iov_iter: fix gap alignment check

Commit Message

Keith Busch May 21, 2020, 2:28 a.m. UTC

The block layer uses the queue's virt_boundary to enforce alignment between
vectors, but iov_iter_gap_alignment() returned the starting address or'ed
with all but the last the length. Fix it to return alignment for each
vector's starting address except the first, and each vector's ending
address except the last.

Signed-off-by: Keith Busch <[e-mail]>
---
 lib/iov_iter.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Patch

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 51595bf3af85..9cfaf2fd5cfd 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1252,12 +1252,12 @@  unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
 	}
 
 	iterate_all_kinds(i, size, v,
-		(res |= (!res ? 0 : (unsigned long)v.iov_base) |
-			(size != v.iov_len ? size : 0), 0),
-		(res |= (!res ? 0 : (unsigned long)v.bv_offset) |
-			(size != v.bv_len ? size : 0)),
-		(res |= (!res ? 0 : (unsigned long)v.iov_base) |
-			(size != v.iov_len ? size : 0))
+		(res |= (size == i->count ? 0 : (unsigned long)v.iov_base) |
+			(size == v.iov_len ? 0 : (unsigned long)v.iov_base + v.iov_len), 0),
+		res |= (size == i->count ? 0 : v.bv_offset) |
+		       (size == v.bv_len ? 0 : v.bv_offset + v.bv_len),
+		res |= (size == i->count ? 0 : (unsigned long)v.iov_base) |
+		       (size == v.iov_len ? 0 : (unsigned long)v.iov_base + v.iov_len)
 		);
 	return res;
 }