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block: warn if !__GFP_DIRECT_RECLAIM in bio_crypt_set_ctx()

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bio_crypt_set_ctx() assumes its gfp_mask argument always includes
__GFP_DIRECT_RECLAIM, so that the mempool_alloc() will always succeed.

For now this assumption is still fine, since no callers violate it.
Making bio_crypt_set_ctx() able to fail would add unneeded complexity.

However, if a caller didn't use __GFP_DIRECT_RECLAIM, it would be very
hard to notice the bug.  Make it easier by adding a WARN_ON_ONCE().

Signed-off-by: Eric Biggers <[email protected]>
Reviewed-by: Satya Tangirala <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Satya Tangirala <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
Eric Biggers authored and Jens Axboe committed 2020-10-05 10:47:43 -06:00
1 parent 93f221ae08
commit cf785af193
1 file changed
+9 -1
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block/blk-crypto.c
+9 -1
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@@ -81,7 +81,15 @@ subsys_initcall(bio_crypt_ctx_init);
void bio_crypt_set_ctx(struct bio *bio, const struct blk_crypto_key *key,
const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask)
{
struct bio_crypt_ctx *bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
struct bio_crypt_ctx *bc;
/*
* The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so
* that the mempool_alloc() can't fail.
*/
WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM));
bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask);
bc->bc_key = key;
memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun));