user/sven/linux.git/include/linux/bio.h, branch v4.4.2

block: Replace SG_GAPS with new queue limits mask

2015-08-19T21:26:02Z

The SG_GAPS queue flag caused checks for bio vector alignment against PAGE_SIZE, but the device may have different constraints. This patch adds a queue limits so a driver with such constraints can set to allow requests that would have been unnecessarily split. The new gaps check takes the request_queue as a parameter to simplify the logic around invoking this function. This new limit makes the queue flag redundant, so removing it and all usage. Device-mappers will inherit the correct settings through blk_stack_limits(). Signed-off-by: Keith Busch Reviewed-by: Martin K. Petersen Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe

block: remove bio_get_nr_vecs()

2015-08-13T18:32:04Z

We can always fill up the bio now, no need to estimate the possible size based on queue parameters. Acked-by: Steven Whitehouse Signed-off-by: Kent Overstreet [hch: rebased and wrote a changelog] Signed-off-by: Christoph Hellwig Signed-off-by: Ming Lin Signed-off-by: Jens Axboe

block: shrink struct bio down to 2 cache lines again

2015-07-29T14:55:25Z

Commit bcf2843b3f8f added ->bi_error to cleanup the error passing for struct bio, but that ended up adding 4 bytes and a 4 byte hole to the size of struct bio. For a clean config, that bumped it from 128 bytes, to 136 bytes, on x86-64. The ->bi_flags member is currently an unsigned long, but it fits easily within an int. Change it to an unsigned int, adjust the the pool offset code, and move ->bi_error into the new hole. Then we end up with a 128 byte bio again. Change the bio flag set/clear to use cmpxchg to ensure we don't lose any flags when manipulating them. Signed-off-by: Jens Axboe

block: manipulate bio->bi_flags through helpers

2015-07-29T14:55:20Z

Some places use helpers now, others don't. We only have the 'is set' helper, add helpers for setting and clearing flags too. It was a bit of a mess of atomic vs non-atomic access. With BIO_UPTODATE gone, we don't have any risk of concurrent access to the flags. So relax the restriction and don't make any of them atomic. The flags that do have serialization issues (reffed and chained), we already handle those separately. Signed-off-by: Jens Axboe

block: add a bi_error field to struct bio

2015-07-29T14:55:15Z

Currently we have two different ways to signal an I/O error on a BIO: (1) by clearing the BIO_UPTODATE flag (2) by returning a Linux errno value to the bi_end_io callback The first one has the drawback of only communicating a single possible error (-EIO), and the second one has the drawback of not beeing persistent when bios are queued up, and are not passed along from child to parent bio in the ever more popular chaining scenario. Having both mechanisms available has the additional drawback of utterly confusing driver authors and introducing bugs where various I/O submitters only deal with one of them, and the others have to add boilerplate code to deal with both kinds of error returns. So add a new bi_error field to store an errno value directly in struct bio and remove the existing mechanisms to clean all this up. Signed-off-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Reviewed-by: NeilBrown Signed-off-by: Jens Axboe

blkcg: implement bio_associate_blkcg()

2015-06-02T14:33:34Z

Currently, a bio can only be associated with the io_context and blkcg of %current using bio_associate_current(). This is too restrictive for cgroup writeback support. Implement bio_associate_blkcg() which associates a bio with the specified blkcg. bio_associate_blkcg() leaves the io_context unassociated. bio_associate_current() is updated so that it considers a bio as already associated if it has a blkcg_css, instead of an io_context, associated with it. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Vivek Goyal Signed-off-by: Jens Axboe

block: remove management of bi_remaining when restoring original bi_end_io

2015-05-22T14:58:55Z

Commit c4cf5261 ("bio: skip atomic inc/dec of ->bi_remaining for non-chains") regressed all existing callers that followed this pattern: 1) saving a bio's original bi_end_io 2) wiring up an intermediate bi_end_io 3) restoring the original bi_end_io from intermediate bi_end_io 4) calling bio_endio() to execute the restored original bi_end_io The regression was due to BIO_CHAIN only ever getting set if bio_inc_remaining() is called. For the above pattern it isn't set until step 3 above (step 2 would've needed to establish BIO_CHAIN). As such the first bio_endio(), in step 2 above, never decremented __bi_remaining before calling the intermediate bi_end_io -- leaving __bi_remaining with the value 1 instead of 0. When bio_inc_remaining() occurred during step 3 it brought it to a value of 2. When the second bio_endio() was called, in step 4 above, it should've called the original bi_end_io but it didn't because there was an extra reference that wasn't dropped (due to atomic operations being optimized away since BIO_CHAIN wasn't set upfront). Fix this issue by removing the __bi_remaining management complexity for all callers that use the above pattern -- bio_chain() is the only interface that _needs_ to be concerned with __bi_remaining. For the above pattern callers just expect the bi_end_io they set to get called! Remove bio_endio_nodec() and also remove all bio_inc_remaining() calls that aren't associated with the bio_chain() interface. Also, the bio_inc_remaining() interface has been moved local to bio.c. Fixes: c4cf5261 ("bio: skip atomic inc/dec of ->bi_remaining for non-chains") Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Signed-off-by: Mike Snitzer Signed-off-by: Jens Axboe

bio: skip atomic inc/dec of ->bi_cnt for most use cases

2015-05-05T19:32:49Z

Struct bio has a reference count that controls when it can be freed. Most uses cases is allocating the bio, which then returns with a single reference to it, doing IO, and then dropping that single reference. We can remove this atomic_dec_and_test() in the completion path, if nobody else is holding a reference to the bio. If someone does call bio_get() on the bio, then we flag the bio as now having valid count and that we must properly honor the reference count when it's being put. Tested-by: Robert Elliott Signed-off-by: Jens Axboe

bio: skip atomic inc/dec of ->bi_remaining for non-chains

2015-05-05T19:32:47Z

Struct bio has an atomic ref count for chained bio's, and we use this to know when to end IO on the bio. However, most bio's are not chained, so we don't need to always introduce this atomic operation as part of ending IO. Add a helper to elevate the bi_remaining count, and flag the bio as now actually needing the decrement at end_io time. Rename the field to __bi_remaining to catch any current users of this doing the incrementing manually. For high IOPS workloads, this reduces the overhead of bio_endio() substantially. Tested-by: Robert Elliott Acked-by: Kent Overstreet Reviewed-by: Jan Kara Signed-off-by: Jens Axboe

block: merge __bio_map_user_iov into bio_map_user_iov

2015-02-05T16:30:43Z

And also remove the unused bdev argument. Signed-off-by: Christoph Hellwig Reviewed-by: Ming Lei Signed-off-by: Jens Axboe