fscache, cachefiles: Display stat of culling events

Add a stat counter of culling events whereby the cache backend culls a file
to make space (when asked by cachefilesd in this case) and display in
/proc/fs/fscache/stats.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819654165.215744.3797804661644212436.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/163906961387.143852.9291157239960289090.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/163967168266.1823006.14436200166581605746.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/164021567619.640689.4339228906248763197.stgit@warthog.procyon.org.uk/

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index ab3ca59..9bd6928 100644 (file)
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -805,6 +805,7 @@ int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
        if (ret < 0)
                goto error;
 
+       fscache_count_culled();
        dput(victim);
        _leave(" = 0");
        return 0;

diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
index db2f4e2..fc94e5e 100644 (file)
--- a/fs/fscache/stats.c
+++ b/fs/fscache/stats.c
@@ -46,6 +46,8 @@ atomic_t fscache_n_no_write_space;
 EXPORT_SYMBOL(fscache_n_no_write_space);
 atomic_t fscache_n_no_create_space;
 EXPORT_SYMBOL(fscache_n_no_create_space);
+atomic_t fscache_n_culled;
+EXPORT_SYMBOL(fscache_n_culled);
 
 /*
  * display the general statistics
@@ -86,9 +88,10 @@ int fscache_stats_show(struct seq_file *m, void *v)
                   atomic_read(&fscache_n_relinquishes_retire),
                   atomic_read(&fscache_n_relinquishes_dropped));
 
-       seq_printf(m, "NoSpace: nwr=%u ncr=%u\n",
+       seq_printf(m, "NoSpace: nwr=%u ncr=%u cull=%u\n",
                   atomic_read(&fscache_n_no_write_space),
-                  atomic_read(&fscache_n_no_create_space));
+                  atomic_read(&fscache_n_no_create_space),
+                  atomic_read(&fscache_n_culled));
 
        seq_printf(m, "IO     : rd=%u wr=%u\n",
                   atomic_read(&fscache_n_read),

diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 007e47f..a174ced 100644 (file)
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -188,15 +188,18 @@ extern atomic_t fscache_n_read;
 extern atomic_t fscache_n_write;
 extern atomic_t fscache_n_no_write_space;
 extern atomic_t fscache_n_no_create_space;
+extern atomic_t fscache_n_culled;
 #define fscache_count_read() atomic_inc(&fscache_n_read)
 #define fscache_count_write() atomic_inc(&fscache_n_write)
 #define fscache_count_no_write_space() atomic_inc(&fscache_n_no_write_space)
 #define fscache_count_no_create_space() atomic_inc(&fscache_n_no_create_space)
+#define fscache_count_culled() atomic_inc(&fscache_n_culled)
 #else
 #define fscache_count_read() do {} while(0)
 #define fscache_count_write() do {} while(0)
 #define fscache_count_no_write_space() do {} while(0)
 #define fscache_count_no_create_space() do {} while(0)
+#define fscache_count_culled() do {} while(0)
 #endif
 
 #endif /* _LINUX_FSCACHE_CACHE_H */