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-rw-r--r--block/ll_rw_blk.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index fb8fb88..de5ba47 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1351,8 +1351,20 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
new_segment:
if (!sg)
sg = sglist;
- else
+ else {
+ /*
+ * If the driver previously mapped a shorter
+ * list, we could see a termination bit
+ * prematurely unless it fully inits the sg
+ * table on each mapping. We KNOW that there
+ * must be more entries here or the driver
+ * would be buggy, so force clear the
+ * termination bit to avoid doing a full
+ * sg_init_table() in drivers for each command.
+ */
+ sg->page_link &= ~0x02;
sg = sg_next(sg);
+ }
sg_set_page(sg, bvec->bv_page);
sg->length = nbytes;
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