• NeilBrown's avatar
    NFSv4: don't set SETATTR for O_RDONLY|O_EXCL · efcbc04e
    NeilBrown authored
    It is unusual to combine the open flags O_RDONLY and O_EXCL, but
    it appears that libre-office does just that.
    
    [pid  3250] stat("/home/USER/.config", {st_mode=S_IFDIR|0700, st_size=8192, ...}) = 0
    [pid  3250] open("/home/USER/.config/libreoffice/4-suse/user/extensions/buildid", O_RDONLY|O_EXCL <unfinished ...>
    
    NFSv4 takes O_EXCL as a sign that a setattr command should be sent,
    probably to reset the timestamps.
    
    When it was an O_RDONLY open, the SETATTR command does not
    identify any actual attributes to change.
    If no delegation was provided to the open, the SETATTR uses the
    all-zeros stateid and the request is accepted (at least by the
    Linux NFS server - no harm, no foul).
    
    If a read-delegation was provided, this is used in the SETATTR
    request, and a Netapp filer will justifiably claim
    NFS4ERR_BAD_STATEID, which the Linux client takes as a sign
    to retry - indefinitely.
    
    So only treat O_EXCL specially if O_CREAT was also given.
    Signed-off-by: default avatarNeilBrown <neilb@suse.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
    efcbc04e
nfs4proc.c 236 KB