f2fs: align direct_io'ed data to section

This patch aligns the start block address of a file for direct io to the f2fs's
section size.

Some flash devices manage an over 4KB-sized page as a write unit, and if the
direct_io'ed data are written but not aligned to that unit, the performance can
be degraded due to the partial page copies.

Thus, since f2fs has a section that is well aligned to FTL units, we can align
the block address to the section size so that f2fs avoids this misalignment.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 3e0f5f303c97..b48b355104c3 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -564,6 +564,7 @@ static int __allocate_data_block(struct dnode_of_data *dn)
 	struct f2fs_inode_info *fi = F2FS_I(dn->inode);
 	struct f2fs_summary sum;
 	struct node_info ni;
+	int seg = CURSEG_WARM_DATA;
 	pgoff_t fofs;
 
 	if (unlikely(is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC)))
@@ -574,8 +575,10 @@ static int __allocate_data_block(struct dnode_of_data *dn)
 	get_node_info(sbi, dn->nid, &ni);
 	set_summary(&sum, dn->nid, dn->ofs_in_node, ni.version);
 
-	allocate_data_block(sbi, NULL, NULL_ADDR, &dn->data_blkaddr, &sum,
-							CURSEG_WARM_DATA);
+	if (dn->ofs_in_node == 0 && dn->inode_page == dn->node_page)
+		seg = CURSEG_DIRECT_IO;
+
+	allocate_data_block(sbi, NULL, NULL_ADDR, &dn->data_blkaddr, &sum, seg);
 
 	/* direct IO doesn't use extent cache to maximize the performance */
 	__set_data_blkaddr(dn);