From: Christoph Hellwig hch@lst.de
This patch has been added to the stable tree. If you have any objections, please let us know.
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[ Upstream commit 41f53350a0f36a7b8e31bec0d0ca907e028ab4cd ]
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 switches nfsd to call vfs_truncate for size changes, and then handle all other attributes through notify_change. As a side effect this also means less boilerplace code around the size change as we can now reuse the VFS code.
Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: J. Bruce Fields bfields@redhat.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- fs/nfsd/vfs.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-)
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 11899f851129..5eaee287be23 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -406,13 +406,19 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
/* * 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 (size_change) { err = nfsd_get_write_access(rqstp, fhp, iap); if (err) return err; + }
+ fh_lock(fhp); + if (size_change) { /* * RFC5661, Section 18.30.4: * Changing the size of a file with SETATTR indirectly @@ -420,16 +426,30 @@ 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, + }; + + host_err = notify_change(dentry, &size_attr, NULL); + if (host_err) + goto out_unlock; + iap->ia_valid &= ~ATTR_SIZE; + + /* + * 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; }
iap->ia_valid |= ATTR_CTIME; - - fh_lock(fhp); host_err = notify_change(dentry, iap, NULL); - fh_unlock(fhp);
+out_unlock: + fh_unlock(fhp); if (size_change) put_write_access(inode); out: