2005-04-16 15:20:36 -07:00
|
|
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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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2009-12-14 18:01:06 -08:00
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2005-04-16 15:20:36 -07:00
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2006-03-27 01:18:20 -08:00
|
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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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2011-07-26 16:09:06 -07:00
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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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2006-03-27 01:17:54 -08:00
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|
dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +01:00
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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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2011-03-17 11:11:05 +01:00
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2011-10-31 20:19:00 +00:00
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2010-08-12 04:14:08 +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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|
|
dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +01:00
|
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2011-01-13 20:00:01 +00:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:02 +01:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:04 +01:00
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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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2007-12-13 14:15:25 +00:00
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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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2006-03-27 01:17:54 -08:00
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2005-04-16 15:20:36 -07:00
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2007-10-19 22:38:51 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 20:00:01 +00:00
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2005-04-16 15:20:36 -07:00
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2013-11-22 19:52:06 -05:00
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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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2008-02-08 02:09:59 +00:00
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2008-10-10 13:37:09 +01:00
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2009-06-22 10:12:29 +01:00
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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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2009-12-10 23:52:23 +00:00
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2010-08-12 04:14:03 +01:00
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2005-04-16 15:20:36 -07:00
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2012-03-28 18:41:24 +01:00
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|
2005-04-16 15:20:36 -07:00
|
|
|
|
dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +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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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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2008-10-10 13:37:09 +01:00
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2005-04-16 15:20:36 -07:00
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2010-11-13 11:55:18 +01:00
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2005-04-16 15:20:36 -07:00
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2010-11-13 11:55:17 +01:00
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block: make blkdev_get/put() handle exclusive access
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>
2010-11-13 11:55:17 +01:00
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2010-11-13 11:55:17 +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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2011-01-14 18:43:57 +01:00
|
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|
block: make blkdev_get/put() handle exclusive access
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>
2010-11-13 11:55:17 +01:00
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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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2009-09-04 20:40:22 +01:00
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2005-04-16 15:20:36 -07:00
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2009-09-04 20:40:22 +01:00
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2005-04-16 15:20:36 -07:00
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2011-05-29 13:02:52 +01:00
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2009-06-22 10:12:34 +01:00
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2009-06-22 10:12:30 +01:00
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2009-06-22 10:12:34 +01:00
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2009-06-22 10:12:30 +01:00
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2007-05-09 02:32:57 -07:00
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2011-05-29 13:02:52 +01:00
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2007-05-09 02:32:57 -07:00
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2009-09-04 20:40:22 +01:00
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2007-05-09 02:32:57 -07:00
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2009-07-23 20:30:42 +01:00
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2009-09-04 20:40:24 +01:00
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2009-09-04 20:40:22 +01:00
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2009-06-22 10:12:30 +01:00
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2009-09-04 20:40:22 +01:00
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2009-06-22 10:12:30 +01:00
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2009-09-04 20:40:24 +01:00
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2009-06-22 10:12:30 +01:00
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2009-06-22 10:12:34 +01:00
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2009-09-04 20:40:22 +01:00
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2009-06-22 10:12:30 +01:00
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2009-07-23 20:30:42 +01:00
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2009-06-22 10:12:30 +01:00
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2009-09-04 20:40:24 +01:00
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2009-06-22 10:12:30 +01:00
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2009-07-23 20:30:42 +01:00
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2009-06-22 10:12:34 +01:00
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2009-09-04 20:40:22 +01:00
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2009-06-22 10:12:30 +01:00
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2009-09-04 20:40:22 +01:00
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2005-04-16 15:20:36 -07:00
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2009-04-02 19:55:28 +01:00
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2005-04-16 15:20:36 -07:00
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2009-04-02 19:55:28 +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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2008-10-10 13:37:09 +01:00
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2005-04-16 15:20:36 -07:00
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2009-04-02 19:55:28 +01:00
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2005-04-16 15:20:36 -07:00
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2009-04-02 19:55:28 +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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2009-04-02 19:55:28 +01:00
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2005-04-16 15:20:36 -07:00
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2009-04-02 19:55:28 +01:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:04 +01:00
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2005-04-16 15:20:36 -07:00
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2008-02-08 02:10:14 +00:00
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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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2011-08-02 12:32:04 +01:00
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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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2005-04-16 15:20:36 -07:00
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2006-03-26 18:22:50 +02:00
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2005-04-16 15:20:36 -07:00
