2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:32 -07:00
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2005-04-16 15:20:36 -07:00
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2006-03-27 01:17:54 -08:00
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2008-02-08 02:09:56 +00:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:35 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:34 -07:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:51:52 +00:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:34 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:06 +01:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 00:09:02 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 00:09:02 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:51:52 +00:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:51:52 +00:00
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2005-04-16 15:20:36 -07:00
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2005-09-27 21:45:44 -07:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:51:52 +00:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:51:52 +00:00
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2005-09-27 21:45:44 -07:00
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2009-12-10 23:52:19 +00:00
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2005-09-27 21:45:44 -07:00
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2005-04-16 15:20:36 -07:00
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dm table: rework reference counting
Rework table reference counting.
The existing code uses a reference counter. When the last reference is
dropped and the counter reaches zero, the table destructor is called.
Table reference counters are acquired/released from upcalls from other
kernel code (dm_any_congested, dm_merge_bvec, dm_unplug_all).
If the reference counter reaches zero in one of the upcalls, the table
destructor is called from almost random kernel code.
This leads to various problems:
* dm_any_congested being called under a spinlock, which calls the
destructor, which calls some sleeping function.
* the destructor attempting to take a lock that is already taken by the
same process.
* stale reference from some other kernel code keeps the table
constructed, which keeps some devices open, even after successful
return from "dmsetup remove". This can confuse lvm and prevent closing
of underlying devices or reusing device minor numbers.
The patch changes reference counting so that the table destructor can be
called only at predetermined places.
The table has always exactly one reference from either mapped_device->map
or hash_cell->new_map. After this patch, this reference is not counted
in table->holders. A pair of dm_create_table/dm_destroy_table functions
is used for table creation/destruction.
Temporary references from the other code increase table->holders. A pair
of dm_table_get/dm_table_put functions is used to manipulate it.
When the table is about to be destroyed, we wait for table->holders to
reach 0. Then, we call the table destructor. We use active waiting with
msleep(1), because the situation happens rarely (to one user in 5 years)
and removing the device isn't performance-critical task: the user doesn't
care if it takes one tick more or not.
This way, the destructor is called only at specific points
(dm_table_destroy function) and the above problems associated with lazy
destruction can't happen.
Finally remove the temporary protection added to dm_any_congested().
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2009-01-06 03:05:10 +00:00
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2006-03-27 01:17:54 -08:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:34 -07:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:55 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:55 +01:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:34 -07:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:55 +01:00
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2006-06-26 00:27:34 -07:00
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2010-08-12 04:13:55 +01:00
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2006-06-26 00:27:34 -07:00
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2010-08-12 04:13:55 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:55 +01:00
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dm: separate device deletion from dm_put
This patch separates the device deletion code from dm_put()
to make sure the deletion happens in the process context.
By this patch, device deletion always occurs in an ioctl (process)
context and dm_put() can be called in interrupt context.
As a result, the request-based dm's bad dm_put() usage pointed out
by Mikulas below disappears.
http://marc.info/?l=dm-devel&m=126699981019735&w=2
Without this patch, I confirmed there is a case to crash the system:
dm_put() => dm_table_destroy() => vfree() => BUG_ON(in_interrupt())
Some more backgrounds and details:
In request-based dm, a device opener can remove a mapped_device
while the last request is still completing, because bios in the last
request complete first and then the device opener can close and remove
the mapped_device before the last request completes:
CPU0 CPU1
=================================================================
<<INTERRUPT>>
blk_end_request_all(clone_rq)
blk_update_request(clone_rq)
bio_endio(clone_bio) == end_clone_bio
blk_update_request(orig_rq)
bio_endio(orig_bio)
<<I/O completed>>
dm_blk_close()
dev_remove()
dm_put(md)
<<Free md>>
blk_finish_request(clone_rq)
....
dm_end_request(clone_rq)
free_rq_clone(clone_rq)
blk_end_request_all(orig_rq)
rq_completed(md)
So request-based dm used dm_get()/dm_put() to hold md for each I/O
until its request completion handling is fully done.
