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NFSv4: Ensure delegation recall and byte range lock removal don't conflict
Add a mutex to the struct nfs4_state_owner to ensure that delegation recall doesn't conflict with byte range lock removal. Note that we nest the new mutex _outside_ the state manager reclaim protection (nfsi->rwsem) in order to avoid deadlocks. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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37380e4264
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@ -71,8 +71,10 @@ static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_
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int status = 0;
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if (inode->i_flock == NULL)
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goto out;
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return 0;
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if (inode->i_flock == NULL)
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goto out;
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/* Protect inode->i_flock using the file locks lock */
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lock_flocks();
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for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
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@ -113,12 +115,15 @@ again:
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get_nfs_open_context(ctx);
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spin_unlock(&inode->i_lock);
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sp = state->owner;
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/* Block nfs4_proc_unlck */
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mutex_lock(&sp->so_delegreturn_mutex);
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seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
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err = nfs4_open_delegation_recall(ctx, state, stateid);
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if (!err)
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err = nfs_delegation_claim_locks(ctx, state);
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if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
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err = -EAGAIN;
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mutex_unlock(&sp->so_delegreturn_mutex);
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put_nfs_open_context(ctx);
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if (err != 0)
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return err;
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@ -93,6 +93,7 @@ struct nfs4_state_owner {
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struct list_head so_states;
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struct nfs_seqid_counter so_seqid;
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seqcount_t so_reclaim_seqcount;
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struct mutex so_delegreturn_mutex;
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};
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enum {
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@ -4485,7 +4485,9 @@ static struct rpc_task *nfs4_do_unlck(struct file_lock *fl,
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static int nfs4_proc_unlck(struct nfs4_state *state, int cmd, struct file_lock *request)
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{
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struct nfs_inode *nfsi = NFS_I(state->inode);
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struct inode *inode = state->inode;
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struct nfs4_state_owner *sp = state->owner;
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struct nfs_inode *nfsi = NFS_I(inode);
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struct nfs_seqid *seqid;
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struct nfs4_lock_state *lsp;
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struct rpc_task *task;
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@ -4495,12 +4497,17 @@ static int nfs4_proc_unlck(struct nfs4_state *state, int cmd, struct file_lock *
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status = nfs4_set_lock_state(state, request);
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/* Unlock _before_ we do the RPC call */
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request->fl_flags |= FL_EXISTS;
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/* Exclude nfs_delegation_claim_locks() */
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mutex_lock(&sp->so_delegreturn_mutex);
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/* Exclude nfs4_reclaim_open_stateid() - note nesting! */
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down_read(&nfsi->rwsem);
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if (do_vfs_lock(request->fl_file, request) == -ENOENT) {
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up_read(&nfsi->rwsem);
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mutex_unlock(&sp->so_delegreturn_mutex);
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goto out;
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}
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up_read(&nfsi->rwsem);
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mutex_unlock(&sp->so_delegreturn_mutex);
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if (status != 0)
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goto out;
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/* Is this a delegated lock? */
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@ -519,6 +519,7 @@ nfs4_alloc_state_owner(struct nfs_server *server,
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atomic_set(&sp->so_count, 1);
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INIT_LIST_HEAD(&sp->so_lru);
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seqcount_init(&sp->so_reclaim_seqcount);
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mutex_init(&sp->so_delegreturn_mutex);
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return sp;
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}
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