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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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2005-04-16 15:20:36 -07:00
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2008-08-11 00:24:08 +02:00
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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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2006-03-27 01:17:59 -08:00
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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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2006-03-27 01:17:59 -08:00
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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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2011-08-02 12:32:04 +01:00
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2005-04-16 15:20:36 -07:00
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2009-06-22 10:12:34 +01:00
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2009-07-23 20:30:42 +01:00
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2005-04-16 15:20:36 -07:00
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2009-06-22 10:12:34 +01:00
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2007-07-24 09:28:11 +02:00
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2008-10-10 13:37:13 +01:00
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2009-06-22 10:12:34 +01:00
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2008-10-10 13:37:13 +01:00
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2006-10-03 01:15:42 -07:00
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2010-01-11 03:21:50 -05:00
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2009-09-04 20:40:24 +01:00
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2010-01-11 03:21:50 -05:00
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2006-10-03 01:15:42 -07:00
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2008-07-21 12:00:39 +01:00
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2006-10-03 01:15:42 -07:00
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2011-08-02 12:32:04 +01:00
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2010-12-17 08:34:20 +01:00
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2009-06-22 10:12:34 +01:00
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2006-10-03 01:15:42 -07:00
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2006-03-27 01:17:49 -08:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:04 +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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2006-03-27 01:17:59 -08:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:04 +01:00
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2005-04-16 15:20:36 -07:00
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2013-10-31 13:55:45 -04:00
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2005-04-16 15:20:36 -07:00
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2013-10-31 13:55:45 -04:00
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2005-04-16 15:20:36 -07:00
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2013-10-31 13:55:45 -04:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:31 -07:00
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2005-04-16 15:20:36 -07:00
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2009-12-14 18:01:06 -08:00
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2005-04-16 15:20:36 -07:00
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2009-06-22 10:12:31 +01:00
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2009-06-22 10:12:34 +01:00
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2009-06-22 10:12:31 +01:00
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2009-06-22 10:12:34 +01:00
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2009-06-22 10:12:31 +01:00
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2009-06-22 10:12:34 +01:00
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2009-06-22 10:12:31 +01:00
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2012-01-11 16:27:11 +01:00
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2009-06-22 10:12:34 +01:00
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2009-06-22 10:12:31 +01:00
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2009-06-22 10:12:34 +01:00
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2009-06-22 10:12:31 +01:00
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2009-09-04 20:40:24 +01:00
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2009-06-22 10:12:31 +01:00
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2009-06-22 10:12:34 +01:00
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2009-06-22 10:12:31 +01:00
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2005-04-16 15:20:36 -07:00
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2011-10-31 20:19:00 +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 00:27:35 -07:00
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2005-04-16 15:20:36 -07:00
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2011-10-31 20:19:00 +00:00
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2011-10-31 20:19:02 +00:00
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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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2013-03-01 22:45:47 +00:00
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2011-08-02 12:32:01 +01:00
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2010-08-12 04:14:08 +01:00
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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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2011-08-02 12:32:04 +01:00
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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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2011-08-02 12:32:04 +01:00
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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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2011-08-02 12:32:04 +01:00
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2010-08-12 04:14:03 +01:00
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dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +01:00
|
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|
2013-08-22 18:21:38 -04:00
|
|
|
|
dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +01:00
|
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|
2013-08-22 18:21:38 -04:00
|
|
|
|
dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +01:00
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2013-08-22 18:21:38 -04:00
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|
dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +01:00
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2013-08-22 18:21:38 -04:00
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|
dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +01:00
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2011-10-31 20:19:04 +00:00
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dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +01:00
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2012-12-21 20:23:38 +00:00
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|
dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +01:00
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2012-12-21 20:23:38 +00:00
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|
dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +01:00
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2005-04-16 15:20:36 -07:00
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2008-02-08 02:10:04 +00:00
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2005-04-16 15:20:36 -07:00
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2010-08-12 04:14:03 +01:00
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2005-04-16 15:20:36 -07:00
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2011-04-01 21:02:31 +02:00
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2010-08-12 04:14:03 +01:00
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2011-04-01 21:02:31 +02:00
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2010-08-12 04:14:03 +01:00
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2011-04-01 21:02:31 +02:00
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2010-08-12 04:14:03 +01:00
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2011-04-01 21:02:31 +02:00
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2010-08-12 04:14:03 +01:00
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2011-04-01 21:02:31 +02:00
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2010-08-12 04:14:03 +01:00
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2006-03-27 01:18:20 -08:00
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2005-04-16 15:20:36 -07:00
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2006-03-27 01:18:20 -08:00
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2005-04-16 15:20:36 -07:00
