Lines Matching +full:i +full:- +full:cache +full:- +full:block +full:- +full:size
1 .. SPDX-License-Identifier: GPL-2.0
10 (1) A cache is logically organised into volumes and data storage objects
18 (4) Cookies have coherency data that allows a cache to determine if the
21 (5) I/O is done asynchronously where possible.
34 (6) Data I/O API
55 maximum size of a filename component (allowing the cache backend one char for
62 their parent volume. The cache backend is responsible for rendering the binary
71 This causes fscache to send the cache backend off to look up/create resources
83 extra pins into the cache to stop cache withdrawal from tearing down the
87 The filesystem is expected to use netfslib to access the cache, but that's not
88 actually required and it can use the fscache I/O API directly.
109 what's stored in the cache.
111 The caller may also specify the name of the cache to use. If specified,
112 fscache will look up or create a cache cookie of that name and will use a cache
113 of that name if it is online or comes online. If no cache name is specified,
114 it will use the first cache that comes to hand and set the name to that.
118 is provided. If the coherency data doesn't match, the entire cache volume will
164 of size aux_data_len will be allocated and the coherency data copied in. It is
165 assumed that the size is invariant over time. The coherency data is used to
166 check the validity of data in the cache. Functions are provided by which the
169 The file size of the object being cached should also be provided. This may be
188 Marking A Cookie In-Use
203 done, this will trigger the cache backend to go and gather the resources it
204 needs to access/store data in the cache. This is done in the background, and
208 It optionally updates the stored coherency data and object size and then
209 decreases the in-use counter. When the last user unuses the cookie, it is
213 A cookie must be marked in-use before it can be accessed for read, write or
214 resize - and an in-use mark must be kept whilst there is dirty data in the
218 Note that in-use marks are cumulative. For each time a cookie is marked
219 in-use, it must be unused.
226 should be called to notify the cache::
231 The caller must have first marked the cookie in-use. The cookie and the new
232 size are passed in and the cache is synchronously resized. This is expected to
233 be called from ``->setattr()`` inode operation under the inode lock.
236 Data I/O API
239 To do data I/O operations directly through a cookie, the following functions
257 the cache resources block from the cookie. Assuming it doesn't return an error
258 (for instance, it will return -ENOBUFS if given a NULL cookie, but otherwise do
261 The *read* and *write* functions initiate a direct-IO operation. Both take the
262 previously set up cache resources block, an indication of the start file
263 position, and an I/O iterator that describes buffer and indicates the amount of
292 To request an update of the coherency data and file size on a cookie, the
299 This will update the cookie's coherency data and/or file size.
307 of a remote third-party change - at which point the filesystem has to throw
311 To indicate that a cache object should be invalidated, the following should be
316 loff_t size,
320 reads to fail with -ESTALE, sets the coherency data and file size from the
321 information supplied, blocks new I/O on the cookie and dispatches the cache to
324 Invalidation runs asynchronously in a worker thread so that it doesn't block
328 Write-Back Resource Management
331 To write data to the cache from network filesystem writeback, the cache
339 in-use is held on the cookie for this inode. It can only be changed if the
377 cache, it needs to mark the pages to indicate that a write is in progress, and
379 (presumably due to an already in-progress operation). This prevents multiple
380 competing DIO writes to the same storage in the cache.
412 attached is passed in and start and len indicate the size of the region that's
419 the cache object to be written to, i_size indicates the size of the netfs file
430 Fscache keeps track of whether we have any data in the cache yet for a cache
433 after which it *has* to look in the cache.
435 To inform fscache that a page might now be in the cache, the following function
452 .. kernel-doc:: include/linux/fscache.h