mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-24 12:20:52 +07:00
1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
48 lines
1.9 KiB
Plaintext
48 lines
1.9 KiB
Plaintext
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);
|
|
|