[PATCH 31/32] xfs: drop compatibility minimum log size computations for reflink

Darrick J. Wong
2024-04-10T01:01:36Z

From: Darrick J. Wong <djwong@kernel.org>

Let's also drop the oversized minimum log computations for reflink and
rmap that were the result of bugs introduced many years ago.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
---
fs/xfs/libxfs/xfs_log_rlimit.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_log_rlimit.c b/fs/xfs/libxfs/xfs_log_rlimit.c
index 3518d5e21df03..d3bd6a86c8fe9 100644
--- a/fs/xfs/libxfs/xfs_log_rlimit.c
+++ b/fs/xfs/libxfs/xfs_log_rlimit.c
@@ -24,6 +24,11 @@
* because that can create the situation where a newer mkfs writes a new
* filesystem that an older kernel won't mount.
*
+ * Several years prior, we also discovered that the transaction reservations
+ * for rmap and reflink operations were unnecessarily large. That was fixed,
+ * but the minimum log size computation was left alone to avoid the
+ * compatibility problems noted above. Fix that too.
+ *
* Therefore, we only may correct the computation starting with filesystem
* features that didn't exist in 2023. In other words, only turn this on if
* the filesystem has parent pointers.
@@ -80,6 +85,15 @@ xfs_log_calc_trans_resv_for_minlogblocks(
{
unsigned int rmap_maxlevels = mp->m_rmap_maxlevels;

+ /*
+ * If the feature set is new enough, drop the oversized minimum log
+ * size computation introduced by the original reflink code.
+ */
+ if (xfs_want_minlogsize_fixes(&mp->m_sb)) {
+ xfs_trans_resv_calc(mp, resv);
+ return;
+ }
+
/*
* In the early days of rmap+reflink, we always set the rmap maxlevels
* to 9 even if the AG was small enough that it would never grow to