kblockd is used for unplugging and may affect IO latency and
throughput and the max number of concurrent work items are bound by
the number of block devices. Make it HIGHPRI workqueue w/ default max
concurrency.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This patch fixes a spelling error in a source code comment and removes
superfluous braces in the function exit_io_context().
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
The major/minor device numbers are always defined and used as `unsigned'.
Signed-off-by: Yang Zhang <kthreadd@gmail.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
When cfq_choose_cfqg() is called in select_queue(), there must be at least one
backlogged CFQ queue waiting for dispatching, hence there must be at least one
backlogged CFQ group on service tree. So we never call choose_service_tree()
with cfqg == NULL.
Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
If priority is changed, continuing to check workload_expires and service tree
count of the previous workload does not make sense. We should always choose
the workload with lowest key of new priority in such case.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
It's able to check whether a CFQ group on a service tree by
checking "cfqg->rb_node". There's no need to maintain an
extra flag here.
Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
When a cfq group is running, it won't be dequeued from service tree, so
there's no need to store the active one in st->active. Just gid rid of it.
Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
o Allow hierarchical cgroup creation for blkio controller
o Currently we disallow it as both the io controller policies (throttling
as well as proportion bandwidth) do not support hierarhical accounting
and control. But the flip side is that blkio controller can not be used with
libvirt as libvirt creates a cgroup hierarchy deeper than 1 level.
<top-level-cgroup-dir>/<controller>/libvirt/qemu/<virtual-machine-groups>
o So this patch will allow creation of cgroup hierarhcy but at the backend
everything will be treated as flat. So if somebody created a an hierarchy
like as follows.
root
/ \
test1 test2
|
test3
CFQ and throttling will practically treat all groups at same level.
pivot
/ | \ \
root test1 test2 test3
o Once we have actual support for hierarchical accounting and control
then we can introduce another cgroup tunable file "blkio.use_hierarchy"
which will be 0 by default but if user wants to enforce hierarhical
control then it can be set to 1. This way there should not be any
ABI problems down the line.
o The only not so pretty part is introduction of extra file "use_hierarchy"
down the line. Kame-san had mentioned that hierarhical accounting is
expensive in memory controller hence they keep it off by default. I
suspect same will be the case for IO controller also as for each IO
completion we shall have to account IO through hierarchy up to the root.
if yes, then it probably is not a very bad idea to introduce this extra
file so that it will be used only when somebody needs it and some people
might enable hierarchy only in part of the hierarchy.
o This is how basically memory controller also uses "use_hierarhcy" and
they also allowed creation of hierarchies when actual backend support
was not available.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Reviewed-by: Ciju Rajan K <ciju@linux.vnet.ibm.com>
Tested-by: Ciju Rajan K <ciju@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Over time, block layer has accumulated a set of APIs dealing with bdev
open, close, claim and release.
* blkdev_get/put() are the primary open and close functions.
* bd_claim/release() deal with exclusive open.
* open/close_bdev_exclusive() are combination of open and claim and
the other way around, respectively.
* bd_link/unlink_disk_holder() to create and remove holder/slave
symlinks.
* open_by_devnum() wraps bdget() + blkdev_get().
The interface is a bit confusing and the decoupling of open and claim
makes it impossible to properly guarantee exclusive access as
in-kernel open + claim sequence can disturb the existing exclusive
open even before the block layer knows the current open if for another
exclusive access. Reorganize the interface such that,
* blkdev_get() is extended to include exclusive access management.
@holder argument is added and, if is @FMODE_EXCL specified, it will
gain exclusive access atomically w.r.t. other exclusive accesses.
* blkdev_put() is similarly extended. It now takes @mode argument and
if @FMODE_EXCL is set, it releases an exclusive access. Also, when
the last exclusive claim is released, the holder/slave symlinks are
removed automatically.
* bd_claim/release() and close_bdev_exclusive() are no longer
necessary and either made static or removed.
* bd_link_disk_holder() remains the same but bd_unlink_disk_holder()
is no longer necessary and removed.
* open_bdev_exclusive() becomes a simple wrapper around lookup_bdev()
and blkdev_get(). It also has an unexpected extra bdev_read_only()
test which probably should be moved into blkdev_get().
