lkml.org 
[lkml]   [2011]   [Sep]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v2 2/2] nbd: map DISCARD requests to a new nbd request type
    Date
    When the feature is enabled, set QUEUE_FLAG_DISCARD and transmit those as
    NBD_CMD_TRIM requests.

    I used "trim" instead of "discard" to avoid confusion with the existing
    NBD_CMD_DISC that is used for disconnect.

    Cc: Paul Clements <Paul.Clements@steeleye.com>
    Cc: <nbd-general@lists.sf.net>
    Reviewed-by: Paul Clements <Paul.Clements@steeleye.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
    ---
    This patch is the same as in v1.

    drivers/block/nbd.c | 14 +++++++++++++-
    include/linux/nbd.h | 4 +++-
    2 files changed, 16 insertions(+), 2 deletions(-)

    diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
    index c4fe9c8..71ebaab 100644
    --- a/drivers/block/nbd.c
    +++ b/drivers/block/nbd.c
    @@ -98,6 +98,7 @@ static const char *nbdcmd_to_ascii(int cmd)
    case NBD_CMD_READ: return "read";
    case NBD_CMD_WRITE: return "write";
    case NBD_CMD_DISC: return "disconnect";
    + case NBD_CMD_TRIM: return "trim (discard)";
    }
    return "invalid";
    }
    @@ -453,12 +453,16 @@ static void nbd_handle_req(struct nbd_device *lo, struct request *req)

    nbd_cmd(req) = NBD_CMD_READ;
    if (rq_data_dir(req) == WRITE) {
    - nbd_cmd(req) = NBD_CMD_WRITE;
    if (lo->flags & NBD_FLAG_READ_ONLY) {
    printk(KERN_ERR "%s: Write on read-only\n",
    lo->disk->disk_name);
    goto error_out;
    }
    + if ((req->cmd_flags & REQ_DISCARD)) {
    + WARN_ON(!(lo->flags & NBD_FLAG_HAS_TRIM));
    + nbd_cmd(req) = NBD_CMD_TRIM;
    + } else
    + nbd_cmd(req) = NBD_CMD_WRITE;
    }

    req->errors = 0;
    @@ -659,6 +664,9 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *lo,
    return -EINVAL;

    mutex_unlock(&lo->tx_lock);
    + if (lo->flags & NBD_FLAG_HAS_TRIM)
    + queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
    + lo->disk->queue);

    thread = kthread_create(nbd_thread, lo, lo->disk->disk_name);
    if (IS_ERR(thread)) {
    @@ -677,6 +685,7 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *lo,
    lo->file = NULL;
    nbd_clear_que(lo);
    printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
    + queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, lo->disk->queue);
    if (file)
    fput(file);
    lo->flags = 0;
    @@ -796,6 +805,9 @@ static int __init nbd_init(void)
    * Tell the block layer that we are not a rotational device
    */
    queue_flag_set_unlocked(QUEUE_FLAG_NONROT, disk->queue);
    + disk->queue->limits.discard_granularity = 512;
    + disk->queue->limits.max_discard_sectors = UINT_MAX;
    + disk->queue->limits.discard_zeroes_data = 0;
    }

    if (register_blkdev(NBD_MAJOR, "nbd")) {
    diff --git a/include/linux/nbd.h b/include/linux/nbd.h
    index 926f19d..7048463 100644
    --- a/include/linux/nbd.h
    +++ b/include/linux/nbd.h
    @@ -33,11 +33,13 @@

    /* values for flags field */
    #define NBD_FLAG_READ_ONLY (1 << 1)
    +#define NBD_FLAG_HAS_TRIM (1 << 2)

    enum {
    NBD_CMD_READ = 0,
    NBD_CMD_WRITE = 1,
    - NBD_CMD_DISC = 2
    + NBD_CMD_DISC = 2,
    + NBD_CMD_TRIM = 3
    };

    #define nbd_cmd(req) ((req)->cmd[0])
    --
    1.7.6


    \
     
     \ /
      Last update: 2011-09-08 09:47    [W:0.024 / U:61.360 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site