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SubjectRe: [PATCH v3 18/68] fscache: Implement cookie user counting and resource pinning
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On Thu, 2021-12-16 at 16:11 +0000, David Howells wrote:
> Provide a pair of functions to count the number of users of a cookie (open
> files, writeback, invalidation, resizing, reads, writes), to obtain and pin
> resources for the cookie and to prevent culling for the whilst there are
> users.
>
> The first function marks a cookie as being in use:
>
> void fscache_use_cookie(struct fscache_cookie *cookie,
> bool will_modify);
>
> The caller should indicate the cookie to use and whether or not the caller
> is in a context that may modify the cookie (e.g. a file open O_RDWR).
>
> If the cookie is not already resourced, fscache will ask the cache backend
> in the background to do whatever it needs to look up, create or otherwise
> obtain the resources necessary to access data. This is pinned to the
> cookie and may not be culled, though it may be withdrawn if the cache as a
> whole is withdrawn.
>
> The second function removes the in-use mark from a cookie and, optionally,
> updates the coherency data:
>
> void fscache_unuse_cookie(struct fscache_cookie *cookie,
> const void *aux_data,
> const loff_t *object_size);
>
> If non-NULL, the aux_data buffer and/or the object_size will be saved into
> the cookie and will be set on the backing store when the object is
> committed.
>
> If this removes the last usage on a cookie, the cookie is placed onto an
> LRU list from which it will be removed and closed after a couple of seconds
> if it doesn't get reused. This prevents resource overload in the cache -
> in particular it prevents it from holding too many files open.
>
> Changes
> =======
> ver #2:
> - Fix fscache_unuse_cookie() to use atomic_dec_and_lock() to avoid a
> potential race if the cookie gets reused before it completes the
> unusement.
> - Added missing transition to LRU_DISCARDING state.
>
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: linux-cachefs@redhat.com
> Link: https://lore.kernel.org/r/163819600612.215744.13678350304176542741.stgit@warthog.procyon.org.uk/ # v1
> Link: https://lore.kernel.org/r/163906907567.143852.16979631199380722019.stgit@warthog.procyon.org.uk/ # v2
> ---
>
> fs/fscache/cookie.c | 218 ++++++++++++++++++++++++++++++++++++++++
> fs/fscache/internal.h | 5 +
> fs/fscache/stats.c | 12 ++
> include/linux/fscache.h | 82 +++++++++++++++
> include/trace/events/fscache.h | 12 ++
> 5 files changed, 327 insertions(+), 2 deletions(-)
>
> diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
> index 336046de08ee..2f5ee717f2bb 100644
> --- a/fs/fscache/cookie.c
> +++ b/fs/fscache/cookie.c
> @@ -15,6 +15,8 @@
>
> struct kmem_cache *fscache_cookie_jar;
>
> +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);
>
> @@ -22,7 +24,12 @@ static void fscache_unhash_cookie(struct fscache_cookie *cookie);
> static struct hlist_bl_head fscache_cookie_hash[1 << fscache_cookie_hash_shift];
> static LIST_HEAD(fscache_cookies);
> static DEFINE_RWLOCK(fscache_cookies_lock);
> -static const char fscache_cookie_states[FSCACHE_COOKIE_STATE__NR] = "-LCAFWRD";
> +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";
> +unsigned int fscache_lru_cookie_timeout = 10 * HZ;
>

Looks like it only pops after 10s? That's a bit more than the "couple of
seconds" mentioned in the changelog. In fact, that seems like quite a
long time.

Did you arrive at this value empirically somehow?

