On Nov 13, 2007 8:43 PM, Greg KH <greg@xxxxxxxxx> wrote:
> >
> > Careful, it looks like you cherry picked commit 4ae3f847 "md: raid5:
> > fix clearing of biofill operations" which ended up misapplied in
> > Linus' tree, You should either also pick up def6ae26 "md: fix
> > misapplied patch in raid5.c" or I can resend the original "raid5: fix
> > clearing of biofill operations."
> >
> > The other patch for -stable "raid5: fix unending write sequence" is
> > currently in -mm.
>
> Hm, I've attached the two patches that I have right now in the -stable
> tree so far (still have over 100 patches to go, so I might not have
> gotten to them yet if you have sent them). These were sent to me by
> Andrew on their way to Linus. if I should drop either one, or add
> another one, please let me know.
>
Drop md-raid5-fix-clearing-of-biofill-operations.patch and replace it
with the attached
md-raid5-not-raid6-fix-clearing-of-biofill-operations.patch (the
original sent to Neil).
The critical difference is that the replacement patch touches
handle_stripe5, not handle_stripe6. Diffing the patches shows the
changes for hunk #3:
-@@ -2903,6 +2907,13 @@ static void handle_stripe6(struct stripe
+@@ -2630,6 +2634,13 @@ static void handle_stripe5(struct stripe_head *sh)
raid5-fix-unending-write-sequence.patch is in -mm and I believe is
waiting on an Acked-by from Neil?
> thanks,
>
> greg k-h
Thanks,
Dan
raid5: fix clearing of biofill operations
From: Dan Williams <dan.j.williams@xxxxxxxxx>
ops_complete_biofill() runs outside of spin_lock(&sh->lock) and clears the
'pending' and 'ack' bits. Since the test_and_ack_op() macro only checks
against 'complete' it can get an inconsistent snapshot of pending work.
Move the clearing of these bits to handle_stripe5(), under the lock.
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Tested-by: Joel Bertrand <joel.bertrand@xxxxxxxxxxx>
Signed-off-by: Neil Brown <neilb@xxxxxxx>
---
drivers/md/raid5.c | 17 ++++++++++++++---
1 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f96dea9..3808f52 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -377,7 +377,12 @@ static unsigned long get_stripe_work(struct stripe_head *sh)
ack++;
sh->ops.count -= ack;
- BUG_ON(sh->ops.count < 0);
+ if (unlikely(sh->ops.count < 0)) {
+ printk(KERN_ERR "pending: %#lx ops.pending: %#lx ops.ack: %#lx "
+ "ops.complete: %#lx\n", pending, sh->ops.pending,
+ sh->ops.ack, sh->ops.complete);
+ BUG();
+ }
return pending;
}
@@ -551,8 +556,7 @@ static void ops_complete_biofill(void *stripe_head_ref)
}
}
}
- clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
- clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
+ set_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
return_io(return_bi);
@@ -2630,6 +2634,13 @@ static void handle_stripe5(struct stripe_head *sh)
s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
/* Now to look around and see what can be done */
+ /* clean-up completed biofill operations */
+ if (test_bit(STRIPE_OP_BIOFILL, &sh->ops.complete)) {
+ clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
+ clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
+ clear_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
+ }
+
rcu_read_lock();
for (i=disks; i--; ) {
mdk_rdev_t *rdev;
raid5: fix unending write sequence
From: Dan Williams <dan.j.williams@xxxxxxxxx>
<debug output from Joel's system>
handling stripe 7629696, state=0x14 cnt=1, pd_idx=2 ops=0:0:0
check 5: state 0x6 toread 0000000000000000 read 0000000000000000 write fffff800ffcffcc0 written 0000000000000000
check 4: state 0x6 toread 0000000000000000 read 0000000000000000 write fffff800fdd4e360 written 0000000000000000
check 3: state 0x1 toread 0000000000000000 read 0000000000000000 write 0000000000000000 written 0000000000000000
check 2: state 0x1 toread 0000000000000000 read 0000000000000000 write 0000000000000000 written 0000000000000000
check 1: state 0x6 toread 0000000000000000 read 0000000000000000 write fffff800ff517e40 written 0000000000000000
check 0: state 0x6 toread 0000000000000000 read 0000000000000000 write fffff800fd4cae60 written 0000000000000000
locked=4 uptodate=2 to_read=0 to_write=4 failed=0 failed_num=0
for sector 7629696, rmw=0 rcw=0
</debug>
These blocks were prepared to be written out, but were never handled in
ops_run_biodrain(), so they remain locked forever. The operations flags
are all clear which means handle_stripe() thinks nothing else needs to be
done.
This state suggests that the STRIPE_OP_PREXOR bit was sampled 'set' when it
should not have been. This patch cleans up cases where the code looks at
sh->ops.pending when it should be looking at the consistent stack-based
snapshot of the operations flags.
Report from Joel:
Resync done. Patch fix this bug.
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Tested-by: Joel Bertrand <joel.bertrand@xxxxxxxxxxx>
Cc: stable@xxxxxxxxxx
---
drivers/md/raid5.c | 16 +++++++++-------
1 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 3808f52..e86cacb 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -689,7 +689,8 @@ ops_run_prexor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
}
static struct dma_async_tx_descriptor *
-ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
+ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
+ unsigned long pending)
{
int disks = sh->disks;
int pd_idx = sh->pd_idx, i;
@@ -697,7 +698,7 @@ ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
/* check if prexor is active which means only process blocks
* that are part of a read-modify-write (Wantprexor)
*/
- int prexor = test_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
+ int prexor = test_bit(STRIPE_OP_PREXOR, &pending);
pr_debug("%s: stripe %llu\n", __FUNCTION__,
(unsigned long long)sh->sector);
@@ -774,7 +775,8 @@ static void ops_complete_write(void *stripe_head_ref)
}
static void
-ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
+ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx,
+ unsigned long pending)
{
/* kernel stack size limits the total number of disks */
int disks = sh->disks;
@@ -782,7 +784,7 @@ ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
int count = 0, pd_idx = sh->pd_idx, i;
struct page *xor_dest;
- int prexor = test_bit(STRIPE_OP_PREXOR, &sh->ops.pending);
+ int prexor = test_bit(STRIPE_OP_PREXOR, &pending);
unsigned long flags;
dma_async_tx_callback callback;
@@ -809,7 +811,7 @@ ops_run_postxor(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
}
/* check whether this postxor is part of a write */
- callback = test_bit(STRIPE_OP_BIODRAIN, &sh->ops.pending) ?
+ callback = test_bit(STRIPE_OP_BIODRAIN, &pending) ?
ops_complete_write : ops_complete_postxor;
/* 1/ if we prexor'd then the dest is reused as a source
@@ -897,12 +899,12 @@ static void raid5_run_ops(struct stripe_head *sh, unsigned long pending)
tx = ops_run_prexor(sh, tx);
if (test_bit(STRIPE_OP_BIODRAIN, &pending)) {
- tx = ops_run_biodrain(sh, tx);
+ tx = ops_run_biodrain(sh, tx, pending);
overlap_clear++;
}
if (test_bit(STRIPE_OP_POSTXOR, &pending))
- ops_run_postxor(sh, tx);
+ ops_run_postxor(sh, tx, pending);
if (test_bit(STRIPE_OP_CHECK, &pending))
ops_run_check(sh);
