exofs: New truncate sequence

These changes are crafted based on the similar
conversion done to ext2 by Nick Piggin.

* Remove the deprecated ->truncate vector. Let exofs_setattr
  take care of on-disk size updates.
* Call truncate_pagecache on the unused pages if
  write_begin/end fails.
* Cleanup exofs_delete_inode that did stupid inode
  writes and updates on an inode that will be
  removed.
* And finally get rid of exofs_get_block. We never
  had any blocks it was all for calling nobh_truncate_page.
  nobh_truncate_page is not actually needed in exofs since
  the last page is complete and gone, just like all the other
  pages. There is no partial blocks in exofs.

I've tested with this patch, and there are no apparent
failures, so far.

CC: Nick Piggin <npiggin@suse.de>
CC: Christoph Hellwig <hch@lst.de>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/exofs/exofs.h

@@ -256,7 +256,6 @@ static inline int exofs_oi_read(struct exofs_i_info *oi,
 }
 
 /* inode.c               */
-void exofs_truncate(struct inode *inode);
 int exofs_setattr(struct dentry *, struct iattr *);
 int exofs_write_begin(struct file *file, struct address_space *mapping,
 		loff_t pos, unsigned len, unsigned flags,

fs/exofs/file.c

@@ -86,6 +86,5 @@ const struct file_operations exofs_file_operations = {
 };
 
 const struct inode_operations exofs_file_inode_operations = {
-	.truncate	= exofs_truncate,
 	.setattr	= exofs_setattr,
 };

fs/exofs/inode.c

@@ -697,6 +697,13 @@ static int exofs_writepage(struct page *page, struct writeback_control *wbc)
 	return write_exec(&pcol);
 }
 
+/* i_mutex held using inode->i_size directly */
+static void _write_failed(struct inode *inode, loff_t to)
+{
+	if (to > inode->i_size)
+		truncate_pagecache(inode, to, inode->i_size);
+}
+
 int exofs_write_begin(struct file *file, struct address_space *mapping,
 		loff_t pos, unsigned len, unsigned flags,
 		struct page **pagep, void **fsdata)
@@ -710,7 +717,7 @@ int exofs_write_begin(struct file *file, struct address_space *mapping,
 					 fsdata);
 		if (ret) {
 			EXOFS_DBGMSG("simple_write_begin faild\n");
-			return ret;
+			goto out;
 		}
 
 		page = *pagep;
@@ -725,6 +732,9 @@ int exofs_write_begin(struct file *file, struct address_space *mapping,
 			EXOFS_DBGMSG("__readpage_filler faild\n");
 		}
 	}
+out:
+	if (unlikely(ret))
+		_write_failed(mapping->host, pos + len);
 
 	return ret;
 }
@@ -750,6 +760,10 @@ static int exofs_write_end(struct file *file, struct address_space *mapping,
 	int ret;
 
 	ret = simple_write_end(file, mapping,pos, len, copied, page, fsdata);
+	if (unlikely(ret))
+		_write_failed(inode, pos + len);
+
+	/* TODO: once simple_write_end marks inode dirty remove */
 	if (i_size != inode->i_size)
 		mark_inode_dirty(inode);
 	return ret;
@@ -808,91 +822,49 @@ static inline int exofs_inode_is_fast_symlink(struct inode *inode)
 	return S_ISLNK(inode->i_mode) && (oi->i_data[0] != 0);
 }
 
-/*
- * get_block_t - Fill in a buffer_head
- * An OSD takes care of block allocation so we just fake an allocation by
- * putting in the inode's sector_t in the buffer_head.
- * TODO: What about the case of create==0 and @iblock does not exist in the
- * object?
- */
-static int exofs_get_block(struct inode *inode, sector_t iblock,
-		    struct buffer_head *bh_result, int create)
-{
-	map_bh(bh_result, inode->i_sb, iblock);
-	return 0;
-}
-
 const struct osd_attr g_attr_logical_length = ATTR_DEF(
 	OSD_APAGE_OBJECT_INFORMATION, OSD_ATTR_OI_LOGICAL_LENGTH, 8);
 
