f2fs: avoid punch_hole overhead when releasing volatile data

index f0a18a0..486113d 100644
@@ -1291,6 +1291,8 @@ int do_write_data_page(struct page *page, struct f2fs_io_info *fio)
 		write_data_page(page, &dn, fio);
 		f2fs_update_extent_cache(&dn);
 		set_inode_flag(F2FS_I(inode), FI_APPEND_WRITE);
+		if (page->index == 0)
+			set_inode_flag(F2FS_I(inode), FI_FIRST_BLOCK_WRITTEN);
 	}
 out_writepage:
 	f2fs_put_dnode(&dn);

index f2909c6..fec8acc 100644
@@ -1223,6 +1223,7 @@ enum {
 	FI_NEED_IPU,		/* used for ipu per file */
 	FI_ATOMIC_FILE,		/* indicate atomic file */
 	FI_VOLATILE_FILE,	/* indicate volatile file */
+	FI_FIRST_BLOCK_WRITTEN,	/* indicate #0 data block was written */
 	FI_DROP_CACHE,		/* drop dirty page cache */
 	FI_DATA_EXIST,		/* indicate data exists */
 };

@@ -1331,6 +1332,11 @@ static inline bool f2fs_is_volatile_file(struct inode *inode)
 	return is_inode_flag_set(F2FS_I(inode), FI_VOLATILE_FILE);
 }
 
+static inline bool f2fs_is_first_block_written(struct inode *inode)
+{
+	return is_inode_flag_set(F2FS_I(inode), FI_FIRST_BLOCK_WRITTEN);
+}
+
 static inline bool f2fs_is_drop_cache(struct inode *inode)
 {
 	return is_inode_flag_set(F2FS_I(inode), FI_DROP_CACHE);

index d927f8e..d17ac60 100644
@@ -437,6 +437,9 @@ int truncate_data_blocks_range(struct dnode_of_data *dn, int count)
 		dn->data_blkaddr = NULL_ADDR;
 		f2fs_update_extent_cache(dn);
 		invalidate_blocks(sbi, blkaddr);
+		if (dn->ofs_in_node == 0 && IS_INODE(dn->node_page))
+			clear_inode_flag(F2FS_I(dn->inode),
+						FI_FIRST_BLOCK_WRITTEN);
 		nr_free++;
 	}
 	if (nr_free) {

@@ -1005,6 +1008,9 @@ static int f2fs_ioc_release_volatile_write(struct file *filp)
 	if (!f2fs_is_volatile_file(inode))
 		return 0;
 
+	if (!f2fs_is_first_block_written(inode))
+		return truncate_partial_data_page(inode, 0, true);
+
 	punch_hole(inode, 0, F2FS_BLKSIZE);
 	return 0;
 }

index b508744..bb58009 100644
@@ -51,6 +51,13 @@ static void __get_inode_rdev(struct inode *inode, struct f2fs_inode *ri)
 	}
 }
 
+static bool __written_first_block(struct f2fs_inode *ri)
+{
+	if (ri->i_addr[0] != NEW_ADDR && ri->i_addr[0] != NULL_ADDR)
+		return true;
+	return false;
+}
+
 static void __set_inode_rdev(struct inode *inode, struct f2fs_inode *ri)
 {
 	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {

@@ -143,6 +150,9 @@ static int do_read_inode(struct inode *inode)
 	/* get rdev by using inline_info */
 	__get_inode_rdev(inode, ri);
 
