tree b74fe0c7e9370dfed956a1607dd10282c9ba1096
parent f6161aa153581da4a3867a2d1a7caf4be19b6ec9
author Al Viro <viro@zeniv.linux.org.uk> 1363799970 -0400
committer Al Viro <viro@zeniv.linux.org.uk> 1363885871 -0400

Don't bother with redoing rw_verify_area() from default_file_splice_from()

default_file_splice_from() ends up calling vfs_write() (via very convoluted
callchain).  It's an overkill, since we already have done rw_verify_area()
in the caller by the time we call vfs_write() we are under set_fs(KERNEL_DS),
so access_ok() is also pointless.  Add a new helper (__kernel_write()),
use it instead of kernel_write() in there.

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