xfs: collect errors from inodegc for unlinked inode recovery

Unlinked list recovery requires errors removing the inode the from
the unlinked list get fed back to the main recovery loop. Now that
we offload the unlinking to the inodegc work, we don't get errors
being fed back when we trip over a corruption that prevents the
inode from being removed from the unlinked list.

This means we never clear the corrupt unlinked list bucket,
resulting in runtime operations eventually tripping over it and
shutting down.

Fix this by collecting inodegc worker errors and feed them
back to the flush caller. This is largely best effort - the only
context that really cares is log recovery, and it only flushes a
single inode at a time so we don't need complex synchronised
handling. Essentially the inodegc workers will capture the first
error that occurs and the next flush will gather them and clear
them. The flush itself will only report the first gathered error.

In the cases where callers can return errors, propagate the
collected inodegc flush error up the error handling chain.

In the case of inode unlinked list recovery, there are several
superfluous calls to flush queued unlinked inodes -
xlog_recover_iunlink_bucket() guarantees that it has flushed the
inodegc and collected errors before it returns. Hence nothing in the
calling path needs to run a flush, even when an error is returned.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 37 insertions, 9 deletions

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 0f60e301eb1f..453890942d9f 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -454,6 +454,27 @@ xfs_inodegc_queue_all(
 	return ret;
 }
 
+/* Wait for all queued work and collect errors */
+static int
+xfs_inodegc_wait_all(
+	struct xfs_mount	*mp)
+{
+	int			cpu;
+	int			error = 0;
+
+	flush_workqueue(mp->m_inodegc_wq);
+	for_each_online_cpu(cpu) {
+		struct xfs_inodegc	*gc;
+
+		gc = per_cpu_ptr(mp->m_inodegc, cpu);
+		if (gc->error && !error)
+			error = gc->error;
+		gc->error = 0;
+	}
+
+	return error;
+}
+
 /*
  * Check the validity of the inode we just found it the cache
  */
@@ -1491,15 +1512,14 @@ xfs_blockgc_free_space(
 	if (error)
 		return error;
 
-	xfs_inodegc_flush(mp);
-	return 0;
+	return xfs_inodegc_flush(mp);
 }
 
 /*
  * Reclaim all the free space that we can by scheduling the background blockgc
  * and inodegc workers immediately and waiting for them all to clear.
  */
-void
+int
 xfs_blockgc_flush_all(
 	struct xfs_mount	*mp)
 {
@@ -1520,7 +1540,7 @@ xfs_blockgc_flush_all(
 	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
 		flush_delayed_work(&pag->pag_blockgc_work);
 
-	xfs_inodegc_flush(mp);
+	return xfs_inodegc_flush(mp);
 }
 
 /*
@@ -1842,13 +1862,17 @@ xfs_inodegc_set_reclaimable(
  * This is the last chance to make changes to an otherwise unreferenced file
  * before incore reclamation happens.
  */
-static void
+static int
 xfs_inodegc_inactivate(
 	struct xfs_inode	*ip)
 {
+	int			error;
+
 	trace_xfs_inode_inactivating(ip);
-	xfs_inactive(ip);
+	error = xfs_inactive(ip);
 	xfs_inodegc_set_reclaimable(ip);
+	return error;
+
 }
 
 void
@@ -1880,8 +1904,12 @@ xfs_inodegc_worker(
 
 	WRITE_ONCE(gc->shrinker_hits, 0);
 	llist_for_each_entry_safe(ip, n, node, i_gclist) {
+		int	error;
+
 		xfs_iflags_set(ip, XFS_INACTIVATING);
-		xfs_inodegc_inactivate(ip);
+		error = xfs_inodegc_inactivate(ip);
+		if (error && !gc->error)
+			gc->error = error;
 	}
 
 	memalloc_nofs_restore(nofs_flag);
@@ -1905,13 +1933,13 @@ xfs_inodegc_push(
  * Force all currently queued inode inactivation work to run immediately and
  * wait for the work to finish.
  */
-void
+int
 xfs_inodegc_flush(
 	struct xfs_mount	*mp)
 {
 	xfs_inodegc_push(mp);
 	trace_xfs_inodegc_flush(mp, __return_address);
-	flush_workqueue(mp->m_inodegc_wq);
+	return xfs_inodegc_wait_all(mp);
 }
 
 /*