From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([65.50.211.133]:56566 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750871AbdBTGVp (ORCPT ); Mon, 20 Feb 2017 01:21:45 -0500 From: Christoph Hellwig To: bfields@redhat.com, jlayton@poochiereds.net Cc: linux-nfs@vger.kernel.org, stable@kernel.org Subject: [PATCH] nfsd: special case truncates some more Date: Mon, 20 Feb 2017 07:21:33 +0100 Message-Id: <20170220062133.26607-2-hch@lst.de> In-Reply-To: <20170220062133.26607-1-hch@lst.de> References: <20170220062133.26607-1-hch@lst.de> Sender: linux-nfs-owner@vger.kernel.org List-ID: Both the NFS protocols and the Linux VFS use a setattr operation with a bitmap of attributs to set to set various file attributes including the file size and the uid/gid. The Linux syscalls never mixes size updates with unrelated updates like the uid/gid, and some file systems like XFS and GFS2 rely on the fact that truncates might not update random other attributes, and many other file systems handle the case but do not update the different attributes in the same transaction. NFSD on the other hand passes the attributes it gets on the wire more or less directly through to the VFS, leading to updates the file systems don't expect. XFS at least has an assert on the allowed attributes, which caught an unusual NFS client setting the size and group at the same time. To handle this issue properly this splits the notify_change call in nfsd_setattr into two separate ones. Signed-off-by: Christoph Hellwig Cc: stable@kernel.org --- fs/nfsd/vfs.c | 59 +++++++++++++++++++++++++++++++++++++---------------------- 1 file changed, 37 insertions(+), 22 deletions(-) diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 26c6fdb4bf67..3c36ed5a1f07 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -377,7 +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; + bool size_change = (iap->ia_valid & ATTR_SIZE); if (iap->ia_valid & (ATTR_ATIME | ATTR_MTIME | ATTR_SIZE)) accmode |= NFSD_MAY_WRITE|NFSD_MAY_OWNER_OVERRIDE; @@ -390,11 +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) - goto out; + return err; if (get_write_count) { host_err = fh_want_write(fhp); if (host_err) - return nfserrno(host_err); + goto out; } dentry = fhp->fh_dentry; @@ -405,20 +405,28 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap, iap->ia_valid &= ~ATTR_MODE; if (!iap->ia_valid) - goto out; + return 0; 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. + * 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 to ->setattr, and do the rest as a separate + * setattr call. */ - if (iap->ia_valid & ATTR_SIZE) { + if (size_change) { err = nfsd_get_write_access(rqstp, fhp, iap); if (err) - goto out; - size_change = 1; + return err; + } + fh_lock(fhp); + if (size_change) { /* * RFC5661, Section 18.30.4: * Changing the size of a file with SETATTR indirectly @@ -426,29 +434,36 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap, * * (and similar for the older RFCs) */ - if (iap->ia_size != i_size_read(inode)) - iap->ia_valid |= ATTR_MTIME; - } + struct iattr size_attr = { + .ia_valid = ATTR_SIZE | ATTR_CTIME | ATTR_MTIME, + .ia_size = iap->ia_size, + }; - iap->ia_valid |= ATTR_CTIME; + host_err = notify_change(dentry, &size_attr, NULL); + if (host_err) + goto out_unlock; + iap->ia_valid &= ~ATTR_SIZE; - if (check_guard && guardtime != inode->i_ctime.tv_sec) { - err = nfserr_notsync; - goto out_put_write_access; + /* + * Avoid the additional setattr call below if the only other + * attribute that the client sends is the mtime, as we update + * it as part of the size change above. + */ + if ((iap->ia_valid & ~ATTR_MTIME) == 0) + goto out_unlock; } - fh_lock(fhp); + iap->ia_valid |= ATTR_CTIME; host_err = notify_change(dentry, iap, NULL); - fh_unlock(fhp); - err = nfserrno(host_err); -out_put_write_access: +out_unlock: + fh_unlock(fhp); if (size_change) put_write_access(inode); - if (!err) - err = nfserrno(commit_metadata(fhp)); out: - return err; + if (!host_err) + host_err = commit_metadata(fhp); + return nfserrno(host_err); } #if defined(CONFIG_NFSD_V4) -- 2.11.0