
[EXT2_FT_BLKDEV] = DT_BLK,
[EXT2_FT_FIFO] = DT_FIFO,
[EXT2_FT_SOCK] = DT_SOCK,
[EXT2_FT_SYMLINK] = DT_LNK,
};
#define S_SHIFT 12
static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
[S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE,
[S_IFDIR >> S_SHIFT] = EXT2_FT_DIR,
[S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV,
[S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV,
[S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO,
[S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK,
[S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK,
};
static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
{
mode_t mode = inode->i_mode;
if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
else
de->file_type = 0;
}
static int
ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
{
loff_t pos = filp->f_pos;
struct inode *inode = filp->f_path.dentry->d_inode;
struct super_block *sb = inode->i_sb;
unsigned int offset = pos & ~PAGE_CACHE_MASK;
unsigned long n = pos >> PAGE_CACHE_SHIFT;
unsigned long npages = dir_pages(inode);
unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
unsigned char *types = NULL;
int need_revalidate = filp->f_version != inode->i_version;
if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
return 0;
if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
types = ext2_filetype_table;
for ( ; n < npages; n++, offset = 0) {
char *kaddr, *limit;
ext2_dirent *de;
struct page *page = ext2_get_page(inode, n);
if (IS_ERR(page)) {
ext2_error(sb, __FUNCTION__,
"bad page in #%lu",
inode->i_ino);
filp->f_pos += PAGE_CACHE_SIZE - offset;
return -EIO;
}
kaddr = page_address(page);
if (unlikely(need_revalidate)) {
if (offset) {
offset = ext2_validate_entry(kaddr, offset, chunk_mask);
filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
}
filp->f_version = inode->i_version;
need_revalidate = 0;
}
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, __FUNCTION__,
"zero-length directory entry");
ext2_put_page(page);
return -EIO;
}
if (de->inode) {
int over;
unsigned char d_type = DT_UNKNOWN;
if (types && de->file_type < EXT2_FT_MAX)
d_type = types[de->file_type];
offset = (char *)de - kaddr;
over = filldir(dirent, de->name, de->name_len,
(n<<PAGE_CACHE_SHIFT) | offset,
le32_to_cpu(de->inode), d_type);
if (over) {
ext2_put_page(page);
return 0;
}
}
filp->f_pos += le16_to_cpu(de->rec_len);
}
ext2_put_page(page);
}
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, and the entry itself
* (as a parameter - res_dir). Page is returned mapped and unlocked.
* Entry is guaranteed to be valid.
*/
struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
struct dentry *dentry, struct page ** res_page)
{
const char *name = dentry->d_name.name;
int namelen = dentry->d_name.len;
unsigned reclen = EXT2_DIR_REC_LEN(namelen);
unsigned long start, n;
unsigned long npages = dir_pages(dir);
struct page *page = NULL;
struct ext2_inode_info *ei = EXT2_I(dir);
ext2_dirent * de;
if (npages == 0)
goto out;
/* OFFSET_CACHE */
*res_page = NULL;
start = ei->i_dir_start_lookup;
if (start >= npages)
start = 0;
n = start;
do {
char *kaddr;
page = ext2_get_page(dir, n);
if (!IS_ERR(page)) {
kaddr = page_address(page);
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, __FUNCTION__,
"zero-length directory entry");
ext2_put_page(page);
goto out;
}
if (ext2_match (namelen, name, de))
goto found;
de = ext2_next_entry(de);
}
ext2_put_page(page);
}
if (++n >= npages)
n = 0;
/* next page is past the blocks we've got */
if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
ext2_error(dir->i_sb, __FUNCTION__,
"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:
*res_page = page;
ei->i_dir_start_lookup = n;
return de;
}
struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
{
struct page *page = ext2_get_page(dir, 0);
ext2_dirent *de = NULL;
if (!IS_ERR(page)) {
de = ext2_next_entry((ext2_dirent *) page_address(page));
*p = page;
}
return de;
}
ino_t ext2_inode_by_name(struct inode * dir, struct dentry *dentry)
{
ino_t res = 0;
struct ext2_dir_entry_2 * de;
struct page *page;
de = ext2_find_entry (dir, dentry, &page);
if (de) {
res = le32_to_cpu(de->inode);
ext2_put_page(page);
}
return res;
}
/* Releases the page */
void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
struct page *page, struct inode *inode)
{
unsigned from = (char *) de - (char *) page_address(page);
unsigned to = from + le16_to_cpu(de->rec_len);
int err;
lock_page(page);
err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
BUG_ON(err);
de->inode = cpu_to_le32(inode->i_ino);
ext2_set_de_type (de, inode);
err = ext2_commit_chunk(page, from, to);
ext2_put_page(page);
dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
mark_inode_dirty(dir);
}
/*
* Parent is locked.
