1
linux/fs/minix/dir.c
Matthew Wilcox (Oracle) 97edbc02b2
buffer: Convert block_write_end() to take a folio
All callers now have a folio, so pass it in instead of converting
from a folio to a page and back to a folio again.  Saves a call
to compound_head().

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-07 11:31:59 +02:00

459 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/minix/dir.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* minix directory handling functions
*
* Updated to filesystem version 3 by Daniel Aragones
*/
#include "minix.h"
#include <linux/buffer_head.h>
#include <linux/highmem.h>
#include <linux/swap.h>
typedef struct minix_dir_entry minix_dirent;
typedef struct minix3_dir_entry minix3_dirent;
static int minix_readdir(struct file *, struct dir_context *);
const struct file_operations minix_dir_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate_shared = minix_readdir,
.fsync = generic_file_fsync,
};
/*
* Return the offset into page `page_nr' of the last valid
* byte in that page, plus one.
*/
static unsigned
minix_last_byte(struct inode *inode, unsigned long page_nr)
{
unsigned last_byte = PAGE_SIZE;
if (page_nr == (inode->i_size >> PAGE_SHIFT))
last_byte = inode->i_size & (PAGE_SIZE - 1);
return last_byte;
}
static void dir_commit_chunk(struct folio *folio, loff_t pos, unsigned len)
{
struct address_space *mapping = folio->mapping;
struct inode *dir = mapping->host;
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 int minix_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;
}
static void *dir_get_folio(struct inode *dir, unsigned long n,
struct folio **foliop)
{
struct folio *folio = read_mapping_folio(dir->i_mapping, n, NULL);
if (IS_ERR(folio))
return ERR_CAST(folio);
*foliop = folio;
return kmap_local_folio(folio, 0);
}
static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi)
{
return (void*)((char*)de + sbi->s_dirsize);
}
static int minix_readdir(struct file *file, struct dir_context *ctx)
{
struct inode *inode = file_inode(file);
struct super_block *sb = inode->i_sb;
struct minix_sb_info *sbi = minix_sb(sb);
unsigned chunk_size = sbi->s_dirsize;
unsigned long npages = dir_pages(inode);
unsigned long pos = ctx->pos;
unsigned offset;
unsigned long n;
ctx->pos = pos = ALIGN(pos, chunk_size);
if (pos >= inode->i_size)
return 0;
offset = pos & ~PAGE_MASK;
n = pos >> PAGE_SHIFT;
for ( ; n < npages; n++, offset = 0) {
char *p, *kaddr, *limit;
struct folio *folio;
kaddr = dir_get_folio(inode, n, &folio);
if (IS_ERR(kaddr))
continue;
p = kaddr+offset;
limit = kaddr + minix_last_byte(inode, n) - chunk_size;
for ( ; p <= limit; p = minix_next_entry(p, sbi)) {
const char *name;
__u32 inumber;
if (sbi->s_version == MINIX_V3) {
minix3_dirent *de3 = (minix3_dirent *)p;
name = de3->name;
inumber = de3->inode;
} else {
minix_dirent *de = (minix_dirent *)p;
name = de->name;
inumber = de->inode;
}
if (inumber) {
unsigned l = strnlen(name, sbi->s_namelen);
if (!dir_emit(ctx, name, l,
inumber, DT_UNKNOWN)) {
folio_release_kmap(folio, p);
return 0;
}
}
ctx->pos += chunk_size;
}
folio_release_kmap(folio, kaddr);
}
return 0;
}
static inline int namecompare(int len, int maxlen,
const char * name, const char * buffer)
{
if (len < maxlen && buffer[len])
return 0;
return !memcmp(name, buffer, len);
}
/*
* minix_find_entry()
*
* finds an entry in the specified directory with the wanted name.
* It does NOT read the inode of the
* entry - you'll have to do that yourself if you want to.
*
* On Success folio_release_kmap() should be called on *foliop.
