On Fri, May 30, 2014 at 09:09:32AM -0400, Jeff Layton wrote:
> From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
>
> Ensure that we only can have a single struct nfs4_file per inode
> in the file_hashtbl and make addition atomic with respect to lookup.
>
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> fs/nfsd/nfs4state.c | 46 +++++++++++++++++++++++++++++++++++-----------
> 1 file changed, 35 insertions(+), 11 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index a500033a2f87..553c2d6d48dc 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -2519,6 +2519,8 @@ static void nfsd4_init_file(struct nfs4_file *fp, struct inode *ino)
> {
> unsigned int hashval = file_hashval(ino);
>
> + lockdep_assert_held(&state_lock);
> +
Oops, lockdep points out we overlooked a deadlock here: this function
also calls igrab(), which takes the i_lock, the reverse ordering from
what we take in the delegation-break case.
Dropping this patch for now.
--b.
> atomic_set(&fp->fi_ref, 1);
> INIT_LIST_HEAD(&fp->fi_stateids);
> INIT_LIST_HEAD(&fp->fi_delegations);
> @@ -2527,9 +2529,7 @@ static void nfsd4_init_file(struct nfs4_file *fp, struct inode *ino)
> fp->fi_lease = NULL;
> memset(fp->fi_fds, 0, sizeof(fp->fi_fds));
> memset(fp->fi_access, 0, sizeof(fp->fi_access));
> - spin_lock(&state_lock);
> hlist_add_head(&fp->fi_hash, &file_hashtbl[hashval]);
> - spin_unlock(&state_lock);
> }
>
> void
> @@ -2695,23 +2695,49 @@ find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open,
>
> /* search file_hashtbl[] for file */
> static struct nfs4_file *
> -find_file(struct inode *ino)
> +find_file_locked(struct inode *ino)
> {
> unsigned int hashval = file_hashval(ino);
> struct nfs4_file *fp;
>
> - spin_lock(&state_lock);
> + lockdep_assert_held(&state_lock);
> +
> hlist_for_each_entry(fp, &file_hashtbl[hashval], fi_hash) {
> if (fp->fi_inode == ino) {
> get_nfs4_file(fp);
> - spin_unlock(&state_lock);
> return fp;
> }
> }
> - spin_unlock(&state_lock);
> return NULL;
> }
>
> +static struct nfs4_file *
> +find_file(struct inode *ino)
> +{
> + struct nfs4_file *fp;
> +
> + spin_lock(&state_lock);
> + fp = find_file_locked(ino);
> + spin_unlock(&state_lock);
> + return fp;
> +}
> +
> +static struct nfs4_file *
> +find_or_add_file(struct inode *ino, struct nfs4_file *new)
> +{
> + struct nfs4_file *fp;
> +
> + spin_lock(&state_lock);
> + fp = find_file_locked(ino);
> + if (fp == NULL) {
> + nfsd4_init_file(new, ino);
> + fp = new;
> + }
> + spin_unlock(&state_lock);
> +
> + return fp;
> +}
> +
> /*
> * Called to check deny when READ with all zero stateid or
> * WRITE with all zero or all one stateid
> @@ -3230,21 +3256,19 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
> * and check for delegations in the process of being recalled.
> * If not found, create the nfs4_file struct
> */
> - fp = find_file(ino);
> - if (fp) {
> + fp = find_or_add_file(ino, open->op_file);
> + if (fp != open->op_file) {
> if ((status = nfs4_check_open(fp, open, &stp)))
> goto out;
> status = nfs4_check_deleg(cl, open, &dp);
> if (status)
> goto out;
> } else {
> + open->op_file = NULL;
> status = nfserr_bad_stateid;
> if (nfsd4_is_deleg_cur(open))
> goto out;
> status = nfserr_jukebox;
> - fp = open->op_file;
> - open->op_file = NULL;
> - nfsd4_init_file(fp, ino);
> }
>
> /*
> --
> 1.9.3
>
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