However, the final dm_put() can call the device deletion code which
must not be run in interrupt context and may cause kernel panic.
To solve the problem, this patch moves the device deletion code,
dm_destroy(), to predetermined places that is actually deleting
the mapped_device in ioctl (process) context, and changes dm_put()
just to decrement the reference count of the mapped_device.
By this change, dm_put() can be used in any context and the symmetric
model below is introduced:
dm_create(): create a mapped_device
dm_destroy(): destroy a mapped_device
dm_get(): increment the reference count of a mapped_device
dm_put(): decrement the reference count of a mapped_device
dm_destroy() waits for all references of the mapped_device to disappear,
then deletes the mapped_device.
dm_destroy() uses active waiting with msleep(1), since deleting
the mapped_device isn't performance-critical task.
And since at this point, nobody opens the mapped_device and no new
reference will be taken, the pending counts are just for racing
completing activity and will eventually decrease to zero.
For the unlikely case of the forced module unload, dm_destroy_immediate(),
which doesn't wait and forcibly deletes the mapped_device, is also
introduced and used in dm_hash_remove_all(). Otherwise, "rmmod -f"
may be stuck and never return.
And now, because the mapped_device is deleted at this point, subsequent
accesses to the mapped_device may cause NULL pointer references.
Cc: stable@kernel.org
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2010-08-12 04:13:56 +01:00
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2010-08-12 04:13:55 +01:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:34 -07:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:55 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2010-08-12 04:13:53 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2005-04-16 15:20:36 -07:00
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2006-01-06 00:20:01 -08:00
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2010-08-12 04:13:53 +01:00
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2011-01-13 19:59:47 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2010-08-12 04:13:53 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2010-08-12 04:13:53 +01:00
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2006-06-26 00:27:24 -07:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2010-08-12 04:13:53 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:53 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2010-08-12 04:13:53 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2005-04-16 15:20:36 -07:00
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2006-01-06 00:20:01 -08:00
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2009-12-10 23:52:19 +00:00
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2006-01-06 00:20:01 -08:00
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2010-08-12 04:13:53 +01:00
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2007-12-13 14:15:57 +00:00
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2010-08-12 04:13:53 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:53 +01:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:34 -07:00
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2005-04-16 15:20:36 -07:00
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2008-09-03 09:01:48 +02:00
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2005-04-16 15:20:36 -07:00
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2005-11-21 21:32:33 -08:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:22 +00:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:26 +00:00
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2005-04-16 15:20:36 -07:00
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2008-09-03 09:01:48 +02:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:34 -07:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:22 +00:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:19 +00:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:22 +00:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:22 +00:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:32 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:32 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:32 -07:00
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2005-04-16 15:20:36 -07:00
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dm: separate device deletion from dm_put
This patch separates the device deletion code from dm_put()
to make sure the deletion happens in the process context.
By this patch, device deletion always occurs in an ioctl (process)
context and dm_put() can be called in interrupt context.
As a result, the request-based dm's bad dm_put() usage pointed out
by Mikulas below disappears.
http://marc.info/?l=dm-devel&m=126699981019735&w=2
Without this patch, I confirmed there is a case to crash the system:
dm_put() => dm_table_destroy() => vfree() => BUG_ON(in_interrupt())
Some more backgrounds and details:
In request-based dm, a device opener can remove a mapped_device
while the last request is still completing, because bios in the last
request complete first and then the device opener can close and remove
the mapped_device before the last request completes:
CPU0 CPU1
=================================================================
<<INTERRUPT>>
blk_end_request_all(clone_rq)
blk_update_request(clone_rq)
bio_endio(clone_bio) == end_clone_bio
blk_update_request(orig_rq)
bio_endio(orig_bio)
<<I/O completed>>
dm_blk_close()
dev_remove()
dm_put(md)
<<Free md>>
blk_finish_request(clone_rq)
....
dm_end_request(clone_rq)
free_rq_clone(clone_rq)
blk_end_request_all(orig_rq)
rq_completed(md)
So request-based dm used dm_get()/dm_put() to hold md for each I/O
until its request completion handling is fully done.