*/
minix_dirent *minix_find_entry(struct dentry *dentry, struct folio **foliop)
{
const char * name = dentry->d_name.name;
int namelen = dentry->d_name.len;
struct inode * dir = d_inode(dentry->d_parent);
struct super_block * sb = dir->i_sb;
struct minix_sb_info * sbi = minix_sb(sb);
unsigned long n;
unsigned long npages = dir_pages(dir);
char *p;
char *namx;
__u32 inumber;
for (n = 0; n < npages; n++) {
char *kaddr, *limit;
kaddr = dir_get_folio(dir, n, foliop);
if (IS_ERR(kaddr))
continue;
limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize;
for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
if (sbi->s_version == MINIX_V3) {
minix3_dirent *de3 = (minix3_dirent *)p;
namx = de3->name;
inumber = de3->inode;
} else {
minix_dirent *de = (minix_dirent *)p;
namx = de->name;
inumber = de->inode;
}
if (!inumber)
continue;
if (namecompare(namelen, sbi->s_namelen, name, namx))
goto found;
}
folio_release_kmap(*foliop, kaddr);
}
return NULL;
found:
return (minix_dirent *)p;
}
int minix_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;
struct super_block * sb = dir->i_sb;
struct minix_sb_info * sbi = minix_sb(sb);
struct folio *folio = NULL;
unsigned long npages = dir_pages(dir);
unsigned long n;
char *kaddr, *p;
minix_dirent *de;
minix3_dirent *de3;
loff_t pos;
int err;
char *namx = NULL;
__u32 inumber;
/*
* 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 *limit, *dir_end;
kaddr = dir_get_folio(dir, n, &folio);
if (IS_ERR(kaddr))
return PTR_ERR(kaddr);
folio_lock(folio);
dir_end = kaddr + minix_last_byte(dir, n);
limit = kaddr + PAGE_SIZE - sbi->s_dirsize;
for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
de = (minix_dirent *)p;
de3 = (minix3_dirent *)p;
if (sbi->s_version == MINIX_V3) {
namx = de3->name;
inumber = de3->inode;
} else {
namx = de->name;
inumber = de->inode;
}
if (p == dir_end) {
/* We hit i_size */
if (sbi->s_version == MINIX_V3)
de3->inode = 0;
else
de->inode = 0;
goto got_it;
}
if (!inumber)
goto got_it;
err = -EEXIST;
if (namecompare(namelen, sbi->s_namelen, name, namx))
goto out_unlock;
}
folio_unlock(folio);
folio_release_kmap(folio, kaddr);
}
BUG();
return -EINVAL;
got_it:
pos = folio_pos(folio) + offset_in_folio(folio, p);
err = minix_prepare_chunk(folio, pos, sbi->s_dirsize);
if (err)
goto out_unlock;
memcpy (namx, name, namelen);
if (sbi->s_version == MINIX_V3) {
memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4);
de3->inode = inode->i_ino;
} else {
memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2);
de->inode = inode->i_ino;
}
dir_commit_chunk(folio, pos, sbi->s_dirsize);
inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
mark_inode_dirty(dir);
err = minix_handle_dirsync(dir);
out_put:
folio_release_kmap(folio, kaddr);
return err;
out_unlock:
folio_unlock(folio);
goto out_put;
}
int minix_delete_entry(struct minix_dir_entry *de, struct folio *folio)
{
struct inode *inode = folio->mapping->host;
loff_t pos = folio_pos(folio) + offset_in_folio(folio, de);
struct minix_sb_info *sbi = minix_sb(inode->i_sb);
unsigned len = sbi->s_dirsize;
int err;
folio_lock(folio);
err = minix_prepare_chunk(folio, pos, len);
if (err) {
folio_unlock(folio);
return err;
}
if (sbi->s_version == MINIX_V3)
((minix3_dirent *)de)->inode = 0;
else
de->inode = 0;
dir_commit_chunk(folio, pos, len);
inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
