iov_iter_gap_alignment(): get rid of iterate_all_kinds()

For one thing, it's only used for iovec (and makes sense only for those).
For another, here we don't care about iov_offset, since the beginning of
the first segment and the end of the last one are ignored.  So it makes
a lot more sense to just walk through the iovec array...

We need to deal with the case of truncated iov_iter, but unlike the
situation with iov_iter_alignment() we don't care where the last
segment ends - just which segment is the last one.

[fixed a braino spotted by Qian Cai <quic_qiancai@quicinc.com>]

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

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index ed93183..6569e3f 100644 (file)
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1398,23 +1398,24 @@ EXPORT_SYMBOL(iov_iter_alignment);
 unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
 {
        unsigned long res = 0;
+       unsigned long v = 0;
        size_t size = i->count;
+       unsigned k;
 
-       if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
-               WARN_ON(1);
+       if (WARN_ON(!iter_is_iovec(i)))
                return ~0U;
-       }
 
-       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 |= (!res ? 0 : (unsigned long)v.bv_offset) |
-                       (size != v.bv_len ? size : 0))
-               );
+       for (k = 0; k < i->nr_segs; k++) {
+               if (i->iov[k].iov_len) {
+                       unsigned long base = (unsigned long)i->iov[k].iov_base;
+                       if (v) // if not the first one
+                               res |= base | v; // this start | previous end
+                       v = base + i->iov[k].iov_len;
+                       if (size <= i->iov[k].iov_len)
+                               break;
+                       size -= i->iov[k].iov_len;
+               }
+       }
        return res;
 }
 EXPORT_SYMBOL(iov_iter_gap_alignment);