* open_by_devnum() is modified to take @holder argument and pass it to
blkdev_get().
Most of bdev open/close operations are unified into blkdev_get/put()
and most exclusive accesses are tested atomically at the open time (as
it should). This cleans up code and removes some, both valid and
invalid, but unnecessary all the same, corner cases.
open_bdev_exclusive() and open_by_devnum() can use further cleanup -
rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop
special features. Well, let's leave them for another day.
Most conversions are straight-forward. drbd conversion is a bit more
involved as there was some reordering, but the logic should stay the
same.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Brown <neilb@suse.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Alex Elder <aelder@sgi.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: dm-devel@redhat.com
Cc: drbd-dev@lists.linbit.com
Cc: Leo Chen <leochen@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Joern Engel <joern@logfs.org>
Cc: reiserfs-devel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
REQ_HARDBARRIER is dead now, so remove the leftovers. What's left
at this point is:
- various checks inside the block layer.
- sanity checks in bio based drivers.
- now unused bio_empty_barrier helper.
- Xen blockfront use of BLKIF_OP_WRITE_BARRIER - it's dead for a while,
but Xen really needs to sort out it's barrier situaton.
- setting of ordered tags in uas - dead code copied from old scsi
drivers.
- scsi different retry for barriers - it's dead and should have been
removed when flushes were converted to FS requests.
- blktrace handling of barriers - removed. Someone who knows blktrace
better should add support for REQ_FLUSH and REQ_FUA, though.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Structure hd_geometry is copied to userland with 4 padding bytes
between cylinders and start fields uninitialized on 64-bit platforms.
It leads to leaking of contents of kernel stack memory.
Currently there is no memset() in real implementations of getgeo()
in drivers/block/, so it makes sense to have memset() in blkdev_ioctl().
Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Convert direct reads of an inode's i_size to using i_size_read().
i_size_{read,write} use a seqcount to protect reads from accessing
incomple writes. Concurrent i_size_write()s require mutual exclussion
to protect the seqcount that is used by i_size_{read,write}. But
i_size_read() callers do not need to use additional locking.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: NeilBrown <neilb@suse.de>
Acked-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Ensure that we pass down properly validated iov segments before
calling into the mapping or copy functions.
Reported-by: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Vivek suggests we don't need schedule a dispatch when an idle queue
becomes nonidle. And he is right, cfq_should_preempt already covers
the logic.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
If a deep seek queue slowly deliver requests but disk is much faster, idle
for the queue just wastes disk throughput. If the queue delevers all requests
before half its slice is used, the patch disable idle for it.
In my test, application delivers 32 requests one time, the disk can accept
128 requests at maxium and disk is fast. without the patch, the throughput
is just around 30m/s, while with it, the speed is about 80m/s. The disk is
a SSD, but is detected as a rotational disk. I can configure it as SSD, but
I thought the deep seek queue logic should be fixed too, for example,
considering a fast raid.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
A queue is idle at cfq_dispatch_requests(), but it gets noidle later. Unless
other task explictly does unplug or all requests are drained, we will not
deliever requests to the disk even cfq_arm_slice_timer doesn't make the
queue idle. For example, cfq_should_idle() returns true because of
service_tree->count == 1, and then other queues are added. Note, I didn't
see obvious performance impacts so far with the patch, but just thought
this could be a problem.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This reverts commit 7681bfeecc.
Conflicts:
include/linux/genhd.h
It has numerous issues with the cleanup path and non-elevator
devices. Revert it for now so we can come up with a clean
version without rushing things.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
blk_throtl_exit() frees the throttle data hanging off the queue
in blk_cleanup_queue(), but blk_put_queue() will indirectly
dereference this data when calling blk_sync_queue() which in
turns calls throtl_shutdown_timer_wq().
Fix this by moving the freeing of the throttle data to when
the queue is truly being released, and post the call to
blk_sync_queue().
Reported-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
I have some systems which need legacy sysfs due to old tools that are
making assumptions that a directory can never be a symlink to another
directory, and it's a big hazzle to compile separate kernels for them.
