Extend the struct vm_page wire_count to u_int to avoid the overflow

of the counter, that may happen when too many sendfile(2) calls are
being executed with this vnode [1].

To keep the size of the struct vm_page and offsets of the fields
accessed by out-of-tree modules, swap the types and locations
of the wire_count and cow fields. Add safety checks to detect cow
overflow and force fallback to the normal copy code for zero-copy
sockets. [2]

Reported by:	Anton Yuzhaninov <citrin citrin ru> [1]
Suggested by:	alc [2]
Reviewed by:	alc
MFC after:	2 weeks

0 files changed, 0 insertions, 0 deletions