+	if (__written_first_block(ri))
+		set_inode_flag(F2FS_I(inode), FI_FIRST_BLOCK_WRITTEN);
+
 	f2fs_put_page(node_page, 1);
 
 	stat_inc_inline_inode(inode);

index 486113d..241b987 100644
@@ -1287,9 +1287,11 @@ int do_write_data_page(struct page *page, struct f2fs_io_info *fio)
 			need_inplace_update(inode))) {
 		rewrite_data_page(page, fio);
 		set_inode_flag(F2FS_I(inode), FI_UPDATE_WRITE);
+		trace_f2fs_do_write_data_page(page, IPU);
 	} else {
 		write_data_page(page, &dn, fio);
 		f2fs_update_extent_cache(&dn);
+		trace_f2fs_do_write_data_page(page, OPU);
 		set_inode_flag(F2FS_I(inode), FI_APPEND_WRITE);
 		if (page->index == 0)
 			set_inode_flag(F2FS_I(inode), FI_FIRST_BLOCK_WRITTEN);

index fec8acc..7d4e3fc 100644
@@ -547,6 +547,10 @@ enum page_type {
 	META,
 	NR_PAGE_TYPE,
 	META_FLUSH,
+	INMEM,		/* the below types are used by tracepoints only. */
+	INMEM_DROP,
+	IPU,
+	OPU,
 };
 
 struct f2fs_io_info {

index eafaf72..f939660 100644
@@ -205,6 +205,8 @@ retry:
 	list_add_tail(&new->list, &fi->inmem_pages);
 	inc_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES);
 	mutex_unlock(&fi->inmem_lock);
+
+	trace_f2fs_register_inmem_page(page, INMEM);
 }
 
 void commit_inmem_pages(struct inode *inode, bool abort)

@@ -238,11 +240,13 @@ void commit_inmem_pages(struct inode *inode, bool abort)
 				f2fs_wait_on_page_writeback(cur->page, DATA);
 				if (clear_page_dirty_for_io(cur->page))
 					inode_dec_dirty_pages(inode);
+				trace_f2fs_commit_inmem_page(cur->page, INMEM);
 				do_write_data_page(cur->page, &fio);
 				submit_bio = true;
 			}
 			f2fs_put_page(cur->page, 1);
 		} else {
+			trace_f2fs_commit_inmem_page(cur->page, INMEM_DROP);
 			put_page(cur->page);
 		}
 		radix_tree_delete(&fi->inmem_root, cur->page->index);

index 09a56dc..75724bd 100644
@@ -14,7 +14,11 @@
 		{ NODE,		"NODE" },				\
 		{ DATA,		"DATA" },				\
 		{ META,		"META" },				\
-		{ META_FLUSH,	"META_FLUSH" })
+		{ META_FLUSH,	"META_FLUSH" },				\
+		{ INMEM,	"INMEM" },				\
+		{ INMEM_DROP,	"INMEM_DROP" },				\
+		{ IPU,		"IN-PLACE" },				\
+		{ OPU,		"OUT-OF-PLACE" })
 
 #define F2FS_BIO_MASK(t)	(t & (READA | WRITE_FLUSH_FUA))
 #define F2FS_BIO_EXTRA_MASK(t)	(t & (REQ_META | REQ_PRIO))

@@ -854,6 +858,13 @@ DEFINE_EVENT(f2fs__page, f2fs_writepage,
 	TP_ARGS(page, type)
 );
 
+DEFINE_EVENT(f2fs__page, f2fs_do_write_data_page,
+
+	TP_PROTO(struct page *page, int type),
+
+	TP_ARGS(page, type)
+);
+
 DEFINE_EVENT(f2fs__page, f2fs_readpage,
 
 	TP_PROTO(struct page *page, int type),

@@ -875,6 +886,20 @@ DEFINE_EVENT(f2fs__page, f2fs_vm_page_mkwrite,
 	TP_ARGS(page, type)
 );
 
+DEFINE_EVENT(f2fs__page, f2fs_register_inmem_page,
+
+	TP_PROTO(struct page *page, int type),
+
+	TP_ARGS(page, type)
+);
+
+DEFINE_EVENT(f2fs__page, f2fs_commit_inmem_page,
+
+	TP_PROTO(struct page *page, int type),
+
+	TP_ARGS(page, type)
+);
+
 TRACE_EVENT(f2fs_writepages,
 
 	TP_PROTO(struct inode *inode, struct writeback_control *wbc, int type),