Further refine r352393, only call vnode_pager_setsize() outside the

node lock when shrinking.

This is similar to r252528, applied to the above commit.

Apparently there is a race which makes necessary at least to keep the
n_size and pager size consistent when extending.  Current suspect is
that iod threads perform vnode_pager_setsize() without taking the
vnode lock, which corrupts the file content.

Reported and tested by:	Masachika ISHIZUKA <ish@amail.plala.or.jp>
Discussed with:	rmacklem (related issues)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week

diff --git a/sys/fs/nfsclient/nfs_clport.c b/sys/fs/nfsclient/nfs_clport.c
index 63ea47367075241f930032ebc8e5d40bedd41ec4..a23b4ba4efaeef764feaa0da1303c46070552c50 100644 (file)
--- a/sys/fs/nfsclient/nfs_clport.c
+++ b/sys/fs/nfsclient/nfs_clport.c
@@ -414,12 +414,12 @@ nfscl_loadattrcache(struct vnode **vpp, struct nfsvattr *nap, void *nvaper,
        struct nfsnode *np;
        struct nfsmount *nmp;
        struct timespec mtime_save;
+       vm_object_t object;
        u_quad_t nsize;
-       int setnsize, error, force_fid_err;
+       int error, force_fid_err;
+       bool setnsize;
 
        error = 0;
-       setnsize = 0;
-       nsize = 0;
 
        /*
         * If v_type == VNON it is a new node, so fill in the v_type,
@@ -511,8 +511,7 @@ nfscl_loadattrcache(struct vnode **vpp, struct nfsvattr *nap, void *nvaper,
                                 * zero np->n_attrstamp to indicate that
                                 * the attributes are stale.
                                 */
-                               nsize = vap->va_size = np->n_size;
-                               setnsize = 1;
+                               vap->va_size = np->n_size;
                                np->n_attrstamp = 0;
                                KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
                        } else if (np->n_flag & NMODIFIED) {
@@ -526,22 +525,9 @@ nfscl_loadattrcache(struct vnode **vpp, struct nfsvattr *nap, void *nvaper,
                                        np->n_size = vap->va_size;
                                        np->n_flag |= NSIZECHANGED;
                                }
-                               nsize = np->n_size;
-                               setnsize = 1;
-                       } else if (vap->va_size < np->n_size) {
-                               /*
-                                * When shrinking the size, the call to
-                                * vnode_pager_setsize() cannot be done
-                                * with the mutex held, so delay it until
-                                * after the mtx_unlock call.
-                                */
-                               nsize = np->n_size = vap->va_size;
-                               np->n_flag |= NSIZECHANGED;
-                               setnsize = 1;
                        } else {
-                               nsize = np->n_size = vap->va_size;
+                               np->n_size = vap->va_size;
                                np->n_flag |= NSIZECHANGED;
-                               setnsize = 1;
                        }
                } else {
                        np->n_size = vap->va_size;
@@ -579,6 +565,23 @@ out:
        if (np->n_attrstamp != 0)
                KDTRACE_NFS_ATTRCACHE_LOAD_DONE(vp, vap, error);
 #endif
+       nsize = vap->va_size;
+       object = vp->v_object;
+       setnsize = false;
+       if (object != NULL) {
+               if (OFF_TO_IDX(nsize + PAGE_MASK) < object->size) {
+                       /*
+                        * When shrinking the size, the call to
+                        * vnode_pager_setsize() cannot be done with
+                        * the mutex held, because we might need to
+                        * wait for a busy page.  Delay it until after
+                        * the node is unlocked.
+                        */
+                       setnsize = true;
+               } else {
+                       vnode_pager_setsize(vp, nsize);
+               }
+       }
        NFSUNLOCKNODE(np);
        if (setnsize)
                vnode_pager_setsize(vp, nsize);