From: Al Viro <viro@zeniv.linux.org.uk>
Date: Mon, 3 May 2021 15:05:29 +0000 (-0400)
Subject: [xarray] iov_iter_npages(): just use DIV_ROUND_UP()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=e4f8df86798aea60aff6cfff40252b709431f850;p=linux.git

[xarray] iov_iter_npages(): just use DIV_ROUND_UP()

Compiler is capable of recognizing division by power of 2 and turning
it into shifts.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 1c65de1753713..72c5bb794e8d1 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1925,20 +1925,8 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages)
 		return min(npages, maxpages);
 	}
 	if (iov_iter_is_xarray(i)) {
-		size_t size = i->count;
-		unsigned offset;
-		int npages;
-
-		offset = (i->xarray_start + i->iov_offset) & ~PAGE_MASK;
-
-		npages = 1;
-		if (size > PAGE_SIZE - offset) {
-			size -= PAGE_SIZE - offset;
-			npages += size >> PAGE_SHIFT;
-			size &= ~PAGE_MASK;
-			if (size)
-				npages++;
-		}
+		unsigned offset = (i->xarray_start + i->iov_offset) % PAGE_SIZE;
+		int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE);
 		return min(npages, maxpages);
 	}
 	return 0;