--- /dev/null
+/*
+ * linux/fs/sysv/dir.c
+ *
+ * minix/dir.c
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ *
+ * coh/dir.c
+ * Copyright (C) 1993 Pascal Haible, Bruno Haible
+ *
+ * sysv/dir.c
+ * Copyright (C) 1993 Bruno Haible
+ *
+ * SystemV/Coherent directory handling functions
+ */
+
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/swap.h>
+#include "sysv.h"
+
+static int sysv_readdir(struct file *, struct dir_context *);
+
+const struct file_operations sysv_dir_operations = {
+ .llseek = generic_file_llseek,
+ .read = generic_read_dir,
+ .iterate = sysv_readdir,
+ .fsync = generic_file_fsync,
+};
+
+static inline void dir_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;
+}
+
+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 int sysv_readdir(struct file *file, struct dir_context *ctx)
+{
+ unsigned long pos = ctx->pos;
+ struct inode *inode = file_inode(file);
+ struct super_block *sb = inode->i_sb;
+ unsigned long npages = dir_pages(inode);
+ unsigned offset;
+ unsigned long n;
+
+ ctx->pos = pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
+ if (pos >= inode->i_size)
+ return 0;
+
+ offset = pos & ~PAGE_CACHE_MASK;
+ n = pos >> PAGE_CACHE_SHIFT;
+
+ for ( ; n < npages; n++, offset = 0) {
+ char *kaddr, *limit;
+ struct sysv_dir_entry *de;
+ struct page *page = dir_get_page(inode, n);
+
+ if (IS_ERR(page))
+ continue;
+ kaddr = (char *)page_address(page);
+ de = (struct sysv_dir_entry *)(kaddr+offset);
+ limit = kaddr + PAGE_CACHE_SIZE - SYSV_DIRSIZE;
+ for ( ;(char*)de <= limit; de++, ctx->pos += sizeof(*de)) {
+ char *name = de->name;
+
+ if (!de->inode)
+ continue;
+
+ if (!dir_emit(ctx, name, strnlen(name,SYSV_NAMELEN),
+ fs16_to_cpu(SYSV_SB(sb), de->inode),
+ DT_UNKNOWN)) {
+ dir_put_page(page);
+ return 0;
+ }
+ }
+ dir_put_page(page);
+ }
+ return 0;
+}
+
+/* compare strings: name[0..len-1] (not zero-terminated) and
+ * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
+ */
+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);
+}
+
+/*
+ * sysv_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.
+ */
+struct sysv_dir_entry *sysv_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);
+ unsigned long start, n;
+ unsigned long npages = dir_pages(dir);
+ struct page *page = NULL;
+ struct sysv_dir_entry *de;
+
+ *res_page = NULL;
+
+ start = SYSV_I(dir)->i_dir_start_lookup;
+ if (start >= npages)
+ start = 0;
+ n = start;
+
+ do {
+ char *kaddr;
+ page = dir_get_page(dir, n);
+ if (!IS_ERR(page)) {
+ kaddr = (char*)page_address(page);
+ de = (struct sysv_dir_entry *) kaddr;
+ kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
+ for ( ; (char *) de <= kaddr ; de++) {
+ if (!de->inode)
+ continue;
+ if (namecompare(namelen, SYSV_NAMELEN,
+ name, de->name))
+ goto found;
+ }
+ dir_put_page(page);
+ }
+
+ if (++n >= npages)
+ n = 0;
+ } while (n != start);
+
+ return NULL;
+
+found:
+ SYSV_I(dir)->i_dir_start_lookup = n;
+ *res_page = page;
+ return de;
+}
+
+int sysv_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 page *page = NULL;
+ struct sysv_dir_entry * de;
+ unsigned long npages = dir_pages(dir);
+ unsigned long n;
+ char *kaddr;
+ loff_t pos;
+ int err;
+
+ /* We take care of directory expansion in the same loop */
+ for (n = 0; n <= npages; n++) {
+ page = dir_get_page(dir, n);
+ err = PTR_ERR(page);
+ if (IS_ERR(page))
+ goto out;
+ kaddr = (char*)page_address(page);
+ de = (struct sysv_dir_entry *)kaddr;
+ kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
+ while ((char *)de <= kaddr) {
+ if (!de->inode)
+ goto got_it;
+ err = -EEXIST;
+ if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
+ goto out_page;
+ de++;
+ }
+ dir_put_page(page);
+ }
+ BUG();
+ return -EINVAL;
+
+got_it:
+ pos = page_offset(page) +
+ (char*)de - (char*)page_address(page);
+ lock_page(page);
