Add more tests for multi fs block atomic writes

Many programs open code these functionalities so add it as a generic helper in common/rc

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 common/rc | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

common/rc +22 -0

index f71cc8f0..9a9d3cc8 100644
@@ -5817,6 +5817,28 @@ _require_program() {
 	_have_program "$1" || _notrun "$tag required"
 }
 
+_min() {
+	local ret
+
+	for arg in "$@"; do
+		if [ -z "$ret" ] || (( $arg < $ret )); then
+			ret="$arg"
+		fi
+	done
+	echo $ret
+}
+
+_max() {
+	local ret
+
+	for arg in "$@"; do
+		if [ -z "$ret" ] || (( $arg > $ret )); then
+			ret="$arg"
+		fi
+	done
+	echo $ret
+}
+
 ################################################################################
 # make sure this script returns success
 /bin/true

Signature · 1 line

2.49.0

Insert range and collapse range only works with bigalloc in case the range is cluster size aligned, which fsx doesnt take care. To work past this, disable insert range and collapse range on ext4, if bigalloc is enabled.

This is achieved by defining a new function _set_default_fsx_avoid called via run_fsx helper. This can be used to selectively disable fsx options based on the configuration.

Co-developed-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 common/rc | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

common/rc +3 -0

index 9a9d3cc8..218cf253 100644
@@ -5113,10 +5113,37 @@ _require_hugepage_fsx()
 		_notrun "fsx binary does not support MADV_COLLAPSE"
 }
 
+_set_default_fsx_avoid() {
+	local file=$1
+

common/rc +11 -0

+		}
+		;;
+	# Add other filesystem types here as needed
+	*)
+		;;
+	esac
+}
+
 _run_fsx()
 {
 	echo "fsx $*"
 	local args=`echo $@ | sed -e "s/ BSIZE / $bsize /g" -e "s/ PSIZE / $psize /g"`
+
+	_set_default_fsx_avoid $testfile
+
 	set -- $FSX_PROG $args $FSX_AVOID $TEST_DIR/junk
 	echo "$@" >>$seqres.full
 	rm -f $TEST_DIR/junk

Signature · 1 line

2.49.0

Quoted 27 lines · Ojaswin Mujoo

Insert range and collapse range only works with bigalloc in case the range is cluster size aligned, which fsx doesnt take care. To work past this, disable insert range and collapse range on ext4, if bigalloc is enabled.

This is achieved by defining a new function _set_default_fsx_avoid called via run_fsx helper. This can be used to selectively disable fsx options based on the configuration.

Co-developed-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 common/rc | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

common/rc +3 -0

index 9a9d3cc8..218cf253 100644
@@ -5113,10 +5113,37 @@ _require_hugepage_fsx()
 		_notrun "fsx binary does not support MADV_COLLAPSE"
 }
 
+_set_default_fsx_avoid() {
+	local file=$1
+

common/rc _require_hugepage_fsx() · line 5128

Quoted 10 lines

common/rc +10 -0

+	case "$FSTYP" in
+	"ext4")
+		local dev=$(findmnt -n -o SOURCE --target $file)
+
+		# open code instead of _require_dumpe2fs cause we don't
+		# want to _notrun if dumpe2fs is not available
+		if [ -z "$DUMPE2FS_PROG" ]; then
+			echo "_set_default_fsx_avoid: dumpe2fs not found, skipping bigalloc check." >> $seqres.full
+			return
+		fi

I hate to be the guy who says one thing and then another, but ...

If we extended _get_file_block_size to report the ext4 bigalloc cluster size, would that be sufficient to keep testing collapse/insert range?

I guess the tricky part here is that bigalloc allows sub-cluster mappings and we might not want to do all file IO testing in such big units.

common/rc _require_hugepage_fsx() · line 5131

Quoted 4 lines

common/rc +3 -0

+
+		$DUMPE2FS_PROG -h $dev 2>&1 | grep -q bigalloc && {
+			export FSX_AVOID+=" -I -C"

No need to export FSX_AVOID to subprocesses.

--D

Quoted 23 lines

common/rc +11 -0

+		}
+		;;
+	# Add other filesystem types here as needed
+	*)
+		;;
+	esac
+}
+
 _run_fsx()
 {
 	echo "fsx $*"
 	local args=`echo $@ | sed -e "s/ BSIZE / $bsize /g" -e "s/ PSIZE / $psize /g"`
+
+	_set_default_fsx_avoid $testfile
+
 	set -- $FSX_PROG $args $FSX_AVOID $TEST_DIR/junk
 	echo "$@" >>$seqres.full
 	rm -f $TEST_DIR/junk

Signature · 1 line

2.49.0

Quoted 41 lines · Darrick J. Wong

Quoted 27 lines · Ojaswin Mujoo

Insert range and collapse range only works with bigalloc in case the range is cluster size aligned, which fsx doesnt take care. To work past this, disable insert range and collapse range on ext4, if bigalloc is enabled.

This is achieved by defining a new function _set_default_fsx_avoid called via run_fsx helper. This can be used to selectively disable fsx options based on the configuration.

Co-developed-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 common/rc | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

common/rc +3 -0

index 9a9d3cc8..218cf253 100644
@@ -5113,10 +5113,37 @@ _require_hugepage_fsx()
 		_notrun "fsx binary does not support MADV_COLLAPSE"
 }
 
+_set_default_fsx_avoid() {
+	local file=$1
+

common/rc _require_hugepage_fsx() · line 5128

Quoted 10 lines

common/rc +10 -0

+	case "$FSTYP" in
+	"ext4")
+		local dev=$(findmnt -n -o SOURCE --target $file)
+
+		# open code instead of _require_dumpe2fs cause we don't
+		# want to _notrun if dumpe2fs is not available
+		if [ -z "$DUMPE2FS_PROG" ]; then
+			echo "_set_default_fsx_avoid: dumpe2fs not found, skipping bigalloc check." >> $seqres.full
+			return
+		fi

I hate to be the guy who says one thing and then another, but ...

Quoted 6 lines

If we extended _get_file_block_size to report the ext4 bigalloc cluster size, would that be sufficient to keep testing collapse/insert range?

I guess the tricky part here is that bigalloc allows sub-cluster mappings and we might not want to do all file IO testing in such big units.

Hmm, so maybe a better way is to just add a parameter like alloc_unit in fsx where we can pass the cluster_size to which INSERT/COLLAPSE range be aligned to. For now we can pass it explicitly in the tests if needed.

I do plan on working on your suggestion of exposing alloc unit via statx(). Once we have that in the kernel, fsx can use that as well.

If this approach sounds okay I can try to maybe send the whole "fixing of insert/collpase range in fsx" as a patchset separate from atomic writes.

Quoted 8 lines

common/rc _require_hugepage_fsx() · line 5131

Quoted 4 lines

common/rc +3 -0

+
+		$DUMPE2FS_PROG -h $dev 2>&1 | grep -q bigalloc && {
+			export FSX_AVOID+=" -I -C"

No need to export FSX_AVOID to subprocesses.

--D

Got it, will fix. Thanks for review!

Regards,
ojaswin

Quoted 23 lines

Quoted 23 lines

common/rc +11 -0

+		}
+		;;
+	# Add other filesystem types here as needed
+	*)
+		;;
+	esac
+}
+
 _run_fsx()
 {
 	echo "fsx $*"
 	local args=`echo $@ | sed -e "s/ BSIZE / $bsize /g" -e "s/ PSIZE / $psize /g"`
+
+	_set_default_fsx_avoid $testfile
+
 	set -- $FSX_PROG $args $FSX_AVOID $TEST_DIR/junk
 	echo "$@" >>$seqres.full
 	rm -f $TEST_DIR/junk

Signature · 1 line

2.49.0

Implement atomic write support to help fuzz atomic writes with fsx.

Suggested-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 ltp/fsx.c | 109 +++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 104 insertions(+), 5 deletions(-)

ltp/fsx.c +34 -0

index 163b9453..ea39ca29 100644
@@ -40,6 +40,7 @@
 #include <liburing.h>
 #endif
 #include <sys/syscall.h>
+#include "statx.h"
 
 #ifndef MAP_FILE
 # define MAP_FILE 0

@@ -49,6 +50,10 @@
 #define RWF_DONTCACHE	0x80
 #endif
 
+#ifndef RWF_ATOMIC
+#define RWF_ATOMIC	0x40
+#endif
+
 #define NUMPRINTCOLUMNS 32	/* # columns of data to print on each line */
 
 /* Operation flags (bitmask) */

@@ -110,6 +115,7 @@ enum {
 	OP_READ_DONTCACHE,
 	OP_WRITE,
 	OP_WRITE_DONTCACHE,
+	OP_WRITE_ATOMIC,
 	OP_MAPREAD,
 	OP_MAPWRITE,
 	OP_MAX_LITE,

@@ -200,6 +206,11 @@ int	uring = 0;
 int	mark_nr = 0;
 int	dontcache_io = 1;
 int	hugepages = 0;                  /* -h flag */
+int	do_atomic_writes = 1;		/* -a flag disables */
+
+/* User for atomic writes */
+int awu_min = 0;
+int awu_max = 0;
 
 /* Stores info needed to periodically collapse hugepages */
 struct hugepages_collapse_info {

@@ -288,6 +299,7 @@ static const char *op_names[] = {
 	[OP_READ_DONTCACHE] = "read_dontcache",
 	[OP_WRITE] = "write",
 	[OP_WRITE_DONTCACHE] = "write_dontcache",
+	[OP_WRITE_ATOMIC] = "write_atomic",
 	[OP_MAPREAD] = "mapread",
 	[OP_MAPWRITE] = "mapwrite",
 	[OP_TRUNCATE] = "truncate",

@@ -422,6 +434,7 @@ logdump(void)
 				prt("\t***RRRR***");
 			break;
 		case OP_WRITE_DONTCACHE:
+		case OP_WRITE_ATOMIC:
 		case OP_WRITE:
 			prt("WRITE    0x%x thru 0x%x\t(0x%x bytes)",
 			    lp->args[0], lp->args[0] + lp->args[1] - 1,

@@ -1073,6 +1086,25 @@ update_file_size(unsigned offset, unsigned size)
 	file_size = offset + size;
 }
 
+static int is_power_of_2(unsigned n) {
+	return ((n & (n - 1)) == 0);
+}
+
+/*
+ * Round down n to nearest power of 2.
+ * If n is already a power of 2, return n;
+ */
+static int rounddown_pow_of_2(int n) {
+	int i = 0;
+
+	if (is_power_of_2(n))
+		return n;
+
+	for (; (1 << i) < n; i++);
+
+	return 1 << (i - 1);
+}
+
 void
 dowrite(unsigned offset, unsigned size, int flags)
 {

@@ -1081,6 +1113,27 @@ dowrite(unsigned offset, unsigned size, int flags)
 	offset -= offset % writebdy;
 	if (o_direct)
 		size -= size % writebdy;
+	if (flags & RWF_ATOMIC) {
+		/* atomic write len must be inbetween awu_min and awu_max */

ltp/fsx.c +60 -5

+
+		/* Skip the write if we are crossing max filesize */
+		if ((offset + size) > maxfilelen) {
+			if (!quiet && testcalls > simulatedopcount)
+				prt("skipping atomic write past maxfilelen\n");
+			log4(OP_WRITE_ATOMIC, offset, size, FL_SKIPPED);
+			return;
+		}
+	}
 	if (size == 0) {
 		if (!quiet && testcalls > simulatedopcount && !o_direct)
 			prt("skipping zero size write\n");

@@ -1088,7 +1141,10 @@ dowrite(unsigned offset, unsigned size, int flags)
 		return;
 	}
 
-	log4(OP_WRITE, offset, size, FL_NONE);
+	if (flags & RWF_ATOMIC)
+		log4(OP_WRITE_ATOMIC, offset, size, FL_NONE);
+	else
+		log4(OP_WRITE, offset, size, FL_NONE);
 
 	gendata(original_buf, good_buf, offset, size);
 	if (offset + size > file_size) {

@@ -1108,8 +1164,9 @@ dowrite(unsigned offset, unsigned size, int flags)
 		       (monitorstart == -1 ||
 			(offset + size > monitorstart &&
 			(monitorend == -1 || offset <= monitorend))))))
-		prt("%lld write\t0x%x thru\t0x%x\t(0x%x bytes)\tdontcache=%d\n", testcalls,
-		    offset, offset + size - 1, size, (flags & RWF_DONTCACHE) != 0);
+		prt("%lld write\t0x%x thru\t0x%x\t(0x%x bytes)\tdontcache=%d atomic_wr=%d\n", testcalls,
+		    offset, offset + size - 1, size, (flags & RWF_DONTCACHE) != 0,
+		    (flags & RWF_ATOMIC) != 0);
 	iret = fsxwrite(fd, good_buf + offset, size, offset, flags);
 	if (iret != size) {
 		if (iret == -1)

