original development tree for Linux kernel GTP module; now long in mainline.
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/*
* dir.c - NILFS directory entry operations
*
* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* Modified for NILFS by Amagai Yoshiji <amagai@osrg.net>
*/
/*
* 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 <linux/pagemap.h>
#include "nilfs.h"
#include "page.h"
/*
* nilfs uses block-sized chunks. Arguably, sector-sized ones would be
* more robust, but we have what we have
*/
static inline unsigned nilfs_chunk_size(struct inode *inode)
{
return inode->i_sb->s_blocksize;
}
static inline void nilfs_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 nilfs_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 nilfs_prepare_chunk(struct page *page, unsigned from, unsigned to)
{
loff_t pos = page_offset(page) + from;
return __block_write_begin(page, pos, to - from, nilfs_get_block);
}
static void nilfs_commit_chunk(struct page *page,
struct address_space *mapping,
unsigned from, unsigned to)
{
struct inode *dir = mapping->host;
loff_t pos = page_offset(page) + from;
unsigned len = to - from;
unsigned nr_dirty, copied;
int err;
nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
copied = block_write_end(NULL, mapping, pos, len, len, page, 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 */
unlock_page(page);
}
static void nilfs_check_page(struct page *page)
{
struct inode *dir = page->mapping->host;
struct super_block *sb = dir->i_sb;
unsigned chunk_size = nilfs_chunk_size(dir);
char *kaddr = page_address(page);
unsigned offs, rec_len;
unsigned limit = PAGE_CACHE_SIZE;
struct nilfs_dir_entry *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 - 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 (offs != limit)
goto Eend;
out:
SetPageChecked(page);
return;
/* Too bad, we had an error */
Ebadsize:
nilfs_error(sb, "nilfs_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";
bad_entry:
nilfs_error(sb, "nilfs_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) le64_to_cpu(p->inode),
rec_len, p->name_len);
goto fail;
Eend:
p = (struct nilfs_dir_entry *)(kaddr + offs);
nilfs_error(sb, "nilfs_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) le64_to_cpu(p->inode));
fail:
SetPageChecked(page);
SetPageError(page);
}
static struct page *nilfs_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))
nilfs_check_page(page);
if (PageError(page))
goto fail;
}
return page;
fail:
nilfs_put_page(page);
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 unsigned char
nilfs_filetype_table[NILFS_FT_MAX] = {
[NILFS_FT_UNKNOWN] = DT_UNKNOWN,
[NILFS_FT_REG_FILE] = DT_REG,
[NILFS_FT_DIR] = DT_DIR,
[NILFS_FT_CHRDEV] = DT_CHR,
[NILFS_FT_BLKDEV] = DT_BLK,
[NILFS_FT_FIFO] = DT_FIFO,
[NILFS_FT_SOCK] = DT_SOCK,
[NILFS_FT_SYMLINK] = DT_LNK,
};
#define S_SHIFT 12
static unsigned char
nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
[S_IFREG >> S_SHIFT] = NILFS_FT_REG_FILE,
[S_IFDIR >> S_SHIFT] = NILFS_FT_DIR,
[S_IFCHR >> S_SHIFT] = NILFS_FT_CHRDEV,
[S_IFBLK >> S_SHIFT] = NILFS_FT_BLKDEV,
[S_IFIFO >> S_SHIFT] = NILFS_FT_FIFO,
[S_IFSOCK >> S_SHIFT] = NILFS_FT_SOCK,
[S_IFLNK >> S_SHIFT] = NILFS_FT_SYMLINK,
};
static void nilfs_set_de_type(struct nilfs_dir_entry *de, struct inode *inode)
{
umode_t mode = inode->i_mode;
de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
}
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_CACHE_MASK;
unsigned long n = pos >> PAGE_CACHE_SHIFT;
unsigned long npages = dir_pages(inode);
/* unsigned chunk_mask = ~(nilfs_chunk_size(inode)-1); */
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 page *page = nilfs_get_page(inode, n);
if (IS_ERR(page)) {
nilfs_error(sb, __func__, "bad page in #%lu",
inode->i_ino);
ctx->pos += PAGE_CACHE_SIZE - offset;
return -EIO;
}
kaddr = page_address(page);
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, __func__,
"zero-length directory entry");
nilfs_put_page(page);
return -EIO;
}
if (de->inode) {
unsigned char t;
if (de->file_type < NILFS_FT_MAX)
t = nilfs_filetype_table[de->file_type];
else
t = DT_UNKNOWN;
if (!dir_emit(ctx, de->name, de->name_len,
le64_to_cpu(de->inode), t)) {
nilfs_put_page(page);
return 0;
}
}
ctx->pos += nilfs_rec_len_from_disk(de->rec_len);
}
nilfs_put_page(page);
}
return 0;
}
/*
* nilfs_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 nilfs_dir_entry *
nilfs_find_entry(struct inode *dir, const struct qstr *qstr,
struct page **res_page)
{
const unsigned char *name = qstr->name;
int namelen = qstr->len;
unsigned reclen = NILFS_DIR_REC_LEN(namelen);
unsigned long start, n;
unsigned long npages = dir_pages(dir);
struct page *page = NULL;
struct nilfs_inode_info *ei = NILFS_I(dir);
struct nilfs_dir_entry *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 = nilfs_get_page(dir, n);
if (!IS_ERR(page)) {
kaddr = page_address(page);
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, __func__,
"zero-length directory entry");
nilfs_put_page(page);
goto out;
}
if (nilfs_match(namelen, name, de))
goto found;
de = nilfs_next_entry(de);
}
nilfs_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)))) {
nilfs_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 NULL;
found:
*res_page = page;
ei->i_dir_start_lookup = n;
return de;
}
struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct page **p)
{
struct page *page = nilfs_get_page(dir, 0);
struct nilfs_dir_entry *de = NULL;
if (!IS_ERR(page)) {
de = nilfs_next_entry(
(struct nilfs_dir_entry *)page_address(page));
*p = page;
}
return de;
}
ino_t nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr)
{
ino_t res = 0;
struct nilfs_dir_entry *de;
struct page *page;
de = nilfs_find_entry(dir, qstr, &page);
if (de) {
res = le64_to_cpu(de->inode);
kunmap(page);
page_cache_release(page);
}
return res;
}
/* Releases the page */
void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
struct page *page, struct inode *inode)
{
unsigned from = (char *) de - (char *) page_address(page);
unsigned to = from + nilfs_rec_len_from_disk(de->rec_len);
struct address_space *mapping = page->mapping;
int err;
lock_page(page);
err = nilfs_prepare_chunk(page, from, to);
BUG_ON(err);
de->inode = cpu_to_le64(inode->i_ino);
nilfs_set_de_type(de, inode);
nilfs_commit_chunk(page, mapping, from, to);
nilfs_put_page(page);
dir->i_mtime = dir->i_ctime = CURRENT_TIME;
}
/*
* Parent is locked.
