Previously O_ATOMIC support was added in commit d01612f3ae25 ("Add support
for O_ATOMIC"). But support was removed in commit a25ba6c64fe1 ("Get rid of
O_ATOMIC"), as support was never added in the Linux kernel.
Linux kernel 6.11 will add support for RWF_ATOMIC, which can be supported
for various ioengines. See latest man pages for details.
The plumbing was left in place for thread option oatomic, so that will be
reused.
Add a flag to say whether an engine supports atomic writes, and reject
when oatomic is set for an engine which does not support atomic writes.
This is a change in behaviour, as since commit a25ba6c64fe1 ("Get rid of
O_ATOMIC"), this oatomic has been ignored. However, it is better to tell
the user that their ioengine of choice does not support atomic writes.
Today RWF_ATOMIC is only supported for direct-IO. In future it may be
supported for buffered IO. As such, do not auto-set odirect=1 when
oatomic==1.
Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
---
init.c | 11 +++++++++++
ioengines.h | 2 ++
options.c | 2 ++
os/os-linux.h | 1 +
4 files changed, 16 insertions(+)
diff --git a/init.c b/init.c
index 414535cc..bad8b75b 100644
--- a/init.c
+++ b/init.c
@@ -855,6 +855,17 @@ static int fixup_options(struct thread_data *td)
o->max_bs[DDIR_WRITE]);
}
+ if (td->o.oatomic) {
+ if (!td_ioengine_flagged(td, FIO_ATOMICWRITES)) {
+ log_err("fio: engine does not support atomic writes\n");
+ td->o.oatomic = 0;
+ ret |= 1;
+ }
+
+ if (!td_write(td))
+ td->o.oatomic = 0;
+ }
+
if (o->pre_read) {
if (o->invalidate_cache)
o->invalidate_cache = 0;
diff --git a/ioengines.h b/ioengines.h
index b9834fec..1531cd89 100644
--- a/ioengines.h
+++ b/ioengines.h
@@ -96,6 +96,7 @@ enum {
__FIO_RO_NEEDS_RW_OPEN, /* open files in rw mode even if we have a read job; only
affects ioengines using generic_open_file */
__FIO_MULTI_RANGE_TRIM, /* ioengine supports trim with more than one range */
+ __FIO_ATOMICWRITES, /* ioengine supports atomic writes */
__FIO_IOENGINE_F_LAST, /* not a real bit; used to count number of bits */
};
@@ -120,6 +121,7 @@ enum fio_ioengine_flags {
FIO_SKIPPABLE_IOMEM_ALLOC = 1 << __FIO_SKIPPABLE_IOMEM_ALLOC,
FIO_RO_NEEDS_RW_OPEN = 1 << __FIO_RO_NEEDS_RW_OPEN,
FIO_MULTI_RANGE_TRIM = 1 << __FIO_MULTI_RANGE_TRIM,
+ FIO_ATOMICWRITES = 1 << __FIO_ATOMICWRITES,
};
/*
diff --git a/options.c b/options.c
index 5a6b0a06..95567de6 100644
--- a/options.c
+++ b/options.c
@@ -2926,6 +2926,7 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
.category = FIO_OPT_C_IO,
.group = FIO_OPT_G_IO_TYPE,
},
+#ifdef FIO_HAVE_RWF_ATOMIC
{
.name = "atomic",
.lname = "Atomic I/O",
@@ -2936,6 +2937,7 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
.category = FIO_OPT_C_IO,
.group = FIO_OPT_G_IO_TYPE,
},
+#endif
{
.name = "buffered",
.lname = "Buffered I/O",
diff --git a/os/os-linux.h b/os/os-linux.h
index 010a8291..ead8295c 100644
--- a/os/os-linux.h
+++ b/os/os-linux.h
@@ -62,6 +62,7 @@
#define FIO_HAVE_BYTEORDER_FUNCS
#define FIO_HAVE_PWRITEV2
#define FIO_HAVE_SHM_ATTACH_REMOVED
+#define FIO_HAVE_RWF_ATOMIC
#ifdef MAP_HUGETLB
#define FIO_HAVE_MMAP_HUGE
--
2.31.1
