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authorPaolo Bonzini <pbonzini@redhat.com>2013-03-20 09:07:08 +0400
committerRusty Russell <rusty@rustcorp.com.au>2013-03-20 09:13:04 +0400
commitc8164d8931fdee9ac5314708c4071adf1d997425 (patch)
treec5d71c82defa52fc3afe7d14e61f44cbb6ff7dc7
parent0d2e1a2926b1839a4b74519e660739b2566c9386 (diff)
downloadlinux-c8164d8931fdee9ac5314708c4071adf1d997425.tar.xz
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>
-rw-r--r--block/blk-integrity.c2
-rw-r--r--block/blk-merge.c2
-rw-r--r--include/linux/scatterlist.h16
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
@@ -172,6 +172,22 @@ static inline void sg_mark_end(struct scatterlist *sg)
}
/**
+ * 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
*