mark_inode_dirty(inode);
return minix_handle_dirsync(inode);
}
int minix_make_empty(struct inode *inode, struct inode *dir)
{
struct folio *folio = filemap_grab_folio(inode->i_mapping, 0);
struct minix_sb_info *sbi = minix_sb(inode->i_sb);
char *kaddr;
int err;
if (IS_ERR(folio))
return PTR_ERR(folio);
err = minix_prepare_chunk(folio, 0, 2 * sbi->s_dirsize);
if (err) {
folio_unlock(folio);
goto fail;
}
kaddr = kmap_local_folio(folio, 0);
memset(kaddr, 0, folio_size(folio));
if (sbi->s_version == MINIX_V3) {
minix3_dirent *de3 = (minix3_dirent *)kaddr;
de3->inode = inode->i_ino;
strcpy(de3->name, ".");
de3 = minix_next_entry(de3, sbi);
de3->inode = dir->i_ino;
strcpy(de3->name, "..");
} else {
minix_dirent *de = (minix_dirent *)kaddr;
de->inode = inode->i_ino;
strcpy(de->name, ".");
de = minix_next_entry(de, sbi);
de->inode = dir->i_ino;
strcpy(de->name, "..");
}
kunmap_local(kaddr);
dir_commit_chunk(folio, 0, 2 * sbi->s_dirsize);
err = minix_handle_dirsync(inode);
fail:
folio_put(folio);
return err;
}
/*
* routine to check that the specified directory is empty (for rmdir)
*/
int minix_empty_dir(struct inode * inode)
{
struct folio *folio = NULL;
unsigned long i, npages = dir_pages(inode);
struct minix_sb_info *sbi = minix_sb(inode->i_sb);
char *name, *kaddr;
__u32 inumber;
for (i = 0; i < npages; i++) {
char *p, *limit;
kaddr = dir_get_folio(inode, i, &folio);
if (IS_ERR(kaddr))
continue;
limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize;
for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
if (sbi->s_version == MINIX_V3) {
minix3_dirent *de3 = (minix3_dirent *)p;
name = de3->name;
inumber = de3->inode;
} else {
minix_dirent *de = (minix_dirent *)p;
name = de->name;
inumber = de->inode;
}
if (inumber != 0) {
/* check for . and .. */
if (name[0] != '.')
goto not_empty;
if (!name[1]) {
if (inumber != inode->i_ino)
goto not_empty;
} else if (name[1] != '.')
goto not_empty;
else if (name[2])
goto not_empty;
}
}
folio_release_kmap(folio, kaddr);
}
return 1;
not_empty:
folio_release_kmap(folio, kaddr);
return 0;
}
/* Releases the page */
int minix_set_link(struct minix_dir_entry *de, struct folio *folio,
struct inode *inode)
{
struct inode *dir = folio->mapping->host;
struct minix_sb_info *sbi = minix_sb(dir->i_sb);
loff_t pos = folio_pos(folio) + offset_in_folio(folio, de);
int err;
folio_lock(folio);
err = minix_prepare_chunk(folio, pos, sbi->s_dirsize);
if (err) {
folio_unlock(folio);
return err;
}
if (sbi->s_version == MINIX_V3)
((minix3_dirent *)de)->inode = inode->i_ino;
else
de->inode = inode->i_ino;
dir_commit_chunk(folio, pos, sbi->s_dirsize);
inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
mark_inode_dirty(dir);
return minix_handle_dirsync(dir);
}
struct minix_dir_entry *minix_dotdot(struct inode *dir, struct folio **foliop)
{
struct minix_sb_info *sbi = minix_sb(dir->i_sb);
struct minix_dir_entry *de = dir_get_folio(dir, 0, foliop);
if (!IS_ERR(de))
return minix_next_entry(de, sbi);
return NULL;
}
ino_t minix_inode_by_name(struct dentry *dentry)
{
struct folio *folio;
struct minix_dir_entry *de = minix_find_entry(dentry, &folio);
ino_t res = 0;
if (de) {
struct inode *inode = folio->mapping->host;
struct minix_sb_info *sbi = minix_sb(inode->i_sb);
if (sbi->s_version == MINIX_V3)
res = ((minix3_dirent *) de)->inode;
else
res = de->inode;
folio_release_kmap(folio, de);
}
return res;
}