This patch turns CONFIG_SYSFS_DEPRECATED into a run time option
that can be switched on/off the kernel command line. This way
the same binary can be used in both cases with just a option
on the command line.
The old CONFIG_SYSFS_DEPRECATED_V2 option is still there to set
the default. I kept the weird name to not break existing
config files.
Also the compat code can be still completely disabled by undefining
CONFIG_SYSFS_DEPRECATED_SWITCH -- just the optimizer takes
care of this now instead of lots of ifdefs. This makes the code
look nicer.
v2: This is an updated version on top of Kay's patch to only
handle the block devices. I tested it on my old systems
and that seems to work.
Cc: axboe@kernel.dk
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
- Andi encountedred following warning with gcc 4.5
linux/block/cfq-iosched.c: In function ‘cfq_dispatch_requests’:
linux/block/cfq-iosched.c:2156:3: warning: array subscript is above array
bounds
- Warning happens due to following code.
slice = group_slice * count /
max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
gcc is complaining about cfqg->busy_queues_avg[] being indexed by CFQ
prio classes (RT, BE and IDLE) while the array size is only 2.
- At run time, we never access cfqg->busy_queues_avg[IDLE] and return from
function before this code hits.
- To fix warning increase the array size though it will remain unused. This
patch also puts some comments to clarify some of the confusions.
- I have taken Jens's patch and modified it a bit.
- Compile tested with gcc 4.4 and boot tested. I don't have gcc 4.5
running, Andi can you please test it with gcc 4.5 to make sure it
worked.
Reported-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
/proc/diskstats would display a strange output as follows.
$ cat /proc/diskstats |grep sda
8 0 sda 90524 7579 102154 20464 0 0 0 0 0 14096 20089
8 1 sda1 19085 1352 21841 4209 0 0 0 0 4294967064 15689 4293424691
~~~~~~~~~~
8 2 sda2 71252 3624 74891 15950 0 0 0 0 232 23995 1562390
8 3 sda3 54 487 2188 92 0 0 0 0 0 88 92
8 4 sda4 4 0 8 0 0 0 0 0 0 0 0
8 5 sda5 81 2027 2130 138 0 0 0 0 0 87 137
Its reason is the wrong way of accounting hd_struct->in_flight. When a bio is
merged into a request belongs to different partition by ELEVATOR_FRONT_MERGE.
The detailed root cause is as follows.
Assuming that there are two partition, sda1 and sda2.
1. A request for sda2 is in request_queue. Hence sda1's hd_struct->in_flight
is 0 and sda2's one is 1.
| hd_struct->in_flight
---------------------------
sda1 | 0
sda2 | 1
---------------------------
2. A bio belongs to sda1 is issued and is merged into the request mentioned on
step1 by ELEVATOR_BACK_MERGE. The first sector of the request is changed
from sda2 region to sda1 region. However the two partition's
hd_struct->in_flight are not changed.
| hd_struct->in_flight
---------------------------
sda1 | 0
sda2 | 1
---------------------------
3. The request is finished and blk_account_io_done() is called. In this case,
sda2's hd_struct->in_flight, not a sda1's one, is decremented.
| hd_struct->in_flight
---------------------------
sda1 | -1
sda2 | 1
---------------------------
The patch fixes the problem by caching the partition lookup
inside the request structure, hence making sure that the increment
and decrement will always happen on the same partition struct. This
also speeds up IO with accounting enabled, since it cuts down on
the number of lookups we have to do.
When reloading partition tables, quiesce IO to ensure that no
request references to the partition struct exists. When it is safe
to free the partition table, the IO for that device is restarted
again.
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
bsg incorrectly returns sg's masked_status value for device_status.
[jejb: fix up expression logic]
Reported-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Stable Tree <stable@kernel.org>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
All file_operations should get a .llseek operation so we can make
nonseekable_open the default for future file operations without a
.llseek pointer.
The three cases that we can automatically detect are no_llseek, seq_lseek
and default_llseek. For cases where we can we can automatically prove that
the file offset is always ignored, we use noop_llseek, which maintains
the current behavior of not returning an error from a seek.
