[PATCH 2/2] xfs: reserve blocks for ifree transaction during log recovery

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

Log recovery frees all the inodes stored in the unlinked list, which can
cause expansion of the free inode btree.  The ifree code skips block
reservations if it thinks there's a per-AG space reservation, but we
don't set up the reservation until after log recovery, which means that
a finobt expansion blows up in xfs_trans_mod_sb when we exceed the
transaction's block reservation.

To fix this, we set the "no finobt reservation" flag to true when we
create the xfs_mount and only set it to false if we confirm that every
AG had enough free space to put aside for the finobt.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_fsops.c |    1 +
 fs/xfs/xfs_super.c |    7 +++++++
 2 files changed, 8 insertions(+)


diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index f3ef70c542e1..584648582ba7 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -533,6 +533,7 @@ xfs_fs_reserve_ag_blocks(
 	int			error = 0;
 	int			err2;
 
+	mp->m_finobt_nores = false;
 	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
 		pag = xfs_perag_get(mp, agno);
 		err2 = xfs_ag_resv_init(pag, NULL);
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index c9097cb0b955..08033ac040d6 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1594,6 +1594,13 @@ xfs_mount_alloc(
 	INIT_DELAYED_WORK(&mp->m_eofblocks_work, xfs_eofblocks_worker);
 	INIT_DELAYED_WORK(&mp->m_cowblocks_work, xfs_cowblocks_worker);
 	mp->m_kobj.kobject.kset = xfs_kset;
+	/*
+	 * We don't create the finobt per-ag space reservation until after log
+	 * recovery, so we must set this to true so that an ifree transaction
+	 * started during log recovery will not depend on space reservations
+	 * for finobt expansion.
+	 */
+	mp->m_finobt_nores = true;
 	return mp;
 }