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ioctl: introduce force xfer length configuration knob #1031

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Merged
igaw merged 1 commit into from
Jun 30, 2025
Merged

ioctl: introduce force xfer length configuration knob #1031

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29 changes: 26 additions & 3 deletions src/nvme/ioctl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -320,6 +320,22 @@ int nvme_get_log(struct nvme_get_log_args *args)
return nvme_submit_admin_passthru(args->fd, &cmd, args->result);
}

static bool force_4k;

__attribute__((constructor))
static void nvme_init_env(void)
{
char *val;

val = getenv("LIBNVME_FORCE_4K");
if (!val)
return;
if (!strcmp(val, "1") ||
!strcasecmp(val, "true") ||
!strncasecmp(val, "enable", 6))
force_4k = true;
}

#ifdef CONFIG_LIBURING
enum {
IO_URING_NOT_AVAILABLE,
Expand Down Expand Up @@ -449,6 +465,9 @@ int nvme_get_log_page(int fd, __u32 xfer_len, struct nvme_get_log_args *args)

args->fd = fd;

if (force_4k)
xfer_len = NVME_LOG_PAGE_PDU_SIZE;

#ifdef CONFIG_LIBURING
int n = 0;
struct io_uring ring;
Expand All @@ -469,9 +488,13 @@ int nvme_get_log_page(int fd, __u32 xfer_len, struct nvme_get_log_args *args)
* avoids having to check the MDTS value of the controller.
*/
do {
xfer = data_len - offset;
if (xfer > xfer_len)
xfer = xfer_len;
if (!force_4k) {
xfer = data_len - offset;
if (xfer > xfer_len)
xfer = xfer_len;
} else {
xfer = NVME_LOG_PAGE_PDU_SIZE;
}

/*
* Always retain regardless of the RAE parameter until the very
Expand Down