block/drbd/drbd_protocol.h

1 /* SPDX-License-Identifier: GPL-2.0-only */
33 	P_SUPERSEDED	      = 0x18, /* Used in proto C, two-primaries conflict detection */
64 	/* Only use these two if both support FF_THIN_RESYNC */
74 	P_ZEROES              = 0x36, /* data sock: zero-out, WRITE_ZEROES */
93 /* This is the layout for a packet on the wire.
154 	u32	    size;	/* == bio->bi_size */
159 	u32           size;     /* == bio->bi_size */
166  *   P_SUPERSEDED (proto C, two-primaries conflict detection)
193 /* supports TRIM/DISCARD on the "wire" protocol */
196 /* Detect all-zeros during resync, and rather TRIM/UNMAP/DISCARD those blocks
200 /* supports REQ_WRITE_SAME on the "wire" protocol.
203  *   - indicates support for 128 MiB "batch bios",
206  *   - indicates that we exchange additional settings in p_sizes
211 /* supports REQ_OP_WRITE_ZEROES on the "wire" protocol.
215  * back to zero-out.
220  * UNMAP if possible, zero-out the rest.
224  * While an un-allocated block on dm-thin reads as zeroes, on a dm-thin
229  * If we cannot distinguish between zero-out and discard on the receiving
231  * on supposedly zero-initialized blocks, we'd need to map all discards to
232  * zero-out on the receiving side.  But that would potentially do a full
234  * unmap/trim/discard/de-allocate.
237  * zeroes (and thus use zero-out, potentially doing the mentioned full-alloc),
239  * zeroing" (by "discarding" blocks aligned to discard-granularity, and zeroing
241  * avoid "false positives" in an online-verify later, hoping that someone
418 	u32     seq_num; /* sequence number to match the two probe packets */