@@ -1785,6 +1842,30 @@ do_dedupe_range(unsigned offset, unsigned length, unsigned dest)
 }
 #endif
 
+int test_atomic_writes(void) {
+	int ret;
+	struct statx stx;
+
+	ret = xfstests_statx(AT_FDCWD, fname, 0, STATX_WRITE_ATOMIC, &stx);
+	if (ret < 0) {
+		fprintf(stderr, "main: Statx failed with %d."
+			" Failed to determine atomic write limits, "
+			" disabling!\n", ret);
+		return 0;
+	}
+
+	if (stx.stx_attributes & STATX_ATTR_WRITE_ATOMIC &&
+	    stx.stx_atomic_write_unit_min > 0) {
+		awu_min = stx.stx_atomic_write_unit_min;
+		awu_max = stx.stx_atomic_write_unit_max;
+		return 1;
+	}
+
+	fprintf(stderr, "main: IO Stack does not support "
+			"atomic writes, disabling!\n");
+	return 0;
+}
+
 #ifdef HAVE_COPY_FILE_RANGE
 int
 test_copy_range(void)

@@ -2356,6 +2437,12 @@ have_op:
 			goto out;
 		}
 		break;
+	case OP_WRITE_ATOMIC:
+		if (!do_atomic_writes) {
+			log4(OP_WRITE_ATOMIC, offset, size, FL_SKIPPED);
+			goto out;
+		}
+		break;
 	}
 
 	switch (op) {

@@ -2385,6 +2472,11 @@ have_op:
 			dowrite(offset, size, 0);
 		break;
 
+	case OP_WRITE_ATOMIC:
+		TRIM_OFF_LEN(offset, size, maxfilelen);
+		dowrite(offset, size, RWF_ATOMIC);
+		break;
+
 	case OP_MAPREAD:
 		TRIM_OFF_LEN(offset, size, file_size);
 		domapread(offset, size);

@@ -2511,13 +2603,14 @@ void
 usage(void)
 {
 	fprintf(stdout, "usage: %s",
-		"fsx [-dfhknqxyzBEFHIJKLORWXZ0]\n\
+		"fsx [-adfhknqxyzBEFHIJKLORWXZ0]\n\
 	   [-b opnum] [-c Prob] [-g filldata] [-i logdev] [-j logid]\n\
 	   [-l flen] [-m start:end] [-o oplen] [-p progressinterval]\n\
 	   [-r readbdy] [-s style] [-t truncbdy] [-w writebdy]\n\
 	   [-A|-U] [-D startingop] [-N numops] [-P dirpath] [-S seed]\n\
 	   [--replay-ops=opsfile] [--record-ops[=opsfile]] [--duration=seconds]\n\
 	   ... fname\n\
+	-a: disable atomic writes\n\
 	-b opnum: beginning operation number (default 1)\n\
 	-c P: 1 in P chance of file close+open at each op (default infinity)\n\
 	-d: debug output for all operations\n\

@@ -3059,9 +3152,13 @@ main(int argc, char **argv)
 	setvbuf(stdout, (char *)0, _IOLBF, 0); /* line buffered stdout */
 
 	while ((ch = getopt_long(argc, argv,
-				 "0b:c:de:fg:hi:j:kl:m:no:p:qr:s:t:uw:xyABD:EFJKHzCILN:OP:RS:UWXZ",
+				 "0ab:c:de:fg:hi:j:kl:m:no:p:qr:s:t:uw:xyABD:EFJKHzCILN:OP:RS:UWXZ",
 				 longopts, NULL)) != EOF)
 		switch (ch) {
+		case 'a':
+			prt("main(): Atomic writes disabled\n");
+			do_atomic_writes = 0;
+			break;
 		case 'b':
 			simulatedopcount = getnum(optarg, &endp);
 			if (!quiet)

@@ -3475,6 +3572,8 @@ main(int argc, char **argv)
 		exchange_range_calls = test_exchange_range();
 	if (dontcache_io)
 		dontcache_io = test_dontcache_io();
+	if (do_atomic_writes)
+		do_atomic_writes = test_atomic_writes();
 
 	while (keep_running())
 		if (!test())

Signature · 1 line

2.49.0

Quoted 25 lines

ltp/fsx.c +18 -0

+
+/*
+ * Round down n to nearest power of 2.
+ * If n is already a power of 2, return n;
+ */
+static int rounddown_pow_of_2(int n) {
+	int i = 0;
+
+	if (is_power_of_2(n))
+		return n;
+
+	for (; (1 << i) < n; i++);
+
+	return 1 << (i - 1);
+}
+
 void
 dowrite(unsigned offset, unsigned size, int flags)
 {

@@ -1081,6 +1113,27 @@ dowrite(unsigned offset, unsigned size, int flags)
 	offset -= offset % writebdy;
 	if (o_direct)
 		size -= size % writebdy;
+	if (flags & RWF_ATOMIC) {
+		/* atomic write len must be inbetween awu_min and awu_max */

ltp/fsx.c dowrite(unsigned offset, unsigned size, int flags) · line 1127

Quoted 10 lines

ltp/fsx.c +10 -0

+		if (size < awu_min)
+			size = awu_min;
+		if (size > awu_max)
+			size = awu_max;
+
+		/* atomic writes need power-of-2 sizes */
+		size = rounddown_pow_of_2(size);
+
+		/* atomic writes need naturally aligned offsets */
+		offset -= offset % size;

I don't think you should be modifying offset/size here. Normally for fsx we do all the rounding of the file range in the switch statement after the "calculate appropriate op to run" comment statement.

--D

Quoted 45 lines

ltp/fsx.c +20 -3

+
+		/* Skip the write if we are crossing max filesize */
+		if ((offset + size) > maxfilelen) {
+			if (!quiet && testcalls > simulatedopcount)
+				prt("skipping atomic write past maxfilelen\n");
+			log4(OP_WRITE_ATOMIC, offset, size, FL_SKIPPED);
+			return;
+		}
+	}
 	if (size == 0) {
 		if (!quiet && testcalls > simulatedopcount && !o_direct)
 			prt("skipping zero size write\n");

@@ -1088,7 +1141,10 @@ dowrite(unsigned offset, unsigned size, int flags)
 		return;
 	}
 
-	log4(OP_WRITE, offset, size, FL_NONE);
+	if (flags & RWF_ATOMIC)
+		log4(OP_WRITE_ATOMIC, offset, size, FL_NONE);
+	else
+		log4(OP_WRITE, offset, size, FL_NONE);
 
 	gendata(original_buf, good_buf, offset, size);
 	if (offset + size > file_size) {

@@ -1108,8 +1164,9 @@ dowrite(unsigned offset, unsigned size, int flags)
 		       (monitorstart == -1 ||
 			(offset + size > monitorstart &&
 			(monitorend == -1 || offset <= monitorend))))))
-		prt("%lld write\t0x%x thru\t0x%x\t(0x%x bytes)\tdontcache=%d\n", testcalls,
-		    offset, offset + size - 1, size, (flags & RWF_DONTCACHE) != 0);
+		prt("%lld write\t0x%x thru\t0x%x\t(0x%x bytes)\tdontcache=%d atomic_wr=%d\n", testcalls,
+		    offset, offset + size - 1, size, (flags & RWF_DONTCACHE) != 0,
+		    (flags & RWF_ATOMIC) != 0);
 	iret = fsxwrite(fd, good_buf + offset, size, offset, flags);
 	if (iret != size) {
 		if (iret == -1)

@@ -1785,6 +1842,30 @@ do_dedupe_range(unsigned offset, unsigned length, unsigned dest)
 }
 #endif
 
+int test_atomic_writes(void) {
+	int ret;
+	struct statx stx;
+

On Thu, Jul 17, 2025 at 09:17:47AM -0700, Darrick J. Wong wrote:

<snip>

Quoted 40 lines

Quoted 25 lines

ltp/fsx.c +18 -0

+
+/*
+ * Round down n to nearest power of 2.
+ * If n is already a power of 2, return n;
+ */
+static int rounddown_pow_of_2(int n) {
+	int i = 0;
+
+	if (is_power_of_2(n))
+		return n;
+
+	for (; (1 << i) < n; i++);
+
+	return 1 << (i - 1);
+}
+
 void
 dowrite(unsigned offset, unsigned size, int flags)
 {

@@ -1081,6 +1113,27 @@ dowrite(unsigned offset, unsigned size, int flags)
 	offset -= offset % writebdy;
 	if (o_direct)
 		size -= size % writebdy;
+	if (flags & RWF_ATOMIC) {
+		/* atomic write len must be inbetween awu_min and awu_max */

ltp/fsx.c dowrite(unsigned offset, unsigned size, int flags) · line 1127

Quoted 10 lines

ltp/fsx.c +10 -0

+		if (size < awu_min)
+			size = awu_min;
+		if (size > awu_max)
+			size = awu_max;
+
+		/* atomic writes need power-of-2 sizes */
+		size = rounddown_pow_of_2(size);
+
+		/* atomic writes need naturally aligned offsets */
+		offset -= offset % size;

I don't think you should be modifying offset/size here. Normally for fsx we do all the rounding of the file range in the switch statement after the "calculate appropriate op to run" comment statement.

Quoted 1 line

--D

Yes, I noticed that but then I saw we make size/offset adjustments in do write for writebdy and I wanted atomic writes adjustments to be done after that.

Regads,
ojaswin

Quoted 45 lines

Quoted 45 lines

ltp/fsx.c +20 -3

+
+		/* Skip the write if we are crossing max filesize */
+		if ((offset + size) > maxfilelen) {
+			if (!quiet && testcalls > simulatedopcount)
+				prt("skipping atomic write past maxfilelen\n");
+			log4(OP_WRITE_ATOMIC, offset, size, FL_SKIPPED);
+			return;
+		}
+	}
 	if (size == 0) {
 		if (!quiet && testcalls > simulatedopcount && !o_direct)
 			prt("skipping zero size write\n");

@@ -1088,7 +1141,10 @@ dowrite(unsigned offset, unsigned size, int flags)
 		return;
 	}
 
-	log4(OP_WRITE, offset, size, FL_NONE);
+	if (flags & RWF_ATOMIC)
+		log4(OP_WRITE_ATOMIC, offset, size, FL_NONE);
+	else
+		log4(OP_WRITE, offset, size, FL_NONE);
 
 	gendata(original_buf, good_buf, offset, size);
 	if (offset + size > file_size) {

@@ -1108,8 +1164,9 @@ dowrite(unsigned offset, unsigned size, int flags)
 		       (monitorstart == -1 ||
 			(offset + size > monitorstart &&
 			(monitorend == -1 || offset <= monitorend))))))
-		prt("%lld write\t0x%x thru\t0x%x\t(0x%x bytes)\tdontcache=%d\n", testcalls,
-		    offset, offset + size - 1, size, (flags & RWF_DONTCACHE) != 0);
+		prt("%lld write\t0x%x thru\t0x%x\t(0x%x bytes)\tdontcache=%d atomic_wr=%d\n", testcalls,
+		    offset, offset + size - 1, size, (flags & RWF_DONTCACHE) != 0,
+		    (flags & RWF_ATOMIC) != 0);
 	iret = fsxwrite(fd, good_buf + offset, size, offset, flags);
 	if (iret != size) {
 		if (iret == -1)

@@ -1785,6 +1842,30 @@ do_dedupe_range(unsigned offset, unsigned length, unsigned dest)
 }
 #endif
 
+int test_atomic_writes(void) {
+	int ret;
+	struct statx stx;
+

From: "Ritesh Harjani (IBM)" <[email protected]>

This adds atomic write test using fio based on it's crc check verifier. fio adds a crc for each data block. If the underlying device supports atomic write then it is guaranteed that we will never have a mix data from two threads writing on the same physical block.

