[PATCH v2 20/53] fscache: Implement cookie invalidation
From: David Howells
Date: Fri Oct 22 2021 - 15:04:18 EST
Add a function to invalidate the cache behind a cookie:
void fscache_invalidate(struct fscache_cookie *cookie,
const void *aux_data,
loff_t size,
unsigned int flags)
If there is one, any cached data for the specified cookie is discarded. If
the cookie is marked as being in use, a new cache object will be created if
possible and future I/O will use that instead. In-flight I/O will be
abandoned (writes) or reperformed (reads).
The coherency data attached to the cookie can be updated and the cookie
size should be reset. One flag is available, FSCACHE_INVAL_DIO_WRITE,
which should be used to indicate invalidation due to a DIO write on a
file. This will temporarily disable caching for this cookie.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: linux-cachefs@xxxxxxxxxx
---
fs/fscache/cookie.c | 72 +++++++++++++++++++++++++++++++++++++++-
fs/fscache/internal.h | 2 +
fs/fscache/stats.c | 5 +++
include/linux/fscache-cache.h | 3 ++
include/linux/fscache.h | 33 ++++++++++++++++++
include/linux/netfs.h | 1 +
include/trace/events/fscache.h | 25 ++++++++++++++
7 files changed, 140 insertions(+), 1 deletion(-)
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index cf987756534c..2ad889f20430 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -20,6 +20,7 @@ static void fscache_cookie_lru_worker(struct work_struct *work);
static void fscache_cookie_worker(struct work_struct *work);
static void fscache_drop_cookie(struct fscache_cookie *cookie);
static void fscache_lookup_cookie(struct fscache_cookie *cookie);
+static void fscache_invalidate_cookie(struct fscache_cookie *cookie);
#define fscache_cookie_hash_shift 15
static struct hlist_bl_head fscache_cookie_hash[1 << fscache_cookie_hash_shift];
@@ -29,7 +30,7 @@ static LIST_HEAD(fscache_cookie_lru);
static DEFINE_SPINLOCK(fscache_cookie_lru_lock);
DEFINE_TIMER(fscache_cookie_lru_timer, fscache_cookie_lru_timed_out);
static DECLARE_WORK(fscache_cookie_lru_work, fscache_cookie_lru_worker);
-static const char fscache_cookie_stages[FSCACHE_COOKIE_STAGE__NR] = "-LCAFMWRD";
+static const char fscache_cookie_stages[FSCACHE_COOKIE_STAGE__NR] = "-LCAIFMWRD";
unsigned int fscache_lru_cookie_timeout = 10 * HZ;
void fscache_print_cookie(struct fscache_cookie *cookie, char prefix)
@@ -504,6 +505,7 @@ void __fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify)
set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags);
break;
case FSCACHE_COOKIE_STAGE_ACTIVE:
+ case FSCACHE_COOKIE_STAGE_INVALIDATING:
if (will_modify &&
!test_and_set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags)) {
set_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags);
@@ -598,6 +600,10 @@ static void __fscache_cookie_worker(struct fscache_cookie *cookie)
cookie->debug_id, cookie->stage);
break;
+ case FSCACHE_COOKIE_STAGE_INVALIDATING:
+ fscache_invalidate_cookie(cookie);
+ goto again;
+
case FSCACHE_COOKIE_STAGE_FAILED:
break;
@@ -723,6 +729,70 @@ static void fscache_cookie_drop_from_lru(struct fscache_cookie *cookie)
}
}
+/*
+ * Ask the cache to effect invalidation of a cookie.
+ */
+static void fscache_invalidate_cookie(struct fscache_cookie *cookie)
+{
+ cookie->volume->cache->ops->invalidate_cookie(cookie);
+ fscache_end_cookie_access(cookie, fscache_access_invalidate_cookie_end);
+}
+
+/*
+ * Invalidate an object.