> void fscache_print_cookie(struct fscache_cookie *cookie, char prefix)
> {
> @@ -47,6 +54,14 @@ void fscache_print_cookie(struct fscache_cookie *cookie, char prefix)
>
> static void fscache_free_cookie(struct fscache_cookie *cookie)
> {
> + if (WARN_ON_ONCE(!list_empty(&cookie->commit_link))) {
> + spin_lock(&fscache_cookie_lru_lock);
> + list_del_init(&cookie->commit_link);
> + spin_unlock(&fscache_cookie_lru_lock);
> + fscache_stat_d(&fscache_n_cookies_lru);
> + fscache_stat(&fscache_n_cookies_lru_removed);
> + }
> +
> if (WARN_ON_ONCE(test_bit(FSCACHE_COOKIE_IS_HASHED, &cookie->flags))) {
> fscache_print_cookie(cookie, 'F');
> return;
> @@ -498,6 +513,126 @@ static void fscache_perform_lookup(struct fscache_cookie *cookie)
> fscache_end_volume_access(cookie->volume, cookie, trace);
> }
>
> +/*
> + * Begin the process of looking up a cookie. We offload the actual process to
> + * a worker thread.
> + */
> +static bool fscache_begin_lookup(struct fscache_cookie *cookie, bool will_modify)
> +{
> + if (will_modify) {
> + set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags);
> + set_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags);
> + }
> + if (!fscache_begin_volume_access(cookie->volume, cookie,
> + fscache_access_lookup_cookie))
> + return false;
> +
> + __fscache_begin_cookie_access(cookie, fscache_access_lookup_cookie);
> + __fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_LOOKING_UP);
> + set_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags);
> + set_bit(FSCACHE_COOKIE_HAS_BEEN_CACHED, &cookie->flags);
> + return true;
> +}
> +
> +/*
> + * Start using the cookie for I/O. This prevents the backing object from being
> + * reaped by VM pressure.
> + */
> +void __fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify)
> +{
> + enum fscache_cookie_state state;
> + bool queue = false;
> +
> + _enter("c=%08x", cookie->debug_id);
> +
> + if (WARN(test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags),
> + "Trying to use relinquished cookie\n"))
> + return;
> +
> + spin_lock(&cookie->lock);
> +
> + atomic_inc(&cookie->n_active);
> +
> +again:
> + state = fscache_cookie_state(cookie);
> + switch (state) {
> + case FSCACHE_COOKIE_STATE_QUIESCENT:
> + queue = fscache_begin_lookup(cookie, will_modify);
> + break;
> +
> + case FSCACHE_COOKIE_STATE_LOOKING_UP:
> + case FSCACHE_COOKIE_STATE_CREATING:
> + if (will_modify)
> + set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags);
> + break;
> + case FSCACHE_COOKIE_STATE_ACTIVE:
> + if (will_modify &&
> + !test_and_set_bit(FSCACHE_COOKIE_LOCAL_WRITE, &cookie->flags)) {
> + set_bit(FSCACHE_COOKIE_DO_PREP_TO_WRITE, &cookie->flags);
> + queue = true;
> + }
> + break;
> +
> + case FSCACHE_COOKIE_STATE_FAILED:
> + case FSCACHE_COOKIE_STATE_WITHDRAWING:
> + break;
> +
> + case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
> + spin_unlock(&cookie->lock);
> + wait_var_event(&cookie->state,
> + fscache_cookie_state(cookie) !=
> + FSCACHE_COOKIE_STATE_LRU_DISCARDING);
> + spin_lock(&cookie->lock);
> + goto again;
> +
> + case FSCACHE_COOKIE_STATE_DROPPED:
> + case FSCACHE_COOKIE_STATE_RELINQUISHING:
> + WARN(1, "Can't use cookie in state %u\n", state);
> + break;
> + }
> +
> + spin_unlock(&cookie->lock);
> + if (queue)
> + fscache_queue_cookie(cookie, fscache_cookie_get_use_work);
> + _leave("");
> +}
> +EXPORT_SYMBOL(__fscache_use_cookie);
> +
> +static void fscache_unuse_cookie_locked(struct fscache_cookie *cookie)
> +{
> + clear_bit(FSCACHE_COOKIE_DISABLED, &cookie->flags);
> + if (!test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags))
> + return;
> +
> + cookie->unused_at = jiffies;
> + spin_lock(&fscache_cookie_lru_lock);
> + if (list_empty(&cookie->commit_link)) {
> + fscache_get_cookie(cookie, fscache_cookie_get_lru);
> + fscache_stat(&fscache_n_cookies_lru);
> + }
> + list_move_tail(&cookie->commit_link, &fscache_cookie_lru);
> +
> + spin_unlock(&fscache_cookie_lru_lock);
> + timer_reduce(&fscache_cookie_lru_timer,
> + jiffies + fscache_lru_cookie_timeout);
> +}
> +
> +/*
> + * Stop using the cookie for I/O.