Co-developed-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
  tests/generic/1226     | 101 +++++++++++++++++++++++++++++++++++++++++
  tests/generic/1226.out |   2 +

  2 files changed, 103 insertions(+)

create mode 100755 tests/generic/1226
create mode 100644 tests/generic/1226.out

tests/generic/1226 new file +24 -0

new file mode 100755
index 00000000..455fc55f
@@ -0,0 +1,101 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 IBM Corporation. All Rights Reserved.
+#
+# FS QA Test 1226
+#
+# Validate FS atomic write using fio crc check verifier.
+#
+. ./common/preamble
+. ./common/atomicwrites
+
+_begin_fstest auto aio rw atomicwrites
+
+_require_scratch_write_atomic
+_require_odirect
+_require_aio
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount
+
+touch "$SCRATCH_MNT/f1"
+awu_min_write=$(_get_atomic_write_unit_min "$SCRATCH_MNT/f1")
+awu_max_write=$(_get_atomic_write_unit_max "$SCRATCH_MNT/f1")
+blocksize=$(_max "$awu_min_write" "$((awu_max_write/2))")

tests/generic/1226 new file +57 -0

+	bs=$blocksize
+	fallocate=native
+	filename=$SCRATCH_MNT/test-file
+	size=$SIZE
+	iodepth=$FIO_LOAD
+	group_reporting=1
+
+	verify_only=1
+	verify=crc32c
+	verify_fatal=1
+	verify_state_save=0
+	verify_write_sequence=0
+EOF
+}
+
+function create_fio_aw_config()
+{
+cat >$fio_aw_config <<EOF
+	[atomicwrite-job]
+	direct=1
+	ioengine=libaio
+	rw=randwrite
+	bs=$blocksize
+	fallocate=native
+	filename=$SCRATCH_MNT/test-file
+	size=$SIZE
+	iodepth=$FIO_LOAD
+	numjobs=$FIO_LOAD
+	group_reporting=1
+	atomic=1
+
+	verify_state_save=0
+	verify=crc32c
+	do_verify=0
+EOF
+}
+
+fio_aw_config=$tmp.aw.fio
+fio_verify_config=$tmp.verify.fio
+
+create_fio_configs
+_require_fio $fio_aw_config
+
+cat $fio_aw_config >> $seqres.full
+cat $fio_verify_config >> $seqres.full
+
+$FIO_PROG $fio_aw_config >> $seqres.full
+ret1=$?
+$FIO_PROG $fio_verify_config >> $seqres.full
+ret2=$?
+
+[[ $ret1 -eq 0 && $ret2 -eq 0 ]] || _fail "fio with atomic write failed"
+
+# success, all done
+echo Silence is golden
+status=0
+exit

tests/generic/1226.out new file +2 -0

new file mode 100644
index 00000000..6dce0ea5
@@ -0,0 +1,2 @@
+QA output created by 1226
+Silence is golden

Quoted 6 lines · Ojaswin Mujoo

From: "Ritesh Harjani (IBM)" <[email protected]>

This adds atomic write test using fio based on it's crc check verifier. fio adds a crc for each data block. If the underlying device supports atomic write then it is guaranteed that we will never have a mix data from two threads writing on the same physical block.

I think that you should mention that 2-phase approach.

Is there something which ensures that we have fio which supports RWF_ATOMIC? fio for some time supported the "atomic" cmdline param, but did not do anything until recently

Quoted 8 lines

Co-developed-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
  tests/generic/1226     | 101 +++++++++++++++++++++++++++++++++++++++++
  tests/generic/1226.out |   2 +

Was this tested with xfs?

Quoted 35 lines

  2 files changed, 103 insertions(+)

create mode 100755 tests/generic/1226
create mode 100644 tests/generic/1226.out

tests/generic/1226 new file +24 -0

new file mode 100755
index 00000000..455fc55f
@@ -0,0 +1,101 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 IBM Corporation. All Rights Reserved.
+#
+# FS QA Test 1226
+#
+# Validate FS atomic write using fio crc check verifier.
+#
+. ./common/preamble
+. ./common/atomicwrites
+
+_begin_fstest auto aio rw atomicwrites
+
+_require_scratch_write_atomic
+_require_odirect
+_require_aio
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount
+
+touch "$SCRATCH_MNT/f1"
+awu_min_write=$(_get_atomic_write_unit_min "$SCRATCH_MNT/f1")
+awu_max_write=$(_get_atomic_write_unit_max "$SCRATCH_MNT/f1")
+blocksize=$(_max "$awu_min_write" "$((awu_max_write/2))")

tests/generic/1226 line 34

Quoted 10 lines

tests/generic/1226 new file +10 -0

+
+fio_config=$tmp.fio
+fio_out=$tmp.fio.out
+
+FIO_LOAD=$(($(nproc) * 2 * LOAD_FACTOR))
+SIZE=$((100 * 1024 * 1024))
+
+function create_fio_configs()
+{
+	create_fio_aw_config

it's strange ordering in this file, since create_fio_aw_config is declared below here

tests/generic/1226 line 35

Quoted 1 line

tests/generic/1226 new file +1 -0

+	create_fio_verify_config

same

tests/generic/1226 line 44

Quoted 10 lines

tests/generic/1226 new file +9 -0

+}
+
+function create_fio_verify_config()
+{
+cat >$fio_verify_config <<EOF
+	[verify-job]
+	direct=1
+	ioengine=libaio
+	rw=randwrite

is this really required? Maybe it is. I would use read if something was required for this param

Quoted 66 lines

tests/generic/1226 new file +57 -0

+	bs=$blocksize
+	fallocate=native
+	filename=$SCRATCH_MNT/test-file
+	size=$SIZE
+	iodepth=$FIO_LOAD
+	group_reporting=1
+
+	verify_only=1
+	verify=crc32c
+	verify_fatal=1
+	verify_state_save=0
+	verify_write_sequence=0
+EOF
+}
+
+function create_fio_aw_config()
+{
+cat >$fio_aw_config <<EOF
+	[atomicwrite-job]
+	direct=1
+	ioengine=libaio
+	rw=randwrite
+	bs=$blocksize
+	fallocate=native
+	filename=$SCRATCH_MNT/test-file
+	size=$SIZE
+	iodepth=$FIO_LOAD
+	numjobs=$FIO_LOAD
+	group_reporting=1
+	atomic=1
+
+	verify_state_save=0
+	verify=crc32c
+	do_verify=0
+EOF
+}
+
+fio_aw_config=$tmp.aw.fio
+fio_verify_config=$tmp.verify.fio
+
+create_fio_configs
+_require_fio $fio_aw_config
+
+cat $fio_aw_config >> $seqres.full
+cat $fio_verify_config >> $seqres.full
+
+$FIO_PROG $fio_aw_config >> $seqres.full
+ret1=$?
+$FIO_PROG $fio_verify_config >> $seqres.full
+ret2=$?
+
+[[ $ret1 -eq 0 && $ret2 -eq 0 ]] || _fail "fio with atomic write failed"
+
+# success, all done
+echo Silence is golden
+status=0
+exit

tests/generic/1226.out new file +2 -0

new file mode 100644
index 00000000..6dce0ea5
@@ -0,0 +1,2 @@
+QA output created by 1226
+Silence is golden

Quoted 9 lines · John Garry

Quoted 6 lines · Ojaswin Mujoo

From: "Ritesh Harjani (IBM)" <[email protected]>

This adds atomic write test using fio based on it's crc check verifier. fio adds a crc for each data block. If the underlying device supports atomic write then it is guaranteed that we will never have a mix data from two threads writing on the same physical block.

I think that you should mention that 2-phase approach.

Sure I can add a comment and update the commit message with this.

Quoted 1 line

Quoted 3 lines

Is there something which ensures that we have fio which supports RWF_ATOMIC? fio for some time supported the "atomic" cmdline param, but did not do anything until recently

We do have _require_fio which ensures the options passed are supported by the current fio. If you are saying some versions of fio have --atomic valid but dont do an RWF_ATOMIC then I'm not really sure if that can be caught though.

Quoted 10 lines

Quoted 9 lines

Co-developed-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
   tests/generic/1226     | 101 +++++++++++++++++++++++++++++++++++++++++
   tests/generic/1226.out |   2 +

Quoted 1 line

Was this tested with xfs?

Yes, I've tested with XFS with software fallback as well. Also, tested xfs while keeping io size as 16kb so we stress the hw paths too.

Both
seem to be passing as expected.

Quoted 1 line

Quoted 18 lines · Ojaswin Mujoo

Quoted 9 lines · John Garry

Quoted 6 lines · Ojaswin Mujoo

From: "Ritesh Harjani (IBM)" <[email protected]>

This adds atomic write test using fio based on it's crc check verifier. fio adds a crc for each data block. If the underlying device supports atomic write then it is guaranteed that we will never have a mix data from two threads writing on the same physical block.

I think that you should mention that 2-phase approach.

Sure I can add a comment and update the commit message with this.

Quoted 4 lines

Is there something which ensures that we have fio which supports RWF_ATOMIC? fio for some time supported the "atomic" cmdline param, but did not do anything until recently

Quoted 4 lines

We do have _require_fio which ensures the options passed are supported by the current fio. If you are saying some versions of fio have --atomic valid but dont do an RWF_ATOMIC then I'm not really sure if that can be caught though.

Can you check the fio version?

Quoted 11 lines

Quoted 11 lines

Quoted 10 lines

Co-developed-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
   tests/generic/1226     | 101 +++++++++++++++++++++++++++++++++++++++++
   tests/generic/1226.out |   2 +

Quoted 4 lines

Quoted 1 line

Was this tested with xfs?

Yes, I've tested with XFS with software fallback as well. Also, tested xfs while keeping io size as 16kb so we stress the hw paths too.

so is that requirement implemented with the _require_scratch_write_atomic check?

Quoted 4 lines

Both
seem to be passing as expected.

Quoted 1 line

Quoted 4 lines

Quoted 2 lines

Yes, I've tested with XFS with software fallback as well. Also, tested xfs while keeping io size as 16kb so we stress the hw paths too.

so is that requirement implemented with the _require_scratch_write_atomic check?

No, its just something i hardcoded for that particular run. This patch doesn't enforce hardware only atomic writes

Quoted 6 lines · Ojaswin Mujoo

Quoted 4 lines

Quoted 2 lines

Yes, I've tested with XFS with software fallback as well. Also, tested xfs while keeping io size as 16kb so we stress the hw paths too.

so is that requirement implemented with the _require_scratch_write_atomic check?

No, its just something i hardcoded for that particular run. This patch doesn't enforce hardware only atomic writes

If we are to test this for XFS then we need to ensure that HW atomics are available.

Thanks,
John

Quoted 4 lines

Quoted 2 lines

No, its just something i hardcoded for that particular run. This patch doesn't enforce hardware only atomic writes

If we are to test this for XFS then we need to ensure that HW atomics are available.

Why is that? Now with the verification step happening after writes, software atomic writes should also pass this test since there are no racing writes to the verify reads.

Quoted 7 lines · Ojaswin Mujoo

Quoted 4 lines

Quoted 2 lines

No, its just something i hardcoded for that particular run. This patch doesn't enforce hardware only atomic writes

If we are to test this for XFS then we need to ensure that HW atomics are available.

Why is that? Now with the verification step happening after writes, software atomic writes should also pass this test since there are no racing writes to the verify reads.

Sure, but racing software atomic writes against other software atomic writes is not safe.

Thanks,
John

Quoted 8 lines · John Garry

Quoted 7 lines · Ojaswin Mujoo

Quoted 4 lines

Quoted 2 lines

No, its just something i hardcoded for that particular run. This patch doesn't enforce hardware only atomic writes

If we are to test this for XFS then we need to ensure that HW atomics are available.

Why is that? Now with the verification step happening after writes, software atomic writes should also pass this test since there are no racing writes to the verify reads.

Quoted 5 lines

Sure, but racing software atomic writes against other software atomic writes is not safe.

Thanks,
John

What do you mean by not safe?

Does it mean the test can fail?

Quoted 9 lines · Ojaswin Mujoo

Quoted 8 lines · John Garry

Quoted 7 lines · Ojaswin Mujoo

Quoted 4 lines

Quoted 2 lines

No, its just something i hardcoded for that particular run. This patch doesn't enforce hardware only atomic writes

If we are to test this for XFS then we need to ensure that HW atomics are available.

Why is that? Now with the verification step happening after writes, software atomic writes should also pass this test since there are no racing writes to the verify reads.

Quoted 6 lines

Quoted 5 lines

Sure, but racing software atomic writes against other software atomic writes is not safe.

Thanks,
John

What do you mean by not safe?

Multiple threads issuing atomic writes may trample over one another.

It is due to the steps used to issue an atomic write in xfs by software method. Here we do 3x steps:
a. allocate blocks for out-of-place write
b. do write in those blocks
c. atomically update extent mapping.

In this, threads wanting to atomic write to the same address will use the new blocks and can trample over one another before we atomically update the mapping.

So we do not guarantee serialization of atomic writes vs atomic writes. And this is why I said that this test is never totally safe for xfs.

We could change this simply to have serialization of software-based atomic writes against all other dio, like follows:

fs/xfs/xfs_file.c +6 -6

@@ -747,6 +747,7 @@ xfs_file_dio_write_atomic(
       unsigned int            iolock = XFS_IOLOCK_SHARED;
       ssize_t                 ret, ocount = iov_iter_count(from);
       const struct iomap_ops  *dops;
+       unsigned int            dio_flags = 0;
 
       /*
        * HW offload should be faster, so try that first if it is already

@@ -766,15 +767,12 @@ xfs_file_dio_write_atomic(
       if (ret)
               goto out_unlock;
 
-       /* Demote similar to xfs_file_dio_write_aligned() */
-       if (iolock == XFS_IOLOCK_EXCL) {
-               xfs_ilock_demote(ip, XFS_IOLOCK_EXCL);
-               iolock = XFS_IOLOCK_SHARED;
-       }
+       if (dio_flags & IOMAP_DIO_FORCE_WAIT)
+               inode_dio_wait(VFS_I(ip));
 
       trace_xfs_file_direct_write(iocb, from);
       ret = iomap_dio_rw(iocb, from, dops, &xfs_dio_write_ops,
-                       0, NULL, 0);
+                       dio_flags, NULL, 0);
 
       /*
        * The retry mechanism is based on the ->iomap_begin method returning

@@ -785,6 +783,8 @@ xfs_file_dio_write_atomic(
       if (ret == -ENOPROTOOPT && dops == &xfs_direct_write_iomap_ops) {
               xfs_iunlock(ip, iolock);
               dops = &xfs_atomic_write_cow_iomap_ops;
+               iolock = XFS_IOLOCK_EXCL;
+               dio_flags = IOMAP_DIO_FORCE_WAIT;
               goto retry;
       }
 

But it may affect performance.

