On Wed, 2016-10-12 at 13:39 +1100, NeilBrown wrote:
> The only time that a lock_context is not available is in setattr.
> In this case, we want to find a lock context relevant to the process if there is one.
> The fallback can easily be handled at a lower level.
>
> So change nfs4_select_rw_stateid to take a lock_context, passing NULL from _nfs4_do_setattr.
> nfs4_copy_lock_state() also now takes a lock_context, and falls back to searching
> for "owner == current->files" if not lock_context is given.
>
> Note that nfs4_set_rw_stateid is *always* passed a non-NULL l_ctx, so the
> fact that we remove the NULL test there does not change correctness.
>
> This change is preparation for correctly support flock stateids.
>
> Signed-off-by: NeilBrown <neilb@xxxxxxxx>
> ---
> fs/nfs/nfs4_fs.h | 2 +-
> fs/nfs/nfs4proc.c | 11 ++---------
> fs/nfs/nfs4state.c | 19 +++++++++++--------
> 3 files changed, 14 insertions(+), 18 deletions(-)
>
> diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
> index 9bf64eacba5b..3f0e459f2499 100644
> --- a/fs/nfs/nfs4_fs.h
> +++ b/fs/nfs/nfs4_fs.h
> @@ -445,7 +445,7 @@ extern void nfs41_handle_server_scope(struct nfs_client *,
> extern void nfs4_put_lock_state(struct nfs4_lock_state *lsp);
> extern int nfs4_set_lock_state(struct nfs4_state *state, struct file_lock *fl);
> extern int nfs4_select_rw_stateid(struct nfs4_state *, fmode_t,
> - const struct nfs_lockowner *, nfs4_stateid *,
> + const struct nfs_lock_context *, nfs4_stateid *,
> struct rpc_cred **);
>
> extern struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter, gfp_t gfp_mask);
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 422ed5ac4efe..6820c44aebe4 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -2764,12 +2764,9 @@ static int _nfs4_do_setattr(struct inode *inode,
> if (nfs4_copy_delegation_stateid(inode, fmode, &arg->stateid, &delegation_cred)) {
> /* Use that stateid */
> } else if (truncate && state != NULL) {
> - struct nfs_lockowner lockowner = {
> - .l_owner = current->files,
> - };
> if (!nfs4_valid_open_stateid(state))
> return -EBADF;
> - if (nfs4_select_rw_stateid(state, FMODE_WRITE, &lockowner,
> + if (nfs4_select_rw_stateid(state, FMODE_WRITE, NULL,
> &arg->stateid, &delegation_cred) == -EIO)
> return -EBADF;
> } else
> @@ -4362,11 +4359,7 @@ int nfs4_set_rw_stateid(nfs4_stateid *stateid,
> const struct nfs_lock_context *l_ctx,
> fmode_t fmode)
> {
> - const struct nfs_lockowner *lockowner = NULL;
> -
> - if (l_ctx != NULL)
> - lockowner = &l_ctx->lockowner;
> - return nfs4_select_rw_stateid(ctx->state, fmode, lockowner, stateid, NULL);
> + return nfs4_select_rw_stateid(ctx->state, fmode, l_ctx, stateid, NULL);
> }
> EXPORT_SYMBOL_GPL(nfs4_set_rw_stateid);
>
> diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
> index cada00aa5096..94a6631e7938 100644
> --- a/fs/nfs/nfs4state.c
> +++ b/fs/nfs/nfs4state.c
> @@ -939,20 +939,23 @@ int nfs4_set_lock_state(struct nfs4_state *state, struct file_lock *fl)
>
> static int nfs4_copy_lock_stateid(nfs4_stateid *dst,
> struct nfs4_state *state,
> - const struct nfs_lockowner *lockowner)
> + const struct nfs_lock_context *l_ctx)
> {
> + /*
> + * If l_ctx is NULL, then this request comes from setattr
> + * and we can choose a lock context relevant for the current process
> + */
> struct nfs4_lock_state *lsp;
> fl_owner_t fl_owner;
> int ret = -ENOENT;
>
> -
> - if (lockowner == NULL)
> - goto out;
> -
> if (test_bit(LK_STATE_IN_USE, &state->flags) == 0)
> goto out;
>
> - fl_owner = lockowner->l_owner;
> + if (l_ctx == NULL)
> + fl_owner = current->files;
> + else
> + fl_owner = l_ctx->lockowner.l_owner;
This I'm less sure of. Suppose we have only a flock lock on a file and
then truncate it. This is going to miss finding that stateid, no?
I wonder if we need to look harder at the state to determine which owner to use in this case?
> spin_lock(&state->state_lock);
> lsp = __nfs4_find_lock_state(state, fl_owner);
> if (lsp && test_bit(NFS_LOCK_LOST, &lsp->ls_flags))
> @@ -986,14 +989,14 @@ static void nfs4_copy_open_stateid(nfs4_stateid *dst, struct nfs4_state *state)
> * requests.
> */
> int nfs4_select_rw_stateid(struct nfs4_state *state,
> - fmode_t fmode, const struct nfs_lockowner *lockowner,
> + fmode_t fmode, const struct nfs_lock_context *l_ctx,
> nfs4_stateid *dst, struct rpc_cred **cred)
> {
> int ret;
>
> if (cred != NULL)
> *cred = NULL;
> - ret = nfs4_copy_lock_stateid(dst, state, lockowner);
> + ret = nfs4_copy_lock_stateid(dst, state, l_ctx);
> if (ret == -EIO)
> /* A lost lock - don't even consider delegations */
> goto out;
>
>
Also, as a side note: There were some changes around the NFS file
locking code that went into the CB_NOTIFY_LOCK patches. Those are in
linux-next now, and I _think_ Anna is going to merge them for v4.9. I
don't see any obvious conflicts here, but you may want to ensure that
you're basing this on top of linux-next to minimize them.
--
Jeff Layton <jlayton@xxxxxxxxxx>
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