This patch add a function to modify 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 <[email protected]>
---
 fs/f2fs/segment.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 9006d8e..5af736b 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -672,6 +672,22 @@ static void __remove_discard_cmd(struct f2fs_sb_info *sbi, 
struct discard_cmd *d
        kmem_cache_free(discard_cmd_slab, dc);
 }
 
+static void __modify_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->lstart + dc->len <= end_block) {
+                __remove_discard_cmd(sbi, dc);
+               return;
+       }
+
+       if (dc->lstart - blkaddr < dc->lstart + dc->len - end_block) {
+               dc->lstart = end_block;
+               dc->len -= (end_block - dc->lstart);
+       } 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)
 {
@@ -699,7 +715,7 @@ void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, 
block_t blkaddr)
                        if (dc->state == D_SUBMIT)
                                wait_for_completion_io(&dc->wait);
                        else
-                               __remove_discard_cmd(sbi, dc);
+                               __modify_discard_cmd(sbi, dc, blkaddr);
                }
        }
        blk_finish_plug(&plug);
-- 
2.10.1


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