New drivers should normally not use noop_llseek but instead use no_llseek
and call nonseekable_open at open time. Existing drivers can be converted
to do the same when the maintainer knows for certain that no user code
relies on calling seek on the device file.
The generated code is often incorrectly indented and right now contains
comments that clarify for each added line why a specific variant was
chosen. In the version that gets submitted upstream, the comments will
be gone and I will manually fix the indentation, because there does not
seem to be a way to do that using coccinelle.
Some amount of new code is currently sitting in linux-next that should get
the same modifications, which I will do at the end of the merge window.
Many thanks to Julia Lawall for helping me learn to write a semantic
patch that does all this.
===== begin semantic patch =====
// This adds an llseek= method to all file operations,
// as a preparation for making no_llseek the default.
//
// The rules are
// - use no_llseek explicitly if we do nonseekable_open
// - use seq_lseek for sequential files
// - use default_llseek if we know we access f_pos
// - use noop_llseek if we know we don't access f_pos,
// but we still want to allow users to call lseek
//
@ open1 exists @
identifier nested_open;
@@
nested_open(...)
{
<+...
nonseekable_open(...)
...+>
}
@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
<+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+>
}
@ read disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
<+...
(
*off = E
|
*off += E
|
func(..., off, ...)
|
E = *off
)
...+>
}
@ read_no_fpos disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
... when != off
}
@ write @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
<+...
(
*off = E
|
*off += E
|
func(..., off, ...)
|
E = *off
)
...+>
}
@ write_no_fpos @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
... when != off
}
@ fops0 @
identifier fops;
@@
struct file_operations fops = {
...
};
@ has_llseek depends on fops0 @
identifier fops0.fops;
identifier llseek_f;
@@
struct file_operations fops = {
...
.llseek = llseek_f,
...
};
@ has_read depends on fops0 @
identifier fops0.fops;
identifier read_f;
@@
struct file_operations fops = {
...
.read = read_f,
...
};
@ has_write depends on fops0 @
identifier fops0.fops;
identifier write_f;
@@
struct file_operations fops = {
...
.write = write_f,
...
};
@ has_open depends on fops0 @
identifier fops0.fops;
identifier open_f;
@@
struct file_operations fops = {
...
.open = open_f,
...
};
// use no_llseek if we call nonseekable_open
////////////////////////////////////////////
@ nonseekable1 depends on !has_llseek && has_open @
identifier fops0.fops;
identifier nso ~= "nonseekable_open";
@@
struct file_operations fops = {
... .open = nso, ...
+.llseek = no_llseek, /* nonseekable */
};
@ nonseekable2 depends on !has_llseek @
identifier fops0.fops;
identifier open.open_f;
@@
struct file_operations fops = {
... .open = open_f, ...
+.llseek = no_llseek, /* open uses nonseekable */
};
// use seq_lseek for sequential files
/////////////////////////////////////
@ seq depends on !has_llseek @
identifier fops0.fops;
identifier sr ~= "seq_read";
@@
struct file_operations fops = {
... .read = sr, ...
+.llseek = seq_lseek, /* we have seq_read */
};
// use default_llseek if there is a readdir
///////////////////////////////////////////
@ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier readdir_e;
@@
// any other fop is used that changes pos
struct file_operations fops = {
... .readdir = readdir_e, ...
+.llseek = default_llseek, /* readdir is present */
};
// use default_llseek if at least one of read/write touches f_pos
/////////////////////////////////////////////////////////////////
@ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read.read_f;
@@
// read fops use offset
struct file_operations fops = {
... .read = read_f, ...
+.llseek = default_llseek, /* read accesses f_pos */
};
@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write.write_f;
@@
// write fops use offset
struct file_operations fops = {
... .write = write_f, ...
+ .llseek = default_llseek, /* write accesses f_pos */
};
// Use noop_llseek if neither read nor write accesses f_pos
///////////////////////////////////////////////////////////
@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
identifier write_no_fpos.write_f;
@@
// write fops use offset
struct file_operations fops = {
...
.write = write_f,
.read = read_f,
...
+.llseek = noop_llseek, /* read and write both use no f_pos */
};
@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write_no_fpos.write_f;
@@
struct file_operations fops = {
... .write = write_f, ...