-static int _do_truncate(struct inode *inode)
+static int _do_truncate(struct inode *inode, loff_t newsize)
 {
 	struct exofs_i_info *oi = exofs_i(inode);
-	loff_t isize = i_size_read(inode);
 	int ret;
 
 	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 
-	nobh_truncate_page(inode->i_mapping, isize, exofs_get_block);
+	ret = exofs_oi_truncate(oi, (u64)newsize);
+	if (likely(!ret))
+		truncate_setsize(inode, newsize);
 
-	ret = exofs_oi_truncate(oi, (u64)isize);
-	EXOFS_DBGMSG("(0x%lx) size=0x%llx\n", inode->i_ino, isize);
+	EXOFS_DBGMSG("(0x%lx) size=0x%llx ret=>%d\n",
+		     inode->i_ino, newsize, ret);
 	return ret;
 }
 
 /*
- * Truncate a file to the specified size - all we have to do is set the size
- * attribute.  We make sure the object exists first.
- */
-void exofs_truncate(struct inode *inode)
-{
-	struct exofs_i_info *oi = exofs_i(inode);
-	int ret;
-
-	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)
-	     || S_ISLNK(inode->i_mode)))
-		return;
-	if (exofs_inode_is_fast_symlink(inode))
-		return;
-	if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
-		return;
-
-	/* if we are about to truncate an object, and it hasn't been
-	 * created yet, wait
-	 */
-	if (unlikely(wait_obj_created(oi)))
-		goto fail;
-
-	ret = _do_truncate(inode);
-	if (ret)
-		goto fail;
-
-out:
-	mark_inode_dirty(inode);
-	return;
-fail:
-	make_bad_inode(inode);
-	goto out;
-}
-
-/*
- * Set inode attributes - just call generic functions.
+ * Set inode attributes - update size attribute on OSD if needed,
+ *                        otherwise just call generic functions.
  */
 int exofs_setattr(struct dentry *dentry, struct iattr *iattr)
 {
 	struct inode *inode = dentry->d_inode;
 	int error;
 
+	/* if we are about to modify an object, and it hasn't been
+	 * created yet, wait
+	 */
+	error = wait_obj_created(exofs_i(inode));
+	if (unlikely(error))
+		return error;
+
 	error = inode_change_ok(inode, iattr);
-	if (error)
+	if (unlikely(error))
 		return error;
 
 	if ((iattr->ia_valid & ATTR_SIZE) &&
 	    iattr->ia_size != i_size_read(inode)) {
-		int error;
-
-		error = vmtruncate(inode, iattr->ia_size);
-		if (error)
+		error = _do_truncate(inode, iattr->ia_size);
+		if (unlikely(error))
 			return error;
 	}
 
@@ -1345,28 +1317,25 @@ void exofs_delete_inode(struct inode *inode)
 
 	truncate_inode_pages(&inode->i_data, 0);
 
+	/* TODO: should do better here */
 	if (is_bad_inode(inode))
 		goto no_delete;
 
-	mark_inode_dirty(inode);
-	exofs_update_inode(inode, inode_needs_sync(inode));
-
 	inode->i_size = 0;
-	if (inode->i_blocks)
-		exofs_truncate(inode);
-
 	clear_inode(inode);
 
-	ret = exofs_get_io_state(&sbi->layout, &ios);
-	if (unlikely(ret)) {
-		EXOFS_ERR("%s: exofs_get_io_state failed\n", __func__);
-		return;
-	}
-
 	/* if we are deleting an obj that hasn't been created yet, wait */
 	if (!obj_created(oi)) {
 		BUG_ON(!obj_2bcreated(oi));
 		wait_event(oi->i_wq, obj_created(oi));
+		/* ignore the error attempt a remove anyway */
+	}
+
+	/* Now Remove the OSD objects */
+	ret = exofs_get_io_state(&sbi->layout, &ios);
+	if (unlikely(ret)) {
+		EXOFS_ERR("%s: exofs_get_io_state failed\n", __func__);
+		return;
 	}
 
 	ios->obj.id = exofs_oi_objno(oi);