There was some looping in submit_partial_cache_hit() and
submit_partial_cache_hit() that isn't needed anymore - originally, we
wouldn't necessarily process the full hit or miss all at once because
when splitting the bio, we took into account the restrictions of the
device we were sending it to.

But, device bio size restrictions are now handled elsewhere, with a
wrapper around generic_make_request() - so that looping has been
unnecessary for awhile now and we can now do quite a bit of cleanup.

And if we trim the key we're reading from to match the subset we're
actually reading, we don't have to explicitly calculate bi_sector
anymore. Neat.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

This is a fairly straightforward conversion, mostly reshuffling -
op->lookup_done goes away, replaced by MAP_DONE/MAP_CONTINUE. And the
code for handling cache hits and misses wasn't really btree code, so it
gets moved to request.c.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

With the new btree_map() functions, we don't need to export the stuff
needed for traversing the btree anymore.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

We needed a dedicated rescuer workqueue for gc anyways... and gc was
conceptually a dedicated thread, just one that wasn't running all the
time. Switch it to a dedicated thread to make the code a bit more
straightforward.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

At one point we did do fancy asynchronous waiting stuff with
bucket_wait, but that's all gone (and bucket_wait is used a lot less
than it used to be). So use the standard primitives.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

Slowly working on pruning struct btree_op - the aim is for it to only
contain things that are actually necessary for traversing the btree.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

Making things less asynchronous that don't need to be - bch_journal()
only has to block when the journal or journal entry is full, which is
emphatically not a fast path. So make it a normal function that just
returns when it finishes, to make the code and control flow easier to
follow.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

More refactoring, and renaming.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

Try to improve some of the naming a bit to be more consistent, and also
improve the flow of control in request_write() a bit.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

More random refactoring.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

Some refactoring - better to explicitly pass stuff around instead of
having it all in the "big bag of state", struct btree_op. Going to prune
struct btree_op quite a bit over time.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

This was the main point of all this refactoring - now,
btree_insert_check_key() won't fail just because the leaf node happened
to be full.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>

Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.10
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit c0f04d88 ("bcache: Fix flushes in writeback mode") was fixing
a reported data corruption bug, but it seems some last minute
refactoring or rebasing introduced a null pointer deref.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.10
Reported-by: NGabriel de Perthuis <g2p.code@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In writeback mode, when we get a cache flush we need to make sure we
issue a flush to the backing device.

The code for sending down an extra flush was wrong - by cloning the bio
we were probably getting flags that didn't make sense for a bare flush,
and also the old code was firing for FUA bios, for which we don't need
to send a flush to the backing device.

This was causing data corruption somehow - the mechanism was never
determined, but this patch fixes it for the users that were seeing it.
Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.10
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Whoops - bcache's flush/FUA was mostly correct, but flushes get filtered
out unless we say we support them...
Signed-off-by: NKent Overstreet <kmo@daterainc.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.10

Some of bcache's utility code has made it into the rest of the kernel,
so drop the bcache versions.

Bcache used to have a workaround for allocating from a bio set under
generic_make_request() (if you allocated more than once, the bios you
already allocated would get stuck on current->bio_list when you
submitted, and you'd risk deadlock) - bcache would mask out __GFP_WAIT
when allocating bios under generic_make_request() so that allocation
could fail and it could retry from workqueue. But bio_alloc_bioset() has
a workaround now, so we can drop this hack and the associated error
handling.
Signed-off-by: NKent Overstreet <koverstreet@google.com>

Journal writes need to be marked FUA, not just REQ_FLUSH. And btree node
writes have... weird ordering requirements.
Signed-off-by: NKent Overstreet <koverstreet@google.com>

Now that we're tracking dirty data per stripe, we can add two
optimizations for raid5/6:

 * If a stripe is already dirty, force writes to that stripe to
   writeback mode - to help build up full stripes of dirty data

 * When flushing dirty data, preferentially write out full stripes first
   if there are any.
Signed-off-by: NKent Overstreet <koverstreet@google.com>

To make background writeback aware of raid5/6 stripes, we first need to
track the amount of dirty data within each stripe - we do this by
breaking up the existing sectors_dirty into per stripe atomic_ts
Signed-off-by: NKent Overstreet <koverstreet@google.com>

The tracepoints were reworked to be more sensible, and fixed a null
pointer deref in one of the tracepoints.

Converted some of the pr_debug()s to tracepoints - this is partly a
performance optimization; it used to be that with DEBUG or
CONFIG_DYNAMIC_DEBUG pr_debug() was an empty macro; but at some point it
was changed to an empty inline function.

Some of the pr_debug() statements had rather expensive function calls as
part of the arguments, so this code was getting run unnecessarily even
on non debug kernels - in some fast paths, too.
Signed-off-by: NKent Overstreet <koverstreet@google.com>

Add a new superblock version, and consolidate related defines.
Signed-off-by: NGabriel de Perthuis <g2p.code+bcache@gmail.com>
Signed-off-by: NKent Overstreet <koverstreet@google.com>

Signed-off-by: NKent Overstreet <koverstreet@google.com>
Cc: linux-bcache@vger.kernel.org
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Took out some nested functions, and fixed some more checkpatch
complaints.
Signed-off-by: NKent Overstreet <koverstreet@google.com>
Cc: linux-bcache@vger.kernel.org
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Does writethrough and writeback caching, handles unclean shutdown, and
has a bunch of other nifty features motivated by real world usage.

See the wiki at http://bcache.evilpiepirate.org for more.
Signed-off-by: NKent Overstreet <koverstreet@google.com>