From 01573e231f18eb2d99162747186f59511f56b64d Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Fri, 08 Dec 2023 10:40:48 +0000
Subject: [PATCH] 移去rt
---
kernel/drivers/block/drbd/drbd_protocol.h | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++------
1 files changed, 53 insertions(+), 6 deletions(-)
diff --git a/kernel/drivers/block/drbd/drbd_protocol.h b/kernel/drivers/block/drbd/drbd_protocol.h
index c3081f9..dea59c9 100644
--- a/kernel/drivers/block/drbd/drbd_protocol.h
+++ b/kernel/drivers/block/drbd/drbd_protocol.h
@@ -57,7 +57,7 @@
P_PROTOCOL_UPDATE = 0x2d, /* data sock: is used in established connections */
/* 0x2e to 0x30 reserved, used in drbd 9 */
- /* REQ_DISCARD. We used "discard" in different contexts before,
+ /* REQ_OP_DISCARD. We used "discard" in different contexts before,
* which is why I chose TRIM here, to disambiguate. */
P_TRIM = 0x31,
@@ -69,6 +69,11 @@
* On a receiving side without REQ_WRITE_SAME,
* we may fall back to an opencoded loop instead. */
P_WSAME = 0x34,
+
+ /* 0x35 already claimed in DRBD 9 */
+ P_ZEROES = 0x36, /* data sock: zero-out, WRITE_ZEROES */
+
+ /* 0x40 .. 0x48 already claimed in DRBD 9 */
P_MAY_IGNORE = 0x100, /* Flag to test if (cmd > P_MAY_IGNORE) ... */
P_MAX_OPT_CMD = 0x101,
@@ -126,10 +131,16 @@
#define DP_UNPLUG 8 /* not used anymore */
#define DP_FUA 16 /* equals REQ_FUA */
#define DP_FLUSH 32 /* equals REQ_PREFLUSH */
-#define DP_DISCARD 64 /* equals REQ_DISCARD */
+#define DP_DISCARD 64 /* equals REQ_OP_DISCARD */
#define DP_SEND_RECEIVE_ACK 128 /* This is a proto B write request */
#define DP_SEND_WRITE_ACK 256 /* This is a proto C write request */
#define DP_WSAME 512 /* equiv. REQ_WRITE_SAME */
+#define DP_ZEROES 1024 /* equiv. REQ_OP_WRITE_ZEROES */
+
+/* possible combinations:
+ * REQ_OP_WRITE_ZEROES: DP_DISCARD | DP_ZEROES
+ * REQ_OP_WRITE_ZEROES + REQ_NOUNMAP: DP_ZEROES
+ */
struct p_data {
u64 sector; /* 64 bits sector number */
@@ -197,6 +208,42 @@
*/
#define DRBD_FF_WSAME 4
+/* supports REQ_OP_WRITE_ZEROES on the "wire" protocol.
+ *
+ * We used to map that to "discard" on the sending side, and if we cannot
+ * guarantee that discard zeroes data, the receiving side would map discard
+ * back to zero-out.
+ *
+ * With the introduction of REQ_OP_WRITE_ZEROES,
+ * we started to use that for both WRITE_ZEROES and DISCARDS,
+ * hoping that WRITE_ZEROES would "do what we want",
+ * UNMAP if possible, zero-out the rest.
+ *
+ * The example scenario is some LVM "thin" backend.
+ *
+ * While an un-allocated block on dm-thin reads as zeroes, on a dm-thin
+ * with "skip_block_zeroing=true", after a partial block write allocated
+ * that block, that same block may well map "undefined old garbage" from
+ * the backends on LBAs that have not yet been written to.
+ *
+ * If we cannot distinguish between zero-out and discard on the receiving
+ * side, to avoid "undefined old garbage" to pop up randomly at later times
+ * on supposedly zero-initialized blocks, we'd need to map all discards to
+ * zero-out on the receiving side. But that would potentially do a full
+ * alloc on thinly provisioned backends, even when the expectation was to
+ * unmap/trim/discard/de-allocate.
+ *
+ * We need to distinguish on the protocol level, whether we need to guarantee
+ * zeroes (and thus use zero-out, potentially doing the mentioned full-alloc),
+ * or if we want to put the emphasis on discard, and only do a "best effort
+ * zeroing" (by "discarding" blocks aligned to discard-granularity, and zeroing
+ * only potential unaligned head and tail clippings), to at least *try* to
+ * avoid "false positives" in an online-verify later, hoping that someone
+ * set skip_block_zeroing=false.
+ */
+#define DRBD_FF_WZEROES 8
+
+
struct p_connection_features {
u32 protocol_min;
u32 feature_flags;
@@ -224,7 +271,7 @@
u32 resync_rate;
/* Since protocol version 88 and higher. */
- char verify_alg[0];
+ char verify_alg[];
} __packed;
struct p_rs_param_89 {
@@ -258,7 +305,7 @@
u32 two_primaries;
/* Since protocol version 87 and higher. */
- char integrity_alg[0];
+ char integrity_alg[];
} __packed;
@@ -313,7 +360,7 @@
u16 dds_flags; /* use enum dds_flags here. */
/* optional queue_limits if (agreed_features & DRBD_FF_WSAME) */
- struct o_qlim qlim[0];
+ struct o_qlim qlim[];
} __packed;
struct p_state {
@@ -362,7 +409,7 @@
*/
u8 encoding;
- u8 code[0];
+ u8 code[];
} __packed;
struct p_delay_probe93 {
--
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