BIO_ALLOC(9) The Linux VFS BIO_ALLOC(9)
NAME bio_alloc - allocate a new bio, memory pool backed
SYNOPSIS struct bio * bio_alloc(gfp_t gfp_mask, int nr_iovecs);
ARGUMENTS gfp_mask allocation mask to use
nr_iovecs number of iovecs
DESCRIPTION bio_alloc will allocate a bio and associated bio_vec array that can hold at least nr_iovecs entries. Allocations will be done from the fs_bio_set. Also see bio_alloc_bioset and bio_kmalloc.
If __GFP_WAIT is set, then bio_alloc will always be able to allocate a bio. This is due to the mempool guarantees. To make this work, callers must never allocate more than 1 bio at a time from this pool. Callers that need to allocate more than 1 bio must always submit the previously allocated bio for IO before attempting to allocate a new one. Failure to do so can cause livelocks under memory pressure.
RETURNS Pointer to new bio on success, NULL on failure.
COPYRIGHT Kernel Hackers Manual 2.6. April 2016 BIO_ALLOC(9)