vfs: exit early from zero length remap operations

If a remap caller asks us to remap to the source file's EOF and the
source file length leaves us with a zero byte request, exit early.

Signed-off-by: Darrick J. Wong <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Dave Chinner <[email protected]>

diff --git a/fs/read_write.c b/fs/read_write.c
index d6e8e242a15fad4f13fd59a688447af3792ffb80..2456da3f8a414f8ec420ed29bf5c79c0925f0ecd 100644 (file)
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1748,6 +1748,8 @@ int vfs_clone_file_prep(struct file *file_in, loff_t pos_in,
                if (pos_in > isize)
                        return -EINVAL;
                *len = isize - pos_in;
                if (pos_in > isize)
                        return -EINVAL;
                *len = isize - pos_in;

+               if (*len == 0)
+                       return 0;

        }
 
        /* Check that we don't violate system file offset limits. */
        }
 
        /* Check that we don't violate system file offset limits. */