The NBD protocol defines a message for zeroing out a region of an export
Add support to the kernel driver for that message.
Signed-off-by: Wouter Verhelst <w@xxxxxxx>
Cc: Eric Blake <eblake@xxxxxxxxxx>
Cc: Damien Le Moal <dlemoal@xxxxxxxxxx>
---
drivers/block/nbd.c | 8 ++++++++
include/uapi/linux/nbd.h | 5 ++++-
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 5b1811b1ba5f..b2b69cc5ca23 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -352,6 +352,8 @@ static int __nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
}
if (nbd->config->flags & NBD_FLAG_ROTATIONAL)
lim.features |= BLK_FEAT_ROTATIONAL;
+ if (nbd->config->flags & NBD_FLAG_SEND_WRITE_ZEROES)
+ lim.max_write_zeroes_sectors = UINT_MAX >> SECTOR_SHIFT;
lim.logical_block_size = blksize;
lim.physical_block_size = blksize;
@@ -421,6 +423,8 @@ static u32 req_to_nbd_cmd_type(struct request *req)
return NBD_CMD_WRITE;
case REQ_OP_READ:
return NBD_CMD_READ;
+ case REQ_OP_WRITE_ZEROES:
+ return NBD_CMD_WRITE_ZEROES;
default:
return U32_MAX;
}
@@ -637,6 +641,8 @@ static blk_status_t nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd,
if (req->cmd_flags & REQ_FUA)
nbd_cmd_flags |= NBD_CMD_FLAG_FUA;
+ if ((req->cmd_flags & REQ_NOUNMAP) && (type == NBD_CMD_WRITE_ZEROES))
+ nbd_cmd_flags |= NBD_CMD_FLAG_NO_HOLE;
/* We did a partial send previously, and we at least sent the whole
* request struct, so just go and send the rest of the pages in the
@@ -1706,6 +1712,8 @@ static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
seq_puts(s, "NBD_FLAG_SEND_FUA\n");
if (flags & NBD_FLAG_SEND_TRIM)
seq_puts(s, "NBD_FLAG_SEND_TRIM\n");
+ if (flags & NBD_FLAG_SEND_WRITE_ZEROES)
+ seq_puts(s, "NBD_FLAG_SEND_WRITE_ZEROES\n");
return 0;
}
diff --git a/include/uapi/linux/nbd.h b/include/uapi/linux/nbd.h
index d75215f2c675..f1d468acfb25 100644
--- a/include/uapi/linux/nbd.h
+++ b/include/uapi/linux/nbd.h
@@ -42,8 +42,9 @@ enum {
NBD_CMD_WRITE = 1,
NBD_CMD_DISC = 2,
NBD_CMD_FLUSH = 3,
- NBD_CMD_TRIM = 4
+ NBD_CMD_TRIM = 4,
/* userspace defines additional extension commands */
+ NBD_CMD_WRITE_ZEROES = 6,
};
/* values for flags field, these are server interaction specific. */
@@ -53,11 +54,13 @@ enum {
#define NBD_FLAG_SEND_FUA (1 << 3) /* send FUA (forced unit access) */
#define NBD_FLAG_ROTATIONAL (1 << 4) /* device is rotational */
#define NBD_FLAG_SEND_TRIM (1 << 5) /* send trim/discard */
+#define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* supports WRITE_ZEROES */
/* there is a gap here to match userspace */
#define NBD_FLAG_CAN_MULTI_CONN (1 << 8) /* Server supports multiple connections per export. */
/* values for cmd flags in the upper 16 bits of request type */
#define NBD_CMD_FLAG_FUA (1 << 16) /* FUA (forced unit access) op */
+#define NBD_CMD_FLAG_NO_HOLE (1 << 17) /* Do not punch a hole for WRITE_ZEROES */
/* These are client behavior specific flags. */
#define NBD_CFLAG_DESTROY_ON_DISCONNECT (1 << 0) /* delete the nbd device on
--
2.43.0
