patch-2.4.6 linux/fs/sysv/dir.c

• Lines: 397
• Date: Mon Jul 2 14:03:04 2001
• Orig file: v2.4.5/linux/fs/sysv/dir.c
• Orig date: Fri Aug 11 14:29:01 2000

diff -u --recursive --new-file v2.4.5/linux/fs/sysv/dir.c linux/fs/sysv/dir.c
@@ -13,63 +13,356 @@
  *  SystemV/Coherent directory handling functions
  */
 
-#include <linux/errno.h>
 #include <linux/fs.h>
 #include <linux/sysv_fs.h>
-#include <linux/stat.h>
-#include <linux/string.h>
+#include <linux/pagemap.h>
 
 static int sysv_readdir(struct file *, void *, filldir_t);
 
 struct file_operations sysv_dir_operations = {
 	read:		generic_read_dir,
 	readdir:	sysv_readdir,
-	fsync:		file_fsync,
+	fsync:		sysv_sync_file,
 };
 
+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, unsigned from, unsigned to)
+{
+	struct inode *dir = (struct inode *)page->mapping->host;
+	int err = 0;
+	page->mapping->a_ops->commit_write(NULL, page, from, to);
+	if (IS_SYNC(dir))
+		err = waitfor_one_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_cache_page(mapping, n,
+				(filler_t*)mapping->a_ops->readpage, NULL);
+	if (!IS_ERR(page)) {
+		wait_on_page(page);
+		kmap(page);
+		if (!Page_Uptodate(page))
+			goto fail;
+	}
+	return page;
+
+fail:
+	dir_put_page(page);
+	return ERR_PTR(-EIO);
+}
+
 static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir)
 {
+	unsigned long pos = filp->f_pos;
 	struct inode *inode = filp->f_dentry->d_inode;
-	struct super_block * sb = inode->i_sb;
-	unsigned int offset,i;
-	struct buffer_head * bh;
-	char* bh_data;
-	struct sysv_dir_entry * de, sde;
-
-	if ((unsigned long)(filp->f_pos) % SYSV_DIRSIZE)
-		return -EBADF;
-	while (filp->f_pos < inode->i_size) {
-		offset = filp->f_pos & sb->sv_block_size_1;
-		bh = sysv_file_bread(inode, filp->f_pos >> sb->sv_block_size_bits, 0);
-		if (!bh) {
-			filp->f_pos += sb->sv_block_size - offset;
+	struct super_block *sb = inode->i_sb;
+	unsigned offset = pos & ~PAGE_CACHE_MASK;
+	unsigned long n = pos >> PAGE_CACHE_SHIFT;
+	unsigned long npages = dir_pages(inode);
+
+	pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
+	if (pos >= inode->i_size)
+		goto done;
+
+	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++) {
+			char *name = de->name;
+			int over;
+
+			if (!de->inode)
+				continue;
+
+			offset = (char *)de - kaddr;
+
+			over = filldir(dirent, name, strnlen(name,SYSV_NAMELEN),
+					(n<<PAGE_CACHE_SHIFT) | offset,
+					fs16_to_cpu(sb, de->inode), DT_UNKNOWN);
+			if (over) {
+				dir_put_page(page);
+				goto done;
+			}
+		}
+		dir_put_page(page);
+	}
+
+done:
+	filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset;
+	UPDATE_ATIME(inode);
+	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 = dentry->d_parent->d_inode;
+	unsigned long n;
+	unsigned long npages = dir_pages(dir);
+	struct page *page = NULL;
+	struct sysv_dir_entry *de;
+
+	*res_page = NULL;
+
+	for (n = 0; n < npages; n++) {
+		char *kaddr;
+		page = dir_get_page(dir, n);
+		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;
+			if (namecompare(namelen, SYSV_NAMELEN, name, de->name)) 
+				goto found;
+		}
+		dir_put_page(page);
+	}
+	return NULL;
+
+found:
+	*res_page = page;
+	return de;
+}
+
+int sysv_add_link(struct dentry *dentry, struct inode *inode)
+{
+	struct inode *dir = dentry->d_parent->d_inode;
+	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;
+	unsigned from, to;
+	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++;
 		}
-		bh_data = bh->b_data;