+.llseek = noop_llseek, /* write uses no f_pos */
};
@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
@@
struct file_operations fops = {
... .read = read_f, ...
+.llseek = noop_llseek, /* read uses no f_pos */
};
@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Julia Lawall <julia@diku.dk>
Cc: Christoph Hellwig <hch@infradead.org>
Commit 3839e4b introduced a kobject_put but failed to remove the
kmem_cache_free beneath it, leading to a double free.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Physical block size was declared unsigned int to accomodate the maximum
size reported by READ CAPACITY(16). Make sure we use the right type in
the related functions.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2.6.36 introduces an API for drivers to switch the IO scheduler
instead of manually calling the elevator exit and init functions.
This API was added since q->elevator must be cleared in between
those two calls. And since we already have this functionality
directly from use by the sysfs interface to switch schedulers
online, it was prudent to reuse it internally too.
But this API needs the queue to be in a fully initialized state
before it is called, or it will attempt to unregister elevator
kobjects before they have been added. This results in an oops
like this:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000051
IP: [<ffffffff8116f15e>] sysfs_create_dir+0x2e/0xc0
PGD 47ddfc067 PUD 47c6a1067 PMD 0
Oops: 0000 [#1] PREEMPT SMP
last sysfs file: /sys/devices/pci0000:00/0000:00:02.0/0000:04:00.1/irq
CPU 2
Modules linked in: t(+) loop hid_apple usbhid ahci ehci_hcd uhci_hcd libahci usbcore nls_base igb
Pid: 7319, comm: modprobe Not tainted 2.6.36-rc6+ #132 QSSC-S4R/QSSC-S4R
RIP: 0010:[<ffffffff8116f15e>] [<ffffffff8116f15e>] sysfs_create_dir+0x2e/0xc0
RSP: 0018:ffff88027da25d08 EFLAGS: 00010246
RAX: ffff88047c68c528 RBX: 00000000fffffffe RCX: 0000000000000000
RDX: 000000000000002f RSI: 000000000000002f RDI: ffff88047e196c88
RBP: ffff88027da25d38 R08: 0000000000000000 R09: d84156c5635688c0
R10: d84156c5635688c0 R11: 0000000000000000 R12: ffff88047e196c88
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88047c68c528
FS: 00007fcb0b26f6e0(0000) GS:ffff880287400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000051 CR3: 000000047e76e000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process modprobe (pid: 7319, threadinfo ffff88027da24000, task ffff88027d377090)
Stack:
ffff88027da25d58 ffff88047c68c528 00000000fffffffe ffff88047e196c88
<0> ffff88047c68c528 ffff88047e05bd90 ffff88027da25d78 ffffffff8123fb77
<0> ffff88047e05bd90 0000000000000000 ffff88047e196c88 ffff88047c68c528
Call Trace:
[<ffffffff8123fb77>] kobject_add_internal+0xe7/0x1f0
[<ffffffff8123fd98>] kobject_add_varg+0x38/0x60
[<ffffffff8123feb9>] kobject_add+0x69/0x90
[<ffffffff8116efe0>] ? sysfs_remove_dir+0x20/0xa0
[<ffffffff8103d48d>] ? sub_preempt_count+0x9d/0xe0
[<ffffffff8143de20>] ? _raw_spin_unlock+0x30/0x50
[<ffffffff8116efe0>] ? sysfs_remove_dir+0x20/0xa0
[<ffffffff8116eff4>] ? sysfs_remove_dir+0x34/0xa0
[<ffffffff81224204>] elv_register_queue+0x34/0xa0
[<ffffffff81224aad>] elevator_change+0xfd/0x250
[<ffffffffa007e000>] ? t_init+0x0/0x361 [t]
[<ffffffffa007e000>] ? t_init+0x0/0x361 [t]
[<ffffffffa007e0a8>] t_init+0xa8/0x361 [t]
[<ffffffff810001de>] do_one_initcall+0x3e/0x170
[<ffffffff8108c3fd>] sys_init_module+0xbd/0x220
[<ffffffff81002f2b>] system_call_fastpath+0x16/0x1b
Code: e5 41 56 41 55 41 54 49 89 fc 53 48 83 ec 10 48 85 ff 74 52 48 8b 47 18 49 c7 c5 00 46 61 81 48 85 c0 74 04 4c 8b 68 30 45 31 f6 <41> 80 7d 51 00 74 0e 49 8b 44 24 28 4c 89 e7 ff 50 20 49 89 c6
RIP [<ffffffff8116f15e>] sysfs_create_dir+0x2e/0xc0
RSP <ffff88027da25d08>
CR2: 0000000000000051
---[ end trace a6541d3bf07945df ]---
Fix this by adding a registered bit to the elevator queue, which is
set when the sysfs kobjects have been registered.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
The block device drivers have all gained new lock_kernel
calls from a recent pushdown, and some of the drivers
were already using the BKL before.