Quoted 1 line

Does it mean the test can fail?

Yes, but it is unlikely if we have HW atomics available. That is because we will rarely be using software-based atomic method, as HW method should often be possible.

Quoted 9 lines

Quoted 1 line

What do you mean by not safe?

Multiple threads issuing atomic writes may trample over one another.

It is due to the steps used to issue an atomic write in xfs by software method. Here we do 3x steps:
a. allocate blocks for out-of-place write
b. do write in those blocks
c. atomically update extent mapping.

Quoted 3 lines

In this, threads wanting to atomic write to the same address will use the new blocks and can trample over one another before we atomically update the mapping.

So iiuc, w/ software fallback, a thread atomically writing to a range will use a new block A. Another parallel thread trying to atomically write to the same range will also use A, and there is no serialization b/w the 2 so A could end up with a mix of data from both threads.

If this is true, aren't we violating the atomic guarantees. Nothing prevents the userspace from doing overlapping parallel atomic writes and it is kernels duty to error out if the write could get torn.

Quoted 9 lines · Ojaswin Mujoo

Quoted 9 lines

Quoted 1 line

What do you mean by not safe?

Multiple threads issuing atomic writes may trample over one another.

It is due to the steps used to issue an atomic write in xfs by software method. Here we do 3x steps:
a. allocate blocks for out-of-place write
b. do write in those blocks
c. atomically update extent mapping.

Quoted 7 lines

Quoted 3 lines

In this, threads wanting to atomic write to the same address will use the new blocks and can trample over one another before we atomically update the mapping.

So iiuc, w/ software fallback, a thread atomically writing to a range will use a new block A. Another parallel thread trying to atomically write to the same range will also use A, and there is no serialization b/w the 2 so A could end up with a mix of data from both threads.

right

Quoted 4 lines

If this is true, aren't we violating the atomic guarantees. Nothing prevents the userspace from doing overlapping parallel atomic writes and it is kernels duty to error out if the write could get torn.

Correct, but simply userspace should not do this. Direct I/O applications are responsible for ordering.

We guarantee that the write is committed all-or-nothing, but do rely on userspace not issuing racing atomic writes or racing regular writes.

I can easily change this, as I mentioned, but I am not convinced that it is a must.

Quoted 5 lines

We guarantee that the write is committed all-or-nothing, but do rely on userspace not issuing racing atomic writes or racing regular writes.

I can easily change this, as I mentioned, but I am not convinced that it is a must.

Purely from a design point of view, I feel we are breaking atomicity and hence we should serialize or just stop userspace from doing this (which is a bit extreme).

I know userspace should ideally not do overwriting atomic writes but if it is something we are allowing (which we do) then it is kernel's responsibility to ensure atomicity. Sure we can penalize them by serializing the writes but not by tearing it.

With that reasoning, I don't think the test should accomodate for this particular scenario.

Quoted 5 lines · Ojaswin Mujoo

Quoted 5 lines

We guarantee that the write is committed all-or-nothing, but do rely on userspace not issuing racing atomic writes or racing regular writes.

I can easily change this, as I mentioned, but I am not convinced that it is a must.

Quoted 3 lines

Purely from a design point of view, I feel we are breaking atomicity and hence we should serialize or just stop userspace from doing this (which is a bit extreme).

If you check the man page description of RWF_ATOMIC, it does not mention serialization. The user should conclude that usual direct IO rules apply, i.e. userspace is responsible for serializing.

Quoted 7 lines

I know userspace should ideally not do overwriting atomic writes but if it is something we are allowing (which we do) then it is kernel's responsibility to ensure atomicity. Sure we can penalize them by serializing the writes but not by tearing it.

Quoted 2 lines

With that reasoning, I don't think the test should accomodate for this particular scenario.

I can send a patch to the community for xfs (to provide serialization), like I showed earlier, to get opinion.

Thanks,
John

Quoted 10 lines · John Garry

Quoted 8 lines · Ojaswin Mujoo

Quoted 5 lines

We guarantee that the write is committed all-or-nothing, but do rely on userspace not issuing racing atomic writes or racing regular writes.

I can easily change this, as I mentioned, but I am not convinced that it is a must.

Purely from a design point of view, I feel we are breaking atomicity and hence we should serialize or just stop userspace from doing this (which is a bit extreme).

Quoted 3 lines

If you check the man page description of RWF_ATOMIC, it does not mention serialization. The user should conclude that usual direct IO rules apply, i.e. userspace is responsible for serializing.

My mental model of serialization in context of atomic writes is that if user does 64k atomic write A followed by a parallel overlapping 64kb atomic write B then the user might see complete A or complete B (we don't guarantee) but not a mix of A and B.

Quoted 7 lines

Quoted 7 lines

I know userspace should ideally not do overwriting atomic writes but if it is something we are allowing (which we do) then it is kernel's responsibility to ensure atomicity. Sure we can penalize them by serializing the writes but not by tearing it.

Quoted 5 lines

Quoted 2 lines

With that reasoning, I don't think the test should accomodate for this particular scenario.

I can send a patch to the community for xfs (to provide serialization), like I showed earlier, to get opinion.

Thanks, that would be great.

Regards,
John

Quoted 4 lines

Thanks,
John

Quoted 11 lines · Ojaswin Mujoo

Quoted 10 lines · John Garry

Quoted 8 lines · Ojaswin Mujoo

Quoted 5 lines

We guarantee that the write is committed all-or-nothing, but do rely on userspace not issuing racing atomic writes or racing regular writes.

I can easily change this, as I mentioned, but I am not convinced that it is a must.

Purely from a design point of view, I feel we are breaking atomicity and hence we should serialize or just stop userspace from doing this (which is a bit extreme).

Quoted 8 lines

Quoted 3 lines

If you check the man page description of RWF_ATOMIC, it does not mention serialization. The user should conclude that usual direct IO rules apply, i.e. userspace is responsible for serializing.

My mental model of serialization in context of atomic writes is that if user does 64k atomic write A followed by a parallel overlapping 64kb atomic write B then the user might see complete A or complete B (we don't guarantee) but not a mix of A and B.

Heh, here comes that feature naming confusing again. This is my definition:

RWF_ATOMIC means the system won't introduce new tearing when persisting file writes. The application is allowed to introduce tearing by writing to overlapping ranges at the same time. The system does not isolate overlapping reads from writes.

--D

Quoted 23 lines

Quoted 8 lines

Quoted 8 lines

I know userspace should ideally not do overwriting atomic writes but if it is something we are allowing (which we do) then it is kernel's responsibility to ensure atomicity. Sure we can penalize them by serializing the writes but not by tearing it.

Quoted 5 lines

Quoted 2 lines

With that reasoning, I don't think the test should accomodate for this particular scenario.

I can send a patch to the community for xfs (to provide serialization), like I showed earlier, to get opinion.

Thanks, that would be great.

Regards,
John

Quoted 4 lines

Thanks,
John

Quoted 9 lines

Heh, here comes that feature naming confusing again. This is my definition:

RWF_ATOMIC means the system won't introduce new tearing when persisting file writes. The application is allowed to introduce tearing by writing to overlapping ranges at the same time. The system does not isolate overlapping reads from writes.

--D

Hey Darrick, John,

So seems like my expectations of RWF_ATOMIC were a bit misplaced. I understand now that we don't really guarantee much when there are overlapping parallel writes going on. Even 2 overlapping RWF_ATOMIC writes can get torn. Seems like there are some edge cases where this might happen with hardware atomic writes as well.

In that sense, if this fio test is doing overlapped atomic io and expecting them to be untorn, I don't think that's the correct way to test it since that is beyond what RWF_ATOMIC guarantees.

I'll try to check if we can modify the tests to write on non-overlapping ranges in a file.

Quoted 17 lines · Ojaswin Mujoo

Quoted 9 lines

Heh, here comes that feature naming confusing again. This is my definition:

RWF_ATOMIC means the system won't introduce new tearing when persisting file writes. The application is allowed to introduce tearing by writing to overlapping ranges at the same time. The system does not isolate overlapping reads from writes.

--D

Hey Darrick, John,

So seems like my expectations of RWF_ATOMIC were a bit misplaced. I understand now that we don't really guarantee much when there are overlapping parallel writes going on. Even 2 overlapping RWF_ATOMIC writes can get torn. Seems like there are some edge cases where this might happen with hardware atomic writes as well.

Quoted 3 lines

In that sense, if this fio test is doing overlapped atomic io and expecting them to be untorn, I don't think that's the correct way to test it since that is beyond what RWF_ATOMIC guarantees.

I think that this test has value, but can only be used for ext4 or any FS which only relies on HW atomics only.

The value is that we prove that we don't get any bios being split in the storage stack, which is essential for HW atomics support.

Both NVMe and SCSI guarantee serialization of atomic writes.

Quoted 4 lines

I'll try to check if we can modify the tests to write on non-overlapping ranges in a file.

JFYI, for testing SW-based atomic writes on XFS, I do something like this. I have multiple threads each writing to separate regions of a file or writing to separate files. I use this for power-fail testing with my RPI. Indeed, I have also being using this sort of test in qemu for shutting down the VM when fio is running - I would like to automate this, but I am not sure how yet.

Please let me know if you want further info on the fio script.

Thanks,
John

Got it, I think I can make this test work for ext4 only but then it might be more appropriate to run the fio tests directly on atomic blkdev and skip the FS, since we anyways want to focus on the storage stack.

Quoted 10 lines

Quoted 2 lines

I'll try to check if we can modify the tests to write on non-overlapping ranges in a file.

JFYI, for testing SW-based atomic writes on XFS, I do something like this. I have multiple threads each writing to separate regions of a file or writing to separate files. I use this for power-fail testing with my RPI. Indeed, I have also being using this sort of test in qemu for shutting down the VM when fio is running - I would like to automate this, but I am not sure how yet.

Please let me know if you want further info on the fio script.

Got it, thanks for the insights. I was thinking of something similar now where I can modify the fio files of this test to write on non overlapping ranges in the same file. The only doubt i have right now is that when I have eg, numjobs=10 filesize=1G, how do i ensure each job writes to its own separate range and not overlap with each other.

I saw the offset_increment= fio options which might help, yet to try it out though. If you know any better way please do share.

Quoted 4 lines · Ojaswin Mujoo

Got it, I think I can make this test work for ext4 only but then it might be more appropriate to run the fio tests directly on atomic blkdev and skip the FS, since we anyways want to focus on the storage stack.

testing on ext4 will prove also that the FS and iomap behave correctly in that they generate a single bio per atomic write (as well as testing the block stack and below).

Quoted 17 lines

Quoted 11 lines

Quoted 3 lines

I'll try to check if we can modify the tests to write on non-overlapping ranges in a file.

JFYI, for testing SW-based atomic writes on XFS, I do something like this. I have multiple threads each writing to separate regions of a file or writing to separate files. I use this for power-fail testing with my RPI. Indeed, I have also being using this sort of test in qemu for shutting down the VM when fio is running - I would like to automate this, but I am not sure how yet.

Please let me know if you want further info on the fio script.

Got it, thanks for the insights. I was thinking of something similar now where I can modify the fio files of this test to write on non overlapping ranges in the same file. The only doubt i have right now is that when I have eg, numjobs=10 filesize=1G, how do i ensure each job writes to its own separate range and not overlap with each other.

Quoted 2 lines

I saw the offset_increment= fio options which might help, yet to try it out though. If you know any better way please do share.

Yeah, so I use something like:
--numjobs=2 --offset_align=0 --offset_increment=1M --size=1M

Thanks,
John

Quoted 5 lines · John Garry

Quoted 4 lines · Ojaswin Mujoo

Got it, I think I can make this test work for ext4 only but then it might be more appropriate to run the fio tests directly on atomic blkdev and skip the FS, since we anyways want to focus on the storage stack.

Quoted 3 lines

testing on ext4 will prove also that the FS and iomap behave correctly in that they generate a single bio per atomic write (as well as testing the block stack and below).

Okay, I think we are already testing those in the ext4/061 ext4/062 tests of this patchset. Just thought blkdev test might be useful to keep in generic. Do you see a value in that or shall I just drop the generic overlapping write tests?

