From: Jens Axboe <axboe@kernel.dk>
Date: Tue, 28 Mar 2023 21:10:31 +0000 (-0600)
Subject: block: ensure bio_alloc_map_data() deals with ITER_UBUF correctly
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=0a2481cde24f78f503cbc066df2c9c160e64cfd6;p=linux.git

block: ensure bio_alloc_map_data() deals with ITER_UBUF correctly

This helper blindly copies the iovec, even if we don't have one.
Make this case a bit smarter by only doing so if we have an iovec
array to copy.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/blk-map.c b/block/blk-map.c
index 9137d16cecdc3..3bfcad64d67c0 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -29,10 +29,11 @@ static struct bio_map_data *bio_alloc_map_data(struct iov_iter *data,
 	bmd = kmalloc(struct_size(bmd, iov, data->nr_segs), gfp_mask);
 	if (!bmd)
 		return NULL;
-	memcpy(bmd->iov, data->iov, sizeof(struct iovec) * data->nr_segs);
 	bmd->iter = *data;
-	if (iter_is_iovec(data))
+	if (iter_is_iovec(data)) {
+		memcpy(bmd->iov, data->iov, sizeof(struct iovec) * data->nr_segs);
 		bmd->iter.iov = bmd->iov;
+	}
 	return bmd;
 }