However, the final dm_put() can call the device deletion code which
must not be run in interrupt context and may cause kernel panic.
To solve the problem, this patch moves the device deletion code,
dm_destroy(), to predetermined places that is actually deleting
the mapped_device in ioctl (process) context, and changes dm_put()
just to decrement the reference count of the mapped_device.
By this change, dm_put() can be used in any context and the symmetric
model below is introduced:
dm_create(): create a mapped_device
dm_destroy(): destroy a mapped_device
dm_get(): increment the reference count of a mapped_device
dm_put(): decrement the reference count of a mapped_device
dm_destroy() waits for all references of the mapped_device to disappear,
then deletes the mapped_device.
dm_destroy() uses active waiting with msleep(1), since deleting
the mapped_device isn't performance-critical task.
And since at this point, nobody opens the mapped_device and no new
reference will be taken, the pending counts are just for racing
completing activity and will eventually decrease to zero.
For the unlikely case of the forced module unload, dm_destroy_immediate(),
which doesn't wait and forcibly deletes the mapped_device, is also
introduced and used in dm_hash_remove_all(). Otherwise, "rmmod -f"
may be stuck and never return.
And now, because the mapped_device is deleted at this point, subsequent
accesses to the mapped_device may cause NULL pointer references.
Cc: stable@kernel.org
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2010-08-12 04:13:56 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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|
dm: separate device deletion from dm_put
This patch separates the device deletion code from dm_put()
to make sure the deletion happens in the process context.
By this patch, device deletion always occurs in an ioctl (process)
context and dm_put() can be called in interrupt context.
As a result, the request-based dm's bad dm_put() usage pointed out
by Mikulas below disappears.
http://marc.info/?l=dm-devel&m=126699981019735&w=2
Without this patch, I confirmed there is a case to crash the system:
dm_put() => dm_table_destroy() => vfree() => BUG_ON(in_interrupt())
Some more backgrounds and details:
In request-based dm, a device opener can remove a mapped_device
while the last request is still completing, because bios in the last
request complete first and then the device opener can close and remove
the mapped_device before the last request completes:
CPU0 CPU1
=================================================================
<<INTERRUPT>>
blk_end_request_all(clone_rq)
blk_update_request(clone_rq)
bio_endio(clone_bio) == end_clone_bio
blk_update_request(orig_rq)
bio_endio(orig_bio)
<<I/O completed>>
dm_blk_close()
dev_remove()
dm_put(md)
<<Free md>>
blk_finish_request(clone_rq)
....
dm_end_request(clone_rq)
free_rq_clone(clone_rq)
blk_end_request_all(orig_rq)
rq_completed(md)
So request-based dm used dm_get()/dm_put() to hold md for each I/O
until its request completion handling is fully done.
However, the final dm_put() can call the device deletion code which
must not be run in interrupt context and may cause kernel panic.
To solve the problem, this patch moves the device deletion code,
dm_destroy(), to predetermined places that is actually deleting
the mapped_device in ioctl (process) context, and changes dm_put()
just to decrement the reference count of the mapped_device.
By this change, dm_put() can be used in any context and the symmetric
model below is introduced:
dm_create(): create a mapped_device
dm_destroy(): destroy a mapped_device
dm_get(): increment the reference count of a mapped_device
dm_put(): decrement the reference count of a mapped_device
dm_destroy() waits for all references of the mapped_device to disappear,
then deletes the mapped_device.
dm_destroy() uses active waiting with msleep(1), since deleting
the mapped_device isn't performance-critical task.
And since at this point, nobody opens the mapped_device and no new
reference will be taken, the pending counts are just for racing
completing activity and will eventually decrease to zero.
