Check that the ring does not have an insane amount of requests
(more than there could fit on the ring).
If we detect this case we will stop processing the requests
and wait until the XenBus disconnects the ring.
The existing check RING_REQUEST_CONS_OVERFLOW which checks for how
many responses we have created in the past (rsp_prod_pvt) vs
requests consumed (req_cons) and whether said difference is greater or
equal to the size of the ring, does not catch this case.
Wha the condition does check if there is a need to process more
as we still have a backlog of responses to finish. Note that both
of those values (rsp_prod_pvt and req_cons) are not exposed on the
shared ring.
To understand this problem a mini crash course in ring protocol
response/request updates is in place.
There are four entries: req_prod and rsp_prod; req_event and rsp_event
to track the ring entries. We are only concerned about the first two -
which set the tone of this bug.
The req_prod is a value incremented by frontend for each request put
on the ring. Conversely the rsp_prod is a value incremented by the backend
for each response put on the ring (rsp_prod gets set by rsp_prod_pvt when
pushing the responses on the ring). Both values can
wrap and are modulo the size of the ring (in block case that is 32).
Please see RING_GET_REQUEST and RING_GET_RESPONSE for the more details.
The culprit here is that if the difference between the
req_prod and req_cons is greater than the ring size we have a problem.
Fortunately for us, the '__do_block_io_op' loop:
rc = blk_rings->common.req_cons;
rp = blk_rings->common.sring->req_prod;
while (rc != rp) {
..
blk_rings->common.req_cons = ++rc; /* before make_response() */
}
will loop up to the point when rc == rp. The macros inside of the
loop (RING_GET_REQUEST) is smart and is indexing based on the modulo
of the ring size. If the frontend has provided a bogus req_prod value
we will loop until the 'rc == rp' - which means we could be processing
already processed requests (or responses) often.
The reason the RING_REQUEST_CONS_OVERFLOW is not helping here is
b/c it only tracks how many responses we have internally produced
and whether we would should process more. The astute reader will
notice that the macro RING_REQUEST_CONS_OVERFLOW provides two
arguments - more on this later.
For example, if we were to enter this function with these values:
blk_rings->common.sring->req_prod = X+31415 (X is the value from
the last time __do_block_io_op was called).
blk_rings->common.req_cons = X
blk_rings->common.rsp_prod_pvt = X
The RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, blk_rings->common.req_cons)
is doing:
req_cons - rsp_prod_pvt >= 32
Which is,
X - X >= 32 or 0 >= 32
And that is false, so we continue on looping (this bug).
If we re-use said macro RING_REQUEST_CONS_OVERFLOW and pass in the rp
instead (sring->req_prod) of rc, the this macro can do the check:
req_prod - rsp_prov_pvt >= 32
Which is,
X + 31415 - X >= 32 , or 31415 >= 32
which is true, so we can error out and break out of the function.
Unfortunatly the difference between rsp_prov_pvt and req_prod can be
at 32 (which would error out in the macro). This condition exists when
the backend is lagging behind with the responses and still has not finished
responding to all of them (so make_response has not been called), and
the rsp_prov_pvt + 32 == req_cons. This ends up with us not being able
to use said macro.
Hence introducing a new macro called RING_REQUEST_PROD_OVERFLOW which does
a simple check of:
req_prod - rsp_prod_pvt > RING_SIZE
And with the X values from above:
X + 31415 - X > 32
Returns true. Also not that if the ring is full (which is where
the RING_REQUEST_CONS_OVERFLOW triggered), we would not hit the
same condition:
X + 32 - X > 32
Which is false.
Lets use that macro.
Note that in v5 of this patchset the macro was different - we used an
earlier version.
Cc: stable@vger.kernel.org
[v1: Move the check outside the loop]
[v2: Add a pr_warn as suggested by David]
[v3: Use RING_REQUEST_CONS_OVERFLOW as suggested by Jan]
[v4: Move wake_up after kthread_stop as suggested by Jan]
[v5: Use RING_REQUEST_PROD_OVERFLOW instead]
[v6: Use RING_REQUEST_PROD_OVERFLOW - Jan's version]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
gadsa
Currently xen-blkback passes the logical sector size over xenbus and
xen-blkfront sets up the paravirt disk with that logical block size.
But newer drives usually have the logical sector size set to 512 for
compatibility reasons and would show the actual sector size only in
physical sector size.
