xfs: update the pag for the last AG at recovery time

Currently log recovery never updates the in-core perag values for the
last allocation group when they were grown by growfs.  This leads to
btree record validation failures for the alloc, ialloc or finotbt
trees if a transaction references this new space.

Found by Brian's new growfs recovery stress test.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: Christoph Hellwig

fs/xfs/libxfs/xfs_ag.c

@@ -273,6 +273,23 @@ xfs_agino_range(
 	return __xfs_agino_range(mp, xfs_ag_block_count(mp, agno), first, last);
 }
 
+int
+xfs_update_last_ag_size(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		prev_agcount)
+{
+	struct xfs_perag	*pag = xfs_perag_grab(mp, prev_agcount - 1);
+
+	if (!pag)
+		return -EFSCORRUPTED;
+	pag->block_count = __xfs_ag_block_count(mp, prev_agcount - 1,
+			mp->m_sb.sb_agcount, mp->m_sb.sb_dblocks);
+	__xfs_agino_range(mp, pag->block_count, &pag->agino_min,
+			&pag->agino_max);
+	xfs_perag_rele(pag);
+	return 0;
+}
+
 int
 xfs_initialize_perag(
 	struct xfs_mount	*mp,

fs/xfs/libxfs/xfs_ag.h

@@ -150,6 +150,7 @@ int xfs_initialize_perag(struct xfs_mount *mp, xfs_agnumber_t old_agcount,
 void xfs_free_perag_range(struct xfs_mount *mp, xfs_agnumber_t first_agno,
 		xfs_agnumber_t end_agno);
 int xfs_initialize_perag_data(struct xfs_mount *mp, xfs_agnumber_t agno);
+int xfs_update_last_ag_size(struct xfs_mount *mp, xfs_agnumber_t prev_agcount);
 
 /* Passive AG references */
 struct xfs_perag *xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno);

fs/xfs/xfs_buf_item_recover.c

@@ -708,6 +708,11 @@ xlog_recover_do_primary_sb_buffer(
 
 	xlog_recover_do_reg_buffer(mp, item, bp, buf_f, current_lsn);
 
+	if (orig_agcount == 0) {
+		xfs_alert(mp, "Trying to grow file system without AGs");
+		return -EFSCORRUPTED;
+	}
+
 	/*
 	 * Update the in-core super block from the freshly recovered on-disk one.
 	 */
@@ -718,15 +723,23 @@ xlog_recover_do_primary_sb_buffer(
 		return -EFSCORRUPTED;
 	}
 
+	/*
+	 * Growfs can also grow the last existing AG.  In this case we also need
+	 * to update the length in the in-core perag structure and values
+	 * depending on it.
+	 */
+	error = xfs_update_last_ag_size(mp, orig_agcount);
+	if (error)
+		return error;
+
 	/*
 	 * Initialize the new perags, and also update various block and inode
 	 * allocator setting based off the number of AGs or total blocks.
 	 * Because of the latter this also needs to happen if the agcount did
 	 * not change.
 	 */
-	error = xfs_initialize_perag(mp, orig_agcount,
-			mp->m_sb.sb_agcount, mp->m_sb.sb_dblocks,
-			&mp->m_maxagi);
+	error = xfs_initialize_perag(mp, orig_agcount, mp->m_sb.sb_agcount,
+			mp->m_sb.sb_dblocks, &mp->m_maxagi);
 	if (error) {
 		xfs_warn(mp, "Failed recovery per-ag init: %d", error);
 		return error;