> + */
> +void __fscache_unuse_cookie(struct fscache_cookie *cookie,
> + const void *aux_data, const loff_t *object_size)
> +{
> + if (aux_data || object_size)
> + __fscache_update_cookie(cookie, aux_data, object_size);
> +
> + if (atomic_dec_and_lock(&cookie->n_active, &cookie->lock)) {
> + fscache_unuse_cookie_locked(cookie);
> + spin_unlock(&cookie->lock);
> + }
> +}
> +EXPORT_SYMBOL(__fscache_unuse_cookie);
> +
> /*
> * Perform work upon the cookie, such as committing its cache state,
> * relinquishing it or withdrawing the backing cache. We're protected from the
> @@ -542,6 +677,12 @@ static void fscache_cookie_state_machine(struct fscache_cookie *cookie)
> fscache_prepare_to_write(cookie);
> spin_lock(&cookie->lock);
> }
> + if (test_bit(FSCACHE_COOKIE_DO_LRU_DISCARD, &cookie->flags)) {
> + __fscache_set_cookie_state(cookie,
> + FSCACHE_COOKIE_STATE_LRU_DISCARDING);
> + wake = true;
> + goto again_locked;
> + }
> fallthrough;
>
> case FSCACHE_COOKIE_STATE_FAILED:
> @@ -561,6 +702,7 @@ static void fscache_cookie_state_machine(struct fscache_cookie *cookie)
> }
> break;
>
> + case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
> case FSCACHE_COOKIE_STATE_RELINQUISHING:
> case FSCACHE_COOKIE_STATE_WITHDRAWING:
> if (cookie->cache_priv) {
> @@ -577,6 +719,9 @@ static void fscache_cookie_state_machine(struct fscache_cookie *cookie)
> FSCACHE_COOKIE_STATE_DROPPED);
> wake = true;
> goto out;
> + case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
> + fscache_see_cookie(cookie, fscache_cookie_see_lru_discard);
> + break;
> case FSCACHE_COOKIE_STATE_WITHDRAWING:
> fscache_see_cookie(cookie, fscache_cookie_see_withdraw);
> break;
> @@ -639,6 +784,76 @@ static void __fscache_withdraw_cookie(struct fscache_cookie *cookie)
> fscache_queue_cookie(cookie, fscache_cookie_get_end_access);
> }
>
> +static void fscache_cookie_lru_do_one(struct fscache_cookie *cookie)
> +{
> + fscache_see_cookie(cookie, fscache_cookie_see_lru_do_one);
> +
> + spin_lock(&cookie->lock);
> + if (cookie->state != FSCACHE_COOKIE_STATE_ACTIVE ||
> + time_before(jiffies, cookie->unused_at + fscache_lru_cookie_timeout) ||
> + atomic_read(&cookie->n_active) > 0) {
> + spin_unlock(&cookie->lock);
> + fscache_stat(&fscache_n_cookies_lru_removed);
> + } else {
> + set_bit(FSCACHE_COOKIE_DO_LRU_DISCARD, &cookie->flags);
> + spin_unlock(&cookie->lock);
> + fscache_stat(&fscache_n_cookies_lru_expired);
> + _debug("lru c=%x", cookie->debug_id);
> + __fscache_withdraw_cookie(cookie);
> + }
> +
> + fscache_put_cookie(cookie, fscache_cookie_put_lru);
> +}
> +
> +static void fscache_cookie_lru_worker(struct work_struct *work)
> +{
> + struct fscache_cookie *cookie;
> + unsigned long unused_at;
> +
> + spin_lock(&fscache_cookie_lru_lock);
> +
> + while (!list_empty(&fscache_cookie_lru)) {
> + cookie = list_first_entry(&fscache_cookie_lru,
> + struct fscache_cookie, commit_link);
> + unused_at = cookie->unused_at + fscache_lru_cookie_timeout;
> + if (time_before(jiffies, unused_at)) {
> + timer_reduce(&fscache_cookie_lru_timer, unused_at);
> + break;
> + }
> +
> + list_del_init(&cookie->commit_link);
> + fscache_stat_d(&fscache_n_cookies_lru);
