f2fs: support fault injection for f2fs_kmem_cache_alloc()

This patch supports to inject fault into f2fs_kmem_cache_alloc().

Usage:
a) echo 32768 > /sys/fs/f2fs/<dev>/inject_type or
b) mount -o fault_type=32768 <dev> <mountpoint>

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
index c8f34de..1d2d29d 100644
--- a/fs/f2fs/xattr.c
+++ b/fs/f2fs/xattr.c
@@ -27,7 +27,8 @@ static void *xattr_alloc(struct f2fs_sb_info *sbi, int size, bool *is_inline)
 {
 	if (likely(size == sbi->inline_xattr_slab_size)) {
 		*is_inline = true;
-		return kmem_cache_zalloc(sbi->inline_xattr_slab, GFP_NOFS);
+		return f2fs_kmem_cache_alloc(sbi->inline_xattr_slab,
+					GFP_F2FS_ZERO, false, sbi);
 	}
 	*is_inline = false;
 	return f2fs_kzalloc(sbi, size, GFP_NOFS);