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2006-03-27 01:18:20 -08:00
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2005-04-16 15:20:36 -07:00
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2006-03-27 01:18:20 -08:00
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2005-04-16 15:20:36 -07:00
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2006-03-27 01:18:20 -08:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:04 +01:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:04 +01:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:27:27 -07:00
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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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2012-09-26 23:45:45 +01:00
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2009-06-22 10:12:34 +01:00
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2012-01-11 16:27:11 +01:00
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2009-06-22 10:12:34 +01:00
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2012-01-11 16:27:11 +01:00
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2009-06-22 10:12:34 +01:00
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2009-09-04 20:40:25 +01:00
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2009-06-22 10:12:34 +01:00
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2009-09-04 20:40:22 +01:00
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2009-06-22 10:12:34 +01:00
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2010-01-11 03:21:50 -05:00
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2009-06-22 10:12:34 +01:00
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2010-01-11 03:21:50 -05:00
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2009-06-22 10:12:34 +01:00
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2009-04-09 00:27:12 +01:00
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2011-04-01 21:02:31 +02:00
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2009-04-09 00:27:12 +01:00
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2011-04-01 21:02:31 +02:00
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2009-04-09 00:27:12 +01:00
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2011-04-01 21:02:31 +02:00
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2011-09-25 23:26:17 +01:00
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2011-04-01 21:02:31 +02:00
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2011-09-25 23:26:17 +01:00
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2009-04-09 00:27:12 +01:00
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2011-08-02 12:32:08 +01:00
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2013-03-01 22:45:47 +00:00
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2011-08-02 12:32:08 +01:00
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2012-07-27 15:08:07 +01:00
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2011-08-02 12:32:08 +01:00
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2011-09-25 23:26:21 +01:00
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2011-10-31 20:18:50 +00:00
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2012-09-26 23:45:43 +01:00
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2011-10-31 20:18:50 +00:00
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2012-09-26 23:45:43 +01:00
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2011-10-31 20:18:50 +00:00
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2012-12-21 20:23:36 +00:00
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2013-03-01 22:45:47 +00:00
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2012-12-21 20:23:36 +00:00
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2013-05-10 14:37:16 +01:00
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2012-12-21 20:23:36 +00:00
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2009-06-22 10:12:34 +01:00
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2005-04-16 15:20:36 -07:00
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2011-08-02 12:32:08 +01:00
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2005-04-16 15:20:36 -07:00
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2009-06-22 10:12:32 +01:00
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2005-04-16 15:20:36 -07:00
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2009-06-22 10:12:34 +01:00
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2008-04-29 19:12:35 +02:00
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2010-08-12 04:14:08 +01:00
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2011-08-02 12:32:08 +01:00
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2011-09-25 23:26:21 +01:00
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2012-09-26 23:45:43 +01:00
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2011-10-31 20:18:50 +00:00
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2012-12-21 20:23:36 +00:00
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2012-12-21 20:23:30 +00:00
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2009-04-09 00:27:12 +01:00
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|
dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +01:00
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2012-09-26 23:45:43 +01:00
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|
dm: enable request based option
This patch enables request-based dm.
o Request-based dm and bio-based dm coexist, since there are
some target drivers which are more fitting to bio-based dm.
Also, there are other bio-based devices in the kernel
(e.g. md, loop).
Since bio-based device can't receive struct request,
there are some limitations on device stacking between
bio-based and request-based.
type of underlying device
bio-based request-based
----------------------------------------------
bio-based OK OK
request-based -- OK
The device type is recognized by the queue flag in the kernel,
so dm follows that.
o The type of a dm device is decided at the first table binding time.
Once the type of a dm device is decided, the type can't be changed.
o Mempool allocations are deferred to at the table loading time, since
mempools for request-based dm are different from those for bio-based
dm and needed mempool type is fixed by the type of table.
o Currently, request-based dm supports only tables that have a single
target. To support multiple targets, we need to support request
splitting or prevent bio/request from spanning multiple targets.
The former needs lots of changes in the block layer, and the latter
needs that all target drivers support merge() function.
Both will take a time.
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>
2009-06-22 10:12:36 +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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2011-08-02 12:32:04 +01:00
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2005-04-16 15:20:36 -07:00
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2005-07-28 21:15:57 -07:00
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2008-04-24 22:10:51 +01:00
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2005-04-16 15:20:36 -07:00
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2005-07-28 21:15:57 -07:00
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2008-04-24 22:10:51 +01:00
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2005-04-16 15:20:36 -07:00
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2006-10-03 01:15:36 -07:00
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2005-04-16 15:20:36 -07:00
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2006-10-03 01:15:36 -07:00
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2013-10-24 14:10:29 -04:00
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2006-10-03 01:15:36 -07:00
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2013-10-24 14:10:29 -04:00
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2006-10-03 01:15:36 -07:00
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2005-04-16 15:20:36 -07:00
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2006-10-03 01:15:36 -07:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 20:00:01 +00:00
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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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2008-02-08 02:09:59 +00:00
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2011-01-13 20:00:01 +00:00
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2005-04-16 15:20:36 -07:00
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2008-02-08 02:09:59 +00:00
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2008-10-10 13:37:09 +01:00
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2008-10-10 13:37:13 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-13 20:00:01 +00:00
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2005-04-16 15:20:36 -07:00
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dm: prepare for request based option
This patch adds core functions for request-based dm.