This turns the BKL into a set of per-driver mutexes.
Still need to check whether this is safe to do.
file=$1
name=$2
if grep -q lock_kernel ${file} ; then
if grep -q 'include.*linux.mutex.h' ${file} ; then
sed -i '/include.*<linux\/smp_lock.h>/d' ${file}
else
sed -i 's/include.*<linux\/smp_lock.h>.*$/include <linux\/mutex.h>/g' ${file}
fi
sed -i ${file} \
-e "/^#include.*linux.mutex.h/,$ {
1,/^\(static\|int\|long\)/ {
/^\(static\|int\|long\)/istatic DEFINE_MUTEX(${name}_mutex);
} }" \
-e "s/\(un\)*lock_kernel\>[ ]*()/mutex_\1lock(\&${name}_mutex)/g" \
-e '/[ ]*cycle_kernel_lock();/d'
else
sed -i -e '/include.*\<smp_lock.h\>/d' ${file} \
-e '/cycle_kernel_lock()/d'
fi
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
o User can specify max iops value of 32bit (UINT_MAX), through cgroup
interface. If a user has specified say 4294967294 (UNIT_MAX - 2), then
on 32bit platform, following multiplication can overflow.
io_allowed = (tg->iops[rw] * jiffy_elapsed_rnd)
o Explicitly cast the multiplication to 64bit and then perform division and
then check whether result is still great then UNINT_MAX.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
- Limit max iops value to UINT_MAX and return error to user if value is more
than that instead of accepting bigger values and truncating implicitly.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
o Do not convert jiffies to mili seconds as it is not required. Just work
with jiffies and HZ.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
o Randy Dunlap reported following linux-next failure. This patch fixes it.
on i386:
blk-throttle.c:(.text+0x1abb8): undefined reference to `__udivdi3'
blk-throttle.c:(.text+0x1b1dc): undefined reference to `__udivdi3'
o bytes_per_second interface is 64bit and I was continuing to do 64 bit
division even on 32bit platform without help of special macros/functions
hence the failure.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
o Currently any cgroup throttle limit changes are processed asynchronousy and
the change does not take affect till a new bio is dispatched from same group.
o It might happen that a user sets a redicuously low limit on throttling.
Say 1 bytes per second on reads. In such cases simple operations like mount
a disk can wait for a very long time.
o Once bio is throttled, there is no easy way to come out of that wait even if
user increases the read limit later.
o This patch fixes it. Now if a user changes the cgroup limits, we recalculate
the bio dispatch time according to new limits.
o Can't take queueu lock under blkcg_lock, hence after the change I wake
up the dispatch thread again which recalculates the time. So there are some
variables being synchronized across two threads without lock and I had to
make use of barriers. Hoping I have used barriers correctly. Any review of
memory barrier code especially will help.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
o Currently all the dynamically allocated groups, except root grp is added
to td->tg_list. This was not a problem so far but in next patch I will
travel through td->tg_list to process any updates of limits on the group.
If root group is not in tg_list, then root group's updates are not
processed.
o It is better to root group also to tg_list instead of doing special
processing for it during limit updates.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
o Now a cgroup list of blkg elements can contain blkg from multiple policies.