> + spin_unlock(&fscache_cookie_lru_lock);
> + fscache_cookie_lru_do_one(cookie);
> + spin_lock(&fscache_cookie_lru_lock);
> + }
> +
> + spin_unlock(&fscache_cookie_lru_lock);
> +}
> +
> +static void fscache_cookie_lru_timed_out(struct timer_list *timer)
> +{
> + queue_work(fscache_wq, &fscache_cookie_lru_work);
> +}
> +
> +static void fscache_cookie_drop_from_lru(struct fscache_cookie *cookie)
> +{
> + bool need_put = false;
> +
> + if (!list_empty(&cookie->commit_link)) {
> + spin_lock(&fscache_cookie_lru_lock);
> + if (!list_empty(&cookie->commit_link)) {
> + list_del_init(&cookie->commit_link);
> + fscache_stat_d(&fscache_n_cookies_lru);
> + fscache_stat(&fscache_n_cookies_lru_dropped);
> + need_put = true;
> + }
> + spin_unlock(&fscache_cookie_lru_lock);
> + if (need_put)
> + fscache_put_cookie(cookie, fscache_cookie_put_lru);
> + }
> +}
> +
> /*
> * Remove a cookie from the hash table.
> */
> @@ -659,6 +874,7 @@ static void fscache_unhash_cookie(struct fscache_cookie *cookie)
>
> static void fscache_drop_withdraw_cookie(struct fscache_cookie *cookie)
> {
> + fscache_cookie_drop_from_lru(cookie);
> __fscache_withdraw_cookie(cookie);
> }
>
> diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
> index e0d8ef212e82..ca938e00eaa0 100644
> --- a/fs/fscache/internal.h
> +++ b/fs/fscache/internal.h
> @@ -57,6 +57,7 @@ static inline bool fscache_set_cache_state_maybe(struct fscache_cache *cache,
> */
> extern struct kmem_cache *fscache_cookie_jar;
> extern const struct seq_operations fscache_cookies_seq_ops;
> +extern struct timer_list fscache_cookie_lru_timer;
>
> extern void fscache_print_cookie(struct fscache_cookie *cookie, char prefix);
> extern bool fscache_begin_cookie_access(struct fscache_cookie *cookie,
> @@ -95,6 +96,10 @@ extern atomic_t fscache_n_volumes;
> extern atomic_t fscache_n_volumes_collision;
> extern atomic_t fscache_n_volumes_nomem;
> extern atomic_t fscache_n_cookies;
> +extern atomic_t fscache_n_cookies_lru;
> +extern atomic_t fscache_n_cookies_lru_expired;
> +extern atomic_t fscache_n_cookies_lru_removed;
> +extern atomic_t fscache_n_cookies_lru_dropped;
>
> extern atomic_t fscache_n_acquires;
> extern atomic_t fscache_n_acquires_ok;
> diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
> index 252e883ae148..5aa4bd9fe207 100644
> --- a/fs/fscache/stats.c
> +++ b/fs/fscache/stats.c
> @@ -17,6 +17,10 @@ atomic_t fscache_n_volumes;
> atomic_t fscache_n_volumes_collision;
> atomic_t fscache_n_volumes_nomem;
> atomic_t fscache_n_cookies;
> +atomic_t fscache_n_cookies_lru;
> +atomic_t fscache_n_cookies_lru_expired;
> +atomic_t fscache_n_cookies_lru_removed;
> +atomic_t fscache_n_cookies_lru_dropped;
>
> atomic_t fscache_n_acquires;
> atomic_t fscache_n_acquires_ok;
> @@ -47,6 +51,14 @@ int fscache_stats_show(struct seq_file *m, void *v)
> atomic_read(&fscache_n_acquires_ok),
> atomic_read(&fscache_n_acquires_oom));
>
> + seq_printf(m, "LRU : n=%u exp=%u rmv=%u drp=%u at=%ld\n",
> + atomic_read(&fscache_n_cookies_lru),
> + atomic_read(&fscache_n_cookies_lru_expired),
> + atomic_read(&fscache_n_cookies_lru_removed),
> + atomic_read(&fscache_n_cookies_lru_dropped),
> + timer_pending(&fscache_cookie_lru_timer) ?
