linux/Documentation/core-api
NeilBrown 84dacdbd53 mm: document and polish read-ahead code
Add some "big-picture" documentation for read-ahead and polish the code
to make it fit this documentation.

The meaning of ->async_size is clarified to match its name.  i.e.  Any
request to ->readahead() has a sync part and an async part.  The caller
will wait for the sync pages to complete, but will not wait for the
async pages.  The first async page is still marked PG_readahead

Note that the current function names page_cache_sync_ra() and
page_cache_async_ra() are misleading.  All ra request are partly sync
and partly async, so either part can be empty.  A page_cache_sync_ra()
request will usually set ->async_size non-zero, implying it is not all
synchronous.

When a non-zero req_count is passed to page_cache_async_ra(), the
implication is that some prefix of the request is synchronous, though
the calculation made there is incorrect - I haven't tried to fix it.

Link: https://lkml.kernel.org/r/164549983734.9187.11586890887006601405.stgit@noble.brown
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lars Ellenberg <lars.ellenberg@linbit.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Paolo Valente <paolo.valente@linaro.org>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-22 15:57:00 -07:00
..
irq irq: remove handle_domain_{irq,nmi}() 2021-10-26 10:13:31 +01:00
assoc_array.rst Documentation: Use "while" instead of "whilst" 2018-11-20 09:30:43 -07:00
boot-time-mm.rst docs/boot-time-mm: remove bootmem documentation 2018-10-31 08:54:16 -07:00
bus-virt-phys-mapping.rst docs: core-api: avoid using ReST :doc:foo markup 2021-06-17 13:24:37 -06:00
cachetlb.rst mm: Add flush_dcache_folio() 2021-10-18 07:49:36 -04:00
circular-buffers.rst doc: Remove ".vnet" from paulmck email addresses 2019-05-28 09:02:57 -07:00
cpu_hotplug.rst Documentation: core-api/cpuhotplug: Rewrite the API section 2021-09-11 00:41:21 +02:00
debug-objects.rst doc: debugobjects: actually pull in the kerneldoc comments 2016-11-29 14:44:14 -07:00
debugging-via-ohci1394.rst docs: debugging-via-ohci1394.txt: add it to the core-api book 2020-05-15 11:59:17 -06:00
dma-api-howto.rst docs: move DMA kAPI to Documentation/core-api 2020-05-15 11:51:54 -06:00
dma-api.rst docs: core-api: avoid using ReST :doc:foo markup 2021-06-17 13:24:37 -06:00
dma-attributes.rst swiotlb: rework "fix info leak with DMA_FROM_DEVICE" 2022-03-07 11:26:02 -08:00
dma-isa-lpc.rst docs: core-api: avoid using ReST :doc:foo markup 2021-06-17 13:24:37 -06:00
errseq.rst errseq: Add to documentation tree 2018-01-01 12:40:27 -07:00
genalloc.rst lib/genalloc.c: rename addr_in_gen_pool to gen_pool_has_addr 2019-12-04 19:44:13 -08:00
generic-radix-tree.rst generic radix trees 2019-03-12 10:04:02 -07:00
genericirq.rst docs: genericirq.rst: don't document chip.c functions twice 2020-10-15 07:49:41 +02:00
gfp_mask-from-fs-io.rst docs: core-api/gfp_mask-from-fs-io: add a label for cross-referencing 2018-09-20 11:02:32 -06:00
idr.rst Core-api: Documentation: Replace deprecated :c:func: Usage 2020-08-11 10:26:08 -06:00
index.rst docs: core-api: avoid using ReST :doc:foo markup 2021-06-17 13:24:37 -06:00
kernel-api.rst Convert xfs/iomap to use folios 2022-01-12 12:51:41 -08:00
kobject.rst kobject documentation: remove default_attrs information 2022-01-07 11:23:37 +01:00
kref.rst docs: move the kref doc into the core-api book 2020-05-15 12:02:19 -06:00
librs.rst docs-rst: convert librs book to ReST 2017-05-16 08:44:16 -03:00
local_ops.rst timer: Remove init_timer() interface 2017-11-21 15:57:09 -08:00
memory-allocation.rst mm: slab: provide krealloc_array() 2020-12-15 12:13:37 -08:00
memory-hotplug.rst mm/memory_hotplug: remove HIGHMEM leftovers 2021-11-06 13:30:42 -07:00
mm-api.rst mm: document and polish read-ahead code 2022-03-22 15:57:00 -07:00
packing.rst docs: packing: move it to core-api book and adjust markups 2019-07-31 13:30:01 -06:00
padata.rst padata: fold padata_alloc_possible() into padata_alloc() 2020-07-23 17:34:18 +10:00
pin_user_pages.rst selftests/vm: only some gup_test items are really benchmarks 2020-12-15 12:13:38 -08:00
printk-basics.rst printk: Move the printk() kerneldoc comment to its new home 2021-07-26 12:36:44 +02:00
printk-formats.rst vsprintf: Update %pGp documentation about that it prints hex value 2021-11-01 15:55:06 +01:00
protection-keys.rst x86/Kconfig: Update config and kernel doc for MPK feature on AMD 2020-05-28 18:27:40 +02:00
rbtree.rst docs: rbtree.rst: Fix a typo 2021-03-25 11:38:51 -06:00
refcount-vs-atomic.rst docs: remove :c:func: from refcount-vs-atomic.rst 2019-10-07 09:08:56 -06:00
symbol-namespaces.rst docs/core-api: Consistent code style 2021-05-03 16:52:50 -06:00
this_cpu_ops.rst docs: move other kAPI documents to core-api 2020-06-26 11:33:42 -06:00
timekeeping.rst docs: timekeeping: Use correct prototype for deprecated functions 2020-04-15 14:48:26 -06:00
tracepoint.rst doc: Sphinxify the tracepoint docbook 2016-11-29 14:44:23 -07:00
unaligned-memory-access.rst docs: move other kAPI documents to core-api 2020-06-26 11:33:42 -06:00
workqueue.rst workqueue: doc: Call out the non-reentrance conditions 2021-10-25 07:18:40 -10:00
xarray.rst XArray: add xas_split 2020-10-16 11:11:15 -07:00