[PATCH] IS_SYNC diretory handling

A forward-port.  ext2, minix and sysv aren't handling directories
correctly when IS_SYNC is in place.  They call waitfor_one_page(),
but forgot to start the I/O.

The patch also moves waitfor_one_page and writeout_one_page
into fs/buffer.c, so mm/filemap.c now does not mention buffer_head
at all.

fs/buffer.c

@@ -1954,6 +1954,48 @@ int block_write_full_page(struct page *page, get_block_t *get_block)
 	goto done;
 }
 
+/*
+ * Commence writeout of all the buffers against a page.  The
+ * page must be locked.   Returns zero on success or a negative
+ * errno.
+ */
+int writeout_one_page(struct page *page)
+{
+	struct buffer_head *bh, *head = page->buffers;
+
+	if (!PageLocked(page))
+		BUG();
+	bh = head;
+	do {
+		if (buffer_locked(bh) || !buffer_dirty(bh) || !buffer_uptodate(bh))
+			continue;
+
+		bh->b_flushtime = jiffies;
+		ll_rw_block(WRITE, 1, &bh);	
+	} while ((bh = bh->b_this_page) != head);
+	return 0;
+}
+EXPORT_SYMBOL(writeout_one_page);
+
+/*
+ * Wait for completion of I/O of all buffers against a page.  The page
+ * must be locked.  Returns zero on success or a negative errno.
+ */
+int waitfor_one_page(struct page *page)
+{
+	int error = 0;
+	struct buffer_head *bh, *head = page->buffers;
+
+	bh = head;
+	do {
+		wait_on_buffer(bh);
+		if (buffer_req(bh) && !buffer_uptodate(bh))
+			error = -EIO;
+	} while ((bh = bh->b_this_page) != head);
+	return error;
+}
+EXPORT_SYMBOL(waitfor_one_page);
+
 sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
 			    get_block_t *get_block)
 {

fs/ext2/dir.c

@@ -52,8 +52,13 @@ static int ext2_commit_chunk(struct page *page, unsigned from, unsigned to)
 	int err = 0;
 	dir->i_version = ++event;
 	page->mapping->a_ops->commit_write(NULL, page, from, to);
-	if (IS_SYNC(dir))
-		err = waitfor_one_page(page);
+	if (IS_SYNC(dir)) {
+		int err2;
+		err = writeout_one_page(page);
+		err2 = waitfor_one_page(page);
+		if (err == 0)
+			err = err2;
+	}
 	return err;
 }
 

fs/minix/dir.c

@@ -36,8 +36,13 @@ 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);
+	if (IS_SYNC(dir)) {
+		int err2;
+		err = writeout_one_page(page);
+		err2 = waitfor_one_page(page);
+		if (err == 0)
+			err = err2;
+	}
 	return err;
 }
 
@@ -236,10 +241,10 @@ int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
 
 	lock_page(page);
 	err = mapping->a_ops->prepare_write(NULL, page, from, to);
-	if (err)
-		BUG();
+	if (err == 0) {
 		de->inode = 0;
 		err = dir_commit_chunk(page, from, to);
+	}
 	UnlockPage(page);
 	dir_put_page(page);
 	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
@@ -336,10 +341,10 @@ void minix_set_link(struct minix_dir_entry *de, struct page *page,
 
 	lock_page(page);
 	err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
-	if (err)
-		BUG();
+	if (err == 0) {
 		de->inode = inode->i_ino;
 		err = dir_commit_chunk(page, from, to);
+	}
 	UnlockPage(page);
 	dir_put_page(page);
 	dir->i_mtime = dir->i_ctime = CURRENT_TIME;

fs/sysv/ChangeLog

+Thu Feb 14 2002  Andrew Morton  <akpm@zip.com.au>
+
+	* dir_commit_chunk(): call writeout_one_page() as well as
+	  waitfor_one_page() for IS_SYNC directories, so that we
+	  actually do sync the directory. (forward-port from 2.4).
+
 Thu Feb  7 2002  Alexander Viro  <viro@math.psu.edu>
 
 	* super.c: switched to ->get_sb()
@@ -97,3 +103,4 @@ Fri Oct 26 2001  Christoph Hellwig  <hch@caldera.de>
 	Remove symlink faking.	Noone really wants to use these as
 	linux filesystems and native OSes don't support it anyway.
 
+

fs/sysv/dir.c

@@ -42,8 +42,13 @@ static int dir_commit_chunk(struct page *page, unsigned from, unsigned to)
 	int err = 0;
 
 	page->mapping->a_ops->commit_write(NULL, page, from, to);
-	if (IS_SYNC(dir))
-		err = waitfor_one_page(page);
+	if (IS_SYNC(dir)) {
+		int err2;
+		err = writeout_one_page(page);
+		err2 = waitfor_one_page(page);
+		if (err == 0)
+			err = err2;
+	}
 	return err;
 }
 

include/linux/fs.h

@@ -1440,8 +1440,9 @@ sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *);
 int generic_commit_write(struct file *, struct page *, unsigned, unsigned);
 int block_truncate_page(struct address_space *, loff_t, get_block_t *);
 extern int generic_direct_IO(int, struct inode *, struct kiobuf *, unsigned long, int, get_block_t *);
+extern int waitfor_one_page(struct page *);
+extern int writeout_one_page(struct page *);
 
-extern int waitfor_one_page(struct page*);
 extern int generic_file_mmap(struct file *, struct vm_area_struct *);
 extern int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);
 extern ssize_t generic_file_read(struct file *, char *, size_t, loff_t *);

kernel/ksyms.c

@@ -213,7 +213,6 @@ EXPORT_SYMBOL(cont_prepare_write);
 EXPORT_SYMBOL(generic_commit_write);
 EXPORT_SYMBOL(block_truncate_page);
 EXPORT_SYMBOL(generic_block_bmap);
-EXPORT_SYMBOL(waitfor_one_page);
 EXPORT_SYMBOL(generic_file_read);
 EXPORT_SYMBOL(do_generic_file_read);
 EXPORT_SYMBOL(generic_file_write);

mm/filemap.c

@@ -449,41 +449,6 @@ static inline struct page * __find_page_nolock(struct address_space *mapping, un
 	return page;
 }
 
-/*
- * By the time this is called, the page is locked and
- * we don't have to worry about any races any more.
- *
- * Start the IO..
- */
-static int writeout_one_page(struct page *page)
-{
-	struct buffer_head *bh, *head = page->buffers;
-
-	bh = head;
-	do {
-		if (buffer_locked(bh) || !buffer_dirty(bh) || !buffer_uptodate(bh))
-			continue;
-
-		bh->b_flushtime = jiffies;
-		ll_rw_block(WRITE, 1, &bh);	
-	} while ((bh = bh->b_this_page) != head);
-	return 0;
-}
-
-int waitfor_one_page(struct page *page)
-{
-	int error = 0;
-	struct buffer_head *bh, *head = page->buffers;
-
-	bh = head;
-	do {
-		wait_on_buffer(bh);
-		if (buffer_req(bh) && !buffer_uptodate(bh))
-			error = -EIO;
-	} while ((bh = bh->b_this_page) != head);
-	return error;
-}
-
 static int do_buffer_fdatasync(struct list_head *head, unsigned long start, unsigned long end, int (*fn)(struct page *))
 {
 	struct list_head *curr;