NFSv4.1: Fix a race in the pNFS return-on-close code

If we sleep after dropping the inode->i_lock, then we are no longer
atomic with respect to the rpc_wake_up() call in pnfs_layout_remove_lseg().

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index e605d41..6d5750c 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2137,6 +2137,7 @@ static void nfs4_close_prepare(struct rpc_task *task, void *data)
 {
        struct nfs4_closedata *calldata = data;
        struct nfs4_state *state = calldata->state;
+       struct inode *inode = calldata->inode;
        int call_close = 0;
 
        dprintk("%s: begin!\n", __func__);
@@ -2170,16 +2171,13 @@ static void nfs4_close_prepare(struct rpc_task *task, void *data)
        if (calldata->arg.fmode == 0) {
                task->tk_msg.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_CLOSE];
                if (calldata->roc &&
-                   pnfs_roc_drain(calldata->inode, &calldata->roc_barrier)) {
-                       rpc_sleep_on(&NFS_SERVER(calldata->inode)->roc_rpcwaitq,
-                                    task, NULL);
+                   pnfs_roc_drain(inode, &calldata->roc_barrier, task))
                        goto out;
-               }
        }
 
        nfs_fattr_init(calldata->res.fattr);
        calldata->timestamp = jiffies;
-       if (nfs4_setup_sequence(NFS_SERVER(calldata->inode),
+       if (nfs4_setup_sequence(NFS_SERVER(inode),
                                &calldata->arg.seq_args,
                                &calldata->res.seq_res,
                                task))

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 9ee3bd7..8b32f87 100644 (file)
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -807,27 +807,29 @@ void pnfs_roc_set_barrier(struct inode *ino, u32 barrier)
        spin_unlock(&ino->i_lock);
 }
 
-bool pnfs_roc_drain(struct inode *ino, u32 *barrier)
+bool pnfs_roc_drain(struct inode *ino, u32 *barrier, struct rpc_task *task)
 {
        struct nfs_inode *nfsi = NFS_I(ino);
+       struct pnfs_layout_hdr *lo;
        struct pnfs_layout_segment *lseg;
+       u32 current_seqid;
        bool found = false;
 
        spin_lock(&ino->i_lock);
        list_for_each_entry(lseg, &nfsi->layout->plh_segs, pls_list)
                if (test_bit(NFS_LSEG_ROC, &lseg->pls_flags)) {
+                       rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
                        found = true;
-                       break;
+                       goto out;
                }
-       if (!found) {
-               struct pnfs_layout_hdr *lo = nfsi->layout;
-               u32 current_seqid = be32_to_cpu(lo->plh_stateid.seqid);
+       lo = nfsi->layout;
+       current_seqid = be32_to_cpu(lo->plh_stateid.seqid);
 
-               /* Since close does not return a layout stateid for use as
-                * a barrier, we choose the worst-case barrier.
-                */
-               *barrier = current_seqid + atomic_read(&lo->plh_outstanding);
-       }
+       /* Since close does not return a layout stateid for use as
+        * a barrier, we choose the worst-case barrier.
+        */
+       *barrier = current_seqid + atomic_read(&lo->plh_outstanding);
+out:
        spin_unlock(&ino->i_lock);
        return found;
 }

diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 9735031..aa9fa1b 100644 (file)
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -210,7 +210,7 @@ int pnfs_mark_matching_lsegs_invalid(struct pnfs_layout_hdr *lo,
 bool pnfs_roc(struct inode *ino);
 void pnfs_roc_release(struct inode *ino);
 void pnfs_roc_set_barrier(struct inode *ino, u32 barrier);
-bool pnfs_roc_drain(struct inode *ino, u32 *barrier);
+bool pnfs_roc_drain(struct inode *ino, u32 *barrier, struct rpc_task *task);
 void pnfs_set_layoutcommit(struct nfs_write_data *wdata);
 void pnfs_cleanup_layoutcommit(struct nfs4_layoutcommit_data *data);
 int pnfs_layoutcommit_inode(struct inode *inode, bool sync);
@@ -442,7 +442,7 @@ pnfs_roc_set_barrier(struct inode *ino, u32 barrier)
 }
 
 static inline bool
-pnfs_roc_drain(struct inode *ino, u32 *barrier)
+pnfs_roc_drain(struct inode *ino, u32 *barrier, struct rpc_task *task)
 {
        return false;
 }