For the unlikely case of the forced module unload, dm_destroy_immediate(),
which doesn't wait and forcibly deletes the mapped_device, is also
introduced and used in dm_hash_remove_all(). Otherwise, "rmmod -f"
may be stuck and never return.
And now, because the mapped_device is deleted at this point, subsequent
accesses to the mapped_device may cause NULL pointer references.
Cc: stable@kernel.org
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2010-08-12 04:13:56 +01:00
|
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|
2005-04-16 15:20:36 -07:00
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2006-01-14 13:20:43 -08:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:06 +01:00
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2006-03-27 01:17:53 -08:00
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2011-08-02 12:32:06 +01:00
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2011-08-02 12:32:06 +01:00
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2011-08-02 12:32:06 +01:00
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2011-08-02 12:32:06 +01:00
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2011-08-02 12:32:06 +01:00
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2011-08-02 12:32:06 +01:00
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2011-08-02 12:32:06 +01:00
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2011-08-02 12:32:06 +01:00
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2006-03-27 01:17:53 -08:00
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2011-08-02 12:32:06 +01:00
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2005-04-16 15:20:36 -07:00
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2006-01-14 13:20:43 -08:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:06 +01:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2006-06-26 00:27:34 -07:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:55 +00:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2006-06-26 00:27:34 -07:00
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2011-01-13 19:59:55 +00:00
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2006-06-26 00:27:34 -07:00
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2005-04-16 15:20:36 -07:00
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2009-06-22 10:12:30 +01:00
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2010-03-06 02:32:31 +00:00
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2009-06-22 10:12:30 +01:00
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2006-06-26 00:27:24 -07:00
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dm: separate device deletion from dm_put
This patch separates the device deletion code from dm_put()
to make sure the deletion happens in the process context.
By this patch, device deletion always occurs in an ioctl (process)
context and dm_put() can be called in interrupt context.
As a result, the request-based dm's bad dm_put() usage pointed out
by Mikulas below disappears.
http://marc.info/?l=dm-devel&m=126699981019735&w=2
Without this patch, I confirmed there is a case to crash the system:
dm_put() => dm_table_destroy() => vfree() => BUG_ON(in_interrupt())
Some more backgrounds and details:
In request-based dm, a device opener can remove a mapped_device
while the last request is still completing, because bios in the last
request complete first and then the device opener can close and remove
the mapped_device before the last request completes:
CPU0 CPU1
=================================================================
<<INTERRUPT>>
blk_end_request_all(clone_rq)
blk_update_request(clone_rq)
bio_endio(clone_bio) == end_clone_bio
blk_update_request(orig_rq)
bio_endio(orig_bio)
<<I/O completed>>
dm_blk_close()
dev_remove()
dm_put(md)
<<Free md>>
blk_finish_request(clone_rq)
....
dm_end_request(clone_rq)
free_rq_clone(clone_rq)
blk_end_request_all(orig_rq)
rq_completed(md)
So request-based dm used dm_get()/dm_put() to hold md for each I/O
until its request completion handling is fully done.
However, the final dm_put() can call the device deletion code which
must not be run in interrupt context and may cause kernel panic.
To solve the problem, this patch moves the device deletion code,
dm_destroy(), to predetermined places that is actually deleting
the mapped_device in ioctl (process) context, and changes dm_put()
just to decrement the reference count of the mapped_device.
By this change, dm_put() can be used in any context and the symmetric
model below is introduced:
dm_create(): create a mapped_device
dm_destroy(): destroy a mapped_device
dm_get(): increment the reference count of a mapped_device
dm_put(): decrement the reference count of a mapped_device
dm_destroy() waits for all references of the mapped_device to disappear,
then deletes the mapped_device.
dm_destroy() uses active waiting with msleep(1), since deleting
the mapped_device isn't performance-critical task.
And since at this point, nobody opens the mapped_device and no new
reference will be taken, the pending counts are just for racing
completing activity and will eventually decrease to zero.
