There is a small problem in handling page bounce.
At the moment blk_max_pfn equals max_pfn, which is in fact not maximum
possible _number_ of a page frame, but the _amount_ of page frames. For
example for the 32bit x86 node with 4Gb RAM, max_pfn = 0x100000, but not
0xFFFF.
request_queue structure has a member q->bounce_pfn and queue needs bounce
pages for the pages _above_ this limit. This routine is handled by
blk_queue_bounce(), where the following check is produced:
if (q->bounce_pfn >= blk_max_pfn)
return;
Assume, that a driver has set q->bounce_pfn to 0xFFFF, but blk_max_pfn
equals 0x10000. In such situation the check above fails and for each bio
we always fall down for iterating over pages tied to the bio.
I want to notice, that for quite a big range of device drivers (ide, md,
...) such problem doesn't happen because they use BLK_BOUNCE_ANY for
bounce_pfn. BLK_BOUNCE_ANY is defined as blk_max_pfn << PAGE_SHIFT, and
then the check above doesn't fail. But for other drivers, which obtain
reuired value from drivers, it fails. For example sata_nv uses
ATA_DMA_MASK or dev->dma_mask.
I propose to use (max_pfn - 1) for blk_max_pfn. And the same for
blk_max_low_pfn. The patch also cleanses some checks related with
bounce_pfn.
Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Several people have reported failures in dynamic major device number handling
due to the recent changes in there to avoid handing out the local/experimental
majors.
Rolf reports that this is due to a gcc-4.1.0 bug.
The patch refactors that code a lot in an attempt to provoke the compiler into
behaving.
Cc: Rolf Eike Beer <eike-kernel@sf-tec.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change I/O scheduler description to correctly show CFQ as being the default
scheduler and not the anticipatory scheduler that previously was default.
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Many struct file_operations in the kernel can be "const". Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data. In addition it'll catch accidental writes at compile time to
these shared resources.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We currently check the FIFO once per slice. Optimize that a bit and
only do it as the first thing for a new slice, so we don't end up
doing a single request and then seek to the FIFO requests.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
It must always be the active queue, otherwise it's a bug. So just
use the active_queue, don't pass it in explicitly.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
If a slice uses less than it is entitled to (or perhaps more), include
that in the decision on how much time to give it the next time it
gets serviced.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Right now we use slice_start, which gives async queues an unfair
advantage. Chance that to service_last, and base the resorter
on that.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Mathieu originally needed to add this for tracing Xen, but it's something
that's needed for any application that can be tracing while cpus are added.
unplug isn't supported by this patch. The thought was that at minumum a new
buffer needs to be added when a cpu comes up, but it wasn't worth the effort
to remove buffers on cpu down since they'd be freed soon anyway when the
channel was closed.
[zanussi@us.ibm.com: avoid lock_cpu_hotplug deadlock]
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Tom Zanussi <zanussi@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some partitioning systems create special partitions that
span the entire disk. One example are Sun partitions, and
this whole-disk partition exists to tell the firmware the
extent of the entire device so it can load the boot block
and do other things.
Such partitions should not be treated as normal partitions,
because all the other partitions overlap this whole-disk one.
So we'd see multiple instances of the same UUID etc. which
we do not want. udev and friends can thus search for this
'whole_disk' attribute and use it to decide to ignore the
partition.
Signed-off-by: Fabio Massimo Di Nitto <fabbione@ubuntu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
It is possible for raid5 to be sent a bio that is too big for an underlying
device. So if it is a READ that we pass stright down to a device, it will
fail and confuse RAID5.
So in 'chunk_aligned_read' we check that the bio fits within the parameters
for the target device and if it doesn't fit, fall back on reading through
the stripe cache and making lots of one-page requests.
Note that this is the earliest time we can check against the device because
earlier we don't have a lock on the device, so it could change underneath
us.
Also, the code for handling a retry through the cache when a read fails has
not been tested and was badly broken. This patch fixes that code.
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: "Kai" <epimetreus@fastmail.fm>
Cc: <stable@suse.de>
Cc: <org@suse.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 85e04e371b cleaned up the timeout
conversion, but did it exactly the wrong way. We get msecs from user
space, and should convert them into jiffies. Not the other way around.
Here is a fix with the overflow check sg.c has added in. This fixes DVD
burnign with Nero.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
[ "you'll be wanting a comma there" - Andrew ]
Cc: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A flag was recently added to the elevator code to avoid
performing an unplug when reuests are being re-queued.
The goal of this flag was to avoid a deep recursion that
can occur when re-queueing requests after a SCSI device/host
reset. See http://lkml.org/lkml/2006/5/17/254
However, that fix added the flag near the bottom of a case
statement, where an earlier break (in an if statement) could
transport one out of the case, without setting the flag.
This patch sets the flag earlier in the case statement.
I re-discovered the deep recursion recently during testing;
I was told that it was a known problem, and the fix to it was
in the kernel I was testing. Indeed it was ... but it didn't
fix the bug. With the patch below, I no longer see the bug.
Signed-off by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Jens Axboe <axboe@suse.de>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
