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    Subject[PATCH 4.9 35/91] nfsd4: fix up replay_matches_cache()
    Date
    From: Scott Mayhew <smayhew@redhat.com>

    commit 6e73e92b155c868ff7fce9d108839668caf1d9be upstream.

    When running an nfs stress test, I see quite a few cached replies that
    don't match up with the actual request. The first comment in
    replay_matches_cache() makes sense, but the code doesn't seem to
    match... fix it.

    This isn't exactly a bugfix, as the server isn't required to catch every
    case of a false retry. So, we may as well do this, but if this is
    fixing a problem then that suggests there's a client bug.

    Fixes: 53da6a53e1d4 ("nfsd4: catch some false session retries")
    Signed-off-by: Scott Mayhew <smayhew@redhat.com>
    Signed-off-by: J. Bruce Fields <bfields@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/nfsd/nfs4state.c | 15 ++++++++++-----
    1 file changed, 10 insertions(+), 5 deletions(-)

    --- a/fs/nfsd/nfs4state.c
    +++ b/fs/nfsd/nfs4state.c
    @@ -3067,12 +3067,17 @@ static bool replay_matches_cache(struct
    (bool)seq->cachethis)
    return false;
    /*
    - * If there's an error than the reply can have fewer ops than
    - * the call. But if we cached a reply with *more* ops than the
    - * call you're sending us now, then this new call is clearly not
    - * really a replay of the old one:
    + * If there's an error then the reply can have fewer ops than
    + * the call.
    */
    - if (slot->sl_opcnt < argp->opcnt)
    + if (slot->sl_opcnt < argp->opcnt && !slot->sl_status)
    + return false;
    + /*
    + * But if we cached a reply with *more* ops than the call you're
    + * sending us now, then this new call is clearly not really a
    + * replay of the old one:
    + */
    + if (slot->sl_opcnt > argp->opcnt)
    return false;
    /* This is the only check explicitly called by spec: */
    if (!same_creds(&rqstp->rq_cred, &slot->sl_cred))

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