Also, just for the records, ext4 passes the fio tests ONLY because we use the same io size for all threads. If we happen to start overlapping RWF_ATOMIC writes with different sizes that can get torn due to racing unwritten conversion.

Quoted 9 lines · Ojaswin Mujoo

Quoted 8 lines · John Garry

Quoted 4 lines · Ojaswin Mujoo

Got it, I think I can make this test work for ext4 only but then it might be more appropriate to run the fio tests directly on atomic blkdev and skip the FS, since we anyways want to focus on the storage stack.

testing on ext4 will prove also that the FS and iomap behave correctly in that they generate a single bio per atomic write (as well as testing the block stack and below).

Quoted 4 lines

Okay, I think we are already testing those in the ext4/061 ext4/062 tests of this patchset. Just thought blkdev test might be useful to keep in generic. Do you see a value in that or shall I just drop the generic overlapping write tests?

If you want to just test fio on the blkdev, then I think that is fine. Indeed, maybe such tests are useful in blktests also.

Quoted 6 lines

Also, just for the records, ext4 passes the fio tests ONLY because we use the same io size for all threads. If we happen to start overlapping RWF_ATOMIC writes with different sizes that can get torn due to racing unwritten conversion.

I'd keep the same io size for all threads in the tests.

Thanks,
John

From: "Ritesh Harjani (IBM)" <[email protected]>

This tests uses fio to first create a file with mixed mappings. Then it does atomic writes using aio dio with parallel jobs to the same file with mixed mappings. This forces the filesystem allocator to allocate extents over mixed mapping regions to stress FS block allocators.

Co-developed-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 tests/generic/1227     | 123 +++++++++++++++++++++++++++++++++++++++++
 tests/generic/1227.out |   2 +
 2 files changed, 125 insertions(+)
 create mode 100755 tests/generic/1227
 create mode 100644 tests/generic/1227.out

tests/generic/1227 new file +123 -0

new file mode 100755
index 00000000..cfdc54ec
@@ -0,0 +1,123 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 IBM Corporation. All Rights Reserved.
+#
+# FS QA Test 1227
+#
+# Validate FS atomic write using fio crc check verifier on mixed mappings
+# of a file.
+#
+. ./common/preamble
+. ./common/atomicwrites
+
+_begin_fstest auto aio rw atomicwrites
+
+_require_scratch_write_atomic_multi_fsblock
+_require_odirect
+_require_aio
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount
+
+touch "$SCRATCH_MNT/f1"
+awu_min_write=$(_get_atomic_write_unit_min "$SCRATCH_MNT/f1")
+awu_max_write=$(_get_atomic_write_unit_max "$SCRATCH_MNT/f1")
+aw_bsize=$(_max "$awu_min_write" "$((awu_max_write/4))")
+
+fsbsize=$(_get_block_size $SCRATCH_MNT)
+
+fio_prep_config=$tmp.prep.fio
+fio_aw_config=$tmp.aw.fio
+fio_verify_config=$tmp.verify.fio
+fio_out=$tmp.fio.out
+
+FIO_LOAD=$(($(nproc) * 2 * LOAD_FACTOR))
+SIZE=$((128 * 1024 * 1024))
+
+cat >$fio_prep_config <<EOF
+# prep file to have mixed mappings
+[global]
+ioengine=libaio
+fallocate=none
+filename=$SCRATCH_MNT/test-file
+filesize=$SIZE
+bs=$fsbsize
+direct=1
+group_reporting=1
+
+# Create written extents
+[prep_written_blocks]
+ioengine=libaio
+rw=randwrite
+io_size=$((SIZE/3))
+random_generator=lfsr
+
+# Create unwritten extents
+[prep_unwritten_blocks]
+ioengine=falloc
+rw=randwrite
+io_size=$((SIZE/3))
+random_generator=lfsr
+EOF
+
+cat >$fio_aw_config <<EOF
+# atomic write to mixed mappings of written/unwritten/holes
+[atomic_write_job]
+ioengine=libaio
+rw=randwrite
+direct=1
+atomic=1
+random_generator=lfsr
+group_reporting=1
+
+filename=$SCRATCH_MNT/test-file
+size=$SIZE
+bs=$aw_bsize
+iodepth=$FIO_LOAD
+numjobs=$FIO_LOAD
+
+verify_state_save=0
+verify=crc32c
+do_verify=0
+EOF
+
+cat >$fio_verify_config <<EOF
+# verify atomic writes done by previous job
+[verify_job]
+ioengine=libaio
+rw=randwrite
+random_generator=lfsr
+group_reporting=1
+
+filename=$SCRATCH_MNT/test-file
+size=$SIZE
+bs=$aw_bsize
+iodepth=$FIO_LOAD
+
+verify_state_save=0
+verify_only=1
+verify=crc32c
+verify_fatal=1
+verify_write_sequence=0
+EOF
+
+_require_fio $fio_aw_config
+_require_fio $fio_verify_config
+
+cat $fio_prep_config >> $seqres.full
+cat $fio_aw_config >> $seqres.full
+cat $fio_verify_config >> $seqres.full
+
+#prepare file with mixed mappings
+$FIO_PROG $fio_prep_config >> $seqres.full
+
+# do atomic writes without verifying
+$FIO_PROG $fio_aw_config >> $seqres.full
+
+# verify data is not torn
+$FIO_PROG $fio_verify_config >> $seqres.full
+
+# success, all done
+echo Silence is golden
+status=0
+exit

tests/generic/1227.out new file +2 -0

new file mode 100644
index 00000000..2605d062
@@ -0,0 +1,2 @@
+QA output created by 1227
+Silence is golden

Signature · 1 line

2.49.0

From: "Ritesh Harjani (IBM)" <[email protected]>

This tests uses fio to first create a file with mixed mappings. Then it does atomic writes using aio dio with parallel jobs to the same file with mixed mappings. This forces the filesystem allocator to allocate extents over mixed mapping regions to stress FS block allocators.

Co-developed-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---

 tests/generic/1227     | 123 +++++++++++++++++++++++++++++++++++++++++
 tests/generic/1227.out |   2 +
 2 files changed, 125 insertions(+)
 create mode 100755 tests/generic/1227
 create mode 100644 tests/generic/1227.out

tests/generic/1227 new file +123 -0

new file mode 100755
index 00000000..cfdc54ec
@@ -0,0 +1,123 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 IBM Corporation. All Rights Reserved.
+#
+# FS QA Test 1227
+#
+# Validate FS atomic write using fio crc check verifier on mixed mappings
+# of a file.
+#
+. ./common/preamble
+. ./common/atomicwrites
+
+_begin_fstest auto aio rw atomicwrites
+
+_require_scratch_write_atomic_multi_fsblock
+_require_odirect
+_require_aio
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount
+
+touch "$SCRATCH_MNT/f1"
+awu_min_write=$(_get_atomic_write_unit_min "$SCRATCH_MNT/f1")
+awu_max_write=$(_get_atomic_write_unit_max "$SCRATCH_MNT/f1")
+aw_bsize=$(_max "$awu_min_write" "$((awu_max_write/4))")
+
+fsbsize=$(_get_block_size $SCRATCH_MNT)
+
+fio_prep_config=$tmp.prep.fio
+fio_aw_config=$tmp.aw.fio
+fio_verify_config=$tmp.verify.fio
+fio_out=$tmp.fio.out
+
+FIO_LOAD=$(($(nproc) * 2 * LOAD_FACTOR))
+SIZE=$((128 * 1024 * 1024))
+
+cat >$fio_prep_config <<EOF
+# prep file to have mixed mappings
+[global]
+ioengine=libaio
+fallocate=none
+filename=$SCRATCH_MNT/test-file
+filesize=$SIZE
+bs=$fsbsize
+direct=1
+group_reporting=1
+
+# Create written extents
+[prep_written_blocks]
+ioengine=libaio
+rw=randwrite
+io_size=$((SIZE/3))
+random_generator=lfsr
+
+# Create unwritten extents
+[prep_unwritten_blocks]
+ioengine=falloc
+rw=randwrite
+io_size=$((SIZE/3))
+random_generator=lfsr
+EOF
+
+cat >$fio_aw_config <<EOF
+# atomic write to mixed mappings of written/unwritten/holes
+[atomic_write_job]
+ioengine=libaio
+rw=randwrite
+direct=1
+atomic=1
+random_generator=lfsr
+group_reporting=1
+
+filename=$SCRATCH_MNT/test-file
+size=$SIZE
+bs=$aw_bsize
+iodepth=$FIO_LOAD
+numjobs=$FIO_LOAD
+
+verify_state_save=0
+verify=crc32c
+do_verify=0
+EOF
+
+cat >$fio_verify_config <<EOF
+# verify atomic writes done by previous job
+[verify_job]
+ioengine=libaio
+rw=randwrite
+random_generator=lfsr
+group_reporting=1
+
+filename=$SCRATCH_MNT/test-file
+size=$SIZE
+bs=$aw_bsize
+iodepth=$FIO_LOAD
+
+verify_state_save=0
+verify_only=1
+verify=crc32c
+verify_fatal=1
+verify_write_sequence=0
+EOF
+
+_require_fio $fio_aw_config
+_require_fio $fio_verify_config
+
+cat $fio_prep_config >> $seqres.full
+cat $fio_aw_config >> $seqres.full
+cat $fio_verify_config >> $seqres.full
+
+#prepare file with mixed mappings
+$FIO_PROG $fio_prep_config >> $seqres.full
+
+# do atomic writes without verifying
+$FIO_PROG $fio_aw_config >> $seqres.full
+
+# verify data is not torn
+$FIO_PROG $fio_verify_config >> $seqres.full
+
+# success, all done
+echo Silence is golden
+status=0
+exit

tests/generic/1227.out new file +2 -0

new file mode 100644
index 00000000..2605d062
@@ -0,0 +1,2 @@
+QA output created by 1227
+Silence is golden

Signature · 1 line

2.49.0

Quoted 11 lines · Ojaswin Mujoo

From: "Ritesh Harjani (IBM)" <[email protected]>

This tests uses fio to first create a file with mixed mappings. Then it does atomic writes using aio dio with parallel jobs to the same file with mixed mappings. This forces the filesystem allocator to allocate extents over mixed mapping regions to stress FS block allocators.

Co-developed-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---

This patch looks good to me, just the subject:
"generic/1227: Add atomic write test using fio verify on file mixed mappings"

generally if we write a new test case, we don't use a temporary case number in commit subject, you can just write as "generic: add atomic write test using ..."

Other patches (with new test cases) refer to this.

With this change,

Reviewed-by Zorro Lang <[email protected]>

This adds various atomic write multi-fsblock stresst tests with mixed mappings and O_SYNC, to ensure the data and metadata is atomically persisted even if there is a shutdown.

Suggested-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 tests/generic/1228     | 139 +++++++++++++++++++++++++++++++++++++++++
 tests/generic/1228.out |   2 +
 2 files changed, 141 insertions(+)
 create mode 100755 tests/generic/1228
 create mode 100644 tests/generic/1228.out

tests/generic/1228 new file +83 -0

new file mode 100755
index 00000000..3f9a6af1
@@ -0,0 +1,139 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 IBM Corporation. All Rights Reserved.
+#
+# FS QA Test 1228
+#
+# Atomic write multi-fsblock data integrity tests with mixed mappings
+# and O_SYNC
+#
+. ./common/preamble
+. ./common/atomicwrites
+_begin_fstest auto quick rw atomicwrites
+
+_require_scratch_write_atomic_multi_fsblock
+_require_atomic_write_test_commands
+_require_scratch_shutdown
+_require_xfs_io_command "truncate"
+
+_scratch_mkfs >> $seqres.full
+_scratch_mount >> $seqres.full
+
+check_data_integrity() {
+	actual=$(_hexdump $testfile)
+	if [[ "$expected" != "$actual" ]]
+	then
+		echo "Integrity check failed"
+		echo "Integrity check failed" >> $seqres.full
+		echo "# Expected file contents:" >> $seqres.full
+		echo "$expected" >> $seqres.full
+		echo "# Actual file contents:" >> $seqres.full
+		echo "$actual" >> $seqres.full
+
+		_fail "Data integrity check failed. The atomic write was torn."
+	fi
+}
+
+prep_mixed_mapping() {
+	$XFS_IO_PROG -c "truncate 0" $testfile >> $seqres.full
+	local off=0
+	local mapping=""
+
+	local operations=("W" "H" "U")
+	local num_blocks=$((awu_max / blksz))
+	for ((i=0; i<num_blocks; i++)); do
+		local index=$((RANDOM % ${#operations[@]}))
+		local map="${operations[$index]}"
+		local mapping="${mapping}${map}"
+
+		case "$map" in
+			"W")
+				$XFS_IO_PROG -dc "pwrite -S 0x61 -b $blksz $off $blksz" $testfile > /dev/null
+				;;
+			"H")
+				# No operation needed for hole
+				;;
+			"U")
+				$XFS_IO_PROG -c "falloc $off $blksz" $testfile >> /dev/null
+				;;
+		esac
+		off=$((off + blksz))
+	done
+
+	echo "+ + Mixed mapping prep done. Full mapping pattern: $mapping" >> $seqres.full
+
+	sync $testfile
+}
+
+verify_atomic_write() {
+	if [[ "$1" == "shutdown" ]]
+	then
+		local do_shutdown=1
+	fi
+
+	test $bytes_written -eq $awu_max || _fail "atomic write len=$awu_max assertion failed"
+
+	if [[ $do_shutdown -eq "1" ]]
+	then
+		echo "Shutting down filesystem" >> $seqres.full
+		_scratch_shutdown >> $seqres.full
+		_scratch_cycle_mount >>$seqres.full 2>&1 || _fail "remount failed for Test-3"
+	fi
+
+	check_data_integrity

