f2fs: support fiemap for inline_data

There is a FIEMAP_EXTENT_INLINE_DATA, pointed out by Marc.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/inline.c

@@ -12,6 +12,7 @@
 #include <linux/f2fs_fs.h>
 
 #include "f2fs.h"
+#include "node.h"
 
 bool f2fs_may_inline_data(struct inode *inode)
 {
@@ -570,3 +571,38 @@ int f2fs_read_inline_dir(struct file *file, struct dir_context *ctx,
 	f2fs_put_page(ipage, 1);
 	return 0;
 }
+
+int f2fs_inline_data_fiemap(struct inode *inode,
+		struct fiemap_extent_info *fieinfo, __u64 start, __u64 len)
+{
+	__u64 byteaddr, ilen;
+	__u32 flags = FIEMAP_EXTENT_DATA_INLINE | FIEMAP_EXTENT_NOT_ALIGNED |
+		FIEMAP_EXTENT_LAST;
+	struct node_info ni;
+	struct page *ipage;
+	int err = 0;
+
+	ipage = get_node_page(F2FS_I_SB(inode), inode->i_ino);
+	if (IS_ERR(ipage))
+		return PTR_ERR(ipage);
+
+	if (!f2fs_has_inline_data(inode)) {
+		err = -EAGAIN;
+		goto out;
+	}
+
+	ilen = min_t(size_t, MAX_INLINE_DATA, i_size_read(inode));
+	if (start >= ilen)
+		goto out;
+	if (start + len < ilen)
+		ilen = start + len;
+	ilen -= start;
+
+	get_node_info(F2FS_I_SB(inode), inode->i_ino, &ni);
+	byteaddr = (__u64)ni.blk_addr << inode->i_sb->s_blocksize_bits;
+	byteaddr += (char *)inline_data_addr(ipage) - (char *)F2FS_INODE(ipage);
+	err = fiemap_fill_next_extent(fieinfo, start, byteaddr, ilen, flags);
+out:
+	f2fs_put_page(ipage, 1);
+	return err;
+}