Add a helper xfs_calc_buf_res() to calcuate out the space log reservations per item which were got
involved in a transaction. It will call the xfs_buf_log_overhead() to figure out the extra space
for the struct xfs_buf_log_format that gets written into the log for every buffer as well as a little
bit of extra space because there also needs a log opheader, i.e. struct xlog_op_header.
Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
---
fs/xfs/xfs_trans.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 06ed520..6c601ea 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -37,14 +37,45 @@
#include "xfs_extent_busy.h"
#include "xfs_bmap.h"
#include "xfs_quota.h"
+#include "xfs_qm.h"
#include "xfs_trans_priv.h"
#include "xfs_trans_space.h"
#include "xfs_inode_item.h"
+#include "xfs_log_priv.h"
+#include "xfs_buf_item.h"
#include "xfs_trace.h"
kmem_zone_t *xfs_trans_zone;
kmem_zone_t *xfs_log_item_desc_zone;
+/*
+ * A buffer has a format structure overhead in the log in addition
+ * to the data, so we need to take this into account when reserving
+ * space in a transaction for a buffer. Round the space required up
+ * to a multiple of 128 bytes so that we don't change the historical
+ * reservation that has been used for this overhead.
+ */
+STATIC uint
+xfs_buf_log_overhead(void)
+{
+ return round_up(sizeof(struct xlog_op_header) +
+ sizeof(struct xfs_buf_log_format), 128);
+}
+
+/*
+ * Calculate out transaction log reservation per item in bytes.
+ *
+ * The nbufs argument is used to indicate the number of items that
+ * will be changed in a transaction. size is used to tell how many
+ * bytes should be reserved per item.
+ */
+STATIC uint
+xfs_calc_buf_res(
+ uint nbufs,
+ uint size)
+{
+ return nbufs * (size + xfs_buf_log_overhead());
+}
/*
* Various log reservation values.
--
1.7.9.5
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