*/
int ext2_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;
unsigned chunk_size = ext2_chunk_size(dir);
unsigned reclen = EXT2_DIR_REC_LEN(namelen);
unsigned short rec_len, name_len;
struct page *page = NULL;
ext2_dirent * de;
unsigned long npages = dir_pages(dir);
unsigned long n;
char *kaddr;
unsigned from, to;
int err;
/*
* 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 = ext2_get_page(dir, n);
err = PTR_ERR(page);
if (IS_ERR(page))
goto out;
lock_page(page);
kaddr = page_address(page);
dir_end = kaddr + ext2_last_byte(dir, n);
de = (ext2_dirent *)kaddr;
kaddr += PAGE_CACHE_SIZE - reclen;
while ((char *)de <= kaddr) {
if ((char *)de == dir_end) {
/* We hit i_size */
name_len = 0;
rec_len = chunk_size;
de->rec_len = cpu_to_le16(chunk_size);
de->inode = 0;
goto got_it;
}
if (de->rec_len == 0) {
ext2_error(dir->i_sb, __FUNCTION__,
"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 = le16_to_cpu(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);
}
unlock_page(page);
ext2_put_page(page);
}
BUG();
return -EINVAL;
got_it:
from = (char*)de - (char*)page_address(page);
to = from + rec_len;
err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
if (err)
goto out_unlock;
if (de->inode) {
ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
de1->rec_len = cpu_to_le16(rec_len - name_len);
de->rec_len = cpu_to_le16(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);
err = ext2_commit_chunk(page, from, to);
dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
mark_inode_dirty(dir);
/* OFFSET_CACHE */
out_put:
ext2_put_page(page);
out:
return err;
out_unlock:
unlock_page(page);
goto out_put;
}
/*
* ext2_delete_entry deletes a directory entry by merging it with the
* previous entry. Page is up-to-date. Releases the page.
*/
int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
{
struct address_space *mapping = page->mapping;
struct inode *inode = mapping->host;
char *kaddr = page_address(page);
unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
unsigned to = ((char*)dir - kaddr) + le16_to_cpu(dir->rec_len);
ext2_dirent * pde = NULL;
ext2_dirent * de = (ext2_dirent *) (kaddr + from);
int err;
while ((char*)de < (char*)dir) {
if (de->rec_len == 0) {
ext2_error(inode->i_sb, __FUNCTION__,
"zero-length directory entry");
err = -EIO;
goto out;
}
pde = de;
de = ext2_next_entry(de);
}
if (pde)
from = (char*)pde - (char*)page_address(page);
lock_page(page);
err = mapping->a_ops->prepare_write(NULL, page, from, to);
BUG_ON(err);
if (pde)
pde->rec_len = cpu_to_le16(to-from);
dir->inode = 0;
err = ext2_commit_chunk(page, from, to);
inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
mark_inode_dirty(inode);
out:
ext2_put_page(page);
return err;
}
/*
* Set the first fragment of directory.
*/
int ext2_make_empty(struct inode *inode, struct inode *parent)
{
struct address_space *mapping = inode->i_mapping;
struct page *page = grab_cache_page(mapping, 0);
unsigned chunk_size = ext2_chunk_size(inode);
struct ext2_dir_entry_2 * de;
int err;
void *kaddr;
if (!page)
return -ENOMEM;
err = mapping->a_ops->prepare_write(NULL, page, 0, chunk_size);
if (err) {
unlock_page(page);
goto fail;
}
kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr, 0, chunk_size);
de = (struct ext2_dir_entry_2 *)kaddr;
de->name_len = 1;
de->rec_len = cpu_to_le16(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 = cpu_to_le16(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_atomic(kaddr, KM_USER0);
err = ext2_commit_chunk(page, 0, chunk_size);
fail:
page_cache_release(page);
return err;
}
/*
* routine to check that the specified directory is empty (for rmdir)
*/
int ext2_empty_dir (struct inode * inode)
{
struct page *page = NULL;
unsigned long i, npages = dir_pages(inode);
for (i = 0; i < npages; i++) {
char *kaddr;
ext2_dirent * de;
page = ext2_get_page(inode, i);
if (IS_ERR(page))
continue;
kaddr = page_address(page);
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, __FUNCTION__,
"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);
}
ext2_put_page(page);
}
return 1;
not_empty:
ext2_put_page(page);
return 0;
}
const struct file_operations ext2_dir_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.readdir = ext2_readdir,
.ioctl = ext2_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ext2_compat_ioctl,
#endif
.fsync = ext2_sync_file,
};
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