From c8164d8931fdee9ac5314708c4071adf1d997425 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 20 Mar 2013 15:37:08 +1030
Subject: [PATCH] scatterlist: introduce sg_unmark_end
This is useful in places that recycle the same scatterlist multiple
times, and do not want to incur the cost of sg_init_table every
time in hot paths.
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
block/blk-integrity.c | 2 +-
block/blk-merge.c | 2 +-
include/linux/scatterlist.h | 16 ++++++++++++++++
3 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/block/blk-integrity.c b/block/blk-integrity.c
index dabd221857e1..03cf7179e8ef 100644
--- a/block/blk-integrity.c
+++ b/block/blk-integrity.c
@@ -110,7 +110,7 @@ new_segment:
if (!sg)
sg = sglist;
else {
- sg->page_link &= ~0x02;
+ sg_unmark_end(sg);
sg = sg_next(sg);
}
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 936a110de0b9..5f2448253797 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -143,7 +143,7 @@ new_segment:
* termination bit to avoid doing a full
* sg_init_table() in drivers for each command.
*/
- (*sg)->page_link &= ~0x02;
+ sg_unmark_end(*sg);
*sg = sg_next(*sg);
}
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 2d8bdaef9611..bfc47e0de81c 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -171,6 +171,22 @@ static inline void sg_mark_end(struct scatterlist *sg)
sg->page_link &= ~0x01;
}
+/**
+ * sg_unmark_end - Undo setting the end of the scatterlist
+ * @sg: SG entryScatterlist
+ *
+ * Description:
+ * Removes the termination marker from the given entry of the scatterlist.
+ *
+ **/
+static inline void sg_unmark_end(struct scatterlist *sg)
+{
+#ifdef CONFIG_DEBUG_SG
+ BUG_ON(sg->sg_magic != SG_MAGIC);
+#endif
+ sg->page_link &= ~0x02;
+}
+
/**
* sg_phys - Return physical address of an sg entry
* @sg: SG entry