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Subject[PATCH 2/3] dm writecache: add unlikely for getting two block with same LBA
Date
From: Huaisheng Ye <yehs1@lenovo.com>

In function writecache_writeback, entries g and f has same original
sector only happens at entry f has been committed, but entry g has
NOT yet.

The probability of this happening is very low in the following
256 blocks at most of entry e.

Signed-off-by: Huaisheng Ye <yehs1@lenovo.com>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
---
drivers/md/dm-writecache.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index 5c7009d..3643084 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -1628,8 +1628,8 @@ static void writecache_writeback(struct work_struct *work)
if (unlikely(!next_node))
break;
g = container_of(next_node, struct wc_entry, rb_node);
- if (read_original_sector(wc, g) ==
- read_original_sector(wc, f)) {
+ if (unlikely(read_original_sector(wc, g) ==
+ read_original_sector(wc, f))) {
f = g;
continue;
}
--
1.8.3.1

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