This results in the device being partitioned and accessed in dom0 with
the correct sector size, but the guest thinks 512 bytes is the correct
block size. And that results in poor performance.
To fix this, blkback gets modified to pass also physical-sector-size
over xenbus and blkfront to use both values to set up the paravirt
disk. I did not just change the passed in sector-size because I am
not sure having a bigger logical sector size than the physical one
is valid (and that would happen if a newer dom0 kernel hits an older
domU kernel). Also this way a domU set up before should still be
accessible (just some tools might detect the unaligned setup).
[v2: Make xenbus write failure non-fatal]
[v3: Use xenbus_scanf instead of xenbus_gather]
[v4: Rebased against segment changes]
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Allocate pending requests in smaller chunks instead of allocating them
all at the same time.
This change also removes the global array of pending_reqs, it is no
longer necessay.
Variables related to the grant mapping have been grouped into a struct
called "grant_page", this allows to allocate them in smaller chunks,
and also improves memory locality.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Tested-by: Sander Eikelenboom <linux@eikelenboom.it>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Indirect descriptors introduce a new block operation
(BLKIF_OP_INDIRECT) that passes grant references instead of segments
in the request. This grant references are filled with arrays of
blkif_request_segment_aligned, this way we can send more segments in a
request.
The proposed implementation sets the maximum number of indirect grefs
(frames filled with blkif_request_segment_aligned) to 256 in the
backend and 32 in the frontend. The value in the frontend has been
chosen experimentally, and the backend value has been set to a sane
value that allows expanding the maximum number of indirect descriptors
in the frontend if needed.
The migration code has changed from the previous implementation, in
which we simply remapped the segments on the shared ring. Now the
maximum number of segments allowed in a request can change depending
on the backend, so we have to requeue all the requests in the ring and
in the queue and split the bios in them if they are bigger than the
new maximum number of segments.
[v2: Fixed minor comments by Konrad.
[v1: Added padding to make the indirect request 64bit aligned.
Added some BUGs, comments; fixed number of indirect pages in
blkif_get_x86_{32/64}_req. Added description about the indirect operation
in blkif.h]
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
[v3: Fixed spaces and tabs mix ups]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Remove the last dependency from blkbk by moving the list of free
requests to blkif. This change reduces the contention on the list of
available requests.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: xen-devel@lists.xen.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This mechanism allows blkback to change the number of grants
persistently mapped at run time.
The algorithm uses a simple LRU mechanism that removes (if needed) the
persistent grants that have not been used since the last LRU run, or
if all grants have been used it removes the first grants in the list
(that are not in use).
The algorithm allows the user to change the maximum number of
persistent grants, by changing max_persistent_grants in sysfs.
Since we are storing the persistent grants used inside the request
struct (to be able to mark them as "unused" when unmapping), we no
longer need the bitmap (unmap_seg).
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: xen-devel@lists.xen.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Using balloon pages for all granted pages allows us to simplify the
logic in blkback, especially in the xen_blkbk_map function, since now
we can decide if we want to map a grant persistently or not after we
have actually mapped it. This could not be done before because
persistent grants used ballooned pages, whereas non-persistent grants
used pages from the kernel.
This patch also introduces several changes, the first one is that the
list of free pages is no longer global, now each blkback instance has
it's own list of free pages that can be used to map grants. Also, a
run time parameter (max_buffer_pages) has been added in order to tune
the maximum number of free pages each blkback instance will keep in
it's buffer.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Cc: xen-devel@lists.xen.org
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
These values shouldn't be negative, but after an overflow their value
can turn into negative, if they are signed. xentop can show bogus
values in this case.
Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
Reported-by: Ichiro Ogino <ichiro.ogino@citrix.co.jp>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
"be->mode" is obtained from xenbus_read(), which does a kmalloc() for
the message body. The short string is never released, so do it along
with freeing "be" itself, and make sure the string isn't kept when
backend_changed() doesn't complete successfully (which made it
desirable to slightly re-structure that function, so that the error
cleanup can be done in one place).
Reported-by: Olaf Hering <olaf@aepfle.de>
CC: stable@vger.kernel.org
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Pull block driver update from Jens Axboe:
"Now that the core bits are in, here are the driver bits for 3.8. The
branch contains:
- A huge pile of drbd bits that were dumped from the 3.7 merge
window. Following that, it was both made perfectly clear that
there is going to be no more over-the-wall pulls and how the
situation on individual pulls can be improved.
- A few cleanups from Akinobu Mita for drbd and cciss.
