rbd: notrim map option

Add an option to turn off discard and write zeroes offload support to
avoid deprovisioning a fully provisioned image.  When enabled, discard
requests will fail with -EOPNOTSUPP, write zeroes requests will fall
back to manually zeroing.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Tested-by: Hitoshi Kamei <hitoshi.kamei.xm@hitachi.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 6a1805858b79b69e8e20292a913281065cc282a7..8e8b04cc569a44222c1e3f4ee4a3a188455ddf04 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -741,6 +741,7 @@ enum {
        Opt_read_write,
        Opt_lock_on_read,
        Opt_exclusive,
+       Opt_notrim,
        Opt_err
 };
 
@@ -755,6 +756,7 @@ static match_table_t rbd_opts_tokens = {
        {Opt_read_write, "rw"},         /* Alternate spelling */
        {Opt_lock_on_read, "lock_on_read"},
        {Opt_exclusive, "exclusive"},
+       {Opt_notrim, "notrim"},
        {Opt_err, NULL}
 };
 
@@ -764,6 +766,7 @@ struct rbd_options {
        bool    read_only;
        bool    lock_on_read;
        bool    exclusive;
+       bool    trim;
 };
 
 #define RBD_QUEUE_DEPTH_DEFAULT        BLKDEV_MAX_RQ
@@ -771,6 +774,7 @@ struct rbd_options {
 #define RBD_READ_ONLY_DEFAULT  false
 #define RBD_LOCK_ON_READ_DEFAULT false
 #define RBD_EXCLUSIVE_DEFAULT  false
+#define RBD_TRIM_DEFAULT       true
 
 static int parse_rbd_opts_token(char *c, void *private)
 {
@@ -820,6 +824,9 @@ static int parse_rbd_opts_token(char *c, void *private)
        case Opt_exclusive:
                rbd_opts->exclusive = true;
                break;
+       case Opt_notrim:
+               rbd_opts->trim = false;
+               break;
        default:
                /* libceph prints "bad option" msg */
                return -EINVAL;
@@ -3976,11 +3983,12 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
        blk_queue_io_min(q, objset_bytes);
        blk_queue_io_opt(q, objset_bytes);
 
-       /* enable the discard support */
-       blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
-       q->limits.discard_granularity = objset_bytes;
-       blk_queue_max_discard_sectors(q, objset_bytes >> SECTOR_SHIFT);
-       blk_queue_max_write_zeroes_sectors(q, objset_bytes >> SECTOR_SHIFT);
+       if (rbd_dev->opts->trim) {
+               blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
+               q->limits.discard_granularity = objset_bytes;
+               blk_queue_max_discard_sectors(q, objset_bytes >> SECTOR_SHIFT);
+               blk_queue_max_write_zeroes_sectors(q, objset_bytes >> SECTOR_SHIFT);
+       }
 
        if (!ceph_test_opt(rbd_dev->rbd_client->client, NOCRC))
                q->backing_dev_info->capabilities |= BDI_CAP_STABLE_WRITES;
@@ -5207,6 +5215,7 @@ static int rbd_add_parse_args(const char *buf,
        rbd_opts->lock_timeout = RBD_LOCK_TIMEOUT_DEFAULT;
        rbd_opts->lock_on_read = RBD_LOCK_ON_READ_DEFAULT;
        rbd_opts->exclusive = RBD_EXCLUSIVE_DEFAULT;
+       rbd_opts->trim = RBD_TRIM_DEFAULT;
 
        copts = ceph_parse_options(options, mon_addrs,
                                        mon_addrs + mon_addrs_size - 1,