lkml.org 
[lkml]   [2019]   [Jan]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.20 46/57] rbd: dont return 0 on unmap if RBD_DEV_FLAG_REMOVING is set
    Date
    4.20-stable review patch.  If anyone has any objections, please let me know.

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

    From: Ilya Dryomov <idryomov@gmail.com>

    commit 85f5a4d666fd9be73856ed16bb36c5af5b406b29 upstream.

    There is a window between when RBD_DEV_FLAG_REMOVING is set and when
    the device is removed from rbd_dev_list. During this window, we set
    "already" and return 0.

    Returning 0 from write(2) can confuse userspace tools because
    0 indicates that nothing was written. In particular, "rbd unmap"
    will retry the write multiple times a second:

    10:28:05.463299 write(4, "0", 1) = 0
    10:28:05.463509 write(4, "0", 1) = 0
    10:28:05.463720 write(4, "0", 1) = 0
    10:28:05.463942 write(4, "0", 1) = 0
    10:28:05.464155 write(4, "0", 1) = 0

    Cc: stable@vger.kernel.org
    Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
    Tested-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/block/rbd.c | 9 ++++-----
    1 file changed, 4 insertions(+), 5 deletions(-)

    --- a/drivers/block/rbd.c
    +++ b/drivers/block/rbd.c
    @@ -5986,7 +5986,6 @@ static ssize_t do_rbd_remove(struct bus_
    struct list_head *tmp;
    int dev_id;
    char opt_buf[6];
    - bool already = false;
    bool force = false;
    int ret;

    @@ -6019,13 +6018,13 @@ static ssize_t do_rbd_remove(struct bus_
    spin_lock_irq(&rbd_dev->lock);
    if (rbd_dev->open_count && !force)
    ret = -EBUSY;
    - else
    - already = test_and_set_bit(RBD_DEV_FLAG_REMOVING,
    - &rbd_dev->flags);
    + else if (test_and_set_bit(RBD_DEV_FLAG_REMOVING,
    + &rbd_dev->flags))
    + ret = -EINPROGRESS;
    spin_unlock_irq(&rbd_dev->lock);
    }
    spin_unlock(&rbd_dev_list_lock);
    - if (ret < 0 || already)
    + if (ret)
    return ret;

    if (force) {

    \
     
     \ /
      Last update: 2019-01-15 17:48    [W:3.745 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site