NFSv4: Ensure that file unlock requests don't conflict with state recovery

The unlock path is currently failing to take the nfs_client->cl_sem read
lock, and hence the recovery path may see locks disappear from underneath
it.
Also ensure that it takes the nfs_inode->rwsem read lock so that it there
is no conflict with delegation recalls.

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

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 660c5dc..aec4e47 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3273,6 +3273,8 @@ static struct rpc_task *nfs4_do_unlck(struct file_lock *fl,
 
 static int nfs4_proc_unlck(struct nfs4_state *state, int cmd, struct file_lock *request)
 {
+       struct nfs_client *clp = state->owner->so_client;
+       struct nfs_inode *nfsi = NFS_I(state->inode);
        struct nfs_seqid *seqid;
        struct nfs4_lock_state *lsp;
        struct rpc_task *task;
@@ -3282,8 +3284,15 @@ static int nfs4_proc_unlck(struct nfs4_state *state, int cmd, struct file_lock *
        status = nfs4_set_lock_state(state, request);
        /* Unlock _before_ we do the RPC call */
        request->fl_flags |= FL_EXISTS;
-       if (do_vfs_lock(request->fl_file, request) == -ENOENT)
+       down_read(&clp->cl_sem);
+       down_read(&nfsi->rwsem);
+       if (do_vfs_lock(request->fl_file, request) == -ENOENT) {
+               up_read(&nfsi->rwsem);
+               up_read(&clp->cl_sem);
                goto out;
+       }
+       up_read(&nfsi->rwsem);
+       up_read(&clp->cl_sem);
        if (status != 0)
                goto out;
        /* Is this a delegated lock? */
@@ -3510,6 +3519,7 @@ static int nfs4_lock_expired(struct nfs4_state *state, struct file_lock *request
 static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
 {
        struct nfs_client *clp = state->owner->so_client;
+       struct nfs_inode *nfsi = NFS_I(state->inode);
        unsigned char fl_flags = request->fl_flags;
        int status;
 
@@ -3522,18 +3532,13 @@ static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock
        if (status < 0)
                goto out;
        down_read(&clp->cl_sem);
+       down_read(&nfsi->rwsem);
        if (test_bit(NFS_DELEGATED_STATE, &state->flags)) {
-               struct nfs_inode *nfsi = NFS_I(state->inode);
                /* Yes: cache locks! */
-               down_read(&nfsi->rwsem);
                /* ...but avoid races with delegation recall... */
-               if (test_bit(NFS_DELEGATED_STATE, &state->flags)) {
-                       request->fl_flags = fl_flags & ~FL_SLEEP;
-                       status = do_vfs_lock(request->fl_file, request);
-                       up_read(&nfsi->rwsem);
-                       goto out_unlock;
-               }
-               up_read(&nfsi->rwsem);
+               request->fl_flags = fl_flags & ~FL_SLEEP;
+               status = do_vfs_lock(request->fl_file, request);
+               goto out_unlock;
        }
        status = _nfs4_do_setlk(state, cmd, request, 0);
        if (status != 0)
@@ -3543,6 +3548,7 @@ static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock
        if (do_vfs_lock(request->fl_file, request) < 0)
                printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
 out_unlock:
+       up_read(&nfsi->rwsem);
        up_read(&clp->cl_sem);
 out:
        request->fl_flags = fl_flags;

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index beade55..16c9fbd 100644 (file)
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -849,9 +849,11 @@ static int nfs4_state_mark_reclaim_nograce(struct nfs_client *clp, struct nfs4_s
 static int nfs4_reclaim_locks(struct nfs4_state *state, const struct nfs4_state_recovery_ops *ops)
 {
        struct inode *inode = state->inode;
+       struct nfs_inode *nfsi = NFS_I(inode);
        struct file_lock *fl;
        int status = 0;
 
+       down_write(&nfsi->rwsem);
        for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
                if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
                        continue;
@@ -874,8 +876,10 @@ static int nfs4_reclaim_locks(struct nfs4_state *state, const struct nfs4_state_
                                goto out_err;
                }
        }
+       up_write(&nfsi->rwsem);
        return 0;
 out_err:
+       up_write(&nfsi->rwsem);
        return status;
 }