tree 7added4d982e03c89599ef7c78c9b69845a7504d
parent d9b942013730c38ac83564d6669c6d0ecf6d754d
author Jeff Layton <jlayton@redhat.com> 1302614024 -0400
committer Steve French <sfrench@us.ibm.com> 1302617995 +0000

cifs: don't allow mmap'ed pages to be dirtied while under writeback (try #3)

This is more or less the same patch as before, but with some merge
conflicts fixed up.

If a process has a dirty page mapped into its page tables, then it has
the ability to change it while the client is trying to write the data
out to the server. If that happens after the signature has been
calculated then that signature will then be wrong, and the server will
likely reset the TCP connection.

This patch adds a page_mkwrite handler for CIFS that simply takes the
page lock. Because the page lock is held over the life of writepage and
writepages, this prevents the page from becoming writeable until
the write call has completed.

With this, we can also remove the "sign_zero_copy" module option and
always inline the pages when writing.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>