+ err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
+ if (err)
+ goto out_unlock;
+ memcpy (de->name, name, namelen);
+ memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
+ de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
+ err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
+ dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
+ mark_inode_dirty(dir);
+out_page:
+ dir_put_page(page);
+out:
+ return err;
+out_unlock:
+ unlock_page(page);
+ goto out_page;
+}
+
+int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
+{
+ struct inode *inode = page->mapping->host;
+ char *kaddr = (char*)page_address(page);
+ loff_t pos = page_offset(page) + (char *)de - kaddr;
+ int err;
+
+ lock_page(page);
+ err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
+ BUG_ON(err);
+ de->inode = 0;
+ err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
+ dir_put_page(page);
+ inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
+ mark_inode_dirty(inode);
+ return err;
+}
+
+int sysv_make_empty(struct inode *inode, struct inode *dir)
+{
+ struct page *page = grab_cache_page(inode->i_mapping, 0);
+ struct sysv_dir_entry * de;
+ char *base;
+ int err;
+
+ if (!page)
+ return -ENOMEM;
+ err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE);
+ if (err) {
+ unlock_page(page);
+ goto fail;
+ }
+ kmap(page);
+
+ base = (char*)page_address(page);
+ memset(base, 0, PAGE_CACHE_SIZE);
+
+ de = (struct sysv_dir_entry *) base;
+ de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
+ strcpy(de->name,".");
+ de++;
+ de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
+ strcpy(de->name,"..");
+
+ kunmap(page);
+ err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
+fail:
+ page_cache_release(page);
+ return err;
+}
+
+/*
+ * routine to check that the specified directory is empty (for rmdir)
+ */
+int sysv_empty_dir(struct inode * inode)
+{
+ struct super_block *sb = inode->i_sb;
+ struct page *page = NULL;
+ unsigned long i, npages = dir_pages(inode);
+
+ for (i = 0; i < npages; i++) {
+ char *kaddr;
+ struct sysv_dir_entry * de;
+ page = dir_get_page(inode, i);
+
+ if (IS_ERR(page))
+ continue;
+
+ kaddr = (char *)page_address(page);
+ de = (struct sysv_dir_entry *)kaddr;
+ kaddr += PAGE_CACHE_SIZE-SYSV_DIRSIZE;
+
+ for ( ;(char *)de <= kaddr; de++) {
+ if (!de->inode)
+ continue;
+ /* check for . and .. */
+ if (de->name[0] != '.')
+ goto not_empty;
+ if (!de->name[1]) {
+ if (de->inode == cpu_to_fs16(SYSV_SB(sb),
+ inode->i_ino))
+ continue;
+ goto not_empty;
+ }
+ if (de->name[1] != '.' || de->name[2])
+ goto not_empty;
+ }
+ dir_put_page(page);
+ }
+ return 1;
+
+not_empty:
+ dir_put_page(page);
+ return 0;
+}
+
+/* Releases the page */
+void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
+ struct inode *inode)
+{
+ struct inode *dir = page->mapping->host;
+ loff_t pos = page_offset(page) +
+ (char *)de-(char*)page_address(page);
+ int err;
+
+ lock_page(page);
+ err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
+ BUG_ON(err);
+ de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
+ err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
+ dir_put_page(page);
+ dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
+ mark_inode_dirty(dir);
+}
+
+struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
+{
+ struct page *page = dir_get_page(dir, 0);
+ struct sysv_dir_entry *de = NULL;
+
+ if (!IS_ERR(page)) {
+ de = (struct sysv_dir_entry*) page_address(page) + 1;
+ *p = page;
+ }
+ return de;
+}
+
+ino_t sysv_inode_by_name(struct dentry *dentry)
+{
+ struct page *page;
+ struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
+ ino_t res = 0;
+
+ if (de) {
+ res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
+ dir_put_page(page);
+ }
+ return res;
+}
Code Review / kvmfornfv.git / blobdiff