Simplify some maths in xlogreader.c

An LSN was calculated from a segment number, a segment size and a
position offset, matching exactly the LSN given by the caller of
XLogReaderValidatePageHeader().  This change removes the extra LSN
calculation, relying only on the LSN given by the function caller
instead.

Author: Bharath Rupireddy
Reviewed-by: Richard Guo, Álvaro Herrera, Kyotaro Horiguchi
Discussion: https://postgr.es/m/CALj2ACXuh4Ms9j9sxMYdtHEe=5sFcyrs-GAHyADu_A_G71kZTg@mail.gmail.com

diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index 5a8fe81f82642ce193d150e9c35d004f3ea6a998..93f667b2544c60cfca916335073b27a90b54a407 100644 (file)
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -1210,7 +1210,6 @@ bool
 XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr,
                             char *phdr)
 {
-   XLogRecPtr  recaddr;
    XLogSegNo   segno;
    int32       offset;
    XLogPageHeader hdr = (XLogPageHeader) phdr;
@@ -1220,8 +1219,6 @@ XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr,
    XLByteToSeg(recptr, segno, state->segcxt.ws_segsize);
    offset = XLogSegmentOffset(recptr, state->segcxt.ws_segsize);
 
-   XLogSegNoOffsetToRecPtr(segno, offset, state->segcxt.ws_segsize, recaddr);
-
    if (hdr->xlp_magic != XLOG_PAGE_MAGIC)
    {
        char        fname[MAXFNAMELEN];
@@ -1296,7 +1293,7 @@ XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr,
     * check typically fails when an old WAL segment is recycled, and hasn't
     * yet been overwritten with new data yet.
     */
-   if (hdr->xlp_pageaddr != recaddr)
+   if (hdr->xlp_pageaddr != recptr)
    {
        char        fname[MAXFNAMELEN];