[PATCH 13/21] verify: fix verify issue with offest modifiers

Offset modifiers such as rw=readwrite:8 or rw=write:4K can create
overlaps. For these cases use RB tree instead of list to log the I/O
entries.

Add a helper function fio_offset_overlap_risk() to decide whether to log
the I/O entry in an RB tree or a list.

Disable header seed verification if there are offset modifiers, unless
its explicitly enabled.

fixes #1503

Signed-off-by: Ankit Kumar <[email protected]>
---
 HOWTO.rst | 4 +++-
 fio.1     | 4 +++-
 fio.h     | 8 ++++++++
 init.c    | 6 ++++--
 iolog.c   | 9 +++++----
 5 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/HOWTO.rst b/HOWTO.rst
index 4293c03c..bb5da1cc 100644
--- a/HOWTO.rst
+++ b/HOWTO.rst
@@ -1185,7 +1185,9 @@ I/O type
 	pattern, then the *<nr>* value specified will be **added** to the generated
 	offset for each I/O turning sequential I/O into sequential I/O with holes.
 	For instance, using ``rw=write:4k`` will skip 4k for every write.  Also see
-	the :option:`rw_sequencer` option.
+	the :option:`rw_sequencer` option. If this is used with :option:`verify`
+	then :option:`verify_header_seed` will be disabled, unless its explicitly
+	enabled.
 
 .. option:: rw_sequencer=str
 
diff --git a/fio.1 b/fio.1
index a0f204c0..4755ca19 100644
--- a/fio.1
+++ b/fio.1
@@ -955,7 +955,9 @@ modifier with a value of 8. If the suffix is used with a sequential I/O
 pattern, then the `<nr>' value specified will be added to the generated
 offset for each I/O turning sequential I/O into sequential I/O with holes.
 For instance, using `rw=write:4k' will skip 4k for every write. Also see
-the \fBrw_sequencer\fR option.
+the \fBrw_sequencer\fR option. If this is used with \fBverify\fR then
+\fBverify_header_seed\fR option will be disabled, unless its explicitly
+enabled.
 .RE
 .TP
 .BI rw_sequencer \fR=\fPstr
diff --git a/fio.h b/fio.h
index b8cf3229..c7c0d147 100644
--- a/fio.h
+++ b/fio.h
@@ -800,6 +800,14 @@ extern void lat_target_reset(struct thread_data *);
 	    	 (i) < (td)->o.nr_files && ((f) = (td)->files[i]) != NULL; \
 		 (i)++)
 
+static inline bool fio_offset_overlap_risk(struct thread_data *td)
+{
+	if (td->o.ddir_seq_add || (td->o.ddir_seq_nr > 1))
+		return true;
+
+	return false;
+}
+
 static inline bool fio_fill_issue_time(struct thread_data *td)
 {
 	if (td->o.read_iolog_file ||
diff --git a/init.c b/init.c
index bf257ea1..feaa3f28 100644
--- a/init.c
+++ b/init.c
@@ -886,11 +886,13 @@ static int fixup_options(struct thread_data *td)
 
 		/*
 		 * Disable rand_seed check when we have verify_backlog,
-		 * zone reset frequency for zonemode=zbd, or norandommap.
+		 * zone reset frequency for zonemode=zbd, norandommap, or
+		 * offset modifiers.
 		 * Unless we were explicitly asked to enable it.
 		 */
 		if (!td_write(td) || (td->flags & TD_F_VER_BACKLOG) ||
-		    o->zrf.u.f || o->norandommap) {
+		    o->zrf.u.f || o->norandommap ||
+		    fio_offset_overlap_risk(td)) {
 			if (!fio_option_is_set(o, verify_header_seed))
 				o->verify_header_seed = 0;
 		}
diff --git a/iolog.c b/iolog.c
index ef173b09..6b5dc9ab 100644
--- a/iolog.c
+++ b/iolog.c
@@ -301,11 +301,12 @@ void log_io_piece(struct thread_data *td, struct io_u *io_u)
 	}
 
 	/*
-	 * Only sort writes if we don't have a random map in which case we need
-	 * to check for duplicate blocks and drop the old one, which we rely on
-	 * the rb insert/lookup for handling.
+	 * Sort writes if we don't have a random map in which case we need to
+	 * check for duplicate blocks and drop the old one, which we rely on
+	 * the rb insert/lookup for handling. Sort writes if we have offset
+	 * modifier which can also create duplicate blocks.
 	 */
-	if (file_randommap(td, ipo->file)) {
+	if (file_randommap(td, ipo->file) && !fio_offset_overlap_risk(td)) {
 		INIT_FLIST_HEAD(&ipo->list);
 		flist_add_tail(&ipo->list, &td->io_hist_list);
 		ipo->flags |= IP_F_ONLIST;
-- 
2.25.1