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authorDavid Howells <dhowells@redhat.com>2016-02-01 16:43:04 +0000
committerAl Viro <viro@zeniv.linux.org.uk>2016-02-01 12:30:10 -0500
commita5b3a80b899bda0f456f1246c4c5a1191ea01519 (patch)
treeb83e19613c5b5dfcf0311afef7d25e61b727bf74 /fs/cachefiles/interface.c
parent92e963f50fc74041b5e9e744c330dca48e04f08d (diff)
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CacheFiles: Provide read-and-reset release counters for cachefilesd
Provide read-and-reset objects- and blocks-released counters for cachefilesd to use to work out whether there's anything new that can be culled. One of the problems cachefilesd has is that if all the objects in the cache are pinned by inodes lying dormant in the kernel inode cache, there isn't anything for it to cull. In such a case, it just spins around walking the filesystem tree and scanning for something to cull. This eats up a lot of CPU time. By telling cachefilesd if there have been any releases, the daemon can sleep until there is the possibility of something to do. cachefilesd finds this information by the following means: (1) When the control fd is read, the kernel presents a list of values of interest. "freleased=N" and "breleased=N" are added to this list to indicate the number of files released and number of blocks released since the last read call. At this point the counters are reset. (2) POLLIN is signalled if the number of files released becomes greater than 0. Note that by 'released' it just means that the kernel has released its interest in those files for the moment, not necessarily that the files should be deleted from the cache. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Steve Dickson <steved@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/cachefiles/interface.c')
-rw-r--r--fs/cachefiles/interface.c11
1 files changed, 2 insertions, 9 deletions
diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index 675a3332d72f..861d611b8c05 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -291,15 +291,8 @@ static void cachefiles_drop_object(struct fscache_object *_object)
}
/* note that the object is now inactive */
- if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
- write_lock(&cache->active_lock);
- if (!test_and_clear_bit(CACHEFILES_OBJECT_ACTIVE,
- &object->flags))
- BUG();
- rb_erase(&object->active_node, &cache->active_nodes);
- wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
- write_unlock(&cache->active_lock);
- }
+ if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags))
+ cachefiles_mark_object_inactive(cache, object);
dput(object->dentry);
object->dentry = NULL;