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author | 2015-08-04 12:17:53 -0700 | |
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committer | 2015-08-04 15:44:42 -0700 | |
commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/device-mapper/kcopyd.txt | |
parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/Documentation/device-mapper/kcopyd.txt')
-rw-r--r-- | kernel/Documentation/device-mapper/kcopyd.txt | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/kernel/Documentation/device-mapper/kcopyd.txt b/kernel/Documentation/device-mapper/kcopyd.txt new file mode 100644 index 000000000..820382c4c --- /dev/null +++ b/kernel/Documentation/device-mapper/kcopyd.txt @@ -0,0 +1,47 @@ +kcopyd +====== + +Kcopyd provides the ability to copy a range of sectors from one block-device +to one or more other block-devices, with an asynchronous completion +notification. It is used by dm-snapshot and dm-mirror. + +Users of kcopyd must first create a client and indicate how many memory pages +to set aside for their copy jobs. This is done with a call to +kcopyd_client_create(). + + int kcopyd_client_create(unsigned int num_pages, + struct kcopyd_client **result); + +To start a copy job, the user must set up io_region structures to describe +the source and destinations of the copy. Each io_region indicates a +block-device along with the starting sector and size of the region. The source +of the copy is given as one io_region structure, and the destinations of the +copy are given as an array of io_region structures. + + struct io_region { + struct block_device *bdev; + sector_t sector; + sector_t count; + }; + +To start the copy, the user calls kcopyd_copy(), passing in the client +pointer, pointers to the source and destination io_regions, the name of a +completion callback routine, and a pointer to some context data for the copy. + + int kcopyd_copy(struct kcopyd_client *kc, struct io_region *from, + unsigned int num_dests, struct io_region *dests, + unsigned int flags, kcopyd_notify_fn fn, void *context); + + typedef void (*kcopyd_notify_fn)(int read_err, unsigned int write_err, + void *context); + +When the copy completes, kcopyd will call the user's completion routine, +passing back the user's context pointer. It will also indicate if a read or +write error occurred during the copy. + +When a user is done with all their copy jobs, they should call +kcopyd_client_destroy() to delete the kcopyd client, which will release the +associated memory pages. + + void kcopyd_client_destroy(struct kcopyd_client *kc); + |