block: don't call bio_uninit from bio_endio

BugLink: https://bugs.launchpad.net/bugs/2085849

[ Upstream commit bf4c89fc8797f5c0964a0c3d561fbe7e8483b62f ]

Commit b222dd2fdd ("block: call bio_uninit in bio_endio") added a call
to bio_uninit in bio_endio to work around callers that use bio_init but
fail to call bio_uninit after they are done to release the resources.
While this is an abuse of the bio_init API we still have quite a few of
those left.  But this early uninit causes a problem for integrity data,
as at least some users need the bio_integrity_payload.  Right now the
only one is the NVMe passthrough which archives this by adding a special
case to skip the freeing if the BIP_INTEGRITY_USER flag is set.

Sort this out by only putting bi_blkg in bio_endio as that is the cause
of the actual leaks - the few users of the crypto context and integrity
data all properly call bio_uninit, usually through bio_put for
dynamically allocated bios.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240702151047.1746127-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Roxana Nicolescu <roxana.nicolescu@canonical.com>

block/bio.c

@@ -1603,8 +1603,18 @@ again:
 	}
 
 	blk_throtl_bio_endio(bio);
-	/* release cgroup info */
-	bio_uninit(bio);
+#ifdef CONFIG_BLK_CGROUP
+	/*
+	 * Release cgroup info.  We shouldn't have to do this here, but quite
+	 * a few callers of bio_init fail to call bio_uninit, so we cover up
+	 * for that here at least for now.
+	 */
+	if (bio->bi_blkg) {
+		blkg_put(bio->bi_blkg);
+		bio->bi_blkg = NULL;
+	}
+#endif
+
 	if (bio->bi_end_io)
 		bio->bi_end_io(bio);
 }