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, 19 insertions, 8 deletions

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8144a30b1567..31c4e5702c7d 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1024,18 +1024,22 @@ static void allocate_segment_by_default(struct f2fs_sb_info *sbi,
         stat_inc_seg_type(sbi, curseg);
 }
 
+static void __allocate_new_segments(struct f2fs_sb_info *sbi, int type)
+{
+        struct curseg_info *curseg = CURSEG_I(sbi, type);
+        unsigned int old_segno;
+
+        old_segno = curseg->segno;
+        SIT_I(sbi)->s_ops->allocate_segment(sbi, type, true);
+        locate_dirty_segment(sbi, old_segno);
+}
+
 void allocate_new_segments(struct f2fs_sb_info *sbi)
 {
-        struct curseg_info *curseg;
-        unsigned int old_curseg;
         int i;
 
-        for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
-                curseg = CURSEG_I(sbi, i);
-                old_curseg = curseg->segno;
-                SIT_I(sbi)->s_ops->allocate_segment(sbi, i, true);
-                locate_dirty_segment(sbi, old_curseg);
-        }
+        for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++)
+                __allocate_new_segments(sbi, i);
 }
 
 static const struct segment_allocation default_salloc_ops = {
@@ -1148,11 +1152,18 @@ void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
 {
         struct sit_info *sit_i = SIT_I(sbi);
         struct curseg_info *curseg;
+        bool direct_io = (type == CURSEG_DIRECT_IO);
+
+        type = direct_io ? CURSEG_WARM_DATA : type;
 
         curseg = CURSEG_I(sbi, type);
 
         mutex_lock(&curseg->curseg_mutex);
 
+        /* direct_io'ed data is aligned to the segment for better performance */
+        if (direct_io && curseg->next_blkoff)
+                __allocate_new_segments(sbi, type);
+
         *new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
 
         /*