kernel/git/next/linux-next.git/drivers/md/dm-bufio.h, branch master

dm bufio: move dm-bufio.h to include/linux/

2018-04-03T19:04:23+00:00

Move dm-bufio.h to include/linux/ so that external GPL'd DM target modules can use it. It is better to allow the use of dm-bufio than force external modules to implement the equivalent buffered IO mechanism in some new way. The hope is this will encourage the use of dm-bufio; which will then make it easier for a GPL'd external DM target module to be included upstream. A couple dm-bufio EXPORT_SYMBOL exports have also been updated to use EXPORT_SYMBOL_GPL. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer

dm integrity: optimize writing dm-bufio buffers that are partially changed

2017-08-28T15:47:17+00:00

Rather than write the entire dm-bufio buffer when only a subset is changed, improve dm-bufio (and dm-integrity) by only writing the subset of the buffer that changed. Update dm-integrity to make use of dm-bufio's new dm_bufio_mark_partial_buffer_dirty() interface. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer

dm bufio: add sector start offset to dm-bufio interface

2017-03-07T18:28:33+00:00

Introduce dm_bufio_set_sector_offset() interface to allow setting a sector offset for a dm-bufio client. This is a prereq for the DM integrity target. Signed-off-by: Mikulas Patocka Signed-off-by: Milan Broz Signed-off-by: Mike Snitzer

dm snapshot: use dm-bufio prefetch

2014-01-15T04:23:03+00:00

This patch modifies dm-snapshot so that it prefetches the buffers when loading the exceptions. The number of buffers read ahead is specified in the DM_PREFETCH_CHUNKS macro. The current value for DM_PREFETCH_CHUNKS (12) was found to provide the best performance on a single 15k SCSI spindle. In the future we may modify this default or make it configurable. Also, introduce the function dm_bufio_set_minimum_buffers to setup bufio's number of internal buffers before freeing happens. dm-bufio may hold more buffers if enough memory is available. There is no guarantee that the specified number of buffers will be available - if you need a guarantee, use the argument reserved_buffers for dm_bufio_client_create. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer

dm snapshot: use dm-bufio

2014-01-15T04:23:02+00:00

Use dm-bufio for initial loading of the exceptions. Introduce a new function dm_bufio_forget that frees the given buffer. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer

dm bufio: prefetch

2012-03-28T17:41:29+00:00

This patch introduces a new function dm_bufio_prefetch. It prefetches the specified range of blocks into dm-bufio cache without waiting for i/o completion. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon

dm: add bufio

2011-10-31T20:19:09+00:00

The dm-bufio interface allows you to do cached I/O on devices, holding recently-read blocks in memory and performing delayed writes. We don't use buffer cache or page cache already present in the kernel, because: * we need to handle block sizes larger than a page * we can't allocate memory to perform reads or we'd have deadlocks Currently, when a cache is required, we limit its size to a fraction of available memory. Usage can be viewed and changed in /sys/module/dm_bufio/parameters/ . The first user is thin provisioning, but more dm users are planned. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon