switch generic_write_checks() to iocb and iter

... returning -E... upon error and amount of data left in iter after
(possible) truncation upon success.  Note, that normal case gives
a non-zero (positive) return value, so any tests for != 0 _must_ be
updated.

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

Conflicts:
	fs/ext4/file.c

1 files changed, 4 insertions, 7 deletions

diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index cec4ec3c1ede..7bb487e663b4 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -339,17 +339,14 @@ static ssize_t ntfs_prepare_file_for_write(struct kiocb *iocb,
         struct inode *vi = file_inode(file);
         ntfs_inode *base_ni, *ni = NTFS_I(vi);
         ntfs_volume *vol = ni->vol;
-        size_t count = iov_iter_count(from);
 
         ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, pos "
                         "0x%llx, count 0x%zx.", vi->i_ino,
                         (unsigned)le32_to_cpu(ni->type),
-                        (unsigned long long)iocb->ki_pos, count);
-        err = generic_write_checks(file, &iocb->ki_pos, &count);
-        if (unlikely(err))
-                goto out;
-        iov_iter_truncate(from, count);
-        if (count == 0)
+                        (unsigned long long)iocb->ki_pos,
+                        iov_iter_count(from));
+        err = generic_write_checks(iocb, from);
+        if (unlikely(err <= 0))
                 goto out;
         /*
          * All checks have passed.  Before we start doing any writing we want