diff options
Diffstat (limited to 'fs/xfs/xfs_log_cil.c')
| -rw-r--r-- | fs/xfs/xfs_log_cil.c | 55 |
1 files changed, 41 insertions, 14 deletions
diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c index b3425b34e3d..f506c457011 100644 --- a/fs/xfs/xfs_log_cil.c +++ b/fs/xfs/xfs_log_cil.c @@ -78,8 +78,6 @@ xlog_cil_init_post_recovery( { log->l_cilp->xc_ctx->ticket = xlog_cil_ticket_alloc(log); log->l_cilp->xc_ctx->sequence = 1; - log->l_cilp->xc_ctx->commit_lsn = xlog_assign_lsn(log->l_curr_cycle, - log->l_curr_block); } /* @@ -465,12 +463,40 @@ xlog_cil_push( spin_unlock(&cil->xc_push_lock); goto out_skip; } - spin_unlock(&cil->xc_push_lock); /* check for a previously pushed seqeunce */ - if (push_seq < cil->xc_ctx->sequence) + if (push_seq < cil->xc_ctx->sequence) { + spin_unlock(&cil->xc_push_lock); goto out_skip; + } + + /* + * We are now going to push this context, so add it to the committing + * list before we do anything else. This ensures that anyone waiting on + * this push can easily detect the difference between a "push in + * progress" and "CIL is empty, nothing to do". + * + * IOWs, a wait loop can now check for: + * the current sequence not being found on the committing list; + * an empty CIL; and + * an unchanged sequence number + * to detect a push that had nothing to do and therefore does not need + * waiting on. If the CIL is not empty, we get put on the committing + * list before emptying the CIL and bumping the sequence number. Hence + * an empty CIL and an unchanged sequence number means we jumped out + * above after doing nothing. + * + * Hence the waiter will either find the commit sequence on the + * committing list or the sequence number will be unchanged and the CIL + * still dirty. In that latter case, the push has not yet started, and + * so the waiter will have to continue trying to check the CIL + * committing list until it is found. In extreme cases of delay, the + * sequence may fully commit between the attempts the wait makes to wait + * on the commit sequence. + */ + list_add(&ctx->committing, &cil->xc_committing); + spin_unlock(&cil->xc_push_lock); /* * pull all the log vectors off the items in the CIL, and @@ -534,7 +560,6 @@ xlog_cil_push( */ spin_lock(&cil->xc_push_lock); cil->xc_current_sequence = new_ctx->sequence; - list_add(&ctx->committing, &cil->xc_committing); spin_unlock(&cil->xc_push_lock); up_write(&cil->xc_ctx_lock); @@ -634,7 +659,7 @@ out_abort_free_ticket: xfs_log_ticket_put(tic); out_abort: xlog_cil_committed(ctx, XFS_LI_ABORTED); - return XFS_ERROR(EIO); + return -EIO; } static void @@ -857,13 +882,15 @@ restart: * Hence by the time we have got here it our sequence may not have been * pushed yet. This is true if the current sequence still matches the * push sequence after the above wait loop and the CIL still contains - * dirty objects. + * dirty objects. This is guaranteed by the push code first adding the + * context to the committing list before emptying the CIL. * - * When the push occurs, it will empty the CIL and atomically increment - * the currect sequence past the push sequence and move it into the - * committing list. Of course, if the CIL is clean at the time of the - * push, it won't have pushed the CIL at all, so in that case we should - * try the push for this sequence again from the start just in case. + * Hence if we don't find the context in the committing list and the + * current sequence number is unchanged then the CIL contents are + * significant. If the CIL is empty, if means there was nothing to push + * and that means there is nothing to wait for. If the CIL is not empty, + * it means we haven't yet started the push, because if it had started + * we would have found the context on the committing list. */ if (sequence == cil->xc_current_sequence && !list_empty(&cil->xc_cil)) { @@ -928,12 +955,12 @@ xlog_cil_init( cil = kmem_zalloc(sizeof(*cil), KM_SLEEP|KM_MAYFAIL); if (!cil) - return ENOMEM; + return -ENOMEM; ctx = kmem_zalloc(sizeof(*ctx), KM_SLEEP|KM_MAYFAIL); if (!ctx) { kmem_free(cil); - return ENOMEM; + return -ENOMEM; } INIT_WORK(&cil->xc_push_work, xlog_cil_push_work); |