From: Trond Myklebust Subject: [PATCH 1/4] NFS: Fix a deadlock with lazy umount Date: Tue, 19 Feb 2008 18:04:59 -0500 Message-ID: <20080219230459.22007.4944.stgit@c-69-242-210-120.hsd1.mi.comcast.net> References: <20080219230459.22007.10990.stgit@c-69-242-210-120.hsd1.mi.comcast.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Cc: linux-nfs@vger.kernel.org To: Neil Brown Return-path: Received: from mx2.netapp.com ([216.240.18.37]:53378 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755104AbYBSXPD (ORCPT ); Tue, 19 Feb 2008 18:15:03 -0500 In-Reply-To: <20080219230459.22007.10990.stgit-KPEdlmqt5P7XOazzY/2fV4TcuzvYVacciM950cveMlzk1uMJSBkQmQ@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: We can't allow rpc callback functions like task->tk_ops->rpc_call_prepare() and task->tk_ops->rpc_call_done() to call mntput() in any way, since that will cause a deadlock when the call to rpc_shutdown_client() attempts to wait on 'task' to complete. We can avoid the above deadlock by moving calls to mntput to task->tk_ops->rpc_release() callback, since at that time the task will be marked as completed, and so rpc_shutdown_client won't attempt to wait on it. Signed-off-by: Trond Myklebust --- fs/nfs/direct.c | 5 +++-- fs/nfs/inode.c | 6 +++++- fs/nfs/read.c | 7 +++++-- fs/nfs/write.c | 13 ++++++++++--- 4 files changed, 23 insertions(+), 8 deletions(-) diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c index 16844f9..e017040 100644 --- a/fs/nfs/direct.c +++ b/fs/nfs/direct.c @@ -323,7 +323,7 @@ static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq, data->inode = inode; data->cred = msg.rpc_cred; data->args.fh = NFS_FH(inode); - data->args.context = ctx; + data->args.context = get_nfs_open_context(ctx); data->args.offset = pos; data->args.pgbase = pgbase; data->args.pages = data->pagevec; @@ -546,6 +546,7 @@ static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq) data->args.fh = NFS_FH(data->inode); data->args.offset = 0; data->args.count = 0; + data->args.context = get_nfs_open_context(dreq->ctx); data->res.count = 0; data->res.fattr = &data->fattr; data->res.verf = &data->verf; @@ -728,7 +729,7 @@ static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq, data->inode = inode; data->cred = msg.rpc_cred; data->args.fh = NFS_FH(inode); - data->args.context = ctx; + data->args.context = get_nfs_open_context(ctx); data->args.offset = pos; data->args.pgbase = pgbase; data->args.pages = data->pagevec; diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 966a885..a499fb5 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -521,8 +521,12 @@ struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx) static void __put_nfs_open_context(struct nfs_open_context *ctx, int wait) { - struct inode *inode = ctx->path.dentry->d_inode; + struct inode *inode; + if (ctx == NULL) + return; + + inode = ctx->path.dentry->d_inode; if (!atomic_dec_and_lock(&ctx->count, &inode->i_lock)) return; list_del(&ctx->list); diff --git a/fs/nfs/read.c b/fs/nfs/read.c index 3d7d963..fab0d37 100644 --- a/fs/nfs/read.c +++ b/fs/nfs/read.c @@ -73,7 +73,10 @@ static void nfs_readdata_free(struct nfs_read_data *rdata) void nfs_readdata_release(void *data) { - nfs_readdata_free(data); + struct nfs_read_data *rdata = data; + + put_nfs_open_context(rdata->args.context); + nfs_readdata_free(rdata); } static @@ -186,7 +189,7 @@ static void nfs_read_rpcsetup(struct nfs_page *req, struct nfs_read_data *data, data->args.pgbase = req->wb_pgbase + offset; data->args.pages = data->pagevec; data->args.count = count; - data->args.context = req->wb_context; + data->args.context = get_nfs_open_context(req->wb_context); data->res.fattr = &data->fattr; data->res.count = count; diff --git a/fs/nfs/write.c b/fs/nfs/write.c index f55c437..fb6232a 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -105,8 +105,11 @@ static void nfs_writedata_free(struct nfs_write_data *wdata) call_rcu_bh(&wdata->task.u.tk_rcu, nfs_writedata_rcu_free); } -void nfs_writedata_release(void *wdata) +void nfs_writedata_release(void *data) { + struct nfs_write_data *wdata = data; + + put_nfs_open_context(wdata->args.context); nfs_writedata_free(wdata); } @@ -816,7 +819,7 @@ static void nfs_write_rpcsetup(struct nfs_page *req, data->args.pgbase = req->wb_pgbase + offset; data->args.pages = data->pagevec; data->args.count = count; - data->args.context = req->wb_context; + data->args.context = get_nfs_open_context(req->wb_context); data->args.stable = NFS_UNSTABLE; if (how & FLUSH_STABLE) { data->args.stable = NFS_DATA_SYNC; @@ -1153,8 +1156,11 @@ int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data) #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4) -void nfs_commit_release(void *wdata) +void nfs_commit_release(void *data) { + struct nfs_write_data *wdata = data; + + put_nfs_open_context(wdata->args.context); nfs_commit_free(wdata); } @@ -1197,6 +1203,7 @@ static void nfs_commit_rpcsetup(struct list_head *head, /* Note: we always request a commit of the entire inode */ data->args.offset = 0; data->args.count = 0; + data->args.context = get_nfs_open_context(first->wb_context); data->res.count = 0; data->res.fattr = &data->fattr; data->res.verf = &data->verf;