Re: [PATCH 1/2] xfs: remove efi from AIL in log recovery error

[Brian Foster <bfoster@redhat.com>]

On Tue, Mar 25, 2014 at 03:06:34PM -0500, Mark Tinguely wrote:
> xlog_recover_process_efi{s}() functions are completing the
> second half of xfs_bmap_finish() which frees extents. If this
> operation fails, the EFI will stay on the AIL and prevents
> the xfs_ail_push all_sync() from completing and the mount will
> fail to unmount.
> 
> Rather than have a special log recovery flag XFS_EFI_RECOVERED
> to decrement the EFI/EFD counter, call the same decrement function
> from the log recovery routine that is called then the EFI is added
> to the AIL from a log write.
> 
> Remove all other unprocessed EFIs from the log recovery AIL
> when one is discovered in error.
> 
> Signed-off-by: Mark Tinguely <tinguely@sgi.com>
> ---
> Rewritten with suggestions from Dave.
> Note: calling xfs_efi_item_unpin() seemed more explainatory than calling
>       the helper __xfs_efi_release().
> 
>  fs/xfs/xfs_extfree_item.c |    9 +++------
>  fs/xfs/xfs_log_recover.c  |   28 +++++++++++++++-------------
>  fs/xfs/xfs_trans.h        |    1 +
>  3 files changed, 19 insertions(+), 19 deletions(-)
> 
> Index: b/fs/xfs/xfs_extfree_item.c
> ===================================================================
> --- a/fs/xfs/xfs_extfree_item.c
> +++ b/fs/xfs/xfs_extfree_item.c
> @@ -134,9 +134,10 @@ xfs_efi_item_pin(
>   * remove the EFI it's because the transaction has been canceled and by
>   * definition that means the EFI cannot be in the AIL so remove it from the
>   * transaction and free it.  Otherwise coordinate with xfs_efi_release()
> - * to determine who gets to free the EFI.
> + * to determine who gets to free the EFI. Call from log recovery of EFI
> + * entries so the EFD or error handling will remove the entry.
>   */
> -STATIC void
> +void
>  xfs_efi_item_unpin(
>  	struct xfs_log_item	*lip,
>  	int			remove)
> @@ -313,10 +314,6 @@ xfs_efi_release(xfs_efi_log_item_t	*efip
>  {
>  	ASSERT(atomic_read(&efip->efi_next_extent) >= nextents);
>  	if (atomic_sub_and_test(nextents, &efip->efi_next_extent)) {
> -		/* recovery needs us to drop the EFI reference, too */
> -		if (test_bit(XFS_EFI_RECOVERED, &efip->efi_flags))
> -			__xfs_efi_release(efip);
> -
>  		__xfs_efi_release(efip);
>  		/* efip may now have been freed, do not reference it again. */
>  	}
> Index: b/fs/xfs/xfs_log_recover.c
> ===================================================================
> --- a/fs/xfs/xfs_log_recover.c
> +++ b/fs/xfs/xfs_log_recover.c
> @@ -3634,6 +3634,7 @@ xlog_recover_process_data(
>  /*
>   * Process an extent free intent item that was recovered from
>   * the log.  We need to free the extents that it describes.
> + * The caller will release this and any following EFIs upon error.
>   */
>  STATIC int
>  xlog_recover_process_efi(
> @@ -3648,6 +3649,13 @@ xlog_recover_process_efi(
>  	xfs_fsblock_t		startblock_fsb;
>  
>  	ASSERT(!test_bit(XFS_EFI_RECOVERED, &efip->efi_flags));
> +	set_bit(XFS_EFI_RECOVERED, &efip->efi_flags);
> +
> +	/*
> +	 * Decrement the EFI/EFD counter so the EFI is removed after
> +	 * processing the EFD or error handling in the caller.
> +	 */
> +	xfs_efi_item_unpin(&efip->efi_item, 0);
>  
>  	/*
>  	 * First check the validity of the extents described by the
> @@ -3662,12 +3670,6 @@ xlog_recover_process_efi(
>  		    (extp->ext_len == 0) ||
>  		    (startblock_fsb >= mp->m_sb.sb_dblocks) ||
>  		    (extp->ext_len >= mp->m_sb.sb_agblocks)) {
> -			/*
> -			 * This will pull the EFI from the AIL and
> -			 * free the memory associated with it.
> -			 */
> -			set_bit(XFS_EFI_RECOVERED, &efip->efi_flags);
> -			xfs_efi_release(efip, efip->efi_format.efi_nextents);
>  			return XFS_ERROR(EIO);
>  		}
>  	}
> @@ -3687,7 +3689,6 @@ xlog_recover_process_efi(
>  					 extp->ext_len);
>  	}
>  
> -	set_bit(XFS_EFI_RECOVERED, &efip->efi_flags);
>  	error = xfs_trans_commit(tp, 0);
>  	return error;
>  
> @@ -3718,8 +3719,8 @@ STATIC int
>  xlog_recover_process_efis(
>  	struct xlog	*log)
>  {
> -	xfs_log_item_t		*lip;
> -	xfs_efi_log_item_t	*efip;
> +	struct xfs_log_item	*lip;
> +	struct xfs_efi_log_item	*efip;
>  	int			error = 0;
>  	struct xfs_ail_cursor	cur;
>  	struct xfs_ail		*ailp;
> @@ -3750,13 +3751,14 @@ xlog_recover_process_efis(
>  		}
>  
>  		spin_unlock(&ailp->xa_lock);
> -		error = xlog_recover_process_efi(log->l_mp, efip);
> -		spin_lock(&ailp->xa_lock);
> +		/* Skip all EFIs after first EFI in error. */
> +		if (!error)
> +			error = xlog_recover_process_efi(log->l_mp, efip);
>  		if (error)
> -			goto out;
> +			xfs_efi_release(efip, efip->efi_format.efi_nextents);

Hi Mark,

If we hit the scenario where we start skipping EFIs after an error, is
the equivalent unpin() call from process_efi() not necessary on the
subsequent EFIs?

Brian

> +		spin_lock(&ailp->xa_lock);
>  		lip = xfs_trans_ail_cursor_next(ailp, &cur);
>  	}
> -out:
>  	xfs_trans_ail_cursor_done(ailp, &cur);
>  	spin_unlock(&ailp->xa_lock);
>  	return error;
> Index: b/fs/xfs/xfs_trans.h
> ===================================================================
> --- a/fs/xfs/xfs_trans.h
> +++ b/fs/xfs/xfs_trans.h
> @@ -216,6 +216,7 @@ void		xfs_trans_ijoin(struct xfs_trans *
>  void		xfs_trans_log_buf(xfs_trans_t *, struct xfs_buf *, uint, uint);
>  void		xfs_trans_log_inode(xfs_trans_t *, struct xfs_inode *, uint);
>  struct xfs_efi_log_item	*xfs_trans_get_efi(xfs_trans_t *, uint);
> +void		xfs_efi_item_unpin(struct xfs_log_item *, int);
>  void		xfs_efi_release(struct xfs_efi_log_item *, uint);
>  void		xfs_trans_log_efi_extent(xfs_trans_t *,
>  					 struct xfs_efi_log_item *,
> 
> 
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