f2fs: issue more large discard command

o Changes from v1
  Use find_next(_zero)_bit suggested by jg.kim

When f2fs issues discard command, if segment is contiguous,
let's issue more large segment to gather adjacent segments.

** blktrace **
179,1    0     5859    42.619023770   971  C   D 131072 + 2097152 [0]
179,1    0    33665   108.840475468   971  C   D 2228224 + 2494464 [0]
179,1    0    33671   109.131616427   971  C   D 14909440 + 344064 [0]
179,1    0    33677   109.137100677   971  C   D 15261696 + 4096 [0]

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 86dc289..fa284d3 100644 (file)
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -139,27 +139,33 @@ static void set_prefree_as_free_segments(struct f2fs_sb_info *sbi)
 void clear_prefree_segments(struct f2fs_sb_info *sbi)
 {
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
-       unsigned int segno = -1;
+       unsigned long *prefree_map = dirty_i->dirty_segmap[PRE];
        unsigned int total_segs = TOTAL_SEGS(sbi);
+       unsigned int start = 0, end = -1;
 
        mutex_lock(&dirty_i->seglist_lock);
+
        while (1) {
-               segno = find_next_bit(dirty_i->dirty_segmap[PRE], total_segs,
-                               segno + 1);
-               if (segno >= total_segs)
+               int i;
+               start = find_next_bit(prefree_map, total_segs, end + 1);
+               if (start >= total_segs)
                        break;
+               end = find_next_zero_bit(prefree_map, total_segs, start + 1);
+
+               for (i = start; i < end; i++)
+                       clear_bit(i, prefree_map);
+
+               dirty_i->nr_dirty[PRE] -= end - start;
+
+               if (!test_opt(sbi, DISCARD))
+                       continue;
 
-               if (test_and_clear_bit(segno, dirty_i->dirty_segmap[PRE]))
-                       dirty_i->nr_dirty[PRE]--;
-
-               /* Let's use trim */
-               if (test_opt(sbi, DISCARD))
-                       blkdev_issue_discard(sbi->sb->s_bdev,
-                                       START_BLOCK(sbi, segno) <<
-                                       sbi->log_sectors_per_block,
-                                       1 << (sbi->log_sectors_per_block +
-                                               sbi->log_blocks_per_seg),
-                                       GFP_NOFS, 0);
+               blkdev_issue_discard(sbi->sb->s_bdev,
+                               START_BLOCK(sbi, start) <<
+                               sbi->log_sectors_per_block,
+                               (1 << (sbi->log_sectors_per_block +
+                               sbi->log_blocks_per_seg)) * (end - start),
+                               GFP_NOFS, 0);
        }
        mutex_unlock(&dirty_i->seglist_lock);
 }