- Queue improvement for loop from Lukas. This grew into adding a
generic interface for waiting/checking an even with a specific
lock, allowing this to be pulled out of md and now loop and drbd is
also using it.
- A few fixes for xen back/front block driver from Roger Pau Monne.
- Partition improvements from Stephen Warren, allowing partiion UUID
to be used as an identifier."
* 'for-3.8/drivers' of git://git.kernel.dk/linux-block: (609 commits)
drbd: update Kconfig to match current dependencies
drbd: Fix drbdsetup wait-connect, wait-sync etc... commands
drbd: close race between drbd_set_role and drbd_connect
drbd: respect no-md-barriers setting also when changed online via disk-options
drbd: Remove obsolete check
drbd: fixup after wait_even_lock_irq() addition to generic code
loop: Limit the number of requests in the bio list
wait: add wait_event_lock_irq() interface
xen-blkfront: free allocated page
xen-blkback: move free persistent grants code
block: partition: msdos: provide UUIDs for partitions
init: reduce PARTUUID min length to 1 from 36
block: store partition_meta_info.uuid as a string
cciss: use check_signature()
cciss: cleanup bitops usage
drbd: use copy_highpage
drbd: if the replication link breaks during handshake, keep retrying
drbd: check return of kmalloc in receive_uuids
drbd: Broadcast sync progress no more often than once per second
drbd: don't try to clear bits once the disk has failed
...
This patch contains fixes for persistent grants implementation v2:
* handle == 0 is a valid handle, so initialize grants in blkback
setting the handle to BLKBACK_INVALID_HANDLE instead of 0. Reported
by Konrad Rzeszutek Wilk.
* new_map is a boolean, use "true" or "false" instead of 1 and 0.
Reported by Konrad Rzeszutek Wilk.
* blkfront announces the persistent-grants feature as
feature-persistent-grants, use feature-persistent instead which is
consistent with blkback and the public Xen headers.
* Add a consistency check in blkfront to make sure we don't try to
access segments that have not been set.
Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
[v1: The new_map int->bool had already been changed]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This patch implements persistent grants for the xen-blk{front,back}
mechanism. The effect of this change is to reduce the number of unmap
operations performed, since they cause a (costly) TLB shootdown. This
allows the I/O performance to scale better when a large number of VMs
are performing I/O.
Previously, the blkfront driver was supplied a bvec[] from the request
queue. This was granted to dom0; dom0 performed the I/O and wrote
directly into the grant-mapped memory and unmapped it; blkfront then
removed foreign access for that grant. The cost of unmapping scales
badly with the number of CPUs in Dom0. An experiment showed that when
Dom0 has 24 VCPUs, and guests are performing parallel I/O to a
ramdisk, the IPIs from performing unmap's is a bottleneck at 5 guests
(at which point 650,000 IOPS are being performed in total). If more
than 5 guests are used, the performance declines. By 10 guests, only
400,000 IOPS are being performed.
This patch improves performance by only unmapping when the connection
between blkfront and back is broken.
On startup blkfront notifies blkback that it is using persistent
grants, and blkback will do the same. If blkback is not capable of
persistent mapping, blkfront will still use the same grants, since it
is compatible with the previous protocol, and simplifies the code
complexity in blkfront.
To perform a read, in persistent mode, blkfront uses a separate pool
of pages that it maps to dom0. When a request comes in, blkfront
transmutes the request so that blkback will write into one of these
free pages. Blkback keeps note of which grefs it has already
mapped. When a new ring request comes to blkback, it looks to see if
it has already mapped that page. If so, it will not map it again. If
the page hasn't been previously mapped, it is mapped now, and a record
is kept of this mapping. Blkback proceeds as usual. When blkfront is
notified that blkback has completed a request, it memcpy's from the
shared memory, into the bvec supplied. A record that the {gref, page}
tuple is mapped, and not inflight is kept.
Writes are similar, except that the memcpy is peformed from the
supplied bvecs, into the shared pages, before the request is put onto
the ring.
Blkback stores a mapping of grefs=>{page mapped to by gref} in
a red-black tree. As the grefs are not known apriori, and provide no
guarantees on their ordering, we have to perform a search
through this tree to find the page, for every gref we receive. This
operation takes O(log n) time in the worst case. In blkfront grants
are stored using a single linked list.
