When the running RAID1/RAID10 need to be set with the fail_fast flag,
we have to remove each device from RAID and re-add it again with the
--fail_fast flag.

Export the fail_fast flag to the userspace to support the read and
write.

Signed-off-by: Li Feng <redacted>
---
 drivers/md/md.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index ae8fe54ea358..ce63972a4555 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c

@@ -3583,6 +3583,35 @@ ppl_size_store(struct md_rdev *rdev, const char *buf, size_t len)
 static struct rdev_sysfs_entry rdev_ppl_size =
 __ATTR(ppl_size, S_IRUGO|S_IWUSR, ppl_size_show, ppl_size_store);

+static ssize_t
+fail_fast_show(struct md_rdev *rdev, char *page)
+{
+       return sprintf(page, "%d\n", test_bit(FailFast, &rdev->flags));
+}
+
+static ssize_t
+fail_fast_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+       int ret;
+       bool bit;
+
+       ret = kstrtobool(buf, &bit);
+       if (ret)
+               return ret;
+
+       if (test_bit(FailFast, &rdev->flags) && !bit) {
+               clear_bit(FailFast, &rdev->flags);
+               md_update_sb(rdev->mddev, 1);
+       } else if (!test_bit(FailFast, &rdev->flags) && bit) {
+               set_bit(FailFast, &rdev->flags);
+               md_update_sb(rdev->mddev, 1);
+       }
+       return len;
+}
+
+static struct rdev_sysfs_entry rdev_fail_fast =
+__ATTR(fail_fast, 0644, fail_fast_show, fail_fast_store);
+
 static struct attribute *rdev_default_attrs[] = {
        &rdev_state.attr,
        &rdev_errors.attr,

@@ -3595,6 +3624,7 @@ static struct attribute *rdev_default_attrs[] = {
        &rdev_unack_bad_blocks.attr,
        &rdev_ppl_sector.attr,
        &rdev_ppl_size.attr,
+       &rdev_fail_fast.attr,
        NULL,
 };
 static ssize_t
--

2.31.1