f2fs: fix handling errors got by f2fs_write_inode

Ruslan reported that f2fs hangs with an infinite loop in f2fs_sync_file():

	while (sync_node_pages(sbi, inode->i_ino, &wbc) == 0)
		f2fs_write_inode(inode, NULL);

The reason was revealed that the cold flag is not set even thought this inode is
a normal file. Therefore, sync_node_pages() skips to write node blocks since it
only writes cold node blocks.

The cold flag is stored to the node_footer in node block, and whenever a new
node page is allocated, it is set according to its file type, file or directory.

But, after sudden-power-off, when recovering the inode page, f2fs doesn't recover
its cold flag.

So, let's assign the cold flag in more right places.

One more thing:
If f2fs_write_inode() returns an error due to whatever situations, there would
be no dirty node pages so that sync_node_pages() returns zero.
(i.e., zero means nothing was written.)
Reported-by: Ruslan N. Marchenko <me@ruff.mobi>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

fs/f2fs/dir.c

@@ -11,6 +11,7 @@
 #include <linux/fs.h>
 #include <linux/f2fs_fs.h>
 #include "f2fs.h"
+#include "node.h"
 #include "acl.h"
 
 static unsigned long dir_blocks(struct inode *inode)
@@ -308,6 +309,7 @@ static int init_inode_metadata(struct inode *inode, struct dentry *dentry)
 		ipage = get_node_page(F2FS_SB(dir->i_sb), inode->i_ino);
 		if (IS_ERR(ipage))
 			return PTR_ERR(ipage);
+		set_cold_node(inode, ipage);
 		init_dent_inode(dentry, ipage);
 		f2fs_put_page(ipage, 1);
 	}

fs/f2fs/file.c

@@ -160,15 +160,17 @@ int f2fs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 	if (need_to_sync_dir(sbi, inode))
 		need_cp = true;
 
-	f2fs_write_inode(inode, NULL);
-
 	if (need_cp) {
 		/* all the dirty node pages should be flushed for POR */
 		ret = f2fs_sync_fs(inode->i_sb, 1);
 		clear_inode_flag(F2FS_I(inode), FI_NEED_CP);
 	} else {
-		while (sync_node_pages(sbi, inode->i_ino, &wbc) == 0)
-			f2fs_write_inode(inode, NULL);
+		/* if there is no written node page, write its inode page */
+		while (!sync_node_pages(sbi, inode->i_ino, &wbc)) {
+			ret = f2fs_write_inode(inode, NULL);
+			if (ret)
+				goto out;
+		}
 		filemap_fdatawait_range(sbi->node_inode->i_mapping,
 							0, LONG_MAX);
 	}

fs/f2fs/inode.c

@@ -203,6 +203,7 @@ void update_inode(struct inode *inode, struct page *node_page)
 	ri->i_flags = cpu_to_le32(F2FS_I(inode)->i_flags);
 	ri->i_pino = cpu_to_le32(F2FS_I(inode)->i_pino);
 	ri->i_generation = cpu_to_le32(inode->i_generation);
+	set_cold_node(inode, node_page);
 	set_page_dirty(node_page);
 }
 

fs/f2fs/node.c

@@ -834,11 +834,11 @@ struct page *new_node_page(struct dnode_of_data *dn, unsigned int ofs)
 		goto fail;
 	}
 	set_node_addr(sbi, &new_ni, NEW_ADDR);
+	set_cold_node(dn->inode, page);
 
 	dn->node_page = page;
 	sync_inode_page(dn);
 	set_page_dirty(page);
-	set_cold_node(dn->inode, page);
 	if (ofs == 0)
 		inc_valid_inode_count(sbi);