For the unlikely case of the forced module unload, dm_destroy_immediate(),
which doesn't wait and forcibly deletes the mapped_device, is also
introduced and used in dm_hash_remove_all(). Otherwise, "rmmod -f"
may be stuck and never return.
And now, because the mapped_device is deleted at this point, subsequent
accesses to the mapped_device may cause NULL pointer references.
Cc: stable@kernel.org
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2010-08-12 04:13:56 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2010-08-12 04:13:53 +01:00
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2011-01-13 19:59:47 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:47 +00:00
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2010-08-12 04:13:53 +01:00
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2010-03-06 02:32:31 +00:00
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2010-08-12 04:13:53 +01:00
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2005-04-16 15:20:36 -07:00
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2006-03-27 01:17:54 -08:00
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dm: reject trailing characters in sccanf input
Device mapper uses sscanf to convert arguments to numbers. The problem is that
the way we use it ignores additional unmatched characters in the scanned string.
For example, this `if (sscanf(string, "%d", &number) == 1)' will match a number,
but also it will match number with some garbage appended, like "123abc".
As a result, device mapper accepts garbage after some numbers. For example
the command `dmsetup create vg1-new --table "0 16384 linear 254:1bla 34816bla"'
will pass without an error.
This patch fixes all sscanf uses in device mapper. It appends "%c" with
a pointer to a dummy character variable to every sscanf statement.
The construct `if (sscanf(string, "%d%c", &number, &dummy) == 1)' succeeds
only if string is a null-terminated number (optionally preceded by some
whitespace characters). If there is some character appended after the number,
sscanf matches "%c", writes the character to the dummy variable and returns 2.
We check the return value for 1 and consequently reject numbers with some
garbage appended.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-03-28 18:41:26 +01:00
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2006-03-27 01:17:54 -08:00
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2008-02-08 02:09:53 +00:00
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2006-03-27 01:17:54 -08:00
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dm: reject trailing characters in sccanf input
Device mapper uses sscanf to convert arguments to numbers. The problem is that
the way we use it ignores additional unmatched characters in the scanned string.
For example, this `if (sscanf(string, "%d", &number) == 1)' will match a number,
but also it will match number with some garbage appended, like "123abc".
As a result, device mapper accepts garbage after some numbers. For example
the command `dmsetup create vg1-new --table "0 16384 linear 254:1bla 34816bla"'
will pass without an error.
This patch fixes all sscanf uses in device mapper. It appends "%c" with
a pointer to a dummy character variable to every sscanf statement.
The construct `if (sscanf(string, "%d%c", &number, &dummy) == 1)' succeeds
only if string is a null-terminated number (optionally preceded by some
whitespace characters). If there is some character appended after the number,
sscanf matches "%c", writes the character to the dummy variable and returns 2.
We check the return value for 1 and consequently reject numbers with some
garbage appended.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2012-03-28 18:41:26 +01:00
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2006-03-27 01:17:54 -08:00
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2005-04-16 15:20:36 -07:00
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2006-12-08 02:41:04 -08:00
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2005-04-16 15:20:36 -07:00
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2006-01-06 00:20:07 -08:00
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2006-12-08 02:41:04 -08:00
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2006-12-08 02:41:07 -08:00
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2006-01-06 00:20:07 -08:00
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2010-08-12 04:13:52 +01:00
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2006-12-08 02:41:04 -08:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2006-12-08 02:41:04 -08:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:24 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 19:59:55 +00:00
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2005-04-16 15:20:36 -07:00
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2006-01-06 00:20:07 -08:00
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2006-12-08 02:41:04 -08:00
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2006-12-08 02:41:07 -08:00
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2009-12-10 23:52:26 +00:00
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2006-12-08 02:41:04 -08:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:24 +00:00
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dm table: rework reference counting
Rework table reference counting.