Before sending an unlink event, make sure blkg belongs to they policy. If
policy does not own the blkg, do not send update for this blkg.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Currently throttling related files were visible even if user had disabled
throttling using config options. It was switching off background throttling
of bio but not the cgroup files. This patch fixes it.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
The bounce_pfn of the request queue in 64 bit systems is set to the
current max_low_pfn. Adding more memory later makes this incorrect.
Memory allocated beyond this boot time max_low_pfn appear to require
bounce buffers (bounce buffers are actually not allocated but used in
calculating segments that may result in "over max segments limit"
errors).
Signed-off-by: Malahal Naineni <malahal@us.ibm.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Revert "block: set the bounce_pfn to the actual DMA limit rather than to max memory"
This reverts commit c49825facf.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Add logic to prevent two I/O requests being merged if
only one of them is a discard. Ditto secure discard.
Without this fix, it is possible for write requests
to transform into discard requests. For example:
Submit bio 1 to discard 8 sectors from sector n
Submit bio 2 to write 8 sectors from sector n + 16
Submit bio 3 to write 8 sectors from sector n + 8
Bio 1 becomes request 1. Bio 2 becomes request 2.
Bio 3 is merged with request 2, and then subsequently
request 2 is merged with request 1 resulting in just
one I/O request which discards all 24 sectors.
Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
(Moved the checks above the position checks /Jens)
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
The bounce_pfn of the request queue in 64 bit systems is set to the
current max_low_pfn. Adding more memory later makes this incorrect.
Memory allocated beyond this boot time max_low_pfn appear to require
bounce buffers (bounce buffers are actually not allocated but used in
calculating segments that may result in "over max segments limit"
errors).
Signed-off-by: Malahal Naineni <malahal@us.ibm.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
During long I/O operations, the hang_check timer may fire,
trigger stack dumps that unnecessarily alarm the user.
Eg. hdparm --security-erase NULL /dev/sdb ## can take *hours* to complete
So, if hang_check is armed, we should wake up periodically
to prevent it from triggering. This patch uses a wake-up interval
equal to half the hang_check timer period, which keeps overhead low enough.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Mike reported a kernel crash when a usb key hotplug is performed while all
kernel thrads are not in a root cgroup and are running in one of the child
cgroups of blkio controller.
BUG: unable to handle kernel NULL pointer dereference at 0000002c
IP: [<c11c7b08>] cfq_get_queue+0x232/0x412
*pde = 00000000
Oops: 0000 [#1] PREEMPT
last sysfs file: /sys/devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1:1.0/host3/scsi_host/host3/uevent
[..]
Pid: 30039, comm: scsi_scan_3 Not tainted 2.6.35.2-fg.roam #1 Volvi2 /Aspire 4315
EIP: 0060:[<c11c7b08>] EFLAGS: 00010086 CPU: 0
EIP is at cfq_get_queue+0x232/0x412
EAX: f705f9c0 EBX: e977abac ECX: 00000000 EDX: 00000000
ESI: f00da400 EDI: f00da4ec EBP: e977a800 ESP: dff8fd00
DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068
Process scsi_scan_3 (pid: 30039, ti=dff8e000 task=f6b6c9a0 task.ti=dff8e000)
Stack:
00000000 00000000 00000001 01ff0000 f00da508 00000000 f00da524 f00da540
<0> e7994940 dd631750 f705f9c0 e977a820 e977ac44 f00da4d0 00000001 f6b6c9a0
<0> 00000010 00008010 0000000b 00000000 00000001 e977a800 dd76fac0 00000246
Call Trace:
[<c11c7f10>] ? cfq_set_request+0x228/0x34c
[<c11c7ce8>] ? cfq_set_request+0x0/0x34c
[<c11bb3b9>] ? elv_set_request+0xf/0x1c
[<c11bdd51>] ? get_request+0x1ad/0x22f
[<c11bddf2>] ? get_request_wait+0x1f/0x11a
[<c11d013b>] ? kvasprintf+0x33/0x3b
[<c127b537>] ? scsi_execute+0x1d/0x103
[<c127b675>] ? scsi_execute_req+0x58/0x83
