tree c506bd7dcacc9d5b25b3295bd1f327e534532c54
parent 585a2858b970cb6e2e5ca4877eefd18b4dba8ed4
author Trond Myklebust <Trond.Myklebust@netapp.com> 1179670707 -0400
committer Trond Myklebust <Trond.Myklebust@netapp.com> 1180017860 -0400

NFS: Avoid a deadlock situation on write

When processes are allowed to attempt to lock a non-contiguous range of nfs
write requests, it is possible for generic_writepages to 'wrap round' the
address space, and call writepage() on a request that is already locked by
the same process.

We avoid the deadlock by checking if the page index is contiguous with the
list of nfs write requests that is already held in our
nfs_pageio_descriptor prior to attempting to lock a new request.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>