When struct mapped device (md) is initialized, md->queue has
an I/O scheduler and the following functions are used for
request-based dm as the queue functions:
make_request_fn: dm_make_request()
pref_fn: dm_prep_fn()
request_fn: dm_request_fn()
softirq_done_fn: dm_softirq_done()
lld_busy_fn: dm_lld_busy()
Actual initializations are done in another patch (PATCH 2).
Below is a brief summary of how request-based dm behaves, including:
- making request from bio
- cloning, mapping and dispatching request
- completing request and bio
- suspending md
- resuming md
bio to request
==============
md->queue->make_request_fn() (dm_make_request()) calls __make_request()
for a bio submitted to the md.
Then, the bio is kept in the queue as a new request or merged into
another request in the queue if possible.
Cloning and Mapping
===================
Cloning and mapping are done in md->queue->request_fn() (dm_request_fn()),
when requests are dispatched after they are sorted by the I/O scheduler.
dm_request_fn() checks busy state of underlying devices using
target's busy() function and stops dispatching requests to keep them
on the dm device's queue if busy.
It helps better I/O merging, since no merge is done for a request
once it is dispatched to underlying devices.
Actual cloning and mapping are done in dm_prep_fn() and map_request()
called from dm_request_fn().
dm_prep_fn() clones not only request but also bios of the request
so that dm can hold bio completion in error cases and prevent
the bio submitter from noticing the error.
(See the "Completion" section below for details.)
After the cloning, the clone is mapped by target's map_rq() function
and inserted to underlying device's queue using
blk_insert_cloned_request().
Completion
==========
Request completion can be hooked by rq->end_io(), but then, all bios
in the request will have been completed even error cases, and the bio
submitter will have noticed the error.
To prevent the bio completion in error cases, request-based dm clones
both bio and request and hooks both bio->bi_end_io() and rq->end_io():
bio->bi_end_io(): end_clone_bio()
rq->end_io(): end_clone_request()
Summary of the request completion flow is below:
blk_end_request() for a clone request
=> blk_update_request()
=> bio->bi_end_io() == end_clone_bio() for each clone bio
=> Free the clone bio
=> Success: Complete the original bio (blk_update_request())
Error: Don't complete the original bio
=> blk_finish_request()
=> rq->end_io() == end_clone_request()
=> blk_complete_request()
=> dm_softirq_done()
=> Free the clone request
=> Success: Complete the original request (blk_end_request())
Error: Requeue the original request
end_clone_bio() completes the original request on the size of
the original bio in successful cases.
Even if all bios in the original request are completed by that
completion, the original request must not be completed yet to keep
the ordering of request completion for the stacking.
So end_clone_bio() uses blk_update_request() instead of
blk_end_request().
In error cases, end_clone_bio() doesn't complete the original bio.
It just frees the cloned bio and gives over the error handling to
end_clone_request().
end_clone_request(), which is called with queue lock held, completes
the clone request and the original request in a softirq context
(dm_softirq_done()), which has no queue lock, to avoid a deadlock
issue on submission of another request during the completion:
- The submitted request may be mapped to the same device
- Request submission requires queue lock, but the queue lock
has been held by itself and it doesn't know that
The clone request has no clone bio when dm_softirq_done() is called.
So target drivers can't resubmit it again even error cases.
Instead, they can ask dm core for requeueing and remapping
the original request in that cases.
suspend
=======
Request-based dm uses stopping md->queue as suspend of the md.
For noflush suspend, just stops md->queue.
For flush suspend, inserts a marker request to the tail of md->queue.
And dispatches all requests in md->queue until the marker comes to
the front of md->queue. Then, stops dispatching request and waits
for the all dispatched requests to complete.
After that, completes the marker request, stops md->queue and
wake up the waiter on the suspend queue, md->wait.
resume
======
Starts md->queue.
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>
2009-06-22 10:12:35 +01:00
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2006-03-27 01:17:54 -08:00
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2011-08-02 12:32:04 +01:00
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2006-03-27 01:17:54 -08:00
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2010-08-12 04:14:08 +01:00
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2011-05-29 12:52:55 +01:00
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2010-08-12 04:14:08 +01:00
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2011-08-02 12:32:01 +01:00
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2010-08-12 04:14:08 +01:00
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2013-03-01 22:45:47 +00:00
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2011-08-02 12:32:01 +01:00
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2011-05-29 12:52:55 +01:00
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2010-08-12 04:14:08 +01:00
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