-		while (offset < sb->sv_block_size && filp->f_pos < inode->i_size) {
-			de = (struct sysv_dir_entry *) (offset + bh_data);
-			if (de->inode) {
-				/* Copy the directory entry first, because the directory
-				 * might be modified while we sleep in filldir()...
-				 */
-				memcpy(&sde, de, sizeof(struct sysv_dir_entry));
-
-				if (sde.inode > inode->i_sb->sv_ninodes)
-					printk("sysv_readdir: Bad inode number on dev "
-					       "%s, ino %ld, offset 0x%04lx: %d is out of range\n",
-					       kdevname(inode->i_dev),
-					       inode->i_ino, (off_t) filp->f_pos, sde.inode);
-
-				i = strnlen(sde.name, SYSV_NAMELEN);
-				if (filldir(dirent, sde.name, i, filp->f_pos, sde.inode, DT_UNKNOWN) < 0) {
-					brelse(bh);
-					return 0;
-				}
+		dir_put_page(page);
+	}
+	BUG();
+	return -EINVAL;
+
+got_it:
+	from = (char*)de - (char*)page_address(page);
+	to = from + SYSV_DIRSIZE;
+	lock_page(page);
+	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
+	if (err)
+		goto out_unlock;
+	memcpy (de->name, name, namelen);
+	memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen);
+	de->inode = cpu_to_fs16(inode->i_sb, inode->i_ino);
+	err = dir_commit_chunk(page, from, to);
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+	mark_inode_dirty(dir);
+out_unlock:
+	UnlockPage(page);
+out_page:
+	dir_put_page(page);
+out:
+	return err;
+}
+
+int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct inode *inode = (struct inode*)mapping->host;
+	char *kaddr = (char*)page_address(page);
+	unsigned from = (char*)de - kaddr;
+	unsigned to = from + SYSV_DIRSIZE;
+	int err;
+
+	lock_page(page);
+	err = mapping->a_ops->prepare_write(NULL, page, from, to);
+	if (err)
+		BUG();
+	de->inode = 0;
+	err = dir_commit_chunk(page, from, to);
+	UnlockPage(page);
+	dir_put_page(page);
+	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+	mark_inode_dirty(inode);
+	return err;
+}
+
+int sysv_make_empty(struct inode *inode, struct inode *dir)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct page *page = grab_cache_page(mapping, 0);
+	struct sysv_dir_entry * de;
+	char *base;
+	int err;
+
+	if (!page)
+		return -ENOMEM;
+	err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * SYSV_DIRSIZE);
+	if (err)
+		goto fail;
+
+	base = (char*)page_address(page);
+	memset(base, 0, PAGE_CACHE_SIZE);
+
+	de = (struct sysv_dir_entry *) base;
+	de->inode = cpu_to_fs16(inode->i_sb, inode->i_ino);
+	strcpy(de->name,".");
+	de++;
+	de->inode = cpu_to_fs16(inode->i_sb, dir->i_ino);
+	strcpy(de->name,"..");
+
+	err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
+fail:
+	UnlockPage(page);
+	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(sb, inode->i_ino))
+					continue;
+				goto not_empty;
 			}
-			offset += SYSV_DIRSIZE;
-			filp->f_pos += SYSV_DIRSIZE;
+			if (de->name[1] != '.' || de->name[2])
+				goto not_empty;
 		}
-		brelse(bh);
+		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 = (struct inode*)page->mapping->host;
+	unsigned from = (char *)de-(char*)page_address(page);
+	unsigned to = from + SYSV_DIRSIZE;
+	int err;
+
+	lock_page(page);
+	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
+	if (err)
+		BUG();
+	de->inode = cpu_to_fs16(inode->i_sb, inode->i_ino);
+	err = dir_commit_chunk(page, from, to);
+	UnlockPage(page);
+	dir_put_page(page);
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME;
+	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(dentry->d_sb, de->inode);
+		dir_put_page(page);
+	}
+	return res;
 }