Daniel Stodden [Tue, 18 Jan 2011 19:53:23 +0000 (11:53 -0800)]
EA-1001: Build VBD ring macros from kernel, not xen headers.
Includes linux/blktap.h, not xen/io/blkif.h. Make therefore wants a
KBUILD argument to find the kernel headers.
Fallout:
* Presently comes with loads of ugly blkif_t/ypedefs and defines to
reduce noise under drivers/. Will go away with later VBD patches.
* BLKTAP_RING_SIZE isn't constant anymore (due to _SC_PAGE_SIZE).
Substituted with a MAX_REQUESTS defined to a fixed 32U. More
flexible queue size dimensions are clearly a field for future work.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Daniel Stodden [Thu, 30 Sep 2010 21:01:47 +0000 (14:01 -0700)]
CA-44322: Restrict I/O request merging on filesystems.
Ensure that every single iocb can be issued with only the memory
reserves held in kernel space. Main resource prone to congestion are
bio structs.
For I/O continguous in physical storage, such as bare LUN mappings, a
single bio will hold up to 256 pages. To accomodate block mappings on
file systems, we reserve a more than 1 bio, but cannot submit iocbs of
arbitrary length without risking to stall once the reserve is
exhausted.
Limits the iocb size on ext. Assumes 4k blocks for now.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Daniel Stodden [Thu, 30 Sep 2010 21:01:45 +0000 (14:01 -0700)]
CA-44322: Add an I/O-submit thread.
Slightly annoying to add threads to core blktap code, but necessary to
avoid potential starvation when dom0 gets under memory
pressure. Blktap can guarantee io_submit makes progress by keeping
memory reserves, but not enough to guarantee that it's
non-blocking. To refill the reserves, we want completion of in-flight
I/O the main even loop.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.comm>
Daniel Stodden [Thu, 30 Sep 2010 21:01:40 +0000 (14:01 -0700)]
CA-46079: Recover the image storage type.
Used to be a message parameter passed in at open time, then down
through the VBD and images up to the driver. Replaced by stat() and
statfs().
The vbd->storage isn't really applicable with cross-SR VHD chains
became more popular, so removed. We keep the driver->storage, but only
for verbosity. Drivers with type-dependent code call
tapdisk_storage_type() during td_open() are encouraged to store the
result here.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Daniel Stodden [Thu, 30 Sep 2010 21:01:35 +0000 (14:01 -0700)]
CA-46079: Remove the image reopen hack.
Used to reopen the image chain on the first request, thereby detecting
guest activation after migration. Obsolete since tapdisk is
spawned/resumed after VM stop/copy now.
Signed-off-by: Daniel Stoddden <daniel.stodden@citrix.com>
Daniel Stodden [Thu, 9 Sep 2010 09:05:17 +0000 (02:05 -0700)]
CA-44974: Make tap_ctl_close idempotent.
Avoid potential freelist/conn vector corruption due to
double-frees. Upgrade the WARN_ON() to a panic(), the present drain
loop doesn't want to be asked after disconnect.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Daniel Stodden [Tue, 7 Sep 2010 02:42:26 +0000 (19:42 -0700)]
CA-44675: Fix parent cache corruption due to I/O crosstalk.
Previous patch requeued completing ring I/O buffers.
An interesting question is why this succeeds without a proper tapdisk
crash. The only sane explanation I can come up with is that the common
path manages to queue AIOs before our response hits the kernel so
unmap goes after GUP page translation. Which sounds not too
improbable, the target leaf vhd bitmap was likely still hot at this
point.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Daniel Stodden [Tue, 17 Aug 2010 08:56:28 +0000 (01:56 -0700)]
blktap: Write tapdisk-control response data asynchronous and fully buffered.
Tapdisk should never block on control connections. We preallocate
connection state for a number of clients, including buffer space for
the response (presently 4k/conn). Then stream back response data
asynchronously, driven by the event loop.
Daniel Stodden [Fri, 6 Aug 2010 10:53:33 +0000 (03:53 -0700)]
CA-43084: Remove blocking opportunities from tapdisk-control.
Certainly should not syslog(), but use tlog instead. While we are at
it, preallocate the connection structs, too. Fixing a memleak by
509:abadd2f7ca77 (control op cancellation). Now uses tlog_syslog. The
noise "received"/"sending" noise should be avoided, but the logging
aids debugging in the meantime.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Andrei Lifchits [Tue, 20 Jul 2010 16:20:24 +0000 (17:20 +0100)]
CP-1732, CP-1733, CP-1734: add local caching support (alpha quality). This includes:
- read caching into the leaf
- mirror write mode
- failover to the secondary image on ENOSPC
- possibility of snapshotting of empty images (for cache setup)
Daniel Stodden [Wed, 14 Jul 2010 00:47:39 +0000 (17:47 -0700)]
blktap2: Redo tap-ctl-list.
Consolidate all outputs to tap_list_t on list_heads, removing the
overcomplicated vectors. Includes a change to the tap_ctl_list
signature, accordingly. Simplifies the old join3 code, now
inlined. Remove the obsolete tap_list id. Introduces list_move and
list_splice_tail macros to list.h.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Daniel Stodden [Tue, 29 Jun 2010 20:03:09 +0000 (13:03 -0700)]
All: Fix RPM install path definitions.
