--- /dev/null
+/*
+ * 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 = minix_readdir,
+ .fsync = generic_file_fsync,
+};
+
+static inline void dir_put_page(struct page *page)
+{
+ kunmap(page);
+ page_cache_release(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_CACHE_SIZE;
+
+ if (page_nr == (inode->i_size >> PAGE_CACHE_SHIFT))
+ last_byte = inode->i_size & (PAGE_CACHE_SIZE - 1);
+ return last_byte;
+}
+
+static inline unsigned long dir_pages(struct inode *inode)
+{
+ return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
+}
+
+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, 1);
+ 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_CACHE_MASK;
+ n = pos >> PAGE_CACHE_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_CACHE_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_SEC;
+ 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_SEC;
+ 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_CACHE_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:
+ page_cache_release(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_SEC;
+ 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;
+}
Code Review / kvmfornfv.git / blobdiff