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-rw-r--r--block/blk-merge.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 247b17f2a0f6..21e87a714a73 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -474,9 +474,21 @@ static unsigned blk_bvec_map_sg(struct request_queue *q,
while (nbytes > 0) {
unsigned offset = bvec->bv_offset + total;
unsigned len = min(get_max_segment_size(q, offset), nbytes);
+ struct page *page = bvec->bv_page;
+
+ /*
+ * Unfortunately a fair number of drivers barf on scatterlists
+ * that have an offset larger than PAGE_SIZE, despite other
+ * subsystems dealing with that invariant just fine. For now
+ * stick to the legacy format where we never present those from
+ * the block layer, but the code below should be removed once
+ * these offenders (mostly MMC/SD drivers) are fixed.
+ */
+ page += (offset >> PAGE_SHIFT);
+ offset &= ~PAGE_MASK;
*sg = blk_next_sg(sg, sglist);
- sg_set_page(*sg, bvec->bv_page, len, offset);
+ sg_set_page(*sg, page, len, offset);
total += len;
nbytes -= len;