1 files changed, 122 insertions, 7 deletions

diff --git a/fs/xfs/libxfs/xfs_log_rlimit.c b/fs/xfs/libxfs/xfs_log_rlimit.c
index 1b542ec11d5d..34bba96d30ca 100644
--- a/fs/xfs/libxfs/xfs_log_rlimit.c
+++ b/fs/xfs/libxfs/xfs_log_rlimit.c
@@ -12,10 +12,37 @@
 #include "xfs_mount.h"
 #include "xfs_da_format.h"
 #include "xfs_trans_space.h"
-#include "xfs_inode.h"
 #include "xfs_da_btree.h"
-#include "xfs_attr_leaf.h"
 #include "xfs_bmap_btree.h"
+#include "xfs_trace.h"
+
+/*
+ * Shortly after enabling the large extents count feature in 2023, longstanding
+ * bugs were found in the code that computes the minimum log size.  Luckily,
+ * the bugs resulted in over-estimates of that size, so there's no impact to
+ * existing users.  However, we don't want to reduce the minimum log size
+ * 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.
+ *
+ * This function can be called before the XFS_HAS_* flags have been set up,
+ * (e.g. mkfs) so we must check the ondisk superblock.
+ */
+static inline bool
+xfs_want_minlogsize_fixes(
+	struct xfs_sb	*sb)
+{
+	return xfs_sb_is_v5(sb) &&
+	       xfs_sb_has_incompat_feature(sb, XFS_SB_FEAT_INCOMPAT_PARENT);
+}
 
 /*
  * Calculate the maximum length in bytes that would be required for a local
@@ -32,6 +59,15 @@ xfs_log_calc_max_attrsetm_res(
 	       MAXNAMELEN - 1;
 	nblks = XFS_DAENTER_SPACE_RES(mp, XFS_ATTR_FORK);
 	nblks += XFS_B_TO_FSB(mp, size);
+
+	/*
+	 * If the feature set is new enough, correct a unit conversion error in
+	 * the xattr transaction reservation code that resulted in oversized
+	 * minimum log size computations.
+	 */
+	if (xfs_want_minlogsize_fixes(&mp->m_sb))
+		size = XFS_B_TO_FSB(mp, size);
+
 	nblks += XFS_NEXTENTADD_SPACE_RES(mp, size, XFS_ATTR_FORK);
 
 	return  M_RES(mp)->tr_attrsetm.tr_logres +
@@ -39,6 +75,78 @@ xfs_log_calc_max_attrsetm_res(
 }
 
