From aad7272a920869b950d937b87562e494af72523c Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Tue, 10 Aug 2021 18:00:40 -0700 Subject: [PATCH] xfs: separate out log shutdown callback processing The iclog callback processing done during a forced log shutdown has different logic to normal runtime IO completion callback processing. Separate out the shutdown callbacks into their own function and call that from the shutdown code instead. We don't need this shutdown specific logic in the normal runtime completion code - we'll always run the shutdown version on shutdown, and it will do what shutdown needs regardless of whether there are racing IO completion callbacks scheduled or in progress. Hence we can also simplify the normal IO completion callpath and only abort if shutdown occurred while we actively were processing callbacks. Further, separating out the IO completion logic from the shutdown logic avoids callback race conditions from being triggered by log IO completion after a shutdown. IO completion will now only run callbacks on iclogs that are in the correct state for a callback to be run, avoiding the possibility of running callbacks on a referenced iclog that hasn't yet been submitted for IO. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_log.c | 53 ++++++++++++++++++++++++++++++++++-------------- 1 file changed, 38 insertions(+), 15 deletions(-) diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index 1f2968d05dd6..38add7bb64e3 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -486,6 +486,32 @@ out_error: return error; } +/* + * Run all the pending iclog callbacks and wake log force waiters and iclog + * space waiters so they can process the newly set shutdown state. We really + * don't care what order we process callbacks here because the log is shut down + * and so state cannot change on disk anymore. + */ +static void +xlog_state_shutdown_callbacks( + struct xlog *log) +{ + struct xlog_in_core *iclog; + LIST_HEAD(cb_list); + + spin_lock(&log->l_icloglock); + iclog = log->l_iclog; + do { + list_splice_init(&iclog->ic_callbacks, &cb_list); + wake_up_all(&iclog->ic_force_wait); + } while ((iclog = iclog->ic_next) != log->l_iclog); + + wake_up_all(&log->l_flush_wait); + spin_unlock(&log->l_icloglock); + + xlog_cil_process_committed(&cb_list); +} + /* * Flush iclog to disk if this is the last reference to the given iclog and the * it is in the WANT_SYNC state. @@ -2840,7 +2866,10 @@ xlog_state_iodone_process_iclog( /* * Loop over all the iclogs, running attached callbacks on them. Return true if - * we ran any callbacks, indicating that we dropped the icloglock. + * we ran any callbacks, indicating that we dropped the icloglock. We don't need + * to handle transient shutdown state here at all because + * xlog_state_shutdown_callbacks() will be run to do the necessary shutdown + * cleanup of the callbacks. */ static bool xlog_state_do_iclog_callbacks( @@ -2855,13 +2884,11 @@ xlog_state_do_iclog_callbacks( do { LIST_HEAD(cb_list); - if (!xlog_is_shutdown(log)) { - if (xlog_state_iodone_process_iclog(log, iclog)) - break; - if (iclog->ic_state != XLOG_STATE_CALLBACK) { - iclog = iclog->ic_next; - continue; - } + if (xlog_state_iodone_process_iclog(log, iclog)) + break; + if (iclog->ic_state != XLOG_STATE_CALLBACK) { + iclog = iclog->ic_next; + continue; } list_splice_init(&iclog->ic_callbacks, &cb_list); spin_unlock(&log->l_icloglock); @@ -2872,10 +2899,7 @@ xlog_state_do_iclog_callbacks( ran_callback = true; spin_lock(&log->l_icloglock); - if (xlog_is_shutdown(log)) - wake_up_all(&iclog->ic_force_wait); - else - xlog_state_clean_iclog(log, iclog); + xlog_state_clean_iclog(log, iclog); iclog = iclog->ic_next; } while (iclog != first_iclog); @@ -2908,8 +2932,7 @@ xlog_state_do_callback( } } - if (log->l_iclog->ic_state == XLOG_STATE_ACTIVE || - xlog_is_shutdown(log)) + if (log->l_iclog->ic_state == XLOG_STATE_ACTIVE) wake_up_all(&log->l_flush_wait); spin_unlock(&log->l_icloglock); @@ -3885,7 +3908,7 @@ xlog_force_shutdown( spin_lock(&log->l_cilp->xc_push_lock); wake_up_all(&log->l_cilp->xc_commit_wait); spin_unlock(&log->l_cilp->xc_push_lock); - xlog_state_do_callback(log); + xlog_state_shutdown_callbacks(log); return log_error; }