fio: add FIO_RO_NEEDS_RW_OPEN ioengine flag

Some oddball cases like sg/bsg require devices to be opened for writing in order to do read commands. So fio has been opening character devices in rw mode for read workloads. However, nvme generic character devices do not need (and may refuse) a writeable open for read workloads. So instead of always opening character devices in rw mode, open devices in rw mode for read workloads only if the ioengine has the FIO_RO_NEEDS_RW_OPEN flag. Link: https://lore.kernel.org/fio/[email protected]/ Signed-off-by: Vincent Fu <[email protected]>
Dummyc0m · Feb 3, 2023 · d72b10e · d72b10e
1 parent 3a6ae7b
commit d72b10e
Show file tree

Hide file tree

Showing 3 changed files with 4 additions and 2 deletions.
diff --git a/engines/sg.c b/engines/sg.c
@@ -1428,7 +1428,7 @@ static struct ioengine_ops ioengine = {
 	.open_file	= fio_sgio_open,
 	.close_file	= fio_sgio_close,
 	.get_file_size	= fio_sgio_get_file_size,
-	.flags		= FIO_SYNCIO | FIO_RAWIO,
+	.flags		= FIO_SYNCIO | FIO_RAWIO | FIO_RO_NEEDS_RW_OPEN,
 	.options	= options,
 	.option_struct_size	= sizeof(struct sg_options)
 };

diff --git a/filesetup.c b/filesetup.c
@@ -768,7 +768,7 @@ int generic_open_file(struct thread_data *td, struct fio_file *f)
 		else
 			from_hash = file_lookup_open(f, flags);
 	} else if (td_read(td)) {
-		if (f->filetype == FIO_TYPE_CHAR && !read_only)
+		if (td_ioengine_flagged(td, FIO_RO_NEEDS_RW_OPEN) && !read_only)
 			flags |= O_RDWR;
 		else
 			flags |= O_RDONLY;

diff --git a/ioengines.h b/ioengines.h
@@ -89,6 +89,8 @@ enum fio_ioengine_flags {
 			= 1 << 16,	/* async ioengine with commit function that sets issue_time */
 	FIO_SKIPPABLE_IOMEM_ALLOC
 			= 1 << 17,	/* skip iomem_alloc & iomem_free if job sets mem/iomem */
+	FIO_RO_NEEDS_RW_OPEN
+			= 1 << 18,	/* open files in rw mode even if we have a read job */
 };
 
 /*