*/
int nilfs_add_link(struct dentry *dentry, struct inode *inode)
{
struct inode *dir = dentry->d_parent->d_inode;
const unsigned char *name = dentry->d_name.name;
int namelen = dentry->d_name.len;
unsigned chunk_size = nilfs_chunk_size(dir);
unsigned reclen = NILFS_DIR_REC_LEN(namelen);
unsigned short rec_len, name_len;
struct page *page = NULL;
struct nilfs_dir_entry *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 = nilfs_get_page(dir, n);
err = PTR_ERR(page);
if (IS_ERR(page))
goto out;
lock_page(page);
kaddr = page_address(page);
dir_end = kaddr + nilfs_last_byte(dir, n);
de = (struct nilfs_dir_entry *)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 = nilfs_rec_len_to_disk(chunk_size);
de->inode = 0;
goto got_it;
}
if (de->rec_len == 0) {
nilfs_error(dir->i_sb, __func__,
"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);
}
unlock_page(page);
nilfs_put_page(page);
}
BUG();
return -EINVAL;
got_it:
from = (char *)de - (char *)page_address(page);
to = from + rec_len;
err = nilfs_prepare_chunk(page, 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);
nilfs_set_de_type(de, inode);
nilfs_commit_chunk(page, page->mapping, from, to);
dir->i_mtime = dir->i_ctime = CURRENT_TIME;
nilfs_mark_inode_dirty(dir);
/* OFFSET_CACHE */
out_put:
nilfs_put_page(page);
out:
return err;
out_unlock:
unlock_page(page);
goto out_put;
}
/*
* nilfs_delete_entry deletes a directory entry by merging it with the
* previous entry. Page is up-to-date. Releases the page.
*/
int nilfs_delete_entry(struct nilfs_dir_entry *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) & ~(nilfs_chunk_size(inode) - 1);
unsigned to = ((char *)dir - kaddr) +
nilfs_rec_len_from_disk(dir->rec_len);
struct nilfs_dir_entry *pde = NULL;
struct nilfs_dir_entry *de = (struct nilfs_dir_entry *)(kaddr + from);
int err;
while ((char *)de < (char *)dir) {
if (de->rec_len == 0) {
nilfs_error(inode->i_sb, __func__,
"zero-length directory entry");
err = -EIO;
goto out;
}
pde = de;
de = nilfs_next_entry(de);
}
if (pde)
from = (char *)pde - (char *)page_address(page);
lock_page(page);
err = nilfs_prepare_chunk(page, from, to);
BUG_ON(err);
if (pde)
pde->rec_len = nilfs_rec_len_to_disk(to - from);
dir->inode = 0;
nilfs_commit_chunk(page, mapping, from, to);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
out:
nilfs_put_page(page);
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 page *page = grab_cache_page(mapping, 0);
unsigned chunk_size = nilfs_chunk_size(inode);
struct nilfs_dir_entry *de;
int err;
void *kaddr;
if (!page)
return -ENOMEM;
err = nilfs_prepare_chunk(page, 0, chunk_size);
if (unlikely(err)) {
unlock_page(page);
goto fail;
}
kaddr = kmap_atomic(page);
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);
nilfs_set_de_type(de, inode);
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);
nilfs_set_de_type(de, inode);
kunmap_atomic(kaddr);
nilfs_commit_chunk(page, mapping, 0, chunk_size);
fail:
page_cache_release(page);
return err;
}
/*
* routine to check that the specified directory is empty (for rmdir)
*/
int nilfs_empty_dir(struct inode *inode)
{
struct page *page = NULL;
unsigned long i, npages = dir_pages(inode);
for (i = 0; i < npages; i++) {
char *kaddr;
struct nilfs_dir_entry *de;
page = nilfs_get_page(inode, i);
if (IS_ERR(page))
continue;
kaddr = page_address(page);
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, __func__,
"zero-length directory entry "
"(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_le64(inode->i_ino))
goto not_empty;
} else if (de->name[1] != '.')
goto not_empty;
}
de = nilfs_next_entry(de);
}
nilfs_put_page(page);
}
return 1;
not_empty:
nilfs_put_page(page);
return 0;
}
const struct file_operations nilfs_dir_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate = nilfs_readdir,
.unlocked_ioctl = nilfs_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = nilfs_compat_ioctl,
#endif /* CONFIG_COMPAT */
.fsync = nilfs_sync_file,
};