On Tue, 2010-06-15 at 13:52 -0400, Fred Isaman wrote:
> On Tue, Jun 15, 2010 at 1:33 PM, Trond Myklebust
> <trond.myklebust@xxxxxxxxxx> wrote:
> > On Tue, 2010-06-15 at 13:32 -0400, Fred Isaman wrote:
> >> On Tue, Jun 15, 2010 at 1:06 PM, Benny Halevy <bhalevy@xxxxxxxxxxx> wrote:
> >> > On Jun. 14, 2010, 21:46 -0400, Fred Isaman <iisaman@xxxxxxxxxx> wrote:
> >> >> This prepares for the next patch.
> >> >>
> >> >> NOTE this doesn't really fix any current race, since
> >> >> layout going to NULL is OK. But layout changing from NULL to nonNULL
> >> >> is a real race that is not fixed
> >> >>
> >> >> Signed-off-by: Fred Isaman <iisaman@xxxxxxxxxx>
> >> >> ---
> >> >> fs/nfs/nfs4state.c | 5 +++--
> >> >> fs/nfs/pnfs.c | 11 +++++++++++
> >> >> include/linux/nfs4_pnfs.h | 2 ++
> >> >> 3 files changed, 16 insertions(+), 2 deletions(-)
> >> >>
> >> >> diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
> >> >> index d5144bd..8a7a64c 100644
> >> >> --- a/fs/nfs/nfs4state.c
> >> >> +++ b/fs/nfs/nfs4state.c
> >> >> @@ -594,11 +594,12 @@ static void __nfs4_close(struct path *path, struct nfs4_state *state,
> >> >> } else {
> >> >> #ifdef CONFIG_NFS_V4_1
> >> >> struct nfs_inode *nfsi = NFS_I(state->inode);
> >> >> + int roc = nfs4_roc_iomode(nfsi);
> >> >>
> >> >> - if (has_layout(nfsi) && nfsi->layout.roc_iomode) {
> >> >> + if (roc) {
> >> >> struct nfs4_pnfs_layout_segment range;
> >> >>
> >> >> - range.iomode = nfsi->layout.roc_iomode;
> >> >> + range.iomode = roc;
> >> >> range.offset = 0;
> >> >> range.length = NFS4_MAX_UINT64;
> >> >> pnfs_return_layout(state->inode, &range, NULL,
> >> >> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> >> >> index 6def09c..bd11ec7 100644
> >> >> --- a/fs/nfs/pnfs.c
> >> >> +++ b/fs/nfs/pnfs.c
> >> >> @@ -321,6 +321,17 @@ pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
> >> >> #define BUG_ON_UNLOCKED_LO(lo) do {} while (0)
> >> >> #endif /* CONFIG_SMP */
> >> >>
> >> >> +int nfs4_roc_iomode(struct nfs_inode *nfsi)
> >> >> +{
> >> >> + int rv = 0;
> >> >> +
> >> >> + spin_lock(&pnfs_spinlock);
> >> >
> >> > Why take the global lock rather than nfsi->lo_lock?
> >> >
> >> > Benny
> >>
> >> You are right. That would be a copy-paste error.
> >
> > What's an nfsi->lo_lock, and why do we need one?
> >
> > Trond
> >
> >
>
> It protects nfsi->layout and its contents.
>
> Fred
Yes, but why do we need an extra spinlock? We already have
inode->i_lock. Why can't you just reuse that?
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