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Subject[PATCH 004 of 9] md: Fix 'safemode' handling for external metadata.

'safemode' relates to marking an array as 'clean' if there has been
no write traffic for a while (a couple of seconds), to reduce the chance
of the array being found dirty on reboot.

->safemode is set to '1' when there have been no write for a while, and
it gets set to '0' when the superblock is updates with the 'clean' flag set.

This requires a few fixes for 'external' metadata:
- When an array is set to 'clean' via sysfs, 'safemode' must be cleared.
- when we write to an array that has 'safemode' set (there must have been
some delay in updating the metadata), we need to clear safemode.
- Don't try to update external metadata in md_check_recovery for safemode
transitions - it won't work.

Also, don't try to support "immediate safe mode" (safemode==2) for external
metadata, it cannot really work (the safemode timeout can be set very low
if this is really needed).

Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
./drivers/md/md.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)

diff .prev/drivers/md/md.c ./drivers/md/md.c
--- .prev/drivers/md/md.c 2008-04-29 12:27:56.000000000 +1000
+++ ./drivers/md/md.c 2008-04-29 12:27:56.000000000 +1000
@@ -2614,6 +2614,8 @@ array_state_store(mddev_t *mddev, const
if (atomic_read(&mddev->writes_pending) == 0) {
if (mddev->in_sync == 0) {
mddev->in_sync = 1;
+ if (mddev->safemode == 1)
+ mddev->safemode = 0;
if (mddev->persistent)
set_bit(MD_CHANGE_CLEAN,
&mddev->flags);
@@ -5391,6 +5393,8 @@ void md_write_start(mddev_t *mddev, stru
md_wakeup_thread(mddev->sync_thread);
}
atomic_inc(&mddev->writes_pending);
+ if (mddev->safemode == 1)
+ mddev->safemode = 0;
if (mddev->in_sync) {
spin_lock_irq(&mddev->write_lock);
if (mddev->in_sync) {
@@ -5815,7 +5819,7 @@ void md_check_recovery(mddev_t *mddev)
return;

if (signal_pending(current)) {
- if (mddev->pers->sync_request) {
+ if (mddev->pers->sync_request && !mddev->external) {
printk(KERN_INFO "md: %s in immediate safe mode\n",
mdname(mddev));
mddev->safemode = 2;
@@ -5827,7 +5831,7 @@ void md_check_recovery(mddev_t *mddev)
(mddev->flags && !mddev->external) ||
test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
- (mddev->safemode == 1) ||
+ (mddev->external == 0 && mddev->safemode == 1) ||
(mddev->safemode == 2 && ! atomic_read(&mddev->writes_pending)
&& !mddev->in_sync && mddev->recovery_cp == MaxSector)
))
@@ -5836,16 +5840,20 @@ void md_check_recovery(mddev_t *mddev)
if (mddev_trylock(mddev)) {
int spares = 0;

- spin_lock_irq(&mddev->write_lock);
- if (mddev->safemode && !atomic_read(&mddev->writes_pending) &&
- !mddev->in_sync && mddev->recovery_cp == MaxSector) {
- mddev->in_sync = 1;
- if (mddev->persistent)
- set_bit(MD_CHANGE_CLEAN, &mddev->flags);
+ if (!mddev->external) {
+ spin_lock_irq(&mddev->write_lock);
+ if (mddev->safemode &&
+ !atomic_read(&mddev->writes_pending) &&
+ !mddev->in_sync &&
+ mddev->recovery_cp == MaxSector) {
+ mddev->in_sync = 1;
+ if (mddev->persistent)
+ set_bit(MD_CHANGE_CLEAN, &mddev->flags);
+ }
+ if (mddev->safemode == 1)
+ mddev->safemode = 0;
+ spin_unlock_irq(&mddev->write_lock);
}
- if (mddev->safemode == 1)
- mddev->safemode = 0;
- spin_unlock_irq(&mddev->write_lock);

if (mddev->flags)
md_update_sb(mddev, 0);

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