The xenbus module provides xenbus_map_ring_valloc() and
xenbus_map_ring_vfree().  Use these to map the ring pages granted by
the frontend.
Acked-by: NJens Axboe <jaxboe@fusionio.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

There are two windows of opportunity to cause a race when
processing a barrier request. This patch fixes this.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The patch titled: "xen/blkback: Fix the inhibition to map pages
when discarding sector ranges." had the right idea except that
it used the wrong comparison operator. It had == instead of !=.

This fixes the bug where all (except discard) operations would
have been ignored.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The 'operation' parameters are the ones provided to the bio layer while
the req->operation are the ones passed in between the backend and
frontend. We used the wrong 'operation' value to squash the
call to map pages when processing the discard operation resulting
in an hypercall that did nothing. Lets guard against going in the
mapping function by checking for the proper operation type.

CC: Li Dongyang <lidongyang@novell.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

We did not increment the amount of sectors written to disk
b/c we tested for the == WRITE which is incorrect - as the
operations are more of WRITE_FLUSH, WRITE_ODIRECT. This patch
fixes it by doing a & WRITE check.

CC: stable@kernel.org
Reported-by: NAndy Burns <xen.lists@burns.me.uk>
Suggested-by: NIan Campbell <Ian.Campbell@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

We emulate the barrier requests by draining the outstanding bio's
and then sending the WRITE_FLUSH command. To drain the I/Os
we use the refcnt that is used during disconnect to wait for all
the I/Os before disconnecting from the frontend. We latch on its
value and if it reaches either the threshold for disconnect or when
there are no more outstanding I/Os, then we have drained all I/Os.
Suggested-by: NChristopher Hellwig <hch@infradead.org>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

This fixes the problem of three of those four memset()-s having
improper size arguments passed: Sizeof a pointer-typed expression
returns the size of the pointer, not that of the pointed to data.

It also reverts using kmalloc() instead of kzalloc() for the allocation
of the pending grant handles array, as that array gets fully
initialized in a subsequent loop.
Reported-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

This patch fixes belows:

1. Fix code style issue.
2. Fix incorrect functions name in comments.
Signed-off-by: NJoe Jin <joe.jin@oracle.com>
Cc: Jens Axboe <jaxboe@fusionio.com>
Cc: Ian Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

..aka ATA TRIM/SCSI UNMAP command to be passed through the frontend
and used as appropiately by the backend. We also advertise
certain granulity parameters to the frontend so it can plug them in.
If the backend is a realy device - we just end up using
'blkdev_issue_discard' while for loopback devices - we just punch
a hole in the image file.
Signed-off-by: NLi Dongyang <lidongyang@novell.com>
[v1: Fixed up pr_debug and commit description]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

If we want to use granted pages for AIO, changing the mappings of a user
vma and the corresponding p2m is not enough, we also need to update the
kernel mappings accordingly.
Currently this is only needed for pages that are created for user usages
through /dev/xen/gntdev. As in, pages that have been in use by the
kernel and use the P2M will not need this special mapping.
However there are no guarantees that in the future the kernel won't
start accessing pages through the 1:1 even for internal usage.

In order to avoid the complexity of dealing with highmem, we allocated
the pages lowmem.
We issue a HYPERVISOR_grant_table_op right away in
m2p_add_override and we remove the mappings using another
HYPERVISOR_grant_table_op in m2p_remove_override.
Considering that m2p_add_override and m2p_remove_override are called
once per page we use multicalls and hypercall batching.

Use the kmap_op pointer directly as argument to do the mapping as it is
guaranteed to be present up until the unmapping is done.
Before issuing any unmapping multicalls, we need to make sure that the
mapping has already being done, because we need the kmap->handle to be
set correctly.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
[v1: Removed GRANT_FRAME_BIT usage]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

It was pointed out by 'make versioncheck' that some includes of
linux/version.h are not needed in drivers/block/.
This patch removes them.
Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

This patch fixes belows:

1. Fix code style issue.
2. Fix incorrect functions name in comments.
Signed-off-by: NJoe Jin <joe.jin@oracle.com>
Cc: Jens Axboe <jaxboe@fusionio.com>
Cc: Ian Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

When do block-attach/block-detach test with below steps, umount hangs
in the guest. Furthermore shutdown ends up being stuck when umounting file-systems.

1. start guest.
2. attach new block device by xm block-attach in Dom0.
3. mount new disk in guest.
4. execute xm block-detach to detach the block device in dom0 until timeout
5. Any request to the disk will hung.

Root cause:
This issue is caused when setting backend device's state to
'XenbusStateClosing', which sends to the frontend the XenbusStateClosing
notification. When frontend receives the notification it tries to release
the disk in blkfront_closing(), but at that moment the disk is still in use
by guest, so frontend refuses to close. Specifically it sets the disk state to
XenbusStateClosing and sends the notification to backend - when backend receives the
event, it disconnects the vbd from real device, and sets the vbd device state to
XenbusStateClosing. The backend disconnects the real device/file, and any IO
requests to the disk in guest will end up in ether, leaving disk DEAD and set to
XenbusStateClosing. When the guest wants to disconnect the disk, umount will
hang on blkif_release()->xlvbd_release_gendisk() as it is unable to send any IO
to the disk, which prevents clean system shutdown.

Solution:
Don't disconnect backend until frontend state switched to XenbusStateClosed.
Signed-off-by: NJoe Jin <joe.jin@oracle.com>
Cc: Daniel Stodden <daniel.stodden@citrix.com>
Cc: Jens Axboe <jaxboe@fusionio.com>
Cc: Annie Li <annie.li@oracle.com>
Cc: Ian Campbell <Ian.Campbell@eu.citrix.com>
[v1: Modified description a bit]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Add xen-backend:vbd module alias to the xen-blkback module. This allows
automatic loading of the module.
Signed-off-by: NBastian Blank <waldi@debian.org>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Running RING_FINAL_CHECK_FOR_REQUESTS from make_response is a bad
idea. It means that in-flight I/O is essentially blocking continued
batches. This essentially kills throughput on frontends which unplug
(or even just notify) early and rightfully assume addtional requests
will be picked up on time, not synchronously.
Signed-off-by: NDaniel Stodden <daniel.stodden@citrix.com>
[v1: Rebased and fixed compile problems]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Use the compiler to verify printf formats and arguments.

Fix fallout.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

blkbk->pending_pages can be NULL here so I added a check for it.
Signed-off-by: NDan Carpenter <error27@gmail.com>
[v1: Redid the loop a bit]
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

...because vbd_size() dereferences bd_disk if bd_part is NULL.

Signed-off-by: Laszlo Ersek<lersek@redhat.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

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: NJan Beulich <jbeulich@novell.com>
Signed-off-by: NKonrad 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=618317Acked-by: NJan Beulich <jbeulich@novell.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NLaszlo Ersek <lersek@redhat.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The recent changes caused this field of the structure to be offset a bit.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

And not depend on the driver being built with -DDEBUG flag.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

No need for that '_st' and xen_blkif is more apt.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Not point of the blkif.h file. It is not used by the frontend.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

CHECK: multiple assignments should be avoided
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

From the blkif.h header, which was exposed to the frontend.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

It is not really used for anything.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

To make it easier to read.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

And also make them uniform and prefix the message with 'xen-blkback'.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Suggested-by: NIan Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

They had the wrong data or were in the wrong spot.
Signed-off-by: NKonrad 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: NKonrad 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: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

This reverts commit 97961ef4 b/c
we lose about 15% performance if we do the unplugging and the
end of the reading the ring buffer.