nfsd: Fix possible BUG_ON firing in set_change_info
Neil Brown [Thu, 2 Dec 2010 00:14:30 +0000 (11:14 +1100)]
If vfs_getattr in fill_post_wcc returns an error, we don't
set fh_post_change.
For NFSv4, this can result in set_change_info triggering a BUG_ON.
i.e. fh_post_saved being zero isn't really a bug.

So:
 - instead of BUGging when fh_post_saved is zero, just clear ->atomic.
 - if vfs_getattr fails in fill_post_wcc, take a copy of i_ctime anyway.
   This will be used i seg_change_info, but not overly trusted.
 - While we are there, remove the pointless 'if' statements in set_change_info.
   There is no harm setting all the values.

Signed-off-by: NeilBrown <neilb@suse.de>
Cc: stable@kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs3xdr.c
fs/nfsd/xdr4.h

index 2a533a0..7e84a85 100644 (file)
@@ -260,9 +260,11 @@ void fill_post_wcc(struct svc_fh *fhp)
        err = vfs_getattr(fhp->fh_export->ex_path.mnt, fhp->fh_dentry,
                        &fhp->fh_post_attr);
        fhp->fh_post_change = fhp->fh_dentry->d_inode->i_version;
-       if (err)
+       if (err) {
                fhp->fh_post_saved = 0;
-       else
+               /* Grab the ctime anyway - set_change_info might use it */
+               fhp->fh_post_attr.ctime = fhp->fh_dentry->d_inode->i_ctime;
+       } else
                fhp->fh_post_saved = 1;
 }
 
index 4d476ff..60fce3d 100644 (file)
@@ -484,18 +484,17 @@ static inline bool nfsd4_not_cached(struct nfsd4_compoundres *resp)
 static inline void
 set_change_info(struct nfsd4_change_info *cinfo, struct svc_fh *fhp)
 {
-       BUG_ON(!fhp->fh_pre_saved || !fhp->fh_post_saved);
-       cinfo->atomic = 1;
+       BUG_ON(!fhp->fh_pre_saved);
+       cinfo->atomic = fhp->fh_post_saved;
        cinfo->change_supported = IS_I_VERSION(fhp->fh_dentry->d_inode);
-       if (cinfo->change_supported) {
-               cinfo->before_change = fhp->fh_pre_change;
-               cinfo->after_change = fhp->fh_post_change;
-       } else {
-               cinfo->before_ctime_sec = fhp->fh_pre_ctime.tv_sec;
-               cinfo->before_ctime_nsec = fhp->fh_pre_ctime.tv_nsec;
-               cinfo->after_ctime_sec = fhp->fh_post_attr.ctime.tv_sec;
-               cinfo->after_ctime_nsec = fhp->fh_post_attr.ctime.tv_nsec;
-       }
+
+       cinfo->before_change = fhp->fh_pre_change;
+       cinfo->after_change = fhp->fh_post_change;
+       cinfo->before_ctime_sec = fhp->fh_pre_ctime.tv_sec;
+       cinfo->before_ctime_nsec = fhp->fh_pre_ctime.tv_nsec;
+       cinfo->after_ctime_sec = fhp->fh_post_attr.ctime.tv_sec;
+       cinfo->after_ctime_nsec = fhp->fh_post_attr.ctime.tv_nsec;
+
 }
 
 int nfs4svc_encode_voidres(struct svc_rqst *, __be32 *, void *);