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 */
53 	P_RS_CANCEL           = 0x29, /* meta: Used to cancel RS_DATA_REQUEST packet by SyncSource */
74 	P_ZEROES              = 0x36, /* data sock: zero-out, WRITE_ZEROES */
83 	P_INITIAL_META	      = 0xfff1, /* First Packet on the MetaSock */
84 	P_INITIAL_DATA	      = 0xfff2, /* First Packet on the Socket */
93 /* This is the layout for a packet on the wire.
104 	u32	  magic;  member
111 	u16	  magic;	/* use DRBD_MAGIC_BIG here */  member
117 	u32	  magic;  member
154 	u32	    size;	/* == bio->bi_size */
159 	u32           size;     /* == bio->bi_size */
166  *   P_SUPERSEDED (proto C, two-primaries conflict detection)
196 /* Detect all-zeros during resync, and rather TRIM/UNMAP/DISCARD those blocks
203  *   - indicates support for 128 MiB "batch bios",
206  *   - indicates that we exchange additional settings in p_sizes
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