The existing code uses a reference counter. When the last reference is
dropped and the counter reaches zero, the table destructor is called.
Table reference counters are acquired/released from upcalls from other
kernel code (dm_any_congested, dm_merge_bvec, dm_unplug_all).
If the reference counter reaches zero in one of the upcalls, the table
destructor is called from almost random kernel code.
This leads to various problems:
* dm_any_congested being called under a spinlock, which calls the
destructor, which calls some sleeping function.
* the destructor attempting to take a lock that is already taken by the
same process.
* stale reference from some other kernel code keeps the table
constructed, which keeps some devices open, even after successful
return from "dmsetup remove". This can confuse lvm and prevent closing
of underlying devices or reusing device minor numbers.
The patch changes reference counting so that the table destructor can be
called only at predetermined places.
The table has always exactly one reference from either mapped_device->map
or hash_cell->new_map. After this patch, this reference is not counted
in table->holders. A pair of dm_create_table/dm_destroy_table functions
is used for table creation/destruction.
Temporary references from the other code increase table->holders. A pair
of dm_table_get/dm_table_put functions is used to manipulate it.
When the table is about to be destroyed, we wait for table->holders to
reach 0. Then, we call the table destructor. We use active waiting with
msleep(1), because the situation happens rarely (to one user in 5 years)
and removing the device isn't performance-critical task: the user doesn't
care if it takes one tick more or not.
This way, the destructor is called only at specific points
(dm_table_destroy function) and the above problems associated with lazy
destruction can't happen.
Finally remove the temporary protection added to dm_any_congested().
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2009-01-06 03:05:10 +00:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:24 +00:00
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2005-04-16 15:20:36 -07:00
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2010-03-06 02:32:24 +00:00
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2005-04-16 15:20:36 -07:00
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2010-03-06 02:32:31 +00:00
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2010-03-06 02:32:24 +00:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:24 +00:00
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2009-06-22 10:12:30 +01:00
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2010-03-06 02:32:24 +00:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2012-07-27 15:08:16 +01:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:44 +00:00
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2005-04-16 15:20:36 -07:00
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2012-07-27 15:08:16 +01:00
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2013-03-01 22:45:44 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:44 +00:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:22 +00:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2008-09-02 15:28:45 -04:00
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2005-04-16 15:20:36 -07:00
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2008-09-02 15:28:45 -04:00
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2005-04-16 15:20:36 -07:00
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2006-03-27 01:17:54 -08:00
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2011-10-31 20:19:04 +00:00
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2005-04-16 15:20:36 -07:00
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2006-03-27 01:17:54 -08:00
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2005-04-16 15:20:36 -07:00
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2006-03-27 01:17:54 -08:00
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2005-04-16 15:20:36 -07:00
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2009-03-16 17:44:26 +00:00
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2006-03-27 01:17:54 -08:00
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2005-04-16 15:20:36 -07:00
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2011-10-31 20:19:04 +00:00
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2010-08-12 04:14:02 +01:00
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2010-08-12 04:14:01 +01:00
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2010-08-12 04:14:02 +01:00
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2010-08-12 04:14:01 +01:00
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2005-04-16 15:20:36 -07:00
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2006-03-27 01:17:54 -08:00
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2009-03-16 17:44:26 +00:00
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2006-03-27 01:17:54 -08:00
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2005-04-16 15:20:36 -07:00
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|
dm table: rework reference counting
Rework table reference counting.
The existing code uses a reference counter. When the last reference is
dropped and the counter reaches zero, the table destructor is called.
Table reference counters are acquired/released from upcalls from other
kernel code (dm_any_congested, dm_merge_bvec, dm_unplug_all).
If the reference counter reaches zero in one of the upcalls, the table
destructor is called from almost random kernel code.
This leads to various problems:
* dm_any_congested being called under a spinlock, which calls the
destructor, which calls some sleeping function.
* the destructor attempting to take a lock that is already taken by the
same process.
