f2fs: add a punch discard command function

This patch add a function to punch discard command if one segment
reuse before discard. Split this segment from multi-segments discard
range, and discard the left bigger range.

Signed-off-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 85c34d4fcf3e43d65a3bea94cf59b7fee5018b25..c5a5258f71c5d25649db1912c44cb5322967a726 100644 (file)
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -759,6 +759,25 @@ static int __queue_discard_cmd(struct f2fs_sb_info *sbi,
        return 0;
 }
 
+static void __punch_discard_cmd(struct f2fs_sb_info *sbi,
+                               struct discard_cmd *dc, block_t blkaddr)
+{
+       block_t end_block = START_BLOCK(sbi, GET_SEGNO(sbi, blkaddr) + 1);
+
+       if (dc->state == D_DONE || dc->lstart + dc->len <= end_block) {
+               __remove_discard_cmd(sbi, dc);
+               return;
+       }
+
+       if (blkaddr - dc->lstart < dc->lstart + dc->len - end_block) {
+               dc->start += (end_block - dc->lstart);
+               dc->len -= (end_block - dc->lstart);
+               dc->lstart = end_block;
+       } else {
+               dc->len = blkaddr - dc->lstart;
+       }
+}
+
 /* This should be covered by global mutex, &sit_i->sentry_lock */
 void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, block_t blkaddr)
 {
@@ -781,8 +800,7 @@ void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, block_t blkaddr)
                if (dc->lstart <= blkaddr && blkaddr < dc->lstart + dc->len) {
                        if (dc->state == D_SUBMIT)
                                wait_for_completion_io(&dc->wait);
-                       else
-                               __remove_discard_cmd(sbi, dc);
+                       __punch_discard_cmd(sbi, dc, blkaddr);
                }
        }
        blk_finish_plug(&plug);