TRACE_BLOCK_BIO_FRON(9) Block IO TRACE_BLOCK_BIO_FRON(9)NAME
trace_block_bio_frontmerge - merging block operation to the beginning of an existing operation
void trace_block_bio_frontmerge(struct request_queue * q, struct request * rq, struct bio * bio);
queue holding operation
request bio is being merged into
new block operation to merge
Merging block IO operation bio to the beginning of an existing block operation in queue q.
Jason Baron <email@example.com>
William Cohen <firstname.lastname@example.org>
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 TRACE_BLOCK_BIO_FRON(9)
Check Out this Related Man Page
BIO_ALLOC_BIOSET(9) The Linux VFS BIO_ALLOC_BIOSET(9)NAME
bio_alloc_bioset - allocate a bio for I/O
struct bio * bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set * bs);
the GFP_ mask given to the slab allocator
number of iovecs to pre-allocate
the bio_set to allocate from.
If bs is NULL, uses kmalloc to allocate the bio; else the allocation is backed by the bs's mempool.
When bs is not NULL, 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 deadlocks under
Note that when running under generic_make_request (i.e. any block driver), bios are not submitted until after you return - see the code in
generic_make_request that converts recursion into iteration, to prevent stack overflows.
This would normally mean allocating multiple bios under generic_make_request would be susceptible to deadlocks, but we have deadlock
avoidance code that resubmits any blocked bios from a rescuer thread.
However, we do not guarantee forward progress for allocations from other mempools. Doing multiple allocations from the same mempool under
generic_make_request should be avoided - instead, use bio_set's front_pad for per bio allocations.
Pointer to new bio on success, NULL on failure.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 BIO_ALLOC_BIOSET(9)
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