vfs_read has been unexported in bd8df82be66 ("fs: unexport vfs_read and vfs_write")
in kernel 4.14.
kernel_read has always™ existed and is actually more appropriate: we can
remove the set_fs calls that are done in kernel_read.
The downside is that the function prototype also changed in 4.14 with
bdd1d2d3d251 ("fs: fix kernel_read prototype")...
(same with kernel_write e13ec939e96b ("fs: fix kernel_write prototype"))
Change-Id: I6f76a6387ae02b4d33bd62952d995a90b1952fc9
ea35954613