Commit26158b8

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Use ExtendBufferedRelTo() in XLogReadBufferExtended()

Instead of extending the relation block-by-block, use ExtendBufferedRelTo(),introduced in31966b1. This is faster and simpler.This also somewhat reduces the danger that disconnected segments pose (whichcan be "discovered" once the previous segment reaches SEGSIZE), asExtendBufferedRelTo() won't extend past the block it has been asked. However,the risk of the content of such a disconnected segment being invalidremains.Discussion:https://postgr.es/m/20221029025420.eplyow6k7tgu6he3@awork3.anarazel.deDiscussion:https://postgr.es/m/20230223010147.32oir7sb66slqnjk@awork3.anarazel.de

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Lines changed: 7 additions & 22 deletions

Original file line number	Diff line number	Diff line change
`@@ -524,28 +524,13 @@ XLogReadBufferExtended(RelFileLocator rlocator, ForkNumber forknum,`
`524`	`524`	`/* OK to extend the file */`
`525`	`525`	`/* we do this in recovery only - no rel-extension lock needed */`
`526`	`526`	`Assert(InRecovery);`
`527`		`-buffer=InvalidBuffer;`
`528`		`-do`
`529`		`-{`
`530`		`-if (buffer!=InvalidBuffer)`
`531`		`-{`
`532`		`-if (mode==RBM_ZERO_AND_LOCK\|\|mode==RBM_ZERO_AND_CLEANUP_LOCK)`
`533`		`-LockBuffer(buffer,BUFFER_LOCK_UNLOCK);`
`534`		`-ReleaseBuffer(buffer);`
`535`		`-}`
`536`		`-buffer=ReadBufferWithoutRelcache(rlocator,forknum,`
`537`		`-P_NEW,mode,NULL, true);`
`538`		`-}`
`539`		`-while (BufferGetBlockNumber(buffer)<blkno);`
`540`		`-/* Handle the corner case that P_NEW returns non-consecutive pages */`
`541`		`-if (BufferGetBlockNumber(buffer)!=blkno)`
`542`		`-{`
`543`		`-if (mode==RBM_ZERO_AND_LOCK\|\|mode==RBM_ZERO_AND_CLEANUP_LOCK)`
`544`		`-LockBuffer(buffer,BUFFER_LOCK_UNLOCK);`
`545`		`-ReleaseBuffer(buffer);`
`546`		`-buffer=ReadBufferWithoutRelcache(rlocator,forknum,blkno,`
`547`		`-mode,NULL, true);`
`548`		`-}`
	`527`	`+buffer=ExtendBufferedRelTo(EB_SMGR(smgr,RELPERSISTENCE_PERMANENT),`
	`528`	`+forknum,`
	`529`	`+NULL,`
	`530`	`+EB_PERFORMING_RECOVERY \|`
	`531`	`+EB_SKIP_EXTENSION_LOCK,`
	`532`	`+blkno+1,`
	`533`	`+mode);`
`549`	`534`	`}`
`550`	`535`
`551`	`536`	`recent_buffer_fast_path:`

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