+ */
+void __fscache_invalidate(struct fscache_cookie *cookie,
+ const void *aux_data, loff_t new_size,
+ unsigned int flags)
+{
+ bool is_caching;
+
+ _enter("c=%x", cookie->debug_id);
+
+ fscache_stat(&fscache_n_invalidates);
+
+ if (WARN(test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags),
+ "Trying to invalidate relinquished cookie\n"))
+ return;
+
+ if ((flags & FSCACHE_INVAL_DIO_WRITE) &&
+ test_and_set_bit(FSCACHE_COOKIE_DISABLED, &cookie->flags))
+ return;
+
+ spin_lock(&cookie->lock);
+ set_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);
+ fscache_update_aux(cookie, aux_data, &new_size);
+ cookie->inval_counter++;
+ trace_fscache_invalidate(cookie, new_size);
+
+ switch (cookie->stage) {
+ case FSCACHE_COOKIE_STAGE_INVALIDATING: /* is_still_valid will catch it */
+ default:
+ spin_unlock(&cookie->lock);
+ _leave(" [no %u]", cookie->stage);
+ return;
+
+ case FSCACHE_COOKIE_STAGE_LOOKING_UP:
+ case FSCACHE_COOKIE_STAGE_CREATING:
+ spin_unlock(&cookie->lock);
+ _leave(" [look %x]", cookie->inval_counter);
+ return;
+
+ case FSCACHE_COOKIE_STAGE_ACTIVE:
+ __fscache_set_cookie_stage(cookie, FSCACHE_COOKIE_STAGE_INVALIDATING);
+ is_caching = fscache_begin_cookie_access(
+ cookie, fscache_access_invalidate_cookie);
+ spin_unlock(&cookie->lock);
+ wake_up_cookie_stage(cookie);
+
+ if (is_caching)
+ fscache_queue_cookie(cookie, fscache_cookie_get_inval_work);
+ _leave(" [inv]");
+ return;
+ }
+}
+EXPORT_SYMBOL(__fscache_invalidate);
+
/*
* Remove a cookie from the hash table.
*/
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index 5aff9c143616..4c45d2af7160 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -82,6 +82,8 @@ extern atomic_t fscache_n_acquires_no_cache;
extern atomic_t fscache_n_acquires_ok;
extern atomic_t fscache_n_acquires_oom;
+extern atomic_t fscache_n_invalidates;
+
extern atomic_t fscache_n_relinquishes;
extern atomic_t fscache_n_relinquishes_retire;
extern atomic_t fscache_n_relinquishes_dropped;
diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
index 17bf57374595..45b7636c7737 100644
--- a/fs/fscache/stats.c
+++ b/fs/fscache/stats.c
@@ -28,6 +28,8 @@ atomic_t fscache_n_acquires_no_cache;
atomic_t fscache_n_acquires_ok;
atomic_t fscache_n_acquires_oom;
+atomic_t fscache_n_invalidates;
+
atomic_t fscache_n_updates;
EXPORT_SYMBOL(fscache_n_updates);
@@ -63,6 +65,9 @@ int fscache_stats_show(struct seq_file *m, void *v)
timer_pending(&fscache_cookie_lru_timer) ?
fscache_cookie_lru_timer.expires - jiffies : 0);
+ seq_printf(m, "Invals : n=%u\n",
+ atomic_read(&fscache_n_invalidates));
+
seq_printf(m, "Updates: n=%u\n",
atomic_read(&fscache_n_updates));
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index a67c29207ad5..46d77a1840cd 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -66,6 +66,9 @@ struct fscache_cache_ops {
/* Withdraw an object without any cookie access counts held */
void (*withdraw_cookie)(struct fscache_cookie *cookie);
+ /* Invalidate an object */
+ bool (*invalidate_cookie)(struct fscache_cookie *cookie);
+
/* Prepare to write to a live cache object */
void (*prepare_to_write)(struct fscache_cookie *cookie);
};
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index df985507fa5e..0b01eaaef44c 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -45,6 +45,8 @@ struct fscache_cookie;
#define FSCACHE_ADV_WRITE_NOCACHE 0x02 /* Don't cache if written to locally */
#define FSCACHE_ADV_FALLBACK_IO 0x04 /* Going to use the fallback I/O API (dangerous) */
+#define FSCACHE_INVAL_DIO_WRITE 0x01 /* Invalidate due to DIO write */
+
/*
* Data object state.
*/
@@ -53,6 +55,7 @@ enum fscache_cookie_stage {
FSCACHE_COOKIE_STAGE_LOOKING_UP, /* The cache object is being looked up */
FSCACHE_COOKIE_STAGE_CREATING, /* The cache object is being created */
FSCACHE_COOKIE_STAGE_ACTIVE, /* The cache is active, readable and writable */
+ FSCACHE_COOKIE_STAGE_INVALIDATING, /* The cache is being invalidated */
FSCACHE_COOKIE_STAGE_FAILED, /* The cache failed, withdraw to clear */
FSCACHE_COOKIE_STAGE_COMMITTING, /* The cookie is being committed */
FSCACHE_COOKIE_STAGE_WITHDRAWING, /* The cookie is being withdrawn */
@@ -158,6 +161,7 @@ extern struct fscache_cookie *__fscache_acquire_cookie(
extern void __fscache_use_cookie(struct fscache_cookie *, bool);
extern void __fscache_unuse_cookie(struct fscache_cookie *, const void *, const loff_t *);
extern void __fscache_relinquish_cookie(struct fscache_cookie *, bool);
+extern void __fscache_invalidate(struct fscache_cookie *, const void *, loff_t, unsigned int);
/**
* fscache_acquire_volume - Register a volume as desiring caching services
@@ -325,4 +329,33 @@ void __fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data
set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);
}
+/**
+ * fscache_invalidate - Notify cache that an object needs invalidation
+ * @cookie: The cookie representing the cache object
+ * @aux_data: The updated auxiliary data for the cookie (may be NULL)
+ * @size: The revised size of the object.
