kernel/drivers/md/bcache/io.c, branch linux-4.3.y

bcache: remove driver private bio splitting code

2015-08-13T18:31:40Z

The bcache driver has always accepted arbitrarily large bios and split them internally. Now that every driver must accept arbitrarily large bios this code isn't nessecary anymore. Cc: linux-bcache@vger.kernel.org Signed-off-by: Kent Overstreet [dpark: add more description in commit message] Signed-off-by: Dongsu Park Signed-off-by: Ming Lin 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

bcache: don't embed 'return' statements in closure macros

2015-07-11T15:57:32Z

This is horribly confusing, it breaks the flow of the code without it being apparent in the caller. Signed-off-by: Jens Axboe Acked-by: Christoph Hellwig

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

block: Introduce new bio_split()

2013-11-24T06:33:57Z

The new bio_split() can split arbitrary bios - it's not restricted to single page bios, like the old bio_split() (previously renamed to bio_pair_split()). It also has different semantics - it doesn't allocate a struct bio_pair, leaving it up to the caller to handle completions. Then convert the existing bio_pair_split() users to the new bio_split() - and also nvme, which was open coding bio splitting. (We have to take that BUG_ON() out of bio_integrity_trim() because this bio_split() needs to use it, and there's no reason it has to be used on bios marked as cloned; BIO_CLONED doesn't seem to have clearly documented semantics anyways.) Signed-off-by: Kent Overstreet Cc: Jens Axboe Cc: Martin K. Petersen Cc: Matthew Wilcox Cc: Keith Busch Cc: Vishal Verma Cc: Jiri Kosina Cc: Neil Brown

block: Generic bio chaining

2013-11-24T06:33:56Z

This adds a generic mechanism for chaining bio completions. This is going to be used for a bio_split() replacement, and it turns out to be very useful in a fair amount of driver code - a fair number of drivers were implementing this in their own roundabout ways, often painfully. Note that this means it's no longer to call bio_endio() more than once on the same bio! This can cause problems for drivers that save/restore bi_end_io. Arguably they shouldn't be saving/restoring bi_end_io at all - in all but the simplest cases they'd be better off just cloning the bio, and immutable biovecs is making bio cloning cheaper. But for now, we add a bio_endio_nodec() for these cases. Signed-off-by: Kent Overstreet Cc: Jens Axboe

block: Remove bi_idx hacks

2013-11-24T06:33:55Z

Now that drivers have been converted to the new bvec_iter primitives, there's no need to trim the bvec before we submit it; and we can't trim it once we start sharing bvecs. It used to be that passing a partially completed bio (i.e. one with nonzero bi_idx) to generic_make_request() was a dangerous thing - various drivers would choke on such things. But with immutable biovecs and our new bio splitting that shares the biovecs, submitting partially completed bios has to work (and should work, now that all the drivers have been completed to the new primitives) Signed-off-by: Kent Overstreet Cc: Jens Axboe

block: Kill bio_segments()/bi_vcnt usage

2013-11-24T06:33:51Z

When we start sharing biovecs, keeping bi_vcnt accurate for splits is going to be error prone - and unnecessary, if we refactor some code. So bio_segments() has to go - but most of the existing users just needed to know if the bio had multiple segments, which is easier - add a bio_multiple_segments() for them. (Two of the current uses of bio_segments() are going to go away in a couple patches, but the current implementation of bio_segments() is unsafe as soon as we start doing driver conversions for immutable biovecs - so implement a dumb version for bisectability, it'll go away in a couple patches) Signed-off-by: Kent Overstreet Cc: Jens Axboe Cc: Neil Brown Cc: Nagalakshmi Nandigama Cc: Sreekanth Reddy Cc: "James E.J. Bottomley"

block: Convert bio_for_each_segment() to bvec_iter

2013-11-24T06:33:49Z

More prep work for immutable biovecs - with immutable bvecs drivers won't be able to use the biovec directly, they'll need to use helpers that take into account bio->bi_iter.bi_bvec_done. This updates callers for the new usage without changing the implementation yet. Signed-off-by: Kent Overstreet Cc: Jens Axboe Cc: Geert Uytterhoeven Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: "Ed L. Cashin" Cc: Nick Piggin Cc: Lars Ellenberg Cc: Jiri Kosina Cc: Paul Clements Cc: Jim Paris Cc: Geoff Levand Cc: Yehuda Sadeh Cc: Sage Weil Cc: Alex Elder Cc: ceph-devel@vger.kernel.org Cc: Joshua Morris Cc: Philip Kelleher Cc: Konrad Rzeszutek Wilk Cc: Jeremy Fitzhardinge Cc: Neil Brown Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: linux390@de.ibm.com Cc: Nagalakshmi Nandigama Cc: Sreekanth Reddy Cc: support@lsi.com Cc: "James E.J. Bottomley" Cc: Greg Kroah-Hartman Cc: Alexander Viro Cc: Steven Whitehouse Cc: Herton Ronaldo Krzesinski Cc: Tejun Heo Cc: Andrew Morton Cc: Guo Chao Cc: Asai Thambi S P Cc: Selvan Mani Cc: Sam Bradshaw Cc: Matthew Wilcox Cc: Keith Busch Cc: Stephen Hemminger Cc: Quoc-Son Anh Cc: Sebastian Ott Cc: Nitin Gupta Cc: Minchan Kim Cc: Jerome Marchand Cc: Seth Jennings Cc: "Martin K. Petersen" Cc: Mike Snitzer Cc: Vivek Goyal Cc: "Darrick J. Wong" Cc: Chris Metcalf Cc: Jan Kara Cc: linux-m68k@lists.linux-m68k.org Cc: linuxppc-dev@lists.ozlabs.org Cc: drbd-user@lists.linbit.com Cc: nbd-general@lists.sourceforge.net Cc: cbe-oss-dev@lists.ozlabs.org Cc: xen-devel@lists.xensource.com Cc: virtualization@lists.linux-foundation.org Cc: linux-raid@vger.kernel.org Cc: linux-s390@vger.kernel.org Cc: DL-MPTFusionLinux@lsi.com Cc: linux-scsi@vger.kernel.org Cc: devel@driverdev.osuosl.org Cc: linux-fsdevel@vger.kernel.org Cc: cluster-devel@redhat.com Cc: linux-mm@kvack.org Acked-by: Geoff Levand

block: Convert bio_iovec() to bvec_iter

2013-11-24T06:33:49Z

For immutable biovecs, we'll be introducing a new bio_iovec() that uses our new bvec iterator to construct a biovec, taking into account bvec_iter->bi_bvec_done - this patch updates existing users for the new usage. Some of the existing users really do need a pointer into the bvec array - those uses are all going to be removed, but we'll need the functionality from immutable to remove them - so for now rename the existing bio_iovec() -> __bio_iovec(), and it'll be removed in a couple patches. Signed-off-by: Kent Overstreet Cc: Jens Axboe Cc: "Ed L. Cashin" Cc: Alasdair Kergon Cc: dm-devel@redhat.com Cc: "James E.J. Bottomley"