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FS module docs: Add documentation for entry_cache_add_missing().

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This was missed when introducing the feature in hrev49558. Thanks Jérôme
for the pointer!

Also add a note explaining that update operations on cached entries and
the removal of uncached entries are safe.
This commit is contained in:
Michael Lotz 2015-08-21 21:02:55 +02:00
parent c4a9344a11
commit 5ca445dfc6
1 changed files with 10 additions and 0 deletions
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10
docs/user/drivers/fs_modules.dox
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@ -316,6 +316,16 @@
entry_cache_add() function when it encounters an entry that might not yet
be known to the entry cache and entry_cache_remove() when a directory
entry has been removed.
The entry cache can also be used for negative caching. If the file system
determines that the requested entry is not present during a lookup, it can
cache this lookup failure by calling entry_cache_add_missing(). Further
calls to fs_vnode_ops::lookup() for the missing entry will then be
avoided.
Note that it is safe to call entry_cache_add() and
entry_cache_add_missing() with the same directory/name pair previously
given to either function to update a cache entry, without needing to call
entry_cache_remove() first. It is also safe to call entry_cache_remove()
for pairs that have never been added to the cache.
*/
// TODO: