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    Subject[PATCH 5.0 054/238] CIFS: Fix read after write for files with read caching
    Date
    5.0-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Pavel Shilovsky <piastryyy@gmail.com>

    commit 6dfbd84684700cb58b34e8602c01c12f3d2595c8 upstream.

    When we have a READ lease for a file and have just issued a write
    operation to the server we need to purge the cache and set oplock/lease
    level to NONE to avoid reading stale data. Currently we do that
    only if a write operation succedeed thus not covering cases when
    a request was sent to the server but a negative error code was
    returned later for some other reasons (e.g. -EIOCBQUEUED or -EINTR).
    Fix this by turning off caching regardless of the error code being
    returned.

    The patches fixes generic tests 075 and 112 from the xfs-tests.

    Cc: <stable@vger.kernel.org>
    Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
    Signed-off-by: Steve French <stfrench@microsoft.com>
    Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/cifs/file.c | 12 +++++++-----
    1 file changed, 7 insertions(+), 5 deletions(-)

    --- a/fs/cifs/file.c
    +++ b/fs/cifs/file.c
    @@ -3028,14 +3028,16 @@ cifs_strict_writev(struct kiocb *iocb, s
    * these pages but not on the region from pos to ppos+len-1.
    */
    written = cifs_user_writev(iocb, from);
    - if (written > 0 && CIFS_CACHE_READ(cinode)) {
    + if (CIFS_CACHE_READ(cinode)) {
    /*
    - * Windows 7 server can delay breaking level2 oplock if a write
    - * request comes - break it on the client to prevent reading
    - * an old data.
    + * We have read level caching and we have just sent a write
    + * request to the server thus making data in the cache stale.
    + * Zap the cache and set oplock/lease level to NONE to avoid
    + * reading stale data from the cache. All subsequent read
    + * operations will read new data from the server.
    */
    cifs_zap_mapping(inode);
    - cifs_dbg(FYI, "Set no oplock for inode=%p after a write operation\n",
    + cifs_dbg(FYI, "Set Oplock/Lease to NONE for inode=%p after write\n",
    inode);
    cinode->oplock = 0;
    }

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