Re: [PATCH] Btrfs: fix crash of starting balance

2013-01-15 Thread Ilya Dryomov 
On Tue, Jan 15, 2013 at 10:47:57PM +0800, Liu Bo wrote:
 We will crash on BUG_ON(ret == -EEXIST) when we do not resume the existing
 balance but attempt to start a new one.
 
 The steps can be:
 1. start balance
 2. pause balance
 3. start balance
 
 Signed-off-by: Liu Bo bo.li@oracle.com
 ---
  fs/btrfs/volumes.c |7 ++-
  1 files changed, 6 insertions(+), 1 deletions(-)
 
 diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
 index 5cce6aa..3901654 100644
 --- a/fs/btrfs/volumes.c
 +++ b/fs/btrfs/volumes.c
 @@ -3100,7 +3100,12 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
   goto out;
  
   if (!(bctl-flags  BTRFS_BALANCE_RESUME)) {
 - BUG_ON(ret == -EEXIST);
 + /*
 +  * This can happen when we do not resume the existing balance
 +  * but try to start a new one instead.
 +  */
 + if (ret == -EEXIST)
 + goto out;
   set_balance_control(bctl);
   } else {
   BUG_ON(ret != -EEXIST);

OK, it seems balance pause/resume logic got broken by dev-replace code
(5ac00addc7ac09110995fe967071d191b5981cc1), which went into v3.8-rc1.
This is most certainly not the right way to fix it, that BUG_ON is there
for a reason.  I'll send a fix in a couple of days.

Thanks,

Ilya

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Re: [PATCH] Btrfs: fix crash of starting balance

2013-01-15 Thread Liu Bo 
On Tue, Jan 15, 2013 at 06:59:04PM +0200, Ilya Dryomov wrote:
 On Tue, Jan 15, 2013 at 10:47:57PM +0800, Liu Bo wrote:
  We will crash on BUG_ON(ret == -EEXIST) when we do not resume the existing
  balance but attempt to start a new one.
  
  The steps can be:
  1. start balance
  2. pause balance
  3. start balance
  
  Signed-off-by: Liu Bo bo.li@oracle.com
  ---
   fs/btrfs/volumes.c |7 ++-
   1 files changed, 6 insertions(+), 1 deletions(-)
  
  diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
  index 5cce6aa..3901654 100644
  --- a/fs/btrfs/volumes.c
  +++ b/fs/btrfs/volumes.c
  @@ -3100,7 +3100,12 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
  goto out;
   
  if (!(bctl-flags  BTRFS_BALANCE_RESUME)) {
  -   BUG_ON(ret == -EEXIST);
  +   /*
  +* This can happen when we do not resume the existing balance
  +* but try to start a new one instead.
  +*/
  +   if (ret == -EEXIST)
  +   goto out;
  set_balance_control(bctl);
  } else {
  BUG_ON(ret != -EEXIST);
 
 OK, it seems balance pause/resume logic got broken by dev-replace code
 (5ac00addc7ac09110995fe967071d191b5981cc1), which went into v3.8-rc1.
 This is most certainly not the right way to fix it, that BUG_ON is there
 for a reason.  I'll send a fix in a couple of days.

Okay, right here waiting for test ;)

thanks,
liubo
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