tests/generic/1228 new file +46 -0

+}
+
+testfile=$SCRATCH_MNT/testfile
+touch $testfile
+
+awu_max=$(_get_atomic_write_unit_max $testfile)
+blksz=$(_get_block_size $SCRATCH_MNT)
+
+# Create an expected pattern to compare with
+$XFS_IO_PROG -tc "pwrite -b $awu_max 0 $awu_max" $testfile >> $seqres.full
+expected=$(_hexdump $testfile)
+echo "# Expected file contents:" >> $seqres.full
+echo "$expected" >> $seqres.full
+echo >> $seqres.full
+
+echo "# Test 1: Do O_DSYNC atomic write on random mixed mapping:" >> $seqres.full
+echo >> $seqres.full
+for ((iteration=1; iteration<=10; iteration++)); do
+	echo "=== Mixed Mapping Test Iteration $iteration ===" >> $seqres.full
+
+	echo "+ Testing without shutdown..." >> $seqres.full
+	mixed_mapping_test
+	echo "Passed!" >> $seqres.full
+
+	echo "+ Testing with sudden shutdown..." >> $seqres.full
+	mixed_mapping_test "shutdown"
+	echo "Passed!" >> $seqres.full
+
+	echo "Iteration $iteration completed: OK" >> $seqres.full
+	echo >> $seqres.full
+done
+echo "# Test 1: Do O_SYNC atomic write on random mixed mapping (10 iterations): OK" >> $seqres.full
+
+
+echo >> $seqres.full
+echo "# Test 2: Do extending O_SYNC atomic writes: " >> $seqres.full
+bytes_written=$($XFS_IO_PROG -dstc "pwrite -A -V1 -b $awu_max 0 $awu_max" $testfile | \
+                grep wrote | awk -F'[/ ]' '{print $2}')
+verify_atomic_write "shutdown"
+echo "# Test 2: Do extending O_SYNC atomic writes: OK" >> $seqres.full
+
+# success, all done
+echo "Silence is golden"
+status=0
+exit
+

tests/generic/1228.out new file +2 -0

new file mode 100644
index 00000000..1baffa91
@@ -0,0 +1,2 @@
+QA output created by 1228
+Silence is golden

Signature · 1 line

2.49.0

Quoted 16 lines

tests/generic/1228 new file +16 -0

+verify_atomic_write() {
+	if [[ "$1" == "shutdown" ]]
+	then
+		local do_shutdown=1
+	fi
+
+	test $bytes_written -eq $awu_max || _fail "atomic write len=$awu_max assertion failed"
+
+	if [[ $do_shutdown -eq "1" ]]
+	then
+		echo "Shutting down filesystem" >> $seqres.full
+		_scratch_shutdown >> $seqres.full
+		_scratch_cycle_mount >>$seqres.full 2>&1 || _fail "remount failed for Test-3"
+	fi
+
+	check_data_integrity

tests/generic/1228 line 93

Quoted 10 lines

tests/generic/1228 new file +10 -0

+}
+
+mixed_mapping_test() {
+	prep_mixed_mapping
+
+	echo "+ + Performing O_DSYNC atomic write from 0 to $awu_max" >> $seqres.full
+	bytes_written=$($XFS_IO_PROG -dc "pwrite -DA -V1 -b $awu_max 0 $awu_max" $testfile | \
+		        grep wrote | awk -F'[/ ]' '{print $2}')
+
+	verify_atomic_write $1

The shutdown happens after the synchronous write completes? If so, then what part of recovery is this testing?

--D

Quoted 3 lines

(quoted diff) +2 -0

+}
+

On Thu, Jul 17, 2025 at 09:35:10AM -0700, Darrick J. Wong wrote:

<snip>

Quoted 30 lines

Quoted 16 lines

tests/generic/1228 new file +16 -0

+verify_atomic_write() {
+	if [[ "$1" == "shutdown" ]]
+	then
+		local do_shutdown=1
+	fi
+
+	test $bytes_written -eq $awu_max || _fail "atomic write len=$awu_max assertion failed"
+
+	if [[ $do_shutdown -eq "1" ]]
+	then
+		echo "Shutting down filesystem" >> $seqres.full
+		_scratch_shutdown >> $seqres.full
+		_scratch_cycle_mount >>$seqres.full 2>&1 || _fail "remount failed for Test-3"
+	fi
+
+	check_data_integrity

tests/generic/1228 line 93

Quoted 10 lines

tests/generic/1228 new file +10 -0

+}
+
+mixed_mapping_test() {
+	prep_mixed_mapping
+
+	echo "+ + Performing O_DSYNC atomic write from 0 to $awu_max" >> $seqres.full
+	bytes_written=$($XFS_IO_PROG -dc "pwrite -DA -V1 -b $awu_max 0 $awu_max" $testfile | \
+		        grep wrote | awk -F'[/ ]' '{print $2}')
+
+	verify_atomic_write $1

The shutdown happens after the synchronous write completes? If so, then what part of recovery is this testing?

Quoted 1 line

--D

Right, it is mostly inspired by [1] where sometimes isize update could be lost after dio completion. Although this might not exactly be affected by atomic writes, we added it here out of caution.

[1] https://lore.kernel.org/fstests/434beffaf18d39f898518ea9eb1cea4548e77c3a.1695383715.git.ritesh.list@gmail.com/

Quoted 2 lines

Quoted 2 lines

(quoted diff) +2 -0

+}
+

Quoted 34 lines · Ojaswin Mujoo

On Thu, Jul 17, 2025 at 09:35:10AM -0700, Darrick J. Wong wrote:

<snip>

Quoted 30 lines

Quoted 16 lines

tests/generic/1228 new file +16 -0

+verify_atomic_write() {
+	if [[ "$1" == "shutdown" ]]
+	then
+		local do_shutdown=1
+	fi
+
+	test $bytes_written -eq $awu_max || _fail "atomic write len=$awu_max assertion failed"
+
+	if [[ $do_shutdown -eq "1" ]]
+	then
+		echo "Shutting down filesystem" >> $seqres.full
+		_scratch_shutdown >> $seqres.full
+		_scratch_cycle_mount >>$seqres.full 2>&1 || _fail "remount failed for Test-3"
+	fi
+
+	check_data_integrity

tests/generic/1228 line 93

Quoted 10 lines

tests/generic/1228 new file +10 -0

+}
+
+mixed_mapping_test() {
+	prep_mixed_mapping
+
+	echo "+ + Performing O_DSYNC atomic write from 0 to $awu_max" >> $seqres.full
+	bytes_written=$($XFS_IO_PROG -dc "pwrite -DA -V1 -b $awu_max 0 $awu_max" $testfile | \
+		        grep wrote | awk -F'[/ ]' '{print $2}')
+
+	verify_atomic_write $1

The shutdown happens after the synchronous write completes? If so, then what part of recovery is this testing?

Quoted 7 lines

Quoted 1 line

--D

Right, it is mostly inspired by [1] where sometimes isize update could be lost after dio completion. Although this might not exactly be affected by atomic writes, we added it here out of caution.

[1] https://lore.kernel.org/fstests/434beffaf18d39f898518ea9eb1cea4548e77c3a.1695383715.git.ritesh.list@gmail.com/

Ah, so we're racing with background log flush then. Would it improve the potential failure detection rate to call shutdown right after the pwrite, e.g.

$XFS_IO_PROG -dxc "pwrite -DA..." -c 'shutdown' $testfile

It can take a few milliseconds to walk down the bash functions and fork/exec another child process.

--D

Quoted 3 lines

Quoted 2 lines

Quoted 2 lines

(quoted diff) +2 -0

+}
+

Stress file with atomic writes to ensure we excercise codepaths where we are mixing different FS operations with atomic writes

Suggested-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 tests/generic/1229     | 41 +++++++++++++++++++++++++++++++++++++++++
 tests/generic/1229.out |  2 ++
 2 files changed, 43 insertions(+)
 create mode 100755 tests/generic/1229
 create mode 100644 tests/generic/1229.out

tests/generic/1229 new file +41 -0

new file mode 100755
index 00000000..98e9b50c
@@ -0,0 +1,41 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 IBM Corporation. All Rights Reserved.
+#
+# FS QA Test 1229
+#
+# fuzz fsx with atomic writes
+#
+. ./common/preamble
+. ./common/atomicwrites
+_begin_fstest rw auto quick atomicwrites
+
+_require_odirect
+_require_scratch_write_atomic
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount  >> $seqres.full 2>&1
+
+testfile=$SCRATCH_MNT/testfile
+touch $testfile
+
+awu_max=$(_get_atomic_write_unit_max $testfile)
+blksz=$(_get_block_size $SCRATCH_MNT)
+bsize=`$here/src/min_dio_alignment $SCRATCH_MNT $SCRATCH_DEV`
+
+# fsx usage:
+#
+# -N numops: total # operations to do
+# -l flen: the upper bound on file size
+# -o oplen: the upper bound on operation size (64k default)
+# -Z: O_DIRECT ()
+
+_run_fsx_on_file $testfile -N 10000 -o $awu_max -A -l 500000 -r $bsize -w $bsize -Z $FSX_AVOID  >> $seqres.full
+if [[ "$?" != "0" ]]
+then
+	_fail "fsx returned error: $?"
+fi
+
+echo "Silence is golden"
+status=0
+exit

tests/generic/1229.out new file +2 -0

new file mode 100644
index 00000000..737d61c6
@@ -0,0 +1,2 @@
+QA output created by 1229
+Silence is golden

Signature · 1 line

2.49.0

Quoted 5 lines · Ojaswin Mujoo

Stress file with atomic writes to ensure we excercise codepaths where we are mixing different FS operations with atomic writes

Suggested-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

Hrm, doesn't generic/521 test this already if the fs happens to support atomic writes?

--D

Quoted 11 lines · Darrick J. Wong

Quoted 5 lines · Ojaswin Mujoo

Stress file with atomic writes to ensure we excercise codepaths where we are mixing different FS operations with atomic writes

Suggested-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

Hrm, doesn't generic/521 test this already if the fs happens to support atomic writes?

--D

Hi Darrick,

Yes but I wanted one with _require_scratch_write_atomic and writes going to SCRATCH fs to explicitly test atomic writes as that can get missed in g/521.

Would you instead prefer to have those changes in g/521?

Regards,
Ojaswin

This test is intended to ensure that multi blocks atomic writes maintain atomic guarantees across sudden FS shutdowns.

The way we work is that we lay out a file with random mix of written, unwritten and hole extents. Then we start performing atomic writes sequentially on the file while we parallely shutdown the FS. Then we note the last offset where the atomic write happened just before shut down and then make sure blocks around it either have completely old data or completely new data, ie the write was not torn during shutdown.

