blkdev_write_iter: expand generic_file_checks() call in there

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

1 files changed, 9 insertions, 6 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index bcd7f97beab9..897ee0503932 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1595,18 +1595,21 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
         struct file *file = iocb->ki_filp;
+        struct inode *bd_inode = file->f_mapping->host;
+        loff_t size = i_size_read(bd_inode);
         struct blk_plug plug;
         ssize_t ret;
-        size_t count = iov_iter_count(from);
 
-        ret = generic_write_checks(file, &iocb->ki_pos, &count, 1);
-        if (ret)
-                return ret;
+        if (bdev_read_only(I_BDEV(bd_inode)))
+                return -EPERM;
 
-        if (count == 0)
+        if (!iov_iter_count(from))
                 return 0;
 
-        iov_iter_truncate(from, count);
+        if (iocb->ki_pos >= size)
+                return -ENOSPC;
+
+        iov_iter_truncate(from, size - iocb->ki_pos);
 
         blk_start_plug(&plug);
         ret = __generic_file_write_iter(iocb, from);