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authorAl Viro <viro@zeniv.linux.org.uk>2021-04-25 07:44:35 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2021-06-10 18:45:10 +0300
commit9221d2e37b729077797e6d02012289892dbdb859 (patch)
tree9c8619d3cc168554eba89d1e31da8934b41d5ab3 /lib/iov_iter.c
parent8409a0d261e20180361e7afe6d89847d1bad4ce8 (diff)
downloadlinux-9221d2e37b729077797e6d02012289892dbdb859.tar.xz
iov_iter_alignment(): don't bother with iterate_all_kinds()
It's easier to go over the array manually. We need to watch out for truncated iov_iter, though - iovec array might cover more than i->count. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'lib/iov_iter.c')
-rw-r--r--lib/iov_iter.c63
1 files changed, 53 insertions, 10 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 2b543bea1e0d..ed9318358b68 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1328,27 +1328,70 @@ void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count)
}
EXPORT_SYMBOL(iov_iter_discard);
-unsigned long iov_iter_alignment(const struct iov_iter *i)
+static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i)
{
unsigned long res = 0;
size_t size = i->count;
+ size_t skip = i->iov_offset;
+ unsigned k;
+
+ for (k = 0; k < i->nr_segs; k++, skip = 0) {
+ size_t len = i->iov[k].iov_len - skip;
+ if (len) {
+ res |= (unsigned long)i->iov[k].iov_base + skip;
+ if (len > size)
+ len = size;
+ res |= len;
+ size -= len;
+ if (!size)
+ break;
+ }
+ }
+ return res;
+}
- if (unlikely(iov_iter_is_pipe(i))) {
+static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i)
+{
+ unsigned res = 0;
+ size_t size = i->count;
+ unsigned skip = i->iov_offset;
+ unsigned k;
+
+ for (k = 0; k < i->nr_segs; k++, skip = 0) {
+ size_t len = i->bvec[k].bv_len - skip;
+ res |= (unsigned long)i->bvec[k].bv_offset + skip;
+ if (len > size)
+ len = size;
+ res |= len;
+ size -= len;
+ if (!size)
+ break;
+ }
+ return res;
+}
+
+unsigned long iov_iter_alignment(const struct iov_iter *i)
+{
+ /* iovec and kvec have identical layouts */
+ if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
+ return iov_iter_alignment_iovec(i);
+
+ if (iov_iter_is_bvec(i))
+ return iov_iter_alignment_bvec(i);
+
+ if (iov_iter_is_pipe(i)) {
unsigned int p_mask = i->pipe->ring_size - 1;
+ size_t size = i->count;
if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask]))
return size | i->iov_offset;
return size;
}
- if (unlikely(iov_iter_is_xarray(i)))
+
+ if (iov_iter_is_xarray(i))
return (i->xarray_start + i->iov_offset) | i->count;
- iterate_all_kinds(i, size, v,
- (res |= (unsigned long)v.iov_base | v.iov_len, 0),
- res |= v.bv_offset | v.bv_len,
- res |= (unsigned long)v.iov_base | v.iov_len,
- res |= v.bv_offset | v.bv_len
- )
- return res;
+
+ return 0;
}
EXPORT_SYMBOL(iov_iter_alignment);