* stale reference from some other kernel code keeps the table
constructed, which keeps some devices open, even after successful
return from "dmsetup remove". This can confuse lvm and prevent closing
of underlying devices or reusing device minor numbers.
The patch changes reference counting so that the table destructor can be
called only at predetermined places.
The table has always exactly one reference from either mapped_device->map
or hash_cell->new_map. After this patch, this reference is not counted
in table->holders. A pair of dm_create_table/dm_destroy_table functions
is used for table creation/destruction.
Temporary references from the other code increase table->holders. A pair
of dm_table_get/dm_table_put functions is used to manipulate it.
When the table is about to be destroyed, we wait for table->holders to
reach 0. Then, we call the table destructor. We use active waiting with
msleep(1), because the situation happens rarely (to one user in 5 years)
and removing the device isn't performance-critical task: the user doesn't
care if it takes one tick more or not.
This way, the destructor is called only at specific points
(dm_table_destroy function) and the above problems associated with lazy
destruction can't happen.
Finally remove the temporary protection added to dm_any_congested().
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2009-01-06 03:05:10 +00:00
|
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2005-04-16 15:20:36 -07:00
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|
2006-03-27 01:17:54 -08:00
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|
2010-08-12 04:13:52 +01:00
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2006-03-27 01:17:54 -08:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:24 -07:00
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2005-04-16 15:20:36 -07:00
|
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2011-01-13 19:59:55 +00:00
|
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2005-04-16 15:20:36 -07:00
|
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|
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|
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|
|
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|
|
|
dm table: rework reference counting
Rework table reference counting.
The existing code uses a reference counter. When the last reference is
dropped and the counter reaches zero, the table destructor is called.
Table reference counters are acquired/released from upcalls from other
kernel code (dm_any_congested, dm_merge_bvec, dm_unplug_all).
If the reference counter reaches zero in one of the upcalls, the table
destructor is called from almost random kernel code.
This leads to various problems:
* dm_any_congested being called under a spinlock, which calls the
destructor, which calls some sleeping function.
* the destructor attempting to take a lock that is already taken by the
same process.
* stale reference from some other kernel code keeps the table
constructed, which keeps some devices open, even after successful
return from "dmsetup remove". This can confuse lvm and prevent closing
of underlying devices or reusing device minor numbers.
The patch changes reference counting so that the table destructor can be
called only at predetermined places.
The table has always exactly one reference from either mapped_device->map
or hash_cell->new_map. After this patch, this reference is not counted
in table->holders. A pair of dm_create_table/dm_destroy_table functions
is used for table creation/destruction.
Temporary references from the other code increase table->holders. A pair
of dm_table_get/dm_table_put functions is used to manipulate it.
When the table is about to be destroyed, we wait for table->holders to
reach 0. Then, we call the table destructor. We use active waiting with
msleep(1), because the situation happens rarely (to one user in 5 years)
and removing the device isn't performance-critical task: the user doesn't
care if it takes one tick more or not.
This way, the destructor is called only at specific points
(dm_table_destroy function) and the above problems associated with lazy
destruction can't happen.
Finally remove the temporary protection added to dm_any_congested().
