The sector number on empty barrier requests may (will?) be -1, which,
given that it's being treated as unsigned 64-bit quantity, will almost
always exceed the actual (virtual) disk's size.
Inspired by Konrad's "When writting barriers set the sector number to
zero...".
While at it also add overflow checking to the math in vbd_translate().
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
vbd_resize() up_read()'s xs_state.suspend_mutex twice in a row via double
xenbus_transaction_end() calls. The next down_read() in
xenbus_transaction_start() (at eg. the next resize attempt) hangs.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=618317
Acked-by: Jan Beulich <jbeulich@novell.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
We do a check for the operations right before calling dispatch_rw_block_io.
And then we do the same check in dispatch_rw_block_io. This patch
squashes those checks into the 'dispatch_rw_block_io' function.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
We drop the support for 'feature-barrier' and add in the support
for the 'feature-flush-cache' if the real backend storage supports
flushing.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The operation BLKIF_OP_WRITE_FLUSH_CACHE has existed in the Xen
tree header file for years but it was never present in the Linux tree
because the frontend (nor the backend) supported this interface.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
If one runs a simple fio request with random read/write with a
20%/80% ratio, the numbers are incredibly bad when using the CFQ scheduler.
IOmeter | | | |
64K, randrw | NOOP | CFQ | deadline |
randrwmix=80 | | | |
--------------+-------+------+----------+
blkback |103/27 |32/10 | 102/27 |
--------------+-------+------+----------+
QEMU qdisk |103/27 |102/27| 102/27 |
The problem as explained by Vivek Goyal was:
".. that difference is that sync vs async requests. In the case of
a kernel thread submitting IO, [..] all the WRITES might be being
considered as async and will go in a different queue. If you mix those
with some READS, they are always sync and will go in differnet queue.
In presence of sync queue, CFQ will idle and choke up WRITES in
an attempt to improve latencies of READs.
In case of AIO [note: this is what QEMU qdisk is doing] , [..]
it is direct IO and both READS and WRITES will be considered SYNC
and will go in a single queue and no choking of WRITES will take place."
The solution is quite simple, tack on REQ_SYNC (which is
what the WRITE_ODIRECT macro points to) and the numbers go
back up.
Suggested-by: Vivek Goyal <vgoyal@redhat.com
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
We used to the plug/unplug on the submit_bio. But that means
if within a stream of WRITE, WRITE, WRITE,...,WRITE we have
one READ, it could stall the pipeline (as the 'submio_bio'
could trigger the unplug_fnc to be called and stall/sync
when doing the READ). Instead we want to move the unplugging
when the whole (or as a much as possible) ring buffer has been
processed. This also eliminates us doing plug/unplug for
each request.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
And also shorten the name if it has blkback to blkbk.
This results in the symbol table (if compiled in the kernel)
to be much shorter, prettier, and also easier to search for.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
There is no need for it, as the address is updated constatly
in the root of the Linux kernel.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Daniel Stodden suggested to eliminate vbd.c and interface.c, inlining the
critical bits where they belong, respectively.
Leaving only blkback.c for the data- and xenbus.c for the control path.
Suggested-by: Daniel Stodden <daniel.stodden@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
They were used to check if the queue does not have QUEUE_FLAG_DEAD
set. That is not necessary anymore as the 'submit_io' call
ends up doing that for us.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
After the commit 0faa8cca88
(" xen/blkback: remove per-queue plugging") we forgot
to retrieve the 'struct request_queue' from the block device.
This puts the functionality back in and fixes a NULL pointer
bug.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The commit 976222e05e
xen/blkback: Move the check for misaligned I/O higher.
moved it a bit to high. The preq->vbdev was not set, so the
check for misaligned I/O would cause a NULL pointer derefence.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The previous name ('fast_flush_area') had nothing to do with what it
does right now. Changing the names so that the code dealing with
mapping pages in and out of the guest is called xen_blkbk_[map|unmap].
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
We move it up higher to be in same loop that actually computes
the sector number.
This way, all of the code that deals with verifying that the
request is correct is all done before we do any of the
page mapping, I/O submission, etc.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
We take out the chunk of code dealing with mapping to the guest
of pages into the xen_blk_map_buf code. And we also move the
vbd_translate to be done much earlier.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Moving it so that the code that 'fast_flush_area' code is
close to the code that deals with it so that the reader
won't lose focus.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
We seperate the bio allocation (bio_alloc) from the bio submission so
that the error paths are much easier, and also so that the bio
submission can be done in one tight loop. It also makes the
plug/unplug calls much much easier.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
commit 7eaceaccab ("block: remove per-queue plugging")
added two new interfaces to plug and unplug: blk_start_plug
and blk_finish_plug. Lets use those.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+ sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring_area->addr;
WARNING: line over 80 characters
+ BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
as breaking them up really does not help that much.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
checkpatch.pl suggested that we don't use the typdef in common.h
and this triggered this avalanche of patches.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The WRITE_BARRIER was missing the REQ_WRITE option. This
was causing the blktap to die.
Signed-off-by: Tom Goetz <tom.goetz@virtualcomputer.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The patch titled:"xen/blkback: Use 'vzalloc' for page arrays and pre-allocate pages."
allocates the structures and its member variables using the 'vzalloc'.
Daniel Stodden pointed out that vzalloc is good when we use
big number of pages - while these are at the max two pages.
We can do this using kzalloc. Also the GFP_HIGHMEM does not
work properly with Xen, so take that out.
We will have to revisit this when a "get_empty_pages_and_pagevec"
type API shows up to leverage that.
BugLink: http://mid.gmane.org/1299898639.11681.227.camel@agari.van.xensource.com
CC: Daniel Stodden <daniel.stodden@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Instead of doing copy grants lets do mapping grants using
the M2P(and P2M) override mechanism.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Conflicts:
drivers/xen/blkback/blkback.c
Jan Beulich
Laszlo Ersek
Konrad Rzeszutek Wilk
Konrad Rzeszutek Wilk
Tom Goetz