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, 6 insertions, 20 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 4202e74b2db5..ca2bc5406306 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2563,7 +2563,6 @@ cifs_write_from_iter(loff_t offset, size_t len, struct iov_iter *from,
 ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from)
 {
         struct file *file = iocb->ki_filp;
-        size_t len;
         ssize_t total_written = 0;
         struct cifsFileInfo *open_file;
         struct cifs_tcon *tcon;
@@ -2579,16 +2578,10 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from)
          * write request.
          */
 
-        len = iov_iter_count(from);
-        rc = generic_write_checks(file, &iocb->ki_pos, &len);
-        if (rc)
+        rc = generic_write_checks(iocb, from);
+        if (rc <= 0)
                 return rc;
 
-        if (!len)
-                return 0;
-
-        iov_iter_truncate(from, len);
-
         INIT_LIST_HEAD(&wdata_list);
         cifs_sb = CIFS_FILE_SB(file);
         open_file = file->private_data;
@@ -2599,8 +2592,8 @@ ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from)
 
         memcpy(&saved_from, from, sizeof(struct iov_iter));
 
-        rc = cifs_write_from_iter(iocb->ki_pos, len, from, open_file, cifs_sb,
-                                  &wdata_list);
+        rc = cifs_write_from_iter(iocb->ki_pos, iov_iter_count(from), from,
+                                  open_file, cifs_sb, &wdata_list);
 
         /*
          * If at least one write was successfully sent, then discard any rc
@@ -2674,7 +2667,6 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
         struct cifsInodeInfo *cinode = CIFS_I(inode);
         struct TCP_Server_Info *server = tlink_tcon(cfile->tlink)->ses->server;
         ssize_t rc;
-        size_t count;
 
         /*
          * We need to hold the sem to be sure nobody modifies lock list
@@ -2683,16 +2675,10 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
         down_read(&cinode->lock_sem);
         mutex_lock(&inode->i_mutex);
 
-        count = iov_iter_count(from);
-        rc = generic_write_checks(file, &iocb->ki_pos, &count);
-        if (rc)
+        rc = generic_write_checks(iocb, from);
+        if (rc <= 0)
                 goto out;
 
-        if (count == 0)
-                goto out;
-
-        iov_iter_truncate(from, count);
-
         if (!cifs_find_lock_conflict(cfile, iocb->ki_pos, iov_iter_count(from),
                                      server->vals->exclusive_lock_type, NULL,
                                      CIFS_WRITE_OP))