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Fix corruption of local buffer state during extend of temp relation

A typo has been introduced by31966b1 when updating the state of alocal buffer when a temporary relation is extended, for the case of ablock included in the relation range extended, when it is already foundin the hash table holding the local buffers. In this case, BM_VALIDshould be cleared, but the buffer state was changed so as BM_VALIDremained while clearing the other flags.As reported on the thread, it was possible to corrupt the state of thelocal buffers on ENOSPC, but the states would be corrupted on any kindof ERROR during the relation extend (like partial writes or some othererrno).Reported-by: Alexander LakhinAuthor: Tender WangReviewed-by: Richard Guo, Alexander Lakhin, Michael PaquierDiscussion:https://postgr.es/m/18259-6e256429825dd435@postgresql.orgBackpatch-through: 16

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src/backend/storage/buffer
- localbuf.c

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`‎src/backend/storage/buffer/localbuf.c`

Lines changed: 2 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -380,7 +380,7 @@ ExtendBufferedRelLocal(BufferManagerRelation bmr,`
`380`	`380`	`hash_search(LocalBufHash, (void*)&tag,HASH_ENTER,&found);`
`381`	`381`	`if (found)`
`382`	`382`	`{`
`383`		`-BufferDesc*existing_hdr=GetLocalBufferDescriptor(hresult->id);`
	`383`	`+BufferDesc*existing_hdr;`
`384`	`384`	`uint32buf_state;`
`385`	`385`
`386`	`386`	`UnpinLocalBuffer(BufferDescriptorGetBuffer(victim_buf_hdr));`
`@@ -392,7 +392,7 @@ ExtendBufferedRelLocal(BufferManagerRelation bmr,`
`392`	`392`	`buf_state=pg_atomic_read_u32(&existing_hdr->state);`
`393`	`393`	`Assert(buf_state&BM_TAG_VALID);`
`394`	`394`	`Assert(!(buf_state&BM_DIRTY));`
`395`		`-buf_state &=BM_VALID;`
	`395`	`+buf_state &=~BM_VALID;`
`396`	`396`	`pg_atomic_unlocked_write_u32(&existing_hdr->state,buf_state);`
`397`	`397`	`}`
`398`	`398`	`else`

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Commit9cd0d77

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`‎src/backend/storage/buffer/localbuf.c`

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