f2fs: introduce readahead mode of node pages

Previously, f2fs reads several node pages ahead when get_dnode_of_data is called
with RDONLY_NODE flag.
And, this flag is set by the following functions.
- get_data_block_ro
- get_lock_data_page
- do_write_data_page
- truncate_blocks
- truncate_hole

However, this readahead mechanism is initially introduced for the use of
get_data_block_ro to enhance the sequential read performance.

So, let's clarify all the cases with the additional modes as follows.

enum {
	ALLOC_NODE,	/* allocate a new node page if needed */
	LOOKUP_NODE,	/* look up a node without readahead */
	LOOKUP_NODE_RA,	/*
			 * look up a node with readahead called
			 * by get_datablock_ro.
			 */
}

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 958a46d..269645e 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -43,7 +43,7 @@ static int f2fs_vm_page_mkwrite(struct vm_area_struct *vma,
 
 	/* block allocation */
 	set_new_dnode(&dn, inode, NULL, NULL, 0);
-	err = get_dnode_of_data(&dn, page->index, 0);
+	err = get_dnode_of_data(&dn, page->index, ALLOC_NODE);
 	if (err) {
 		mutex_unlock_op(sbi, DATA_NEW);
 		goto out;
@@ -258,7 +258,7 @@ static int truncate_blocks(struct inode *inode, u64 from)
 	mutex_lock_op(sbi, DATA_TRUNC);
 
 	set_new_dnode(&dn, inode, NULL, NULL, 0);
-	err = get_dnode_of_data(&dn, free_from, RDONLY_NODE);
+	err = get_dnode_of_data(&dn, free_from, LOOKUP_NODE);
 	if (err) {
 		if (err == -ENOENT)
 			goto free_next;
@@ -420,7 +420,7 @@ int truncate_hole(struct inode *inode, pgoff_t pg_start, pgoff_t pg_end)
 
 		mutex_lock_op(sbi, DATA_TRUNC);
 		set_new_dnode(&dn, inode, NULL, NULL, 0);
-		err = get_dnode_of_data(&dn, index, RDONLY_NODE);
+		err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
 		if (err) {
 			mutex_unlock_op(sbi, DATA_TRUNC);
 			if (err == -ENOENT)
@@ -504,7 +504,7 @@ static int expand_inode_data(struct inode *inode, loff_t offset,
 		mutex_lock_op(sbi, DATA_NEW);
 
 		set_new_dnode(&dn, inode, NULL, NULL, 0);
-		ret = get_dnode_of_data(&dn, index, 0);
+		ret = get_dnode_of_data(&dn, index, ALLOC_NODE);
 		if (ret) {
 			mutex_unlock_op(sbi, DATA_NEW);
 			break;