BIO_ALLOC

Section: The Linux VFS (9)
Updated: February 2011
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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