From 9549332df4ed4e761a1d41c83f2c25d28bb22431 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 20 Oct 2021 15:00:26 +0100 Subject: fscache: Implement cache registration Implement a register of caches and provide functions to manage it. Two functions are provided for the cache backend to use: (1) Acquire a cache cookie: struct fscache_cache *fscache_acquire_cache(const char *name) This gets the cache cookie for a cache of the specified name and moves it to the preparation state. If a nameless cache cookie exists, that will be given this name and used. (2) Relinquish a cache cookie: void fscache_relinquish_cache(struct fscache_cache *cache); This relinquishes a cache cookie, cleans it and makes it available if it's still referenced by a network filesystem. Note that network filesystems don't deal with cache cookies directly, but rather go straight to the volume registration. Signed-off-by: David Howells Reviewed-by: Jeff Layton cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819587157.215744.13523139317322503286.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906889665.143852.10378009165231294456.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967085081.1823006.2218944206363626210.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021494847.640689.10109692261640524343.stgit@warthog.procyon.org.uk/ # v4 --- include/linux/fscache-cache.h | 34 +++++++++++++++++++++++++++++++++ include/trace/events/fscache.h | 43 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 77 insertions(+) (limited to 'include') diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h index d6910a913918..18cd5c9877bb 100644 --- a/include/linux/fscache-cache.h +++ b/include/linux/fscache-cache.h @@ -16,6 +16,40 @@ #include +enum fscache_cache_trace; +enum fscache_access_trace; + +enum fscache_cache_state { + FSCACHE_CACHE_IS_NOT_PRESENT, /* No cache is present for this name */ + FSCACHE_CACHE_IS_PREPARING, /* A cache is preparing to come live */ + FSCACHE_CACHE_IS_ACTIVE, /* Attached cache is active and can be used */ + FSCACHE_CACHE_GOT_IOERROR, /* Attached cache stopped on I/O error */ + FSCACHE_CACHE_IS_WITHDRAWN, /* Attached cache is being withdrawn */ +#define NR__FSCACHE_CACHE_STATE (FSCACHE_CACHE_IS_WITHDRAWN + 1) +}; + +/* + * Cache cookie. + */ +struct fscache_cache { + struct list_head cache_link; /* Link in cache list */ + void *cache_priv; /* Private cache data (or NULL) */ + refcount_t ref; + atomic_t n_volumes; /* Number of active volumes; */ + atomic_t n_accesses; /* Number of in-progress accesses on the cache */ + atomic_t object_count; /* no. of live objects in this cache */ + unsigned int debug_id; + enum fscache_cache_state state; + char *name; +}; + extern struct workqueue_struct *fscache_wq; +/* + * out-of-line cache backend functions + */ +extern struct rw_semaphore fscache_addremove_sem; +extern struct fscache_cache *fscache_acquire_cache(const char *name); +extern void fscache_relinquish_cache(struct fscache_cache *cache); + #endif /* _LINUX_FSCACHE_CACHE_H */ diff --git a/include/trace/events/fscache.h b/include/trace/events/fscache.h index fe214c5cc87f..3b8e0597b2c1 100644 --- a/include/trace/events/fscache.h +++ b/include/trace/events/fscache.h @@ -19,11 +19,27 @@ #ifndef __FSCACHE_DECLARE_TRACE_ENUMS_ONCE_ONLY #define __FSCACHE_DECLARE_TRACE_ENUMS_ONCE_ONLY +enum fscache_cache_trace { + fscache_cache_collision, + fscache_cache_get_acquire, + fscache_cache_new_acquire, + fscache_cache_put_cache, + fscache_cache_put_prep_failed, + fscache_cache_put_relinquish, +}; + #endif /* * Declare tracing information enums and their string mappings for display. */ +#define fscache_cache_traces \ + EM(fscache_cache_collision, "*COLLIDE*") \ + EM(fscache_cache_get_acquire, "GET acq ") \ + EM(fscache_cache_new_acquire, "NEW acq ") \ + EM(fscache_cache_put_cache, "PUT cache") \ + EM(fscache_cache_put_prep_failed, "PUT pfail") \ + E_(fscache_cache_put_relinquish, "PUT relnq") /* * Export enum symbols via userspace. @@ -33,6 +49,8 @@ #define EM(a, b) TRACE_DEFINE_ENUM(a); #define E_(a, b) TRACE_DEFINE_ENUM(a); +fscache_cache_traces; + /* * Now redefine the EM() and E_() macros to map the enums to the strings that * will be printed in the output. @@ -43,6 +61,31 @@ #define E_(a, b) { a, b } +TRACE_EVENT(fscache_cache, + TP_PROTO(unsigned int cache_debug_id, + int usage, + enum fscache_cache_trace where), + + TP_ARGS(cache_debug_id, usage, where), + + TP_STRUCT__entry( + __field(unsigned int, cache ) + __field(int, usage ) + __field(enum fscache_cache_trace, where ) + ), + + TP_fast_assign( + __entry->cache = cache_debug_id; + __entry->usage = usage; + __entry->where = where; + ), + + TP_printk("C=%08x %s r=%d", + __entry->cache, + __print_symbolic(__entry->where, fscache_cache_traces), + __entry->usage) + ); + #endif /* _TRACE_FSCACHE_H */ /* This part must be outside protection */ -- cgit v1.2.3