[PATCH 10/21] xfs: calculate the log reservation for logging data checksum buffers

[Christoph Hellwig <hch@lst.de>]

The data checksum is logged in its own transaction, and only logs
transactions buffers.  While the maximum size of a checksummed data write
is the same as that of a single checksum buffer, the Zone Append based
zoned write path can't guarantee alignment, so it might be spread over
up to three buffers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_trans_resv.c | 21 +++++++++++++++++++++
 fs/xfs/libxfs/xfs_trans_resv.h |  4 ++++
 2 files changed, 25 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_trans_resv.c b/fs/xfs/libxfs/xfs_trans_resv.c
index 5382ece51812..8854253afba0 100644
--- a/fs/xfs/libxfs/xfs_trans_resv.c
+++ b/fs/xfs/libxfs/xfs_trans_resv.c
@@ -11,6 +11,7 @@
 #include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
 #include "xfs_mount.h"
+#include "xfs_rtcsumfile.h"
 #include "xfs_da_format.h"
 #include "xfs_da_btree.h"
 #include "xfs_inode.h"
@@ -1233,6 +1234,22 @@ xfs_calc_qm_dqalloc_reservation_minlogsize(
 	return xfs_calc_qm_dqalloc_reservation(mp, true);
 }
 
+/*
+ * Log data checksums for a write.
+ *
+ * Must cover a checksum for each FSB of data written, and the checksums can
+ * span the FSB-sized checksum buffers at both ends.
+ */
+unsigned int
+xfs_calc_csum_reservation(
+	struct xfs_mount	*mp,
+	unsigned int		csum_len)
+{
+	return xfs_calc_buf_res(
+			howmany(csum_len, xfs_rtcsum_payload_size(mp)) + 1,
+			mp->m_rtcsum_bsize);
+}
+
 /*
  * Syncing the incore super block changes to disk.
  *     the super block to reflect the changes: sector size
@@ -1354,6 +1371,10 @@ xfs_trans_resv_calc(
 
 	xfs_calc_namespace_reservations(mp, resp);
 
+	resp->tr_csum.tr_logres =
+		xfs_calc_csum_reservation(mp, XFS_RTCSUM_MAX_WRITE);
+	resp->tr_csum.tr_logcount = XFS_DEFAULT_LOG_COUNT;
+
 	/*
 	 * The following transactions are logged in logical format with
 	 * a default log count.
diff --git a/fs/xfs/libxfs/xfs_trans_resv.h b/fs/xfs/libxfs/xfs_trans_resv.h
index 1804e821f382..127db4da31c1 100644
--- a/fs/xfs/libxfs/xfs_trans_resv.h
+++ b/fs/xfs/libxfs/xfs_trans_resv.h
@@ -49,6 +49,7 @@ struct xfs_trans_resv {
 	struct xfs_trans_res	tr_sb;		/* modify superblock */
 	struct xfs_trans_res	tr_fsyncts;	/* update timestamps on fsync */
 	struct xfs_trans_res	tr_atomic_ioend; /* untorn write completion */
+	struct xfs_trans_res	tr_csum;	/* data checksums in metafile */
 };
 
 /* shorthand way of accessing reservation structure */
@@ -122,6 +123,9 @@ unsigned int xfs_calc_itruncate_reservation_minlogsize(struct xfs_mount *mp);
 unsigned int xfs_calc_write_reservation_minlogsize(struct xfs_mount *mp);
 unsigned int xfs_calc_qm_dqalloc_reservation_minlogsize(struct xfs_mount *mp);
 
+unsigned int xfs_calc_csum_reservation(struct xfs_mount *mp,
+		unsigned int csum_len);
+
 xfs_extlen_t xfs_calc_max_atomic_write_fsblocks(struct xfs_mount *mp);
 xfs_extlen_t xfs_calc_atomic_write_log_geometry(struct xfs_mount *mp,
 		xfs_extlen_t blockcount, unsigned int *new_logres);
-- 
2.53.0