From: Yu Kuai <[email protected]> bio_alloc_clone(), bio_init_clone(), and bio_alloc_bioset() can be called with non-blocking GFP masks. Passing a bdev into bio initialization may need to associate blkcg state and, after missing blkg creation is serialized by q->blkcg_mutex, that association can sleep.
Keep the generic block layer simple by letting bio_alloc_bioset() handle this case directly. Non-blocking allocations initialize the bio without a bdev, set the bdev fields, and associate the blkg with nowait=true. If the needed blkg is missing and would have to be created, allocation fails normally so the caller can retry from a blocking context. Blocking callers keep the existing allocation-time association behavior. Signed-off-by: Yu Kuai <[email protected]> --- block/bio.c | 46 ++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 40 insertions(+), 6 deletions(-) diff --git a/block/bio.c b/block/bio.c index b74e9961c8ee..863ae73a4222 100644 --- a/block/bio.c +++ b/block/bio.c @@ -259,6 +259,20 @@ void bio_init(struct bio *bio, struct block_device *bdev, struct bio_vec *table, } EXPORT_SYMBOL(bio_init); +static bool bio_init_nowait(struct bio *bio, struct block_device *bdev, + struct bio_vec *table, unsigned short max_vecs, blk_opf_t opf) +{ + bio_init(bio, NULL, table, max_vecs, opf); + if (bdev) { + bio_set_dev_no_blkg(bio, bdev); + if (bio_associate_blkg(bio, true)) + return true; + bio_uninit(bio); + return false; + } + return true; +} + /** * bio_reset - reinitialize a bio * @bio: bio to reset @@ -599,12 +613,25 @@ struct bio *bio_alloc_bioset(struct block_device *bdev, unsigned short nr_vecs, } } - if (nr_vecs && nr_vecs <= BIO_INLINE_VECS) - bio_init_inline(bio, bdev, nr_vecs, opf); - else - bio_init(bio, bdev, bvecs, nr_vecs, opf); + if (nr_vecs && nr_vecs <= BIO_INLINE_VECS) { + bvecs = bio_inline_vecs(bio); + if (gfpflags_allow_blocking(saved_gfp)) + bio_init(bio, bdev, bvecs, nr_vecs, opf); + else if (!bio_init_nowait(bio, bdev, bvecs, nr_vecs, opf)) + goto fail_free_bio; + } else { + if (gfpflags_allow_blocking(saved_gfp)) + bio_init(bio, bdev, bvecs, nr_vecs, opf); + else if (!bio_init_nowait(bio, bdev, bvecs, nr_vecs, opf)) + goto fail_free_bio; + } bio->bi_pool = bs; return bio; + +fail_free_bio: + bio->bi_pool = bs; + bio_put(bio); + return NULL; } EXPORT_SYMBOL(bio_alloc_bioset); @@ -857,7 +884,9 @@ static int __bio_clone(struct bio *bio, struct bio *bio_src, gfp_t gfp) if (bio->bi_bdev == bio_src->bi_bdev && bio_flagged(bio_src, BIO_REMAPPED)) bio_set_flag(bio, BIO_REMAPPED); - bio_clone_blkg_association(bio, bio_src, false); + if (!bio_clone_blkg_association(bio, bio_src, + !gfpflags_allow_blocking(gfp))) + return -ENOMEM; } if (bio_crypt_clone(bio, bio_src, gfp) < 0) @@ -913,9 +942,14 @@ EXPORT_SYMBOL(bio_alloc_clone); int bio_init_clone(struct block_device *bdev, struct bio *bio, struct bio *bio_src, gfp_t gfp) { + bool blocking = gfpflags_allow_blocking(gfp); int ret; - bio_init(bio, bdev, bio_src->bi_io_vec, 0, bio_src->bi_opf); + if (blocking) + bio_init(bio, bdev, bio_src->bi_io_vec, 0, bio_src->bi_opf); + else if (!bio_init_nowait(bio, bdev, bio_src->bi_io_vec, 0, + bio_src->bi_opf)) + return -ENOMEM; ret = __bio_clone(bio, bio_src, gfp); if (ret) bio_uninit(bio); -- 2.51.0