The maximum number of grants that blkback will persistenly map is
currently set to RING_SIZE * BLKIF_MAX_SEGMENTS_PER_REQUEST, to
prevent a malicios guest from attempting a DoS, by supplying fresh
grefs, causing the Dom0 kernel to map excessively. If a guest
is using persistent grants and exceeds the maximum number of grants to
map persistenly the newly passed grefs will be mapped and unmaped.
Using this approach, we can have requests that mix persistent and
non-persistent grants, and we need to handle them correctly.
This allows us to set the maximum number of persistent grants to a
lower value than RING_SIZE * BLKIF_MAX_SEGMENTS_PER_REQUEST, although
setting it will lead to unpredictable performance.
In writing this patch, the question arrises as to if the additional
cost of performing memcpys in the guest (to/from the pool of granted
pages) outweigh the gains of not performing TLB shootdowns. The answer
to that question is `no'. There appears to be very little, if any
additional cost to the guest of using persistent grants. There is
perhaps a small saving, from the reduced number of hypercalls
performed in granting, and ending foreign access.
Signed-off-by: Oliver Chick <oliver.chick@citrix.com>
Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[v1: Fixed up the misuse of bool as int]
Using kmem_cache_zalloc() instead of kmem_cache_alloc() and memset().
spatch with a semantic match is used to found this problem.
(http://coccinelle.lip6.fr/)
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
drivers/block/xen-blkback/xenbus.c:260:5: warning: symbol 'xenvbd_sysfs_addif' was not declared. Should it be static?
drivers/block/xen-blkback/xenbus.c:284:6: warning: symbol 'xenvbd_sysfs_delif' was not declared. Should it be static?
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
drivers/block/xen-blkback/xenbus.c: In function 'xen_blkbk_discard':
drivers/block/xen-blkback/xenbus.c:419:4: warning: passing argument 1 of 'dev_warn' makes pointer from integer without a cast
+[enabled by default]
include/linux/device.h:894:5: note: expected 'const struct device *' but argument is of type 'long int'
It is unclear how that mistake made it in. It surely is wrong.
Acked-by: Jens Axboe <axboe@kernel.dk>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
They were using the xenbus_dev_fatal() function which would
change the state of the connection immediately. Which is not
what we want when we advertise optional features.
So make 'feature-discard','feature-barrier','feature-flush-cache'
optional.
Suggested-by: Jan Beulich <JBeulich@suse.com>
[v1: Made the discard function void and static]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The only reason for the distinction was for the special case of
'file' (which is assumed to be loopback device), was to reach inside
the loopback device, find the underlaying file, and call fallocate on it.
Fortunately "xen-blkback: convert hole punching to discard request on
loop devices" removes that use-case and we now based the discard
support based on blk_queue_discard(q) and extract all appropriate
parameters from the 'struct request_queue'.
CC: Li Dongyang <lidongyang@novell.com>
Acked-by: Jan Beulich <JBeulich@suse.com>
[v1: Dropping pointless initializer and keeping blank line]
[v2: Remove the kfree as it is not used anymore]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* 'for-3.3/drivers' of git://git.kernel.dk/linux-block:
mtip32xx: do rebuild monitoring asynchronously
xen-blkfront: Use kcalloc instead of kzalloc to allocate array
mtip32xx: uninitialized variable in mtip_quiesce_io()
mtip32xx: updates based on feedback
xen-blkback: convert hole punching to discard request on loop devices
xen/blkback: Move processing of BLKIF_OP_DISCARD from dispatch_rw_block_io
xen/blk[front|back]: Enhance discard support with secure erasing support.
xen/blk[front|back]: Squash blkif_request_rw and blkif_request_discard together
mtip32xx: update to new ->make_request() API
mtip32xx: add module.h include to avoid conflict with moduleh tree
mtip32xx: mark a few more items static
mtip32xx: ensure that all local functions are static
mtip32xx: cleanup compat ioctl handling
mtip32xx: fix warnings/errors on 32-bit compiles
block: Add driver for Micron RealSSD pcie flash cards
* 'stable/for-linus-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: (37 commits)
xen/pciback: Expand the warning message to include domain id.
xen/pciback: Fix "device has been assigned to X domain!" warning
xen/pciback: Move the PCI_DEV_FLAGS_ASSIGNED ops to the "[un|]bind"
xen/xenbus: don't reimplement kvasprintf via a fixed size buffer
xenbus: maximum buffer size is XENSTORE_PAYLOAD_MAX
xen/xenbus: Reject replies with payload > XENSTORE_PAYLOAD_MAX.
