postgres.git / summary / log / commit / refs

commit    26158b852d3adf6936008ce09c9ff2b947c8df40
Author:   Andres Freund <andres@anarazel.de>
Date:     Fri Apr 07 00:45:42 2023 +0000

    Use ExtendBufferedRelTo() in XLogReadBufferExtended()
    
    Instead of extending the relation block-by-block, use ExtendBufferedRelTo(),
    introduced in 31966b151e6. This is faster and simpler.
    
    This also somewhat reduces the danger that disconnected segments pose (which
    can be "discovered" once the previous segment reaches SEGSIZE), as
    ExtendBufferedRelTo() won't extend past the block it has been asked. However,
    the risk of the content of such a disconnected segment being invalid
    remains.
    
    Discussion: https://postgr.es/m/20221029025420.eplyow6k7tgu6he3@awork3.anarazel.de
    Discussion: https://postgr.es/m/20230223010147.32oir7sb66slqnjk@awork3.anarazel.de


 src/backend/access/transam/xlogutils.c | 29 +++++++----------------------
 1 file changed, 7 insertions(+), 22 deletions(-)

diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 2c28956b1aa..e174a2a8919 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -524,28 +524,13 @@ XLogReadBufferExtended(RelFileLocator rlocator, ForkNumber forknum,
 		/* OK to extend the file */
 		/* we do this in recovery only - no rel-extension lock needed */
 		Assert(InRecovery);
-		buffer = InvalidBuffer;
-		do
-		{
-			if (buffer != InvalidBuffer)
-			{
-				if (mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK)
-					LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-				ReleaseBuffer(buffer);
-			}
-			buffer = ReadBufferWithoutRelcache(rlocator, forknum,
-											   P_NEW, mode, NULL, true);
-		}
-		while (BufferGetBlockNumber(buffer) < blkno);
-		/* Handle the corner case that P_NEW returns non-consecutive pages */
-		if (BufferGetBlockNumber(buffer) != blkno)
-		{
-			if (mode == RBM_ZERO_AND_LOCK || mode == RBM_ZERO_AND_CLEANUP_LOCK)
-				LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-			ReleaseBuffer(buffer);
-			buffer = ReadBufferWithoutRelcache(rlocator, forknum, blkno,
-											   mode, NULL, true);
-		}
+		buffer = ExtendBufferedRelTo(EB_SMGR(smgr, RELPERSISTENCE_PERMANENT),
+									 forknum,
+									 NULL,
+									 EB_PERFORMING_RECOVERY |
+									 EB_SKIP_EXTENSION_LOCK,
+									 blkno + 1,
+									 mode);
 	}
 
 recent_buffer_fast_path:


[parent: ae78cae3be62]