This patch adds a user interface to prevent from issuing discard requests onto the specified rbd device. This is needed for thick-provisioned images. To avoid discarding allocated blocks on thick-provision image, users can specify this flag bit via sysfs (/sys/bus/rbd/devices/<dev-id>/thick).
When users write "1" to the file, rbd doesn't issue discard operation; meanwhile, if users write "0" to the file then rbd issues discard operation. Signed-off-by: Hitoshi Kamei <[email protected]> Cc: Mitsuo Hayasaka <[email protected]> --- drivers/block/rbd.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 8e40da093766..dba60ef43a47 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -427,6 +427,7 @@ enum rbd_dev_flags { RBD_DEV_FLAG_EXISTS, /* mapped snapshot has not been deleted */ RBD_DEV_FLAG_REMOVING, /* this mapping is being removed */ RBD_DEV_FLAG_BLACKLISTED, /* our ceph_client is blacklisted */ + RBD_DEV_FLAG_THICK, /* image is thick-provisioned */ }; static DEFINE_MUTEX(client_mutex); /* Serialize client creation */ @@ -4011,6 +4012,15 @@ static void rbd_queue_workfn(struct work_struct *work) goto err; } + /* Ignore/skip discard requests for thick-provision image */ + + if (op_type == OBJ_OP_DISCARD && + test_bit(RBD_DEV_FLAG_THICK, &rbd_dev->flags)) { + dout("%s: Ignored a discard request\n", __func__); + result = 0; + goto err_rq; + } + /* Ignore/skip any zero-length requests */ if (!length) { @@ -4600,6 +4610,32 @@ static ssize_t rbd_image_refresh(struct device *dev, return size; } +static ssize_t rbd_thick_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t size) +{ + struct rbd_device *rbd_dev = dev_to_rbd_dev(dev); + + spin_lock_irq(&rbd_dev->lock); + if (!strncmp(buf, "1", size)) + set_bit(RBD_DEV_FLAG_THICK, &rbd_dev->flags); + else if (!strncmp(buf, "0", size)) + clear_bit(RBD_DEV_FLAG_THICK, &rbd_dev->flags); + spin_unlock_irq(&rbd_dev->lock); + + return size; +} + +static ssize_t rbd_thick_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct rbd_device *rbd_dev = dev_to_rbd_dev(dev); + int is_thick = test_bit(RBD_DEV_FLAG_THICK, &rbd_dev->flags) ? 1 : 0; + + return sprintf(buf, "%d\n", is_thick); +} + static DEVICE_ATTR(size, S_IRUGO, rbd_size_show, NULL); static DEVICE_ATTR(features, S_IRUGO, rbd_features_show, NULL); static DEVICE_ATTR(major, S_IRUGO, rbd_major_show, NULL); @@ -4616,6 +4652,7 @@ static DEVICE_ATTR(refresh, S_IWUSR, NULL, rbd_image_refresh); static DEVICE_ATTR(current_snap, S_IRUGO, rbd_snap_show, NULL); static DEVICE_ATTR(snap_id, S_IRUGO, rbd_snap_id_show, NULL); static DEVICE_ATTR(parent, S_IRUGO, rbd_parent_show, NULL); +static DEVICE_ATTR(thick, 0644, rbd_thick_show, rbd_thick_store); static struct attribute *rbd_attrs[] = { &dev_attr_size.attr, @@ -4634,6 +4671,7 @@ static struct attribute *rbd_attrs[] = { &dev_attr_snap_id.attr, &dev_attr_parent.attr, &dev_attr_refresh.attr, + &dev_attr_thick.attr, NULL }; -- 2.15.1