We repeat the same with completely written, completely unwritten and completely empty file to ensure these cases are not torn either. Finally, we have a similar test for append atomic writes

Suggested-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 tests/generic/1230     | 397 +++++++++++++++++++++++++++++++++++++++++
 tests/generic/1230.out |   2 +
 2 files changed, 399 insertions(+)
 create mode 100755 tests/generic/1230
 create mode 100644 tests/generic/1230.out

tests/generic/1230 new file +397 -0

new file mode 100755
index 00000000..cff5adc0
@@ -0,0 +1,397 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 IBM Corporation. All Rights Reserved.
+#
+# FS QA Test No. 1230
+#
+# Test multi block atomic writes with sudden FS shutdowns to ensure
+# the FS is not tearing the write operation
+. ./common/preamble
+. ./common/atomicwrites
+_begin_fstest auto atomicwrites
+
+_require_scratch_write_atomic_multi_fsblock
+_require_atomic_write_test_commands
+_require_scratch_shutdown
+_require_xfs_io_command "truncate"
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount >> $seqres.full
+
+testfile=$SCRATCH_MNT/testfile
+touch $testfile
+
+awu_max=$(_get_atomic_write_unit_max $testfile)
+blksz=$(_get_block_size $SCRATCH_MNT)
+echo "Awu max: $awu_max" >> $seqres.full
+
+num_blocks=$((awu_max / blksz))
+# keep initial value high for dry run. This will be
+# tweaked in dry_run() based on device write speed.
+filesize=$(( 10 * 1024 * 1024 * 1024 ))
+
+_cleanup() {
+	[ -n "$awloop_pid" ] && kill $awloop_pid &> /dev/null
+	wait
+}
+
+atomic_write_loop() {
+	local off=0
+	local size=$awu_max
+	for ((i=0; i<$((filesize / $size )); i++)); do
+		# Due to sudden shutdown this can produce errors so just
+		# redirect them to seqres.full
+		$XFS_IO_PROG -c "open -fsd $testfile" -c "pwrite -S 0x61 -DA -V1 -b $size $off $size" >> /dev/null 2>>$seqres.full
+		echo "Written to offset: $off" >> $tmp.aw
+		off=$((off + $size))
+	done
+}
+
+# This test has the following flow:
+# 1. Start doing sequential atomic writes in bg, upto $filesize
+# 2. Sleep for 0.2s and shutdown the FS
+# 3. kill the atomic write process
+# 4. verify the writes were not torn
+#
+# We ideally want the shutdown to happen while an atomic write is ongoing
+# but this gets tricky since faster devices can actually finish the whole
+# atomic write loop before sleep 0.2s completes, resulting in the shutdown
+# happening after the write loop which is not what we want. A simple solution
+# to this is to increase $filesize so step 1 takes long enough but a big
+# $filesize leads to create_mixed_mappings() taking very long, which is not
+# ideal.
+#
+# Hence, use the dry_run function to figure out the rough device speed and set
+# $filesize accordingly.
+dry_run() {
+	echo >> $seqres.full
+	echo "# Estimating ideal filesize..." >> $seqres.full
+	atomic_write_loop &
+	awloop_pid=$!
+
+	local i=0
+	# Wait for atleast first write to be recorded or 10s
+	while [ ! -f "$tmp.aw" -a $i -le 50 ]; do i=$((i + 1)); sleep 0.2; done
+
+	if [[ $i -gt 50 ]]
+	then
+		_fail "atomic write process took too long to start"
+	fi
+
+	echo >> $seqres.full
+	echo "# Shutting down filesystem while write is running" >> $seqres.full
+	_scratch_shutdown
+
+	kill $awloop_pid 2>/dev/null  # the process might have finished already
+	wait $awloop_pid
+	unset $awloop_pid
+
+	bytes_written=$(tail -n 1 $tmp.aw | cut -d" " -f4)
+	echo "# Bytes written in 0.2s: $bytes_written" >> $seqres.full
+
+	filesize=$((bytes_written * 3))
+	echo "# Setting \$filesize=$filesize" >> $seqres.full
+
+	rm $tmp.aw
+	sleep 0.5
+
+	_scratch_cycle_mount
+
+}
+
+create_mixed_mappings() {
+	local file=$1
+	local size_bytes=$2
+
+	echo "# Filling file $file with alternate mappings till size $size_bytes" >> $seqres.full
+	#Fill the file with alternate written and unwritten blocks
+	local off=0
+	local operations=("W" "U")
+
+	for ((i=0; i<$((size_bytes / blksz )); i++)); do
+		index=$(($i % ${#operations[@]}))
+		map="${operations[$index]}"
+
+		case "$map" in
+		    "W")
+			$XFS_IO_PROG -fc "pwrite -b $blksz $off $blksz" $file  >> /dev/null
+			;;
+		    "U")
+			$XFS_IO_PROG -fc "falloc $off $blksz" $file >> /dev/null
+			;;
+		esac
+		off=$((off + blksz))
+	done
+
+	sync $file
+}
+
+populate_expected_data() {
+	# create a dummy file with expected old data for different cases
+	create_mixed_mappings $testfile.exp_old_mixed $awu_max
+	expected_data_old_mixed=$(od -An -t x1 -j 0 -N $awu_max $testfile.exp_old_mixed)
+
+	$XFS_IO_PROG -fc "falloc 0 $awu_max" $testfile.exp_old_zeroes >> $seqres.full
+	expected_data_old_zeroes=$(od -An -t x1 -j 0 -N $awu_max $testfile.exp_old_zeroes)
+
+	$XFS_IO_PROG -fc "pwrite -b $awu_max 0 $awu_max" $testfile.exp_old_mapped >> $seqres.full
+	expected_data_old_mapped=$(od -An -t x1 -j 0 -N $awu_max $testfile.exp_old_mapped)
+
+	# create a dummy file with expected new data
+	$XFS_IO_PROG -fc "pwrite -S 0x61 -b $awu_max 0 $awu_max" $testfile.exp_new >> $seqres.full
+	expected_data_new=$(od -An -t x1 -j 0 -N $awu_max $testfile.exp_new)
+}
+
+verify_data_blocks() {
+	local verify_start=$1
+	local verify_end=$2
+	local expected_data_old="$3"
+	local expected_data_new="$4"
+
+	echo >> $seqres.full
+	echo "# Checking data integrity from $verify_start to $verify_end" >> $seqres.full
+
+	# After an atomic write, for every chunk we ensure that the underlying
+	# data is either the old data or new data as writes shouldn't get torn.
+	local off=$verify_start
+	while [[ "$off" -lt "$verify_end" ]]
+	do
+		#actual_data=$(xxd -s $off -l $awu_max -p $testfile)
+		actual_data=$(od -An -t x1 -j $off -N $awu_max $testfile)
+		if [[ "$actual_data" != "$expected_data_new" ]] && [[ "$actual_data" != "$expected_data_old" ]]
+		then
+			echo "Checksum match failed at off: $off size: $awu_max"
+			echo "Expected contents: (Either of the 2 below):"
+			echo
+			echo "Expected old: "
+			echo "$expected_data_old"
+			echo
+			echo "Expected new: "
+			echo "$expected_data_new"
+			echo
+			echo "Actual contents: "
+			echo "$actual_data"
+
+			_fail
+		fi
+		echo -n "Check at offset $off suceeded! " >> $seqres.full
+		if [[ "$actual_data" == "$expected_data_new" ]]
+		then
+			echo "matched new" >> $seqres.full
+		elif [[ "$actual_data" == "$expected_data_old" ]]
+		then
+			echo "matched old" >> $seqres.full
+		fi
+		off=$(( off + awu_max ))
+	done
+}
+
+# test data integrity for file by shutting down in between atomic writes
+test_data_integrity() {
+	echo >> $seqres.full
+	echo "# Writing atomically to file in background" >> $seqres.full
+	atomic_write_loop &
+	awloop_pid=$!
+
+	local i=0
+	# Wait for atleast first write to be recorded or 10s
+	while [ ! -f "$tmp.aw" -a $i -le 50 ]; do i=$((i + 1)); sleep 0.2; done
+
+	if [[ $i -gt 50 ]]
+	then
+		_fail "atomic write process took too long to start"
+	fi
+
+	echo >> $seqres.full
+	echo "# Shutting down filesystem while write is running" >> $seqres.full
+	_scratch_shutdown
+
+	kill $awloop_pid 2>/dev/null  # the process might have finished already
+	wait $awloop_pid
+	unset $awloop_pid
+
+	last_offset=$(tail -n 1 $tmp.aw | cut -d" " -f4)
+	if [[ -z $last_offset ]]
+	then
+		last_offset=0
+	fi
+
+	echo >> $seqres.full
+	echo "# Last offset of atomic write: $last_offset" >> $seqres.full
+
+	rm $tmp.aw
+	sleep 0.5
+
+	_scratch_cycle_mount
+
+	# we want to verify all blocks around which the shutdown happended
+	verify_start=$(( last_offset - (awu_max * 5)))
+	if [[ $verify_start < 0 ]]
+	then
+		verify_start=0
+	fi
+
+	verify_end=$(( last_offset + (awu_max * 5)))
+	if [[ "$verify_end" -gt "$filesize" ]]
+	then
+		verify_end=$filesize
+	fi
+}
+
+# test data integrity for file wiht written and unwritten mappings
+test_data_integrity_mixed() {
+	$XFS_IO_PROG -fc "truncate 0" $testfile >> $seqres.full
+
+	echo >> $seqres.full
+	echo "# Creating testfile with mixed mappings" >> $seqres.full
+	create_mixed_mappings $testfile $filesize
+
+	test_data_integrity
+
+	verify_data_blocks $verify_start $verify_end "$expected_data_old_mixed" "$expected_data_new"
+}
+
+# test data integrity for file with completely written mappings
+test_data_integrity_writ() {
+	$XFS_IO_PROG -fc "truncate 0" $testfile >> $seqres.full
+
+	echo >> $seqres.full
+	echo "# Creating testfile with fully written mapping" >> $seqres.full
+	$XFS_IO_PROG -c "pwrite -b $filesize 0 $filesize" $testfile >> $seqres.full
+	sync $testfile
+
+	test_data_integrity
+
+	verify_data_blocks $verify_start $verify_end "$expected_data_old_mapped" "$expected_data_new"
+}
+
+# test data integrity for file with completely unwritten mappings
+test_data_integrity_unwrit() {
+	$XFS_IO_PROG -fc "truncate 0" $testfile >> $seqres.full
+
+	echo >> $seqres.full
+	echo "# Creating testfile with fully unwritten mappings" >> $seqres.full
+	$XFS_IO_PROG -c "falloc 0 $filesize" $testfile >> $seqres.full
+	sync $testfile
+
+	test_data_integrity
+
+	verify_data_blocks $verify_start $verify_end "$expected_data_old_zeroes" "$expected_data_new"
+}
+
+# test data integrity for file with no mappings
+test_data_integrity_hole() {
+	$XFS_IO_PROG -fc "truncate 0" $testfile >> $seqres.full
+
+	echo >> $seqres.full
+	echo "# Creating testfile with no mappings" >> $seqres.full
+	$XFS_IO_PROG -c "truncate $filesize" $testfile >> $seqres.full
+	sync $testfile
+
+	test_data_integrity
+
+	verify_data_blocks $verify_start $verify_end "$expected_data_old_zeroes" "$expected_data_new"
+}
+
+test_filesize_integrity() {
+	$XFS_IO_PROG -c "truncate 0" $testfile >> $seqres.full
+
+	echo >> $seqres.full
+	echo "# Performing extending atomic writes over file in background" >> $seqres.full
+	atomic_write_loop &
+	awloop_pid=$!
+
+	local i=0
+	# Wait for atleast first write to be recorded or 10s
+	while [ ! -f "$tmp.aw" -a $i -le 50 ]; do i=$((i + 1)); sleep 0.2; done
+
+	if [[ $i -gt 50 ]]
+	then
+		_fail "atomic write process took too long to start"
+	fi
+
+	echo >> $seqres.full
+	echo "# Shutting down filesystem while write is running" >> $seqres.full
+	_scratch_shutdown
+
+	kill $awloop_pid 2>/dev/null  # the process might have finished already
+	wait $awloop_pid
+	unset $awloop_pid
+
+	local last_offset=$(tail -n 1 $tmp.aw | cut -d" " -f4)
+	if [[ -z $last_offset ]]
+	then
+		last_offset=0
+	fi
+
+	echo >> $seqres.full
+	echo "# Last offset of atomic write: $last_offset" >> $seqres.full
+	rm $tmp.aw
+	sleep 0.5
+
+	_scratch_cycle_mount
+	local filesize=$(_get_filesize $testfile)
+	echo >> $seqres.full
+	echo "# Filesize after shutdown: $filesize" >> $seqres.full
+
+	# To confirm that the write went atomically, we check:
+	# 1. The last block should be a multiple of awu_max
+	# 2. The last block should be the completely new data
+
+	if (( $filesize % $awu_max ))
+	then
+		echo "Filesize after shutdown ($filesize) not a multiple of atomic write unit ($awu_max)"
+	fi
+
+	verify_start=$(( filesize - (awu_max * 5)))
+	if [[ $verify_start < 0 ]]
+	then
+		verify_start=0
+	fi
+
+	local verify_end=$filesize
+
+	# Here the blocks should always match new data hence, for simplicity of
+	# code, just corrupt the $expected_data_old buffer so it never matches
+	local expected_data_old="POISON"
+	verify_data_blocks $verify_start $verify_end "$expected_data_old" "$expected_data_new"
+}
+
+$XFS_IO_PROG -fc "truncate 0" $testfile >> $seqres.full
+
+dry_run
+
+echo >> $seqres.full
+echo "# Populating expected data buffers" >> $seqres.full
+populate_expected_data
+
+# Loop 20 times to shake out any races due to shutdown
+for ((iter=0; iter<20; iter++))
+do
+	echo >> $seqres.full
+	echo "------ Iteration $iter ------" >> $seqres.full
+
+	echo >> $seqres.full
+	echo "# Starting data integrity test for atomic writes over mixed mapping" >> $seqres.full
+	test_data_integrity_mixed
+
+	echo >> $seqres.full
+	echo "# Starting data integrity test for atomic writes over fully written mapping" >> $seqres.full
+	test_data_integrity_writ
+
+	echo >> $seqres.full
+	echo "# Starting data integrity test for atomic writes over fully unwritten mapping" >> $seqres.full
+	test_data_integrity_unwrit
+
+	echo >> $seqres.full
+	echo "# Starting data integrity test for atomic writes over holes" >> $seqres.full
+	test_data_integrity_hole
+
+	echo >> $seqres.full
+	echo "# Starting filesize integrity test for atomic writes" >> $seqres.full
+	test_filesize_integrity
+done
+
+echo "Silence is golden"
+status=0
+exit

tests/generic/1230.out new file +2 -0

new file mode 100644
index 00000000..d01f54ea
@@ -0,0 +1,2 @@
+QA output created by 1230
+Silence is golden

Signature · 1 line

2.49.0

From: "Ritesh Harjani (IBM)" <[email protected]>

We brute force all possible blocksize & clustersize combinations on a bigalloc filesystem for stressing atomic write using fio data crc verifier. We run nproc * $LOAD_FACTOR threads in parallel writing to a single $SCRATCH_MNT/test-file. With atomic writes this test ensures that we never see the mix of data contents from different threads on a given bsrange.