Xen: consolidate and simplify struct xenbus_driver instantiation
xen-gntalloc: introduce missing kfree
xen/xenbus: Fix compile error - missing header for xen_initial_domain()
xen/netback: Enable netback on HVM guests
xen/grant-table: Support mappings required by blkback
xenbus: Use grant-table wrapper functions
xenbus: Support HVM backends
xen/xenbus-frontend: Fix compile error with randconfig
xen/xenbus-frontend: Make error message more clear
xen/privcmd: Remove unused support for arch specific privcmp mmap
xen: Add xenbus_backend device
xen: Add xenbus device driver
xen: Add privcmd device driver
xen/gntalloc: fix reference counts on multi-page mappings
...
The 'name', 'owner', and 'mod_name' members are redundant with the
identically named fields in the 'driver' sub-structure. Rather than
switching each instance to specify these fields explicitly, introduce
a macro to simplify this.
Eliminate further redundancy by allowing the drvname argument to
DEFINE_XENBUS_DRIVER() to be blank (in which case the first entry from
the ID table will be used for .driver.name).
Also eliminate the questionable xenbus_register_{back,front}end()
wrappers - their sole remaining purpose was the checking of the
'owner' field, proper setting of which shouldn't be an issue anymore
when the macro gets used.
v2: Restore DRV_NAME for the driver name in xen-pciback.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
The below patch fixes some typos in various parts of the kernel, as well as fixes some comments.
Please let me know if I missed anything, and I will try to get it changed and resent.
Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Part of the blkdev_issue_discard(xx) operation is that it can also
issue a secure discard operation that will permanantly remove the
sectors in question. We advertise that we can support that via the
'discard-secure' attribute and on the request, if the 'secure' bit
is set, we will attempt to pass in REQ_DISCARD | REQ_SECURE.
CC: Li Dongyang <lidongyang@novell.com>
[v1: Used 'flag' instead of 'secure:1' bit]
[v2: Use 'reserved' uint8_t instead of adding a new value]
[v3: Check for nseg when mapping instead of operation]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* 'stable/vmalloc-3.2' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
net: xen-netback: use API provided by xenbus module to map rings
block: xen-blkback: use API provided by xenbus module to map rings
xen: use generic functions instead of xen_{alloc, free}_vm_area()
* 'for-3.2/drivers' of git://git.kernel.dk/linux-block: (30 commits)
virtio-blk: use ida to allocate disk index
hpsa: add small delay when using PCI Power Management to reset for kump
cciss: add small delay when using PCI Power Management to reset for kump
xen/blkback: Fix two races in the handling of barrier requests.
xen/blkback: Check for proper operation.
xen/blkback: Fix the inhibition to map pages when discarding sector ranges.
xen/blkback: Report VBD_WSECT (wr_sect) properly.
xen/blkback: Support 'feature-barrier' aka old-style BARRIER requests.
xen-blkfront: plug device number leak in xlblk_init() error path
xen-blkfront: If no barrier or flush is supported, use invalid operation.
xen-blkback: use kzalloc() in favor of kmalloc()+memset()
xen-blkback: fixed indentation and comments
xen-blkfront: fix a deadlock while handling discard response
xen-blkfront: Handle discard requests.
xen-blkback: Implement discard requests ('feature-discard')
xen-blkfront: add BLKIF_OP_DISCARD and discard request struct
drivers/block/loop.c: remove unnecessary bdev argument from loop_clr_fd()
drivers/block/loop.c: emit uevent on auto release
drivers/block/cpqarray.c: use pci_dev->revision
loop: always allow userspace partitions and optionally support automatic scanning
...
Fic up trivial header file includsion conflict in drivers/block/loop.c
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: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad 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: Christopher Hellwig <hch@infradead.org>
Signed-off-by: Konrad 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: Joe Jin <joe.jin@oracle.com>
Cc: Jens Axboe <jaxboe@fusionio.com>
Cc: Ian Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: Konrad 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: Li Dongyang <lidongyang@novell.com>
[v1: Fixed up pr_debug and commit description]
Signed-off-by: Konrad 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: Joe Jin <joe.jin@oracle.com>
Cc: Jens Axboe <jaxboe@fusionio.com>
Cc: Ian Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: Konrad 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: Joe 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: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Use the compiler to verify printf formats and arguments.
Fix fallout.
Signed-off-by: Joe Perches <joe@perches.com>
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>
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>
