nfsd: Revert "nfsd: special case truncates some more"

This patch incorrectly attempted nested mnt_want_write, and incorrectly
disabled nfsd's owner override for truncate.  We'll fix those problems
and make another attempt soon, for the moment I think the safest is to
revert.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 60 insertions, 37 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index ca13236dbb1f..26c6fdb4bf67 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -332,6 +332,37 @@ nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
         }
 }
 
+static __be32
+nfsd_get_write_access(struct svc_rqst *rqstp, struct svc_fh *fhp,
+                struct iattr *iap)
+{
+        struct inode *inode = d_inode(fhp->fh_dentry);
+        int host_err;
+
+        if (iap->ia_size < inode->i_size) {
+                __be32 err;
+
+                err = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
+                                NFSD_MAY_TRUNC | NFSD_MAY_OWNER_OVERRIDE);
+                if (err)
+                        return err;
+        }
+
+        host_err = get_write_access(inode);
+        if (host_err)
+                goto out_nfserrno;
+
+        host_err = locks_verify_truncate(inode, NULL, iap->ia_size);
+        if (host_err)
+                goto out_put_write_access;
+        return 0;
+
+out_put_write_access:
+        put_write_access(inode);
+out_nfserrno:
+        return nfserrno(host_err);
+}
+
 /*
  * Set various file attributes.  After this call fhp needs an fh_put.
  */
@@ -346,6 +377,7 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
         __be32          err;
         int             host_err;
         bool            get_write_count;
+        int             size_change = 0;
 
         if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME | ATTR_SIZE))
                 accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE;
@@ -358,11 +390,11 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
         /* Get inode */
         err = fh_verify(rqstp, fhp, ftype, accmode);
         if (err)
-                return err;
+                goto out;
         if (get_write_count) {
                 host_err = fh_want_write(fhp);
                 if (host_err)
-                        goto out_host_err;
+                        return nfserrno(host_err);
         }
 
         dentry = fhp->fh_dentry;
@@ -373,59 +405,50 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
                 iap->ia_valid &= ~ATTR_MODE;
 
         if (!iap->ia_valid)
-                return 0;
+                goto out;
 
         nfsd_sanitize_attrs(inode, iap);
 
-        if (check_guard && guardtime != inode->i_ctime.tv_sec)
-                return nfserr_notsync;
-
         /*
          * The size case is special, it changes the file in addition to the
-         * attributes, and file systems don't expect it to be mixed with
-         * "random" attribute changes.  We thus split out the size change
-         * into a separate call for vfs_truncate, and do the rest as a
-         * a separate setattr call.
+         * attributes.
          */
         if (iap->ia_valid & ATTR_SIZE) {
-                struct path path = {
-                        .mnt    = fhp->fh_export->ex_path.mnt,
-                        .dentry = dentry,
-                };
-                bool implicit_mtime = false;
+                err = nfsd_get_write_access(rqstp, fhp, iap);
+                if (err)
+                        goto out;
+                size_change = 1;
 
                 /*
-                 * vfs_truncate implicity updates the mtime IFF the file size
-                 * actually changes.  Avoid the additional seattr call below if
-                 * the only other attribute that the client sends is the mtime.
+                 * RFC5661, Section 18.30.4:
+                 *   Changing the size of a file with SETATTR indirectly
+                 *   changes the time_modify and change attributes.
+                 *
+                 * (and similar for the older RFCs)
                  */
-                if (iap->ia_size != i_size_read(inode) &&
-                    ((iap->ia_valid & ~(ATTR_SIZE | ATTR_MTIME)) == 0))
-                        implicit_mtime = true;
-
-                host_err = vfs_truncate(&path, iap->ia_size);
-                if (host_err)
-                        goto out_host_err;
-
-                iap->ia_valid &= ~ATTR_SIZE;
-                if (implicit_mtime)
-                        iap->ia_valid &= ~ATTR_MTIME;
-                if (!iap->ia_valid)
-                        goto done;
+                if (iap->ia_size != i_size_read(inode))
+                        iap->ia_valid |= ATTR_MTIME;
         }
 
         iap->ia_valid |= ATTR_CTIME;
 
+        if (check_guard && guardtime != inode->i_ctime.tv_sec) {
+                err = nfserr_notsync;
+                goto out_put_write_access;
+        }
+
         fh_lock(fhp);
         host_err = notify_change(dentry, iap, NULL);
         fh_unlock(fhp);
-        if (host_err)
-                goto out_host_err;
+        err = nfserrno(host_err);
 
-done:
-        host_err = commit_metadata(fhp);
-out_host_err:
-        return nfserrno(host_err);
+out_put_write_access:
+        if (size_change)
+                put_write_access(inode);
+        if (!err)
+                err = nfserrno(commit_metadata(fhp));
+out:
+        return err;
 }
 
 #if defined(CONFIG_NFSD_V4)