Add support for journal disk hot add/remove. Mostly trival checks in md
part. The raid5 part is a little tricky. For hot-remove, we can't wait
pending write as it's called from raid5d. The wait will cause deadlock.
We simplily fail the hot-remove. A hot-remove retry can success
eventually since if journal disk is faulty all pending write will be
failed and finish. For hot-add, since an array supporting journal but
without journal disk will be marked read-only, we are safe to hot add
journal without stopping IO (should be read IO, while journal only
handles write IO).
Signed-off-by: Shaohua Li <shli@xxxxxx>
---
drivers/md/md.c | 44 +++++++++++++++++++++++++++++++++-----------
drivers/md/raid5.c | 31 +++++++++++++++++++++++--------
2 files changed, 56 insertions(+), 19 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 807095f..de9e3a1 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2053,7 +2053,9 @@ static int bind_rdev_to_array(struct md_rdev *rdev, struct mddev *mddev)
/* make sure rdev->sectors exceeds mddev->dev_sectors */
if (rdev->sectors && (mddev->dev_sectors == 0 ||
- rdev->sectors < mddev->dev_sectors)) {
+ rdev->sectors < mddev->dev_sectors) &&
+ !(test_bit(MD_HAS_JOURNAL, &mddev->flags) &&
+ test_bit(Journal, &rdev->flags))) {
if (mddev->pers) {
/* Cannot change size, so fail
* If mddev->level <= 0, then we don't care
@@ -2084,7 +2086,9 @@ static int bind_rdev_to_array(struct md_rdev *rdev, struct mddev *mddev)
}
}
rcu_read_unlock();
- if (mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {
+ if (mddev->max_disks && rdev->desc_nr >= mddev->max_disks &&
+ !(test_bit(MD_HAS_JOURNAL, &mddev->flags) &&
+ test_bit(Journal, &rdev->flags))) {
printk(KERN_WARNING "md: %s: array is limited to %d devices\n",
mdname(mddev), mddev->max_disks);
return -EBUSY;
@@ -6031,8 +6035,25 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
else
clear_bit(WriteMostly, &rdev->flags);
- if (info->state & (1<<MD_DISK_JOURNAL))
+ if (info->state & (1<<MD_DISK_JOURNAL)) {
+ struct md_rdev *rdev2;
+ bool has_journal = false;
+
+ /* make sure no existing journal disk */
+ rcu_read_lock();
+ rdev_for_each(rdev2, mddev) {
+ if (test_bit(Journal, &rdev2->flags)) {
+ has_journal = true;
+ break;
+ }
+ }
+ rcu_read_unlock();
+ if (has_journal) {
+ export_rdev(rdev);
+ return -EBUSY;
+ }
set_bit(Journal, &rdev->flags);
+ }
/*
* check whether the device shows up in other nodes
*/
@@ -8162,19 +8183,20 @@ static int remove_and_add_spares(struct mddev *mddev,
continue;
if (test_bit(Faulty, &rdev->flags))
continue;
- if (test_bit(Journal, &rdev->flags))
- continue;
- if (mddev->ro &&
- ! (rdev->saved_raid_disk >= 0 &&
- !test_bit(Bitmap_sync, &rdev->flags)))
- continue;
+ if (!test_bit(Journal, &rdev->flags)) {
+ if (mddev->ro &&
+ ! (rdev->saved_raid_disk >= 0 &&
+ !test_bit(Bitmap_sync, &rdev->flags)))
+ continue;
- rdev->recovery_offset = 0;
+ rdev->recovery_offset = 0;
+ }
if (mddev->pers->
hot_add_disk(mddev, rdev) == 0) {
if (sysfs_link_rdev(mddev, rdev))
/* failure here is OK */;
- spares++;
+ if (!test_bit(Journal, &rdev->flags))
+ spares++;
md_new_event(mddev);
set_bit(MD_CHANGE_DEVS, &mddev->flags);
}
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 704ef7f..f8f3d52 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7141,14 +7141,16 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
struct disk_info *p = conf->disks + number;
print_raid5_conf(conf);
- if (test_bit(Journal, &rdev->flags)) {
+ if (test_bit(Journal, &rdev->flags) && conf->log) {
/*
- * journal disk is not removable, but we need give a chance to
- * update superblock of other disks. Otherwise journal disk
- * will be considered as 'fresh'
+ * we can't wait pending write here, as this is called in
+ * raid5d, wait will deadlock.
*/
- set_bit(MD_CHANGE_DEVS, &mddev->flags);
- return -EINVAL;
+ if (atomic_read(&mddev->writes_pending))
+ return -EBUSY;
+ r5l_exit_log(conf->log);
+ conf->log = NULL;
+ return 0;
}
if (rdev == p->rdev)
rdevp = &p->rdev;
@@ -7212,8 +7214,21 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
int first = 0;
int last = conf->raid_disks - 1;
- if (test_bit(Journal, &rdev->flags))
- return -EINVAL;
+ if (test_bit(Journal, &rdev->flags)) {
+ char b[BDEVNAME_SIZE];
+ if (conf->log)
+ return -EBUSY;
+
+ rdev->raid_disk = mddev->raid_disks;
+ /*
+ * The array is in readonly mode if journal is missing, so no
+ * write requests running. We should be safe
+ */
+ r5l_init_log(conf, rdev);
+ printk(KERN_INFO"md/raid:%s: using device %s as journal\n",
+ mdname(mddev), bdevname(rdev->bdev, b));
+ return 0;
+ }
if (mddev->recovery_disabled == conf->recovery_disabled)
return -EBUSY;
--
2.4.6
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