+ * @flags: Invalidation flags (FSCACHE_INVAL_*)
+ *
+ * Notify the cache that an object is needs to be invalidated and that it
+ * should abort any retrievals or stores it is doing on the cache. The object
+ * is then marked non-caching until such time as the invalidation is complete.
+ *
+ * FSCACHE_INVAL_LIGHT indicates that if the object has been invalidated and
+ * replaced by a temporary object, the temporary object need not be replaced
+ * again. This is primarily intended for use with FSCACHE_ADV_SINGLE_CHUNK.
+ *
+ * FSCACHE_INVAL_DIO_WRITE indicates that this is due to a direct I/O write and
+ * may cause caching to be suspended on this cookie.
+ *
+ * See Documentation/filesystems/caching/netfs-api.rst for a complete
+ * description.
+ */
+static inline
+void fscache_invalidate(struct fscache_cookie *cookie,
+ const void *aux_data, loff_t size, unsigned int flags)
+{
+ if (fscache_cookie_enabled(cookie))
+ __fscache_invalidate(cookie, aux_data, size, flags);
+}
+
#endif /* _LINUX_FSCACHE_H */
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 99137486d351..3c70eef56599 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -103,6 +103,7 @@ struct netfs_cache_resources {
void *cache_priv;
void *cache_priv2;
unsigned int debug_id; /* Cookie debug ID */
+ unsigned int inval_counter; /* object->inval_counter at begin_op */
};
/*
diff --git a/include/trace/events/fscache.h b/include/trace/events/fscache.h
index 2b31ef34efa2..b705ff36bddc 100644
--- a/include/trace/events/fscache.h
+++ b/include/trace/events/fscache.h
@@ -50,6 +50,7 @@ enum fscache_cookie_trace {
fscache_cookie_discard,
fscache_cookie_get_end_access,
fscache_cookie_get_hash_collision,
+ fscache_cookie_get_inval_work,
fscache_cookie_get_lru,
fscache_cookie_get_use_work,
fscache_cookie_new_acquire,
@@ -72,6 +73,8 @@ enum fscache_access_trace {
fscache_access_acquire_volume_end,
fscache_access_cache_pin,
fscache_access_cache_unpin,
+ fscache_access_invalidate_cookie,
+ fscache_access_invalidate_cookie_end,
fscache_access_lookup_cookie,
fscache_access_lookup_cookie_end,
fscache_access_relinquish_volume,
@@ -113,6 +116,7 @@ enum fscache_access_trace {
EM(fscache_cookie_discard, "DISCARD ") \
EM(fscache_cookie_get_hash_collision, "GET hcoll") \
EM(fscache_cookie_get_end_access, "GQ endac") \
+ EM(fscache_cookie_get_inval_work, "GQ inval") \
EM(fscache_cookie_get_lru, "GET lru ") \
EM(fscache_cookie_get_use_work, "GQ use ") \
EM(fscache_cookie_new_acquire, "NEW acq ") \
@@ -134,6 +138,8 @@ enum fscache_access_trace {
EM(fscache_access_acquire_volume_end, "END acq_vol") \
EM(fscache_access_cache_pin, "PIN cache ") \
EM(fscache_access_cache_unpin, "UNPIN cache ") \
+ EM(fscache_access_invalidate_cookie, "BEGIN inval ") \
+ EM(fscache_access_invalidate_cookie_end,"END inval ") \
EM(fscache_access_lookup_cookie, "BEGIN lookup ") \
EM(fscache_access_lookup_cookie_end, "END lookup ") \
EM(fscache_access_relinquish_volume, "BEGIN rlq_vol") \
@@ -378,6 +384,25 @@ TRACE_EVENT(fscache_relinquish,
__entry->n_active, __entry->flags, __entry->retire)
);
+TRACE_EVENT(fscache_invalidate,
+ TP_PROTO(struct fscache_cookie *cookie, loff_t new_size),
+
+ TP_ARGS(cookie, new_size),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, cookie )
+ __field(loff_t, new_size )
+ ),
+
+ TP_fast_assign(
+ __entry->cookie = cookie->debug_id;
+ __entry->new_size = new_size;
+ ),
+
+ TP_printk("c=%08x sz=%llx",
+ __entry->cookie, __entry->new_size)
+ );
+
#endif /* _TRACE_FSCACHE_H */
/* This part must be outside protection */