Help make libraries install to the correct location without Makefile
divergence from OSS org. Removes private defintions of LIBDIR from the
Makefiles. LIBDIR is globally defined by the toplevel make at xen.org,
and now by the RPM build accordingly.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Daniel Stodden [Tue, 29 Jun 2010 20:03:09 +0000 (13:03 -0700)]
blktap2: Update tap-ctl timeouts and blocking behavior.
Adds a -t <timeout> switch to the destroy, pause and close operations,
which are known to block. Changes the library call interfaces to use
timeval structs, not <int> secs, which are then passed around
internally. On Linux, the effect should be that we track the total
timeout across calls, not a maximum for individual operations.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Daniel Stodden [Tue, 29 Jun 2010 20:03:09 +0000 (13:03 -0700)]
blktap2: Synchronize device removal when removing the vbd.
Employ a new ring ioctl, BLKTAP2_IOCTL_REMOVE_DEVICE, which succeeds
only once the bdev is closed. Iterating events then safely drains the
queue. If not implemented, fall back to the previous behavior, which
may fail requests.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Daniel Stodden [Tue, 29 Jun 2010 20:03:09 +0000 (13:03 -0700)]
blktap2: Secure control event loop recursions.
Mask connection from the loop fdset while processing pending
requests.
Annotate message types, separating reentrant from non-rentrant control
operations. Non-reentrant operations fail with EBUSY. There is no
usecase for deferrals, arbitration is up to to upper levels in the
control stack.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Daniel Stodden [Sat, 5 Jun 2010 02:05:01 +0000 (19:05 -0700)]
blktap: Fix tapdisk disktype issues.
Stop coercing drivers/disktype code into the tool stack. Make both
blktapctrl and tap-ctl transfer type/path pairs as "<type>:<path>"
strings. Remove the message.disktype integer altogether.
Daniel Stodden [Sun, 30 May 2010 01:34:14 +0000 (18:34 -0700)]
blktap2: The tap-ctl control utility and library.
Tapdisk control in userspace, a replacement for the original blktap2
control stack, which had to pass a kernel space interface based on
sysfs nodes.
All tapdisk processes listen for commands on a unix stream socket. The
control library supports scanning the socket namespace for running
tapdisks, VBD minors allocated, associated images and state inquiry.
Control operations include allocating/releasing devices, spawning
tapdisks, opening/closing images, attaching disk images to
devices. disk pause/resume operations and runtime switching of disk
images.
Signed-off-by: Jake Wires <jake.wires@citrix.com> Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Daniel Stodden [Fri, 16 Apr 2010 02:06:04 +0000 (19:06 -0700)]
CA-40171: Validate vhd parent chain during LV reactivation.
Implementation of tapdisk_vbd_reactivate_volumes follows the vhd
parent chain, but therein lacks a critical check matching child and
parent uuids.
This creates a race window wherein reactivation hits an lv resize on
the master. The new last sector, while unrewritten, may carry garbage
footers. Results may vary, from plain reactivation failures to chain
traversal running off into the weeds.
Fixed with a proper uuid check. Adds some eprintfs to aid debugging
the corner cases.
Daniel Stodden [Mon, 5 Apr 2010 19:35:18 +0000 (12:35 -0700)]
CA-29373: Unwedge queue after new request failure.
A tapdisk_vbd_issue_request failure is indication to back of from
further queue processing. The call however will also return error
status of a synchronous request failure.
When failing a new request immediately, we stop making progress. We
break out of the loop, subsequent incoming requests stay on the
new_requests lists, failed_requests is empty, so we block
indefinitely.
Patch decouples queue status from request status, we only back off if
the queue test fails, not the request. Otoh, this means we won't back
off after the first EBUSY encountered. One may argue the decision
about what's busy and not is better made by the driver, not the VBD.
Daniel Stodden [Mon, 5 Apr 2010 19:35:16 +0000 (12:35 -0700)]
CA-29373: Stop retrying the pathetic case.
Separating the retryable from the recoverable errors should make the
control path more responsive to broken SRs or images. Fail vreqs with
irrecoverable errors immediately. Presently known ones comprise ESTALE
and ENOSPC. Both don't have a great prospect to improve within the
next two minutes.
Note that this somewhat obsoletes ENOSPC, as our original reason for
adding a tapdisk-level forced-shutdown. However, there may still be
reasons to discard retryable requests.
Daniel Stodden [Mon, 5 Apr 2010 19:35:16 +0000 (12:35 -0700)]
CP-1613: Fix compiler warnings
The vhd_cache_init/enabled calls were redeclared inline after their
original declaration, yielding an ugly warning. These are module
members, not header macros. Safe to leave the inlining to the
compiler.
Daniel Stodden [Mon, 5 Apr 2010 19:35:15 +0000 (12:35 -0700)]
CA-39535: Break call chain recursion during force-shutdown.
Pending requests during shutdown flag TD_VBD_SHUTDOWN_REQUESTED,
resulting in an endless vbd_close -> vbd_kick -> vbd_check_state ->
vbd_close loop.
The vbd_check_state call was added to unblock canonical (synchronous)
I/O mode in cset 45c15fdaed55 (Separate tapdisk raw I/O into different
backends).
We only need the queue dispatch during vbd_kick. Fixed by breaking a
vbd_check_queue_state out of vbd_check_state.
Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
projects / people / dstodden / blktap.git / log