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Re: [PATCH 18/47] xfs: refactor redo intent item processing

To: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
Subject: Re: [PATCH 18/47] xfs: refactor redo intent item processing
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Tue, 2 Aug 2016 14:47:34 -0400
Cc: david@xxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, vishal.l.verma@xxxxxxxxx, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <146907708421.25461.405239727630066080.stgit@xxxxxxxxxxxxxxxx>
References: <146907695530.25461.3225785294902719773.stgit@xxxxxxxxxxxxxxxx> <146907708421.25461.405239727630066080.stgit@xxxxxxxxxxxxxxxx>
User-agent: Mutt/1.6.2 (2016-07-01)
On Wed, Jul 20, 2016 at 09:58:04PM -0700, Darrick J. Wong wrote:
> Refactor the EFI intent item recovery (and cancellation) functions
> into a general function that scans the AIL and an intent item type
> specific handler.  Move the function that recovers a single EFI item
> into the extent free item code.  We'll want the generalized function
> when we start wiring up more redo item types.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
>  fs/xfs/xfs_extfree_item.c |   65 ++++++++++++++++
>  fs/xfs/xfs_extfree_item.h |    3 +
>  fs/xfs/xfs_log_recover.c  |  182 
> +++++++++++++++++++++------------------------
>  3 files changed, 151 insertions(+), 99 deletions(-)
> 
> 
...
> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
> index 080b54b..af608aa 100644
> --- a/fs/xfs/xfs_log_recover.c
> +++ b/fs/xfs/xfs_log_recover.c
> @@ -24,7 +24,6 @@
>  #include "xfs_bit.h"
>  #include "xfs_sb.h"
>  #include "xfs_mount.h"
> -#include "xfs_defer.h"
>  #include "xfs_da_format.h"
>  #include "xfs_da_btree.h"
>  #include "xfs_inode.h"
> @@ -4165,126 +4164,112 @@ xlog_recover_process_data(
...
>  STATIC int
> -xlog_recover_process_efis(
> +xlog_recover_process_intents(
>       struct xlog             *log)
>  {
>       struct xfs_log_item     *lip;
> -     struct xfs_efi_log_item *efip;
>       int                     error = 0;
>       struct xfs_ail_cursor   cur;
>       struct xfs_ail          *ailp;
> +     xfs_lsn_t               last_lsn;
>  
>       ailp = log->l_ailp;
>       spin_lock(&ailp->xa_lock);
>       lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
> +     last_lsn = xlog_assign_lsn(log->l_curr_cycle, log->l_curr_block);
>       while (lip != NULL) {
>               /*
> -              * We're done when we see something other than an EFI.
> -              * There should be no EFIs left in the AIL now.
> +              * We're done when we see something other than an intent.
> +              * There should be no intents left in the AIL now.
>                */
> -             if (lip->li_type != XFS_LI_EFI) {
> +             if (!xlog_item_is_intent(lip)) {
>  #ifdef DEBUG
>                       for (; lip; lip = xfs_trans_ail_cursor_next(ailp, &cur))
> -                             ASSERT(lip->li_type != XFS_LI_EFI);
> +                             ASSERT(!xlog_item_is_intent(lip));
>  #endif
>                       break;
>               }
>  
>               /*
> -              * Skip EFIs that we've already processed.
> +              * We should never see a redo item with a LSN higher than
> +              * the last transaction we found in the log at the start
> +              * of recovery.
>                */
> -             efip = container_of(lip, struct xfs_efi_log_item, efi_item);
> -             if (test_bit(XFS_EFI_RECOVERED, &efip->efi_flags)) {
> -                     lip = xfs_trans_ail_cursor_next(ailp, &cur);
> -                     continue;
> -             }
> +             ASSERT(XFS_LSN_CMP(last_lsn, lip->li_lsn) >= 0);
>  
> -             spin_unlock(&ailp->xa_lock);
> -             error = xlog_recover_process_efi(log->l_mp, efip);
> -             spin_lock(&ailp->xa_lock);
> +             switch (lip->li_type) {
> +             case XFS_LI_EFI:
> +                     error = xlog_recover_process_efi(log->l_mp, ailp, lip);
> +                     break;
> +             }

I think I'd prefer to see the locking remain here rather than get buried
in the helper functions. That said, this allows us to check the
recovered bit without a lock cycle. Meh, either way:

Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>

>               if (error)
>                       goto out;
>               lip = xfs_trans_ail_cursor_next(ailp, &cur);
> @@ -4296,15 +4281,14 @@ out:
>  }
>  
>  /*
> - * A cancel occurs when the mount has failed and we're bailing out. Release 
> all
> - * pending EFIs so they don't pin the AIL.
> + * A cancel occurs when the mount has failed and we're bailing out.
> + * Release all pending log intent items so they don't pin the AIL.
>   */
>  STATIC int
> -xlog_recover_cancel_efis(
> +xlog_recover_cancel_intents(
>       struct xlog             *log)
>  {
>       struct xfs_log_item     *lip;
> -     struct xfs_efi_log_item *efip;
>       int                     error = 0;
>       struct xfs_ail_cursor   cur;
>       struct xfs_ail          *ailp;
> @@ -4314,22 +4298,22 @@ xlog_recover_cancel_efis(
>       lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
>       while (lip != NULL) {
>               /*
> -              * We're done when we see something other than an EFI.
> -              * There should be no EFIs left in the AIL now.
> +              * We're done when we see something other than an intent.
> +              * There should be no intents left in the AIL now.
>                */
> -             if (lip->li_type != XFS_LI_EFI) {
> +             if (!xlog_item_is_intent(lip)) {
>  #ifdef DEBUG
>                       for (; lip; lip = xfs_trans_ail_cursor_next(ailp, &cur))
> -                             ASSERT(lip->li_type != XFS_LI_EFI);
> +                             ASSERT(!xlog_item_is_intent(lip));
>  #endif
>                       break;
>               }
>  
> -             efip = container_of(lip, struct xfs_efi_log_item, efi_item);
> -
> -             spin_unlock(&ailp->xa_lock);
> -             xfs_efi_release(efip);
> -             spin_lock(&ailp->xa_lock);
> +             switch (lip->li_type) {
> +             case XFS_LI_EFI:
> +                     xlog_recover_cancel_efi(log->l_mp, ailp, lip);
> +                     break;
> +             }
>  
>               lip = xfs_trans_ail_cursor_next(ailp, &cur);
>       }
> @@ -5140,16 +5124,16 @@ xlog_recover_finish(
>        */
>       if (log->l_flags & XLOG_RECOVERY_NEEDED) {
>               int     error;
> -             error = xlog_recover_process_efis(log);
> +             error = xlog_recover_process_intents(log);
>               if (error) {
> -                     xfs_alert(log->l_mp, "Failed to recover EFIs");
> +                     xfs_alert(log->l_mp, "Failed to recover intents");
>                       return error;
>               }
>               /*
> -              * Sync the log to get all the EFIs out of the AIL.
> +              * Sync the log to get all the intents out of the AIL.
>                * This isn't absolutely necessary, but it helps in
>                * case the unlink transactions would have problems
> -              * pushing the EFIs out of the way.
> +              * pushing the intents out of the way.
>                */
>               xfs_log_force(log->l_mp, XFS_LOG_SYNC);
>  
> @@ -5174,7 +5158,7 @@ xlog_recover_cancel(
>       int             error = 0;
>  
>       if (log->l_flags & XLOG_RECOVERY_NEEDED)
> -             error = xlog_recover_cancel_efis(log);
> +             error = xlog_recover_cancel_intents(log);
>  
>       return error;
>  }
> 
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