1 files changed, 469 insertions, 0 deletions

diff --git a/fs/minix/dir.c b/fs/minix/dir.c
new file mode 100644
index 000000000..dcfe5b253
--- /dev/null
+++ b/fs/minix/dir.c
@@ -0,0 +1,469 @@
+// 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,
+};
+
+static inline void dir_put_page(struct page *page)
+{
+	kunmap(page);
+	put_page(page);
+}
+
+/*
+ * 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 int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
+{
+	struct address_space *mapping = page->mapping;
+	struct inode *dir = mapping->host;
+	int err = 0;
+	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);
+	else
+		unlock_page(page);
+	return err;
+}
+
+static struct page * dir_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);
+	return page;
+}
+
+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 page *page = dir_get_page(inode, n);
+
+		if (IS_ERR(page))
+			continue;
+		kaddr = (char *)page_address(page);
+		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)) {
+					dir_put_page(page);
+					return 0;
+				}
+			}
+			ctx->pos += chunk_size;
+		}
+		dir_put_page(page);
+	}
+	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
+ * returns the cache buffer in which the entry was found, and the entry
+ * itself (as a parameter - res_dir). It does NOT read the inode of the
+ * entry - you'll have to do that yourself if you want to.
+ */
+minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page)
+{
+	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);
+	struct page *page = NULL;
+	char *p;
+
+	char *namx;
+	__u32 inumber;
+	*res_page = NULL;
+
+	for (n = 0; n < npages; n++) {
+		char *kaddr, *limit;
+
+		page = dir_get_page(dir, n);
+		if (IS_ERR(page))
+			continue;
+
+		kaddr = (char*)page_address(page);
+		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;
+		}
+		dir_put_page(page);
+	}
+	return NULL;
+
+found:
+	*res_page = page;
+	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 page *page = 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;
+
+		page = dir_get_page(dir, n);
+		err = PTR_ERR(page);
+		if (IS_ERR(page))
+			goto out;
+		lock_page(page);
+		kaddr = (char*)page_address(page);
+		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;
+		}
+		unlock_page(page);
+		dir_put_page(page);
+	}
+	BUG();
+	return -EINVAL;
+
+got_it:
+	pos = page_offset(page) + p - (char *)page_address(page);
+	err = minix_prepare_chunk(page, 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;
+	}
+	err = dir_commit_chunk(page, pos, sbi->s_dirsize);
+	dir->i_mtime = dir->i_ctime = current_time(dir);
+	mark_inode_dirty(dir);
+out_put:
+	dir_put_page(page);
+out:
+	return err;
+out_unlock:
+	unlock_page(page);
+	goto out_put;
+}
+
+int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
+{
+	struct inode *inode = page->mapping->host;
+	char *kaddr = page_address(page);
+	loff_t pos = page_offset(page) + (char*)de - kaddr;
+	struct minix_sb_info *sbi = minix_sb(inode->i_sb);
+	unsigned len = sbi->s_dirsize;
+	int err;
+
+	lock_page(page);
+	err = minix_prepare_chunk(page, pos, len);
+	if (err == 0) {
+		if (sbi->s_version == MINIX_V3)
+			((minix3_dirent *) de)->inode = 0;
+		else
+			de->inode = 0;
+		err = dir_commit_chunk(page, pos, len);
+	} else {
+		unlock_page(page);
+	}
+	dir_put_page(page);
+	inode->i_ctime = inode->i_mtime = current_time(inode);
+	mark_inode_dirty(inode);
+	return err;
+}
+
+int minix_make_empty(struct inode *inode, struct inode *dir)
+{
+	struct page *page = grab_cache_page(inode->i_mapping, 0);
+	struct minix_sb_info *sbi = minix_sb(inode->i_sb);
+	char *kaddr;
+	int err;
+
+	if (!page)
+		return -ENOMEM;
+	err = minix_prepare_chunk(page, 0, 2 * sbi->s_dirsize);
+	if (err) {
+		unlock_page(page);
+		goto fail;
+	}
+
+	kaddr = kmap_atomic(page);
+	memset(kaddr, 0, PAGE_SIZE);
+
+	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_atomic(kaddr);
+
+	err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
+fail:
+	put_page(page);
+	return err;
+}
+
+/*
+ * routine to check that the specified directory is empty (for rmdir)
+ */
+int minix_empty_dir(struct inode * inode)
+{
+	struct page *page = NULL;
+	unsigned long i, npages = dir_pages(inode);
+	struct minix_sb_info *sbi = minix_sb(inode->i_sb);
+	char *name;
+	__u32 inumber;
+
+	for (i = 0; i < npages; i++) {
+		char *p, *kaddr, *limit;
+
+		page = dir_get_page(inode, i);
+		if (IS_ERR(page))
+			continue;
+
+		kaddr = (char *)page_address(page);
+		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;
+			}
+		}
+		dir_put_page(page);
+	}
+	return 1;
+
+not_empty:
+	dir_put_page(page);
+	return 0;
+}
+
+/* Releases the page */
+void minix_set_link(struct minix_dir_entry *de, struct page *page,
+	struct inode *inode)
+{
+	struct inode *dir = page->mapping->host;
+	struct minix_sb_info *sbi = minix_sb(dir->i_sb);
+	loff_t pos = page_offset(page) +
+			(char *)de-(char*)page_address(page);
+	int err;
+
+	lock_page(page);
+
+	err = minix_prepare_chunk(page, pos, sbi->s_dirsize);
+	if (err == 0) {
+		if (sbi->s_version == MINIX_V3)
+			((minix3_dirent *) de)->inode = inode->i_ino;
+		else
+			de->inode = inode->i_ino;
+		err = dir_commit_chunk(page, pos, sbi->s_dirsize);
+	} else {
+		unlock_page(page);
+	}
+	dir_put_page(page);
+	dir->i_mtime = dir->i_ctime = current_time(dir);
+	mark_inode_dirty(dir);
+}
+
+struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p)
+{
+	struct page *page = dir_get_page(dir, 0);
+	struct minix_sb_info *sbi = minix_sb(dir->i_sb);
+	struct minix_dir_entry *de = NULL;
+
+	if (!IS_ERR(page)) {
+		de = minix_next_entry(page_address(page), sbi);
+		*p = page;
+	}
+	return de;
+}
+
+ino_t minix_inode_by_name(struct dentry *dentry)
+{
+	struct page *page;
+	struct minix_dir_entry *de = minix_find_entry(dentry, &page);
+	ino_t res = 0;
+
+	if (de) {
+		struct address_space *mapping = page->mapping;
+		struct inode *inode = 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;
+		dir_put_page(page);
+	}
+	return res;
+}