From 30736bdda7b665fd89304017609678a2e35cd70c Mon Sep 17 00:00:00 2001
From: ChenXiaoSong <chenxiaosong@chenxiaosong.com>
Date: Fri, 31 May 2024 04:43:56 +0000
Subject: [PATCH] debug drop bio

Signed-off-by: ChenXiaoSong <chenxiaosong@chenxiaosong.com>
---
 block/bio.c               |  3 +-
 block/blk-core.c          | 78 +++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_aops.c         |  4 +-
 fs/xfs/xfs_buf.c          |  1 +
 fs/xfs/xfs_discard.c      |  1 +
 fs/xfs/xfs_log.c          |  5 +++
 include/linux/blk_types.h |  1 +
 7 files changed, 91 insertions(+), 2 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index e9e809a63c59..b0f535789578 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1390,7 +1390,8 @@ int submit_bio_wait(struct bio *bio)
 	bio->bi_end_io = submit_bio_wait_endio;
 	bio->bi_opf |= REQ_SYNC;
 	submit_bio(bio);
-	blk_wait_io(&done);
+	if (!bio->debug)
+		blk_wait_io(&done);
 
 	return blk_status_to_errno(bio->bi_status);
 }
diff --git a/block/blk-core.c b/block/blk-core.c
index 82c3ae22d76d..3433ce2e7846 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -51,6 +51,9 @@
 #include "blk-throttle.h"
 #include "blk-ioprio.h"
 
+int debug_drop_bio = 0;
+EXPORT_SYMBOL_GPL(debug_drop_bio);
+
 struct dentry *blk_debugfs_root;
 
 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
@@ -864,6 +867,75 @@ static void bio_set_ioprio(struct bio *bio)
 	blkcg_set_ioprio(bio);
 }
 
+/**
+ * bio_memscan - Find a character in an area of memory.
+ * @addr: The memory area
+ * @c: The byte to search for
+ * @size: The size of the area.
+ *
+ * returns the address of the first occurrence of @c,
+ * or NULL if @c is not found
+ */
+static void *bio_memscan(void *addr, int c, size_t size)
+{
+	unsigned char *p = addr;
+
+	while (size) {
+		if (*p == (unsigned char)c)
+			return (void *)p;
+		p++;
+		size--;
+	}
+	return NULL;
+}
+
+/*
+ * return 0 if bio have special data,
+ * or 1 if it is not found
+ */
+static int check_bio_data(struct bio *bio) {
+	int ret = 1;
+	struct bio_vec *bvec;
+	struct bvec_iter_all iter_all;
+	char *kaddr;
+	char *tmp;
+	char *last_addr;
+	unsigned int len;
+
+	bio_for_each_segment_all(bvec, bio, iter_all) {
+		kaddr = kmap_local_page(bvec->bv_page);
+		last_addr = kaddr + bvec->bv_offset + bvec->bv_len - 1;
+		tmp = kaddr + bvec->bv_offset;
+		goto scan;
+again:
+		tmp++;
+scan:
+		len = last_addr - tmp + 1;
+		tmp = bio_memscan(tmp, 'X', len);
+		if (!tmp)
+			goto unmap;
+
+		printk("%s:%d, find X\n", __func__, __LINE__);
+		if (!(tmp + 1 <= last_addr && tmp[1] == 'A'))
+			goto again;
+		printk("%s:%d, find A\n", __func__, __LINE__);
+		if (!(tmp + 2 <= last_addr && tmp[2] == 'G'))
+			goto again;
+		printk("%s:%d, find G\n", __func__, __LINE__);
+		if (!(tmp + 3 <= last_addr && tmp[3] == 'F'))
+			goto again;
+		printk("%s:%d, find F\n", __func__, __LINE__);
+		printk("%s:%d, find success\n", __func__, __LINE__);
+		ret = 0;
+unmap:
+		kunmap_local(kaddr);
+		if (!ret)
+			return ret;
+	}
+	return ret;
+}
+
+
 /**
  * submit_bio - submit a bio to the block device layer for I/O
  * @bio: The &struct bio which describes the I/O
@@ -879,6 +951,12 @@ static void bio_set_ioprio(struct bio *bio)
  */
 void submit_bio(struct bio *bio)
 {
+	if (bio->debug && debug_drop_bio && !check_bio_data(bio)) {
+		printk("%s:%d, exec bi_end_io\n", __func__, __LINE__);
+		bio->bi_end_io(bio);
+		return;
+	}
+	bio->debug = 0;
 	if (bio_op(bio) == REQ_OP_READ) {
 		task_io_account_read(bio->bi_iter.bi_size);
 		count_vm_events(PGPGIN, bio_sectors(bio));
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 6dead20338e2..0a1668a8817f 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -418,8 +418,10 @@ xfs_prepare_ioend(
 
 	/* send ioends that might require a transaction to the completion wq */
 	if (xfs_ioend_is_append(ioend) || ioend->io_type == IOMAP_UNWRITTEN ||
-	    (ioend->io_flags & IOMAP_F_SHARED))
+	    (ioend->io_flags & IOMAP_F_SHARED)) {
+		ioend->io_bio.debug = 1;
 		ioend->io_bio.bi_end_io = xfs_end_bio;
+	}
 	return status;
 }
 
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index aa4dbda7b536..c4a253a7798c 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1558,6 +1558,7 @@ xfs_buf_ioapply_map(
 
 	bio = bio_alloc(bp->b_target->bt_bdev, nr_pages, op, GFP_NOIO);
 	bio->bi_iter.bi_sector = sector;
+	bio->debug = 1;
 	bio->bi_end_io = xfs_buf_bio_end_io;
 	bio->bi_private = bp;
 
diff --git a/fs/xfs/xfs_discard.c b/fs/xfs/xfs_discard.c
index 25fe3b932b5a..b52cbab160ee 100644
--- a/fs/xfs/xfs_discard.c
+++ b/fs/xfs/xfs_discard.c
@@ -135,6 +135,7 @@ xfs_discard_extents(
 
 	if (bio) {
 		bio->bi_private = extents;
+		bio->debug = 1;
 		bio->bi_end_io = xfs_discard_endio;
 		submit_bio(bio);
 	} else {
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 416c15494983..aa64695c2157 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -2253,6 +2253,11 @@ xlog_write_full(
 		struct xfs_log_iovec	*reg = &lv->lv_iovecp[index];
 		struct xlog_op_header	*ophdr = reg->i_addr;
 
+		char *log_data = (char *)ophdr + sizeof(struct xlog_op_header);
+		if (log_data[0] == 'X' && log_data[1] == 'A' && log_data[2] == 'G' && log_data[3] == 'F')
+			printk("%s:%d, 0x%02x 0x%02x 0x%02x 0x%02x\n", __func__, __LINE__,
+			       log_data[0], log_data[1], log_data[2], log_data[3]);
+
 		ophdr->oh_tid = cpu_to_be32(ticket->t_tid);
 		xlog_write_iovec(iclog, log_offset, reg->i_addr,
 				reg->i_len, len, record_cnt, data_cnt);
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 781c4500491b..ee38a29f728f 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -262,6 +262,7 @@ struct bio {
 	struct bio_vec		*bi_io_vec;	/* the actual vec list */
 
 	struct bio_set		*bi_pool;
+	char			debug;
 
 	/*
 	 * We can inline a number of vecs at the end of the bio, to avoid
-- 
2.34.1