[pnfs] [PATCH 5/12] cleanup nfsd state lock

[William A. (Andy) Adamson]

On 5/7/07, Benny Halevy <bhalevy at panasas.com> wrote:
>
>
>
> From 8ad07658b24efa9a284f9edc38c54c95f80b4bde Mon Sep 17 00:00:00 2001
> From: Benny Halevy <bhalevy at ns1.bhalevy.com>
> Date: Mon, 7 May 2007 16:58:42 +0300
> Subject: [PATCH] cleanup nfsd state lock
>
> make sure nfs4 file and client are got and freed
> under the state lock
> get... code asserts that the lock is taken (with BUG_ON)
> free... code just takes the lock if needed
> ---
> fs/nfsd/nfs4state.c |   19 ++++++++++++++++++-
> 1 files changed, 18 insertions(+), 1 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index d1355b2..71c9ec3 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -108,6 +108,12 @@ static kmem_cache_t *file_slab = NULL;
> static kmem_cache_t *stateid_slab = NULL;
> static kmem_cache_t *deleg_slab = NULL;
>
> +static int
> +nfs4_trylock_state(void)
> +{
> +       return mutex_trylock(&client_mutex);
> +}
> +
> void
> nfs4_lock_state(void)
> {
> @@ -120,6 +126,8 @@ nfs4_unlock_state(void)
>         mutex_unlock(&client_mutex);
> }
>
> +#define BUG_ON_UNLOCKED_STATE() BUG_ON(nfs4_trylock_state());
> +
> static inline u32
> opaque_hashval(const void *ptr, int nbytes)
> {
> @@ -148,8 +156,12 @@ static struct list_head del_recall_lru;
> static void
> free_nfs4_file(struct kref *kref)
> {
> +       int did_lock;
>         struct nfs4_file *fp = container_of(kref, struct nfs4_file,
> fi_ref);
> +       did_lock = nfs4_trylock_state();
>         list_del(&fp->fi_hash);
> +       if (did_lock)
> +               nfs4_unlock_state();
>         iput(fp->fi_inode);
>         kmem_cache_free(file_slab, fp);
> }
> @@ -157,12 +169,15 @@ free_nfs4_file(struct kref *kref)
> static inline void
> put_nfs4_file(struct nfs4_file *fi)
> {
> -       kref_put(&fi->fi_ref, free_nfs4_file);
> +       BUG_ON_UNLOCKED_STATE();
> +       if (fi)
> +               kref_put(&fi->fi_ref, free_nfs4_file);
> }



I'm confused. When can put_nfs4_file be called when not under
nfs4_lock_state?

static inline void
> get_nfs4_file(struct nfs4_file *fi)
> {
> +       BUG_ON_UNLOCKED_STATE();
>         kref_get(&fi->fi_ref);
> }
>
> @@ -538,6 +553,7 @@ alloc_client(struct xdr_netobj name)
> static inline struct nfs4_client *
> get_nfs4_client(struct nfs4_client *clp)
> {
> +       BUG_ON_UNLOCKED_STATE();
>         kref_get(&clp->cl_ref);
>         return clp;
> }
> @@ -1661,6 +1677,7 @@ find_file(struct inode *ino)
>         unsigned int hashval = file_hashval(ino);
>         struct nfs4_file *fp;
>
> +       BUG_ON_UNLOCKED_STATE();
>         list_for_each_entry(fp, &file_hashtbl[hashval], fi_hash) {
>                 if (fp->fi_inode == ino) {
>                         get_nfs4_file(fp);
> --
> 1.5.1
>
>
> _______________________________________________
> pNFS mailing list
> pNFS at linux-nfs.org
> http://linux-nfs.org/cgi-bin/mailman/listinfo/pnfs
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://linux-nfs.org/pipermail/pnfs/attachments/20070515/e45e6939/attachment.htm