Merge branch 'work.splice_read' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull splice fixups from Al Viro:
 "A couple of fixups for interaction of pipe-backed iov_iter with
  O_DIRECT reads + constification of a couple of primitives in uio.h
  missed by previous rounds.

  Kudos to davej - his fuzzing has caught those bugs"

* 'work.splice_read' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  [btrfs] fix check_direct_IO() for non-iovec iterators
  constify iov_iter_count() and iter_is_iovec()
  fix ITER_PIPE interaction with direct_IO

5 files changed, 8 insertions, 14 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 92346a403a89..a0d3016f6c26 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8619,7 +8619,7 @@ static ssize_t check_direct_IO(struct btrfs_root *root, struct kiocb *iocb,
                 goto out;
 
         /* If this is a write we don't need to check anymore */
-        if (iov_iter_rw(iter) == WRITE)
+        if (iov_iter_rw(iter) != READ || !iter_is_iovec(iter))
                 return 0;
         /*
          * Check to make sure we don't have duplicate iov_base's in this
diff --git a/fs/splice.c b/fs/splice.c
index aa38901a4f10..153d4f3bd441 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -315,15 +315,9 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
                 *ppos = kiocb.ki_pos;
                 file_accessed(in);
         } else if (ret < 0) {
-                if (WARN_ON(to.idx != idx || to.iov_offset)) {
-                        /*
-                         * a bogus ->read_iter() has copied something and still
-                         * returned an error instead of a short read.
-                         */
-                        to.idx = idx;
-                        to.iov_offset = 0;
-                        iov_iter_advance(&to, 0); /* to free what was emitted */
-                }
+                to.idx = idx;
+                to.iov_offset = 0;
+                iov_iter_advance(&to, 0); /* to free what was emitted */
                 /*
                  * callers of ->splice_read() expect -EAGAIN on
                  * "can't put anything in there", rather than -EFAULT.
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 62511687385c..2bc58b3fd37d 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -319,7 +319,7 @@ xfs_file_dio_aio_read(
         data = *to;
         ret = __blockdev_direct_IO(iocb, inode, target->bt_bdev, &data,
                         xfs_get_blocks_direct, NULL, NULL, 0);
-        if (ret > 0) {
+        if (ret >= 0) {
                 iocb->ki_pos += ret;
                 iov_iter_advance(to, ret);
         }
diff --git a/include/linux/uio.h b/include/linux/uio.h
index a00d525bbffa..6e22b544d039 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -109,12 +109,12 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages);
 
 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
 
-static inline size_t iov_iter_count(struct iov_iter *i)
+static inline size_t iov_iter_count(const struct iov_iter *i)
 {
         return i->count;
 }
 
-static inline bool iter_is_iovec(struct iov_iter *i)
+static inline bool iter_is_iovec(const struct iov_iter *i)
 {
         return !(i->type & (ITER_BVEC | ITER_KVEC | ITER_PIPE));
 }
diff --git a/mm/filemap.c b/mm/filemap.c
index 2f7b7783bd6b..849f459ad078 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1941,7 +1941,7 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
                 file_accessed(file);
 
                 retval = mapping->a_ops->direct_IO(iocb, &data);
-                if (retval > 0) {
+                if (retval >= 0) {
                         iocb->ki_pos += retval;
                         iov_iter_advance(iter, retval);
                 }