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 tests/ext4/061     | 130 +++++++++++++++++++++++++++++++++++++++++++++
 tests/ext4/061.out |   2 +
 2 files changed, 132 insertions(+)
 create mode 100755 tests/ext4/061
 create mode 100644 tests/ext4/061.out

tests/ext4/061 new file +130 -0

new file mode 100755
index 00000000..a0e49249
@@ -0,0 +1,130 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 IBM Corporation. All Rights Reserved.
+#
+# FS QA Test 061
+#
+# Brute force all possible blocksize clustersize combination on a bigalloc
+# filesystem for stressing atomic write using fio data crc verifier. We run
+# nproc * 2 * $LOAD_FACTOR threads in parallel writing to a single
+# $SCRATCH_MNT/test-file. With fio aio-dio atomic write this test ensures that
+# we should never see the mix of data contents from different threads for any
+# given fio blocksize.
+#
+
+. ./common/preamble
+. ./common/atomicwrites
+
+_begin_fstest auto rw stress atomicwrites
+
+_require_scratch_write_atomic
+_require_aiodio
+
+FIO_LOAD=$(($(nproc) * 2 * LOAD_FACTOR))
+SIZE=$((100*1024*1024))
+fiobsize=4096
+
+# Calculate fsblocksize as per bdev atomic write units.
+bdev_awu_min=$(_get_atomic_write_unit_min $SCRATCH_DEV)
+bdev_awu_max=$(_get_atomic_write_unit_max $SCRATCH_DEV)
+fsblocksize=$(_max 4096 "$bdev_awu_min")
+
+function create_fio_configs()
+{
+	create_fio_aw_config
+	create_fio_verify_config
+}
+
+function create_fio_verify_config()
+{
+cat >$fio_verify_config <<EOF
+	[aio-dio-aw-verify]
+	direct=1
+	ioengine=libaio
+	rw=randwrite
+	bs=$fiobsize
+	fallocate=native
+	filename=$SCRATCH_MNT/test-file
+	size=$SIZE
+	iodepth=$FIO_LOAD
+	numjobs=$FIO_LOAD
+	atomic=1
+	group_reporting=1
+
+	verify_only=1
+	verify_state_save=0
+	verify=crc32c
+	verify_fatal=1
+	verify_write_sequence=0
+EOF
+}
+
+function create_fio_aw_config()
+{
+cat >$fio_aw_config <<EOF
+	[aio-dio-aw]
+	direct=1
+	ioengine=libaio
+	rw=randwrite
+	bs=$fiobsize
+	fallocate=native
+	filename=$SCRATCH_MNT/test-file
+	size=$SIZE
+	iodepth=$FIO_LOAD
+	numjobs=$FIO_LOAD
+	group_reporting=1
+	atomic=1
+
+	verify_state_save=0
+	verify=crc32c
+	do_verify=0
+
+EOF
+}
+
+# Let's create a sample fio config to check whether fio supports all options.
+fio_aw_config=$tmp.aw.fio
+fio_verify_config=$tmp.verify.fio
+fio_out=$tmp.fio.out
+
+create_fio_configs
+_require_fio $fio_aw_config
+
+for ((fsblocksize=$fsblocksize; fsblocksize <= $(_get_page_size); fsblocksize = $fsblocksize << 1)); do
+	# cluster sizes above 16 x blocksize are experimental so avoid them
+	# Also, cap cluster size at 128kb to keep it reasonable for large
+	# blocks size
+	fs_max_clustersize=$(_min $((16 * fsblocksize)) "$bdev_awu_max" $((128 * 1024)))
+
+	for ((fsclustersize=$fsblocksize; fsclustersize <= $fs_max_clustersize; fsclustersize = $fsclustersize << 1)); do
+		for ((fiobsize = $fsblocksize; fiobsize <= $fsclustersize; fiobsize = $fiobsize << 1)); do
+			MKFS_OPTIONS="-O bigalloc -b $fsblocksize -C $fsclustersize"
+			_scratch_mkfs_ext4  >> $seqres.full 2>&1 || continue
+			if _try_scratch_mount >> $seqres.full 2>&1; then
+				echo "== FIO test for fsblocksize=$fsblocksize fsclustersize=$fsclustersize fiobsize=$fiobsize ==" >> $seqres.full
+
+				touch $SCRATCH_MNT/f1
+				create_fio_configs
+
+				cat $fio_aw_config >> $seqres.full
+				echo >> $seqres.full
+				cat $fio_verify_config >> $seqres.full
+
+				$FIO_PROG $fio_aw_config >> $seqres.full
+				ret1=$?
+
+				$FIO_PROG $fio_verify_config >> $seqres.full
+				ret2=$?
+
+				_scratch_unmount
+
+				[[ $ret1 -eq 0 && $ret2 -eq 0 ]] || _fail "fio with atomic write failed"
+			fi
+		done
+	done
+done
+
+# success, all done
+echo Silence is golden
+status=0
+exit

tests/ext4/061.out new file +2 -0

new file mode 100644
index 00000000..273be9e0
@@ -0,0 +1,2 @@
+QA output created by 061
+Silence is golden

Signature · 1 line

2.49.0

Quoted 8 lines · Ojaswin Mujoo

From: "Ritesh Harjani (IBM)" <[email protected]>

We brute force all possible blocksize & clustersize combinations on a bigalloc filesystem for stressing atomic write using fio data crc verifier. We run nproc * $LOAD_FACTOR threads in parallel writing to a single $SCRATCH_MNT/test-file. With atomic writes this test ensures that we never see the mix of data contents from different threads on a given bsrange.

Err, how does this differ from the next patch? It looks like this one creates one IO thread, whereas the next one creates 8? If so, what does this test add over ext4/062?

(and now that I look at it, ext4/062 says "FS QA Test 061"...)

--D

Quoted 157 lines

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 tests/ext4/061     | 130 +++++++++++++++++++++++++++++++++++++++++++++
 tests/ext4/061.out |   2 +
 2 files changed, 132 insertions(+)
 create mode 100755 tests/ext4/061
 create mode 100644 tests/ext4/061.out

tests/ext4/061 new file +130 -0

new file mode 100755
index 00000000..a0e49249
@@ -0,0 +1,130 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025 IBM Corporation. All Rights Reserved.
+#
+# FS QA Test 061
+#
+# Brute force all possible blocksize clustersize combination on a bigalloc
+# filesystem for stressing atomic write using fio data crc verifier. We run
+# nproc * 2 * $LOAD_FACTOR threads in parallel writing to a single
+# $SCRATCH_MNT/test-file. With fio aio-dio atomic write this test ensures that
+# we should never see the mix of data contents from different threads for any
+# given fio blocksize.
+#
+
+. ./common/preamble
+. ./common/atomicwrites
+
+_begin_fstest auto rw stress atomicwrites
+
+_require_scratch_write_atomic
+_require_aiodio
+
+FIO_LOAD=$(($(nproc) * 2 * LOAD_FACTOR))
+SIZE=$((100*1024*1024))
+fiobsize=4096
+
+# Calculate fsblocksize as per bdev atomic write units.
+bdev_awu_min=$(_get_atomic_write_unit_min $SCRATCH_DEV)
+bdev_awu_max=$(_get_atomic_write_unit_max $SCRATCH_DEV)
+fsblocksize=$(_max 4096 "$bdev_awu_min")
+
+function create_fio_configs()
+{
+	create_fio_aw_config
+	create_fio_verify_config
+}
+
+function create_fio_verify_config()
+{
+cat >$fio_verify_config <<EOF
+	[aio-dio-aw-verify]
+	direct=1
+	ioengine=libaio
+	rw=randwrite
+	bs=$fiobsize
+	fallocate=native
+	filename=$SCRATCH_MNT/test-file
+	size=$SIZE
+	iodepth=$FIO_LOAD
+	numjobs=$FIO_LOAD
+	atomic=1
+	group_reporting=1
+
+	verify_only=1
+	verify_state_save=0
+	verify=crc32c
+	verify_fatal=1
+	verify_write_sequence=0
+EOF
+}
+
+function create_fio_aw_config()
+{
+cat >$fio_aw_config <<EOF
+	[aio-dio-aw]
+	direct=1
+	ioengine=libaio
+	rw=randwrite
+	bs=$fiobsize
+	fallocate=native
+	filename=$SCRATCH_MNT/test-file
+	size=$SIZE
+	iodepth=$FIO_LOAD
+	numjobs=$FIO_LOAD
+	group_reporting=1
+	atomic=1
+
+	verify_state_save=0
+	verify=crc32c
+	do_verify=0
+
+EOF
+}
+
+# Let's create a sample fio config to check whether fio supports all options.
+fio_aw_config=$tmp.aw.fio
+fio_verify_config=$tmp.verify.fio
+fio_out=$tmp.fio.out
+
+create_fio_configs
+_require_fio $fio_aw_config
+
+for ((fsblocksize=$fsblocksize; fsblocksize <= $(_get_page_size); fsblocksize = $fsblocksize << 1)); do
+	# cluster sizes above 16 x blocksize are experimental so avoid them
+	# Also, cap cluster size at 128kb to keep it reasonable for large
+	# blocks size
+	fs_max_clustersize=$(_min $((16 * fsblocksize)) "$bdev_awu_max" $((128 * 1024)))
+
+	for ((fsclustersize=$fsblocksize; fsclustersize <= $fs_max_clustersize; fsclustersize = $fsclustersize << 1)); do
+		for ((fiobsize = $fsblocksize; fiobsize <= $fsclustersize; fiobsize = $fiobsize << 1)); do
+			MKFS_OPTIONS="-O bigalloc -b $fsblocksize -C $fsclustersize"
+			_scratch_mkfs_ext4  >> $seqres.full 2>&1 || continue
+			if _try_scratch_mount >> $seqres.full 2>&1; then
+				echo "== FIO test for fsblocksize=$fsblocksize fsclustersize=$fsclustersize fiobsize=$fiobsize ==" >> $seqres.full
+
+				touch $SCRATCH_MNT/f1
+				create_fio_configs
+
+				cat $fio_aw_config >> $seqres.full
+				echo >> $seqres.full
+				cat $fio_verify_config >> $seqres.full
+
+				$FIO_PROG $fio_aw_config >> $seqres.full
+				ret1=$?
+
+				$FIO_PROG $fio_verify_config >> $seqres.full
+				ret2=$?
+
+				_scratch_unmount
+
+				[[ $ret1 -eq 0 && $ret2 -eq 0 ]] || _fail "fio with atomic write failed"
+			fi
+		done
+	done
+done
+
+# success, all done
+echo Silence is golden
+status=0
+exit

tests/ext4/061.out new file +2 -0

new file mode 100644
index 00000000..273be9e0
@@ -0,0 +1,2 @@
+QA output created by 061
+Silence is golden

Signature · 1 line

2.49.0

From: "Ritesh Harjani (IBM)" <[email protected]>

Brute force all possible blocksize clustersize combination on a bigalloc filesystem for stressing atomic write using fio data crc verifier. We run multiple threads in parallel with each job writing to its own file. The parallel jobs running on a constrained filesystem size ensure that we stress the ext4 allocator to allocate contiguous extents.

Signed-off-by Ritesh Harjani (IBM) <[email protected]>

Signed-off-by Ojaswin Mujoo <[email protected]>

---
 tests/ext4/062     | 176 +++++++++++++++++++++++++++++++++++++++++++++
 tests/ext4/062.out |   2 +
 2 files changed, 178 insertions(+)
 create mode 100755 tests/ext4/062
 create mode 100644 tests/ext4/062.out

tests/ext4/062 new file +2 -0

new file mode 100755
index 00000000..85b82f97
@@ -0,0 +1,176 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0