[<c127c391>] ? scsi_probe_and_add_lun+0x188/0x7c2
[<c12718c6>] ? attribute_container_add_device+0x15/0xfa
[<c11c95d1>] ? kobject_get+0xf/0x13
[<c126d1db>] ? get_device+0x10/0x14
[<c127be93>] ? scsi_alloc_target+0x217/0x24d
[<c127cbd8>] ? __scsi_scan_target+0x95/0x480
[<c10204eb>] ? dequeue_entity+0x14/0x1fe
[<c1020491>] ? update_curr+0x165/0x1ab
[<c1020491>] ? update_curr+0x165/0x1ab
[<c127d00d>] ? scsi_scan_channel+0x4a/0x76
[<c127d0b0>] ? scsi_scan_host_selected+0x77/0xad
[<c127d13c>] ? do_scan_async+0x0/0x11a
[<c127d137>] ? do_scsi_scan_host+0x51/0x56
[<c127d13c>] ? do_scan_async+0x0/0x11a
[<c127d14a>] ? do_scan_async+0xe/0x11a
[<c127d13c>] ? do_scan_async+0x0/0x11a
[<c10354c5>] ? kthread+0x5e/0x63
[<c1035467>] ? kthread+0x0/0x63
[<c1002af6>] ? kernel_thread_helper+0x6/0x10
Code: 44 24 1c 54 83 44 24 18 54 83 fa 03 75 94 8b 06 c7 86 64 02 00 00 01 00 00 00 83 e0 03 09 f0 89 06 8b 44 24 28 8b 90 58 01 00 00 <8b> 42 2c 85 c0 75 03 8b 42 08 8d 54 24 48 52 8d 4c 24 50 51 68
EIP: [<c11c7b08>] cfq_get_queue+0x232/0x412 SS:ESP 0068:dff8fd00
CR2: 000000000000002c
---[ end trace 9a88306573f69b12 ]---
The problem here is that we don't have bdi->dev information available when
thread does some IO. Hence when dev_name() tries to access bdi->dev, it
crashes.
This problem does not happen if kernel threads are in root group as root
group is statically allocated at device initialization time and we don't
hit this piece of code.
Fix it by delaying the filling of major and minor number information of
device in blk_group. Initially a blk_group is created with 0 as device
information and this information is filled later once some more IO comes
in from same group.
Reported-by: Mike Kazantsev <mk.fraggod@gmail.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This bug was introduced in 7b6d91daee
"block: unify flags for struct bio and struct request"
Cc: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Fsync performance for small files achieved by cfq on high-end disks is
lower than what deadline can achieve, due to idling introduced between
the sync write happening in process context and the journal commit.
Moreover, when competing with a sequential reader, a process writing
small files and fsync-ing them is starved.
This patch fixes the two problems by:
- marking journal commits as WRITE_SYNC, so that they get the REQ_NOIDLE
flag set,
- force all queues that have REQ_NOIDLE requests to be put in the noidle
tree.
Having the queue associated to the fsync-ing process and the one associated
to journal commits in the noidle tree allows:
- switching between them without idling,
- fairness vs. competing idling queues, since they will be serviced only
after the noidle tree expires its slice.
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Tested-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Corrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
All the blkdev_issue_* helpers can only sanely be used for synchronous
caller. To issue cache flushes or barriers asynchronously the caller needs
to set up a bio by itself with a completion callback to move the asynchronous
state machine ahead. So drop the BLKDEV_IFL_WAIT flag that is always
specified when calling blkdev_issue_* and also remove the now unused flags
argument to blkdev_issue_flush and blkdev_issue_zeroout. For
blkdev_issue_discard we need to keep it for the secure discard flag, which
gains a more descriptive name and loses the bitops vs flag confusion.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
When a new disk is being discovered, add_disk() first ties the bdev to gendisk
(via register_disk()->blkdev_get()) and only after that calls
bdi_register_bdev(). Because register_disk() also creates disk's kobject, it
can happen that userspace manages to open and modify the device's data (or
inode) before its BDI is properly initialized leading to a warning in
__mark_inode_dirty().
Fix the problem by registering BDI early enough.
This patch addresses https://bugzilla.kernel.org/show_bug.cgi?id=16312
Cc: stable@kernel.org
Reported-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Tejun Heo