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author | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-06-12 20:52:43 +0300 |
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committer | Jonathan Corbet <corbet@lwn.net> | 2019-06-14 23:21:04 +0300 |
commit | f0ba43774cea3fc14732bb9243ce7238ae8a3202 (patch) | |
tree | 5579b300bfc410ed14bb3112586cef02750d7eb0 /Documentation/device-mapper/dm-io.txt | |
parent | 8ea618899b6b4fbe97c8462e7d769867307de011 (diff) | |
download | linux-f0ba43774cea3fc14732bb9243ce7238ae8a3202.tar.xz |
docs: convert docs to ReST and rename to *.rst
The conversion is actually:
- add blank lines and indentation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/device-mapper/dm-io.txt')
-rw-r--r-- | Documentation/device-mapper/dm-io.txt | 75 |
1 files changed, 0 insertions, 75 deletions
diff --git a/Documentation/device-mapper/dm-io.txt b/Documentation/device-mapper/dm-io.txt deleted file mode 100644 index 3b5d9a52cdcf..000000000000 --- a/Documentation/device-mapper/dm-io.txt +++ /dev/null @@ -1,75 +0,0 @@ -dm-io -===== - -Dm-io provides synchronous and asynchronous I/O services. There are three -types of I/O services available, and each type has a sync and an async -version. - -The user must set up an io_region structure to describe the desired location -of the I/O. Each io_region indicates a block-device along with the starting -sector and size of the region. - - struct io_region { - struct block_device *bdev; - sector_t sector; - sector_t count; - }; - -Dm-io can read from one io_region or write to one or more io_regions. Writes -to multiple regions are specified by an array of io_region structures. - -The first I/O service type takes a list of memory pages as the data buffer for -the I/O, along with an offset into the first page. - - struct page_list { - struct page_list *next; - struct page *page; - }; - - int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw, - struct page_list *pl, unsigned int offset, - unsigned long *error_bits); - int dm_io_async(unsigned int num_regions, struct io_region *where, int rw, - struct page_list *pl, unsigned int offset, - io_notify_fn fn, void *context); - -The second I/O service type takes an array of bio vectors as the data buffer -for the I/O. This service can be handy if the caller has a pre-assembled bio, -but wants to direct different portions of the bio to different devices. - - int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, - int rw, struct bio_vec *bvec, - unsigned long *error_bits); - int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, - int rw, struct bio_vec *bvec, - io_notify_fn fn, void *context); - -The third I/O service type takes a pointer to a vmalloc'd memory buffer as the -data buffer for the I/O. This service can be handy if the caller needs to do -I/O to a large region but doesn't want to allocate a large number of individual -memory pages. - - int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw, - void *data, unsigned long *error_bits); - int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw, - void *data, io_notify_fn fn, void *context); - -Callers of the asynchronous I/O services must include the name of a completion -callback routine and a pointer to some context data for the I/O. - - typedef void (*io_notify_fn)(unsigned long error, void *context); - -The "error" parameter in this callback, as well as the "*error" parameter in -all of the synchronous versions, is a bitset (instead of a simple error value). -In the case of an write-I/O to multiple regions, this bitset allows dm-io to -indicate success or failure on each individual region. - -Before using any of the dm-io services, the user should call dm_io_get() -and specify the number of pages they expect to perform I/O on concurrently. -Dm-io will attempt to resize its mempool to make sure enough pages are -always available in order to avoid unnecessary waiting while performing I/O. - -When the user is finished using the dm-io services, they should call -dm_io_put() and specify the same number of pages that were given on the -dm_io_get() call. - |