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authorDavid Howells <dhowells@redhat.com>2021-10-20 17:53:34 +0300
committerDavid Howells <dhowells@redhat.com>2022-01-07 12:22:19 +0300
commitd24af13e2e2358a602740c7817ea90da43d3e740 (patch)
tree344a8b83aff3845d17f46eaa8fae751351b9a233 /fs/fscache
parent12bb21a29c19aae50cfad4e2bb5c943108f34a7d (diff)
downloadlinux-d24af13e2e2358a602740c7817ea90da43d3e740.tar.xz
fscache: Implement cookie invalidation
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) This causes any cached data for the specified cookie to be 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 should be abandoned (writes) or reconsidered (reads). Each time it is called cookie->inval_counter is incremented and this can be used to detect invalidation at the end of an I/O operation. 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. Changes ======= ver #2: - Should only change to inval state if can get access to cache. 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/163819602231.215744.11206598147269491575.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906909707.143852.18056070560477964891.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967107447.1823006.5945029409592119962.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021512640.640689.11418616313147754172.stgit@warthog.procyon.org.uk/ # v4
Diffstat (limited to 'fs/fscache')
-rw-r--r--fs/fscache/cookie.c88
-rw-r--r--fs/fscache/internal.h2
-rw-r--r--fs/fscache/stats.c5
3 files changed, 94 insertions, 1 deletions
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index 2f5ee717f2bb..a7ea7d1db032 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -19,6 +19,7 @@ static void fscache_cookie_lru_timed_out(struct timer_list *timer);
static void fscache_cookie_lru_worker(struct work_struct *work);
static void fscache_cookie_worker(struct work_struct *work);
static void fscache_unhash_cookie(struct fscache_cookie *cookie);
+static void fscache_perform_invalidation(struct fscache_cookie *cookie);
#define fscache_cookie_hash_shift 15
static struct hlist_bl_head fscache_cookie_hash[1 << fscache_cookie_hash_shift];
@@ -28,7 +29,7 @@ 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_states[FSCACHE_COOKIE_STATE__NR] = "-LCAFUWRD";
+static const char fscache_cookie_states[FSCACHE_COOKIE_STATE__NR] = "-LCAIFUWRD";
unsigned int fscache_lru_cookie_timeout = 10 * HZ;
void fscache_print_cookie(struct fscache_cookie *cookie, char prefix)
@@ -237,6 +238,19 @@ void fscache_cookie_lookup_negative(struct fscache_cookie *cookie)
EXPORT_SYMBOL(fscache_cookie_lookup_negative);
/**
+ * fscache_resume_after_invalidation - Allow I/O to resume after invalidation
+ * @cookie: The cookie that was invalidated
+ *
+ * Tell fscache that invalidation is sufficiently complete that I/O can be
+ * allowed again.
+ */
+void fscache_resume_after_invalidation(struct fscache_cookie *cookie)
+{
+ fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_ACTIVE);
+}
+EXPORT_SYMBOL(fscache_resume_after_invalidation);
+
+/**
* fscache_caching_failed - Report that a failure stopped caching on a cookie
* @cookie: The cookie that was affected
*
@@ -566,6 +580,7 @@ again:
set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags);
break;
case FSCACHE_COOKIE_STATE_ACTIVE:
+ case FSCACHE_COOKIE_STATE_INVALIDATING:
if (will_modify &&
!test_and_set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags)) {
set_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags);
@@ -671,6 +686,11 @@ again_locked:
fscache_perform_lookup(cookie);
goto again;
+ case FSCACHE_COOKIE_STATE_INVALIDATING:
+ spin_unlock(&cookie->lock);
+ fscache_perform_invalidation(cookie);
+ goto again;
+
case FSCACHE_COOKIE_STATE_ACTIVE:
if (test_and_clear_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags)) {
spin_unlock(&cookie->lock);
@@ -963,6 +983,72 @@ struct fscache_cookie *fscache_get_cookie(struct fscache_cookie *cookie,
EXPORT_SYMBOL(fscache_get_cookie);
/*
+ * Ask the cache to effect invalidation of a cookie.
+ */
+static void fscache_perform_invalidation(struct fscache_cookie *cookie)
+{
+ if (!cookie->volume->cache->ops->invalidate_cookie(cookie))
+ fscache_caching_failed(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->state) {
+ case FSCACHE_COOKIE_STATE_INVALIDATING: /* is_still_valid will catch it */
+ default:
+ spin_unlock(&cookie->lock);
+ _leave(" [no %u]", cookie->state);
+ return;
+
+ case FSCACHE_COOKIE_STATE_LOOKING_UP:
+ case FSCACHE_COOKIE_STATE_CREATING:
+ spin_unlock(&cookie->lock);
+ _leave(" [look %x]", cookie->inval_counter);
+ return;
+
+ case FSCACHE_COOKIE_STATE_ACTIVE:
+ is_caching = fscache_begin_cookie_access(
+ cookie, fscache_access_invalidate_cookie);
+ if (is_caching)
+ __fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_INVALIDATING);
+ spin_unlock(&cookie->lock);
+ wake_up_cookie_state(cookie);
+
+ if (is_caching)
+ fscache_queue_cookie(cookie, fscache_cookie_get_inval_work);
+ _leave(" [inv]");
+ return;
+ }
+}
+EXPORT_SYMBOL(__fscache_invalidate);
+
+/*
* Generate a list of extant cookies in /proc/fs/fscache/cookies
*/
static int fscache_cookies_seq_show(struct seq_file *m, void *v)
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index ca938e00eaa0..7fb83d216360 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -105,6 +105,8 @@ extern atomic_t fscache_n_acquires;
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 5aa4bd9fe207..cdbb672a274f 100644
--- a/fs/fscache/stats.c
+++ b/fs/fscache/stats.c
@@ -26,6 +26,8 @@ atomic_t fscache_n_acquires;
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);
@@ -59,6 +61,9 @@ 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));