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2009-01-06 03:05:10 +00:00
|
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|
2005-04-16 15:20:36 -07:00
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|
2010-08-12 04:13:52 +01:00
|
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2006-06-26 00:27:24 -07:00
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|
2005-04-16 15:20:36 -07:00
|
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|
2006-06-26 00:27:24 -07:00
|
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|
2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2008-10-10 13:37:09 +01:00
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2005-04-16 15:20:36 -07:00
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2008-10-10 13:37:09 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:22 +00:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:22 +00:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:13:52 +01:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:49 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:49 +00:00
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2005-04-16 15:20:36 -07:00
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2007-10-19 22:38:36 +01:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:03 +01:00
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2012-03-07 19:09:34 +00:00
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2011-08-02 12:32:03 +01:00
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2013-03-01 22:45:49 +00:00
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2009-12-10 23:52:19 +00:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:20 +00:00
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2007-12-13 14:15:25 +00:00
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2005-04-16 15:20:36 -07:00
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2007-12-13 14:15:25 +00:00
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2005-04-16 15:20:36 -07:00
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2009-12-10 23:52:20 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:49 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:49 +00:00
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2012-12-21 20:23:36 +00:00
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2013-03-01 22:45:49 +00:00
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2012-12-21 20:23:36 +00:00
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2013-03-01 22:45:49 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:49 +00:00
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2011-03-24 13:54:30 +00:00
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2013-03-01 22:45:49 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:49 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:49 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:49 +00:00
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2011-03-24 13:54:30 +00:00
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2012-12-21 20:23:36 +00:00
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2013-03-01 22:45:49 +00:00
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2012-12-21 20:23:36 +00:00
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2012-12-21 20:23:36 +00:00
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2012-12-21 20:23:36 +00:00
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2012-12-21 20:23:36 +00:00
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2013-03-01 22:45:49 +00:00
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2012-12-21 20:23:36 +00:00
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2011-03-24 13:54:30 +00:00
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2013-03-01 22:45:49 +00:00
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2011-03-24 13:54:30 +00:00
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2005-04-16 15:20:36 -07:00
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2011-03-24 13:54:30 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:49 +00:00
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2011-03-24 13:54:28 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:49 +00:00
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2012-12-21 20:23:30 +00:00
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2013-03-01 22:45:49 +00:00
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2012-12-21 20:23:30 +00:00
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2011-03-24 13:54:30 +00:00
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2013-03-01 22:45:49 +00:00
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2011-03-24 13:54:30 +00:00
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2005-04-16 15:20:36 -07:00
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2011-03-24 13:54:28 +00:00
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2013-03-01 22:45:49 +00:00
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2012-12-21 20:23:36 +00:00
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2011-03-24 13:54:28 +00:00
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2005-04-16 15:20:36 -07:00
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2010-03-06 02:32:31 +00:00
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2011-03-24 13:54:30 +00:00
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2013-03-01 22:45:49 +00:00
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2005-04-16 15:20:36 -07:00
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2008-02-08 02:09:53 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2012-12-21 20:23:36 +00:00
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2005-04-16 15:20:36 -07:00
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2008-02-08 02:10:16 +00:00
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2005-04-16 15:20:36 -07:00
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2011-03-24 13:54:28 +00:00
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2013-03-01 22:45:49 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:49 +00:00
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2005-04-16 15:20:36 -07:00
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2006-02-01 03:04:52 -08:00
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2005-04-16 15:20:36 -07:00
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2011-03-24 13:54:30 +00:00
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2005-04-16 15:20:36 -07:00
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2011-03-24 13:54:28 +00:00
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2005-04-16 15:20:36 -07:00
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2013-03-01 22:45:48 +00:00
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2005-04-16 15:20:36 -07:00
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2011-03-24 13:54:28 +00:00
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2012-12-21 20:23:36 +00:00
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2005-04-16 15:20:36 -07:00
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2008-02-08 02:09:53 +00:00
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2008-02-08 02:09:56 +00:00
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2007-02-12 00:55:33 -08:00
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2010-08-12 04:13:57 +01:00
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2008-02-08 02:09:53 +00:00
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2008-02-08 02:09:56 +00:00
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2005-04-16 15:20:36 -07:00
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|
llseek: automatically add .llseek fop
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>
2010-08-15 18:52:59 +02:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:14:05 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:14:05 +01:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:14:05 +01:00
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2005-04-16 15:20:36 -07:00
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2007-10-19 22:47:59 +01:00
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2009-12-10 23:51:52 +00:00
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2007-10-19 22:47:59 +01:00
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2009-01-06 03:05:04 +00:00
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2007-10-19 22:47:59 +01:00
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2009-12-10 23:51:52 +00:00
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2007-10-19 22:47:59 +01:00
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