On Thu, 28 Oct 2010 08:34:35 -0400
Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> On Thu, 28 Oct 2010 08:17:54 -0400
> Steve Dickson <steved@xxxxxxxxxx> wrote:
>
> > A typo, introduced by commit f11ac8db, in the nfs_direct_write()
> > routine causes writes with O_DIRECT set to fail with a ENOMEM error.
> >
> > Found-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > Signed-off-by: Steve Dickson <steved@xxxxxxxxxx>
> > ---
> > fs/nfs/direct.c | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
> > index 064a809..84d3c8b 100644
> > --- a/fs/nfs/direct.c
> > +++ b/fs/nfs/direct.c
> > @@ -873,7 +873,7 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
> > dreq->inode = inode;
> > dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
> > dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
> > - if (dreq->l_ctx != NULL)
> > + if (dreq->l_ctx == NULL)
> > goto out_release;
> > if (!is_sync_kiocb(iocb))
> > dreq->iocb = iocb;
>
> Also, since get_lock_context holds references, this prevents the fs
> from being unmounted. It looks like this bug is in 2.6.36 too, so this
> may be suitable for stable series as well.
>
Oh...and another thing I noticed too...
nfs_create_request doesn't check for a NULL return from
nfs_get_lock_context. If it ever does, it looks like that will likely
trickle down to an oops in encode_stateid.
It might be good to fix that as well. Maybe something like this
compile-tested-only patch?
--------------------[snip]---------------------
nfs: handle lock context allocation failures in nfs_create_request
nfs_get_lock_context can return NULL on an allocation failure.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/nfs/pagelist.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 9194902..137b549 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -65,6 +65,13 @@ nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
if (req == NULL)
return ERR_PTR(-ENOMEM);
+ /* get lock context early so we can deal with alloc failures */
+ req->wb_lock_context = nfs_get_lock_context(ctx);
+ if (req->wb_lock_context == NULL) {
+ nfs_page_free(req);
+ return ERR_PTR(-ENOMEM);
+ }
+
/* Initialize the request struct. Initially, we assume a
* long write-back delay. This will be adjusted in
* update_nfs_request below if the region is not locked. */
@@ -79,7 +86,6 @@ nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
req->wb_pgbase = offset;
req->wb_bytes = count;
req->wb_context = get_nfs_open_context(ctx);
- req->wb_lock_context = nfs_get_lock_context(ctx);
kref_init(&req->wb_kref);
return req;
}
--
1.7.2.3
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