 /*
+ * Compute an alternate set of log reservation sizes for use exclusively with
+ * minimum log size calculations.
+ */
+static void
+xfs_log_calc_trans_resv_for_minlogblocks(
+	struct xfs_mount	*mp,
+	struct xfs_trans_resv	*resv)
+{
+	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);
+		resv->tr_atomic_ioend = M_RES(mp)->tr_atomic_ioend;
+		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
+	 * that height.  Transaction reservation sizes influence the minimum
+	 * log size calculation, which influences the size of the log that mkfs
+	 * creates.  Use the old value here to ensure that newly formatted
+	 * small filesystems will mount on older kernels.
+	 */
+	if (xfs_has_rmapbt(mp) && xfs_has_reflink(mp))
+		mp->m_rmap_maxlevels = XFS_OLD_REFLINK_RMAP_MAXLEVELS;
+
+	xfs_trans_resv_calc(mp, resv);
+
+	/* Copy the dynamic transaction reservation types from the running fs */
+	resv->tr_atomic_ioend = M_RES(mp)->tr_atomic_ioend;
+
+	if (xfs_has_reflink(mp)) {
+		/*
+		 * In the early days of reflink, typical log operation counts
+		 * were greatly overestimated.
+		 */
+		resv->tr_write.tr_logcount = XFS_WRITE_LOG_COUNT_REFLINK;
+		resv->tr_itruncate.tr_logcount =
+				XFS_ITRUNCATE_LOG_COUNT_REFLINK;
+		resv->tr_qm_dqalloc.tr_logcount = XFS_WRITE_LOG_COUNT_REFLINK;
+	} else if (xfs_has_rmapbt(mp)) {
+		/*
+		 * In the early days of non-reflink rmap, the impact of rmapbt
+		 * updates on log counts were not taken into account at all.
+		 */
+		resv->tr_write.tr_logcount = XFS_WRITE_LOG_COUNT;
+		resv->tr_itruncate.tr_logcount = XFS_ITRUNCATE_LOG_COUNT;
+		resv->tr_qm_dqalloc.tr_logcount = XFS_WRITE_LOG_COUNT;
+	}
+
+	/*
+	 * In the early days of reflink, we did not use deferred refcount
+	 * update log items, so log reservations must be recomputed using the
+	 * old calculations.
+	 */
+	resv->tr_write.tr_logres =
+			xfs_calc_write_reservation_minlogsize(mp);
+	resv->tr_itruncate.tr_logres =
+			xfs_calc_itruncate_reservation_minlogsize(mp);
+	resv->tr_qm_dqalloc.tr_logres =
+			xfs_calc_qm_dqalloc_reservation_minlogsize(mp);
+
+	/* Put everything back the way it was.  This goes at the end. */
+	mp->m_rmap_maxlevels = rmap_maxlevels;
+}
+
+/*
  * Iterate over the log space reservation table to figure out and return
  * the maximum one in terms of the pre-calculated values which were done
  * at mount time.
@@ -48,19 +156,25 @@ xfs_log_get_max_trans_res(
 	struct xfs_mount	*mp,
 	struct xfs_trans_res	*max_resp)
 {
+	struct xfs_trans_resv	resv = {};
 	struct xfs_trans_res	*resp;
 	struct xfs_trans_res	*end_resp;
+	unsigned int		i;
 	int			log_space = 0;
 	int			attr_space;
 
 	attr_space = xfs_log_calc_max_attrsetm_res(mp);
 
-	resp = (struct xfs_trans_res *)M_RES(mp);
-	end_resp = (struct xfs_trans_res *)(M_RES(mp) + 1);
-	for (; resp < end_resp; resp++) {
+	xfs_log_calc_trans_resv_for_minlogblocks(mp, &resv);
+
+	resp = (struct xfs_trans_res *)&resv;
+	end_resp = (struct xfs_trans_res *)(&resv + 1);
+	for (i = 0; resp < end_resp; i++, resp++) {
 		int		tmp = resp->tr_logcount > 1 ?
 				      resp->tr_logres * resp->tr_logcount :
 				      resp->tr_logres;
+
+		trace_xfs_trans_resv_calc_minlogsize(mp, i, resp);
 		if (log_space < tmp) {
 			log_space = tmp;
 			*max_resp = *resp;		/* struct copy */
@@ -68,9 +182,10 @@ xfs_log_get_max_trans_res(
 	}
 
 	if (attr_space > log_space) {
-		*max_resp = M_RES(mp)->tr_attrsetm;	/* struct copy */
+		*max_resp = resv.tr_attrsetm;	/* struct copy */
 		max_resp->tr_logres = attr_space;
 	}
+	trace_xfs_log_get_max_trans_res(mp, max_resp);
 }
 
 /*
@@ -94,7 +209,7 @@ xfs_log_calc_minimum_size(
 	if (tres.tr_logcount > 1)
 		max_logres *= tres.tr_logcount;
 
-	if (xfs_sb_version_haslogv2(&mp->m_sb) && mp->m_sb.sb_logsunit > 1)
+	if (xfs_has_logv2(mp) && mp->m_sb.sb_logsunit > 1)
 		lsunit = BTOBB(mp->m_sb.sb_logsunit);
 
 	/*