md/raid10: locking changes for 'enough()'.
As 'enough' accesses conf->prev and conf->geo, which can change
spontanously, it should guard against changes.
This can be done with device_lock as start_reshape holds device_lock
while updating 'geo' and end_reshape holds it while updating 'prev'.
So 'error' needs to hold 'device_lock'.
On the other hand, raid10_end_read_request knows which of the two it
really wants to access, and as it is an active request on that one,
the value cannot change underneath it.
So change _enough to take flag rather than a pointer, pass the
appropriate flag from raid10_end_read_request(), and remove the locking.
All other calls to 'enough' are made with reconfig_mutex held, so
neither 'prev' nor 'geo' can change.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 3c6b193..5169ed2 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -97,7 +97,7 @@
static void allow_barrier(struct r10conf *conf);
static void lower_barrier(struct r10conf *conf);
-static int enough(struct r10conf *conf, int ignore);
+static int _enough(struct r10conf *conf, int previous, int ignore);
static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
int *skipped);
static void reshape_request_write(struct mddev *mddev, struct r10bio *r10_bio);
@@ -392,11 +392,9 @@
* than fail the last device. Here we redefine
* "uptodate" to mean "Don't want to retry"
*/
- unsigned long flags;
- spin_lock_irqsave(&conf->device_lock, flags);
- if (!enough(conf, rdev->raid_disk))
+ if (!_enough(conf, test_bit(R10BIO_Previous, &r10_bio->state),
+ rdev->raid_disk))
uptodate = 1;
- spin_unlock_irqrestore(&conf->device_lock, flags);
}
if (uptodate) {
raid_end_bio_io(r10_bio);
@@ -1632,9 +1630,17 @@
* Don't consider the device numbered 'ignore'
* as we might be about to remove it.
*/
-static int _enough(struct r10conf *conf, struct geom *geo, int ignore)
+static int _enough(struct r10conf *conf, int previous, int ignore)
{
int first = 0;
+ int disks, ncopies;
+ if (previous) {
+ disks = conf->prev.raid_disks;
+ ncopies = conf->prev.near_copies;
+ } else {
+ disks = conf->geo.raid_disks;
+ ncopies = conf->geo.near_copies;
+ }
do {
int n = conf->copies;
@@ -1644,25 +1650,31 @@
if (conf->mirrors[this].rdev &&
this != ignore)
cnt++;
- this = (this+1) % geo->raid_disks;
+ this = (this+1) % disks;
}
if (cnt == 0)
return 0;
- first = (first + geo->near_copies) % geo->raid_disks;
+ first = (first + ncopies) % disks;
} while (first != 0);
return 1;
}
static int enough(struct r10conf *conf, int ignore)
{
- return _enough(conf, &conf->geo, ignore) &&
- _enough(conf, &conf->prev, ignore);
+ /* when calling 'enough', both 'prev' and 'geo' must
+ * be stable.
+ * This is ensured if ->reconfig_mutex or ->device_lock
+ * is held.
+ */
+ return _enough(conf, 0, ignore) &&
+ _enough(conf, 1, ignore);
}
static void error(struct mddev *mddev, struct md_rdev *rdev)
{
char b[BDEVNAME_SIZE];
struct r10conf *conf = mddev->private;
+ unsigned long flags;
/*
* If it is not operational, then we have already marked it as dead
@@ -1670,18 +1682,18 @@
* next level up know.
* else mark the drive as failed
*/
+ spin_lock_irqsave(&conf->device_lock, flags);
if (test_bit(In_sync, &rdev->flags)
- && !enough(conf, rdev->raid_disk))
+ && !enough(conf, rdev->raid_disk)) {
/*
* Don't fail the drive, just return an IO error.
*/
- return;
- if (test_and_clear_bit(In_sync, &rdev->flags)) {
- unsigned long flags;
- spin_lock_irqsave(&conf->device_lock, flags);
- mddev->degraded++;
spin_unlock_irqrestore(&conf->device_lock, flags);
- /*
+ return;
+ }
+ if (test_and_clear_bit(In_sync, &rdev->flags)) {
+ mddev->degraded++;
+ /*
* if recovery is running, make sure it aborts.
*/
set_bit(MD_RECOVERY_INTR, &mddev->recovery);
@@ -1689,6 +1701,7 @@
set_bit(Blocked, &rdev->flags);
set_bit(Faulty, &rdev->flags);
set_bit(MD_CHANGE_DEVS, &mddev->flags);
+ spin_unlock_irqrestore(&conf->device_lock, flags);
printk(KERN_ALERT
"md/raid10:%s: Disk failure on %s, disabling device.\n"
"md/raid10:%s: Operation continuing on %d devices.\n",
@@ -1791,7 +1804,7 @@
* very different from resync
*/
return -EBUSY;
- if (rdev->saved_raid_disk < 0 && !_enough(conf, &conf->prev, -1))
+ if (rdev->saved_raid_disk < 0 && !_enough(conf, 1, -1))
return -EINVAL;
if (rdev->raid_disk >= 0)