> + fscache_cookie_lru_timer.expires - jiffies : 0);
> +
> seq_printf(m, "Updates: n=%u\n",
> atomic_read(&fscache_n_updates));
>
> diff --git a/include/linux/fscache.h b/include/linux/fscache.h
> index 5c57a3ee2145..822d544114b0 100644
> --- a/include/linux/fscache.h
> +++ b/include/linux/fscache.h
> @@ -22,12 +22,14 @@
> #define fscache_available() (1)
> #define fscache_volume_valid(volume) (volume)
> #define fscache_cookie_valid(cookie) (cookie)
> -#define fscache_cookie_enabled(cookie) (cookie)
> +#define fscache_resources_valid(cres) ((cres)->cache_priv)
> +#define fscache_cookie_enabled(cookie) (cookie && !test_bit(FSCACHE_COOKIE_DISABLED, &cookie->flags))
> #else
> #define __fscache_available (0)
> #define fscache_available() (0)
> #define fscache_volume_valid(volume) (0)
> #define fscache_cookie_valid(cookie) (0)
> +#define fscache_resources_valid(cres) (false)
> #define fscache_cookie_enabled(cookie) (0)
> #endif
>
> @@ -46,6 +48,7 @@ enum fscache_cookie_state {
> FSCACHE_COOKIE_STATE_CREATING, /* The cache object is being created */
> FSCACHE_COOKIE_STATE_ACTIVE, /* The cache is active, readable and writable */
> FSCACHE_COOKIE_STATE_FAILED, /* The cache failed, withdraw to clear */
> + FSCACHE_COOKIE_STATE_LRU_DISCARDING, /* The cookie is being discarded by the LRU */
> FSCACHE_COOKIE_STATE_WITHDRAWING, /* The cookie is being withdrawn */
> FSCACHE_COOKIE_STATE_RELINQUISHING, /* The cookie is being relinquished */
> FSCACHE_COOKIE_STATE_DROPPED, /* The cookie has been dropped */
> @@ -147,6 +150,8 @@ extern struct fscache_cookie *__fscache_acquire_cookie(
> const void *, size_t,
> const void *, size_t,
> loff_t);
> +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);
>
> /**
> @@ -229,6 +234,39 @@ struct fscache_cookie *fscache_acquire_cookie(struct fscache_volume *volume,
> object_size);
> }
>
> +/**
> + * fscache_use_cookie - Request usage of cookie attached to an object
> + * @object: Object description
> + * @will_modify: If cache is expected to be modified locally
> + *
> + * Request usage of the cookie attached to an object. The caller should tell
> + * the cache if the object's contents are about to be modified locally and then
> + * the cache can apply the policy that has been set to handle this case.
> + */
> +static inline void fscache_use_cookie(struct fscache_cookie *cookie,
> + bool will_modify)
> +{
> + if (fscache_cookie_valid(cookie))
> + __fscache_use_cookie(cookie, will_modify);
> +}
> +
> +/**
> + * fscache_unuse_cookie - Cease usage of cookie attached to an object
> + * @object: Object description
> + * @aux_data: Updated auxiliary data (or NULL)
> + * @object_size: Revised size of the object (or NULL)
> + *
> + * Cease usage of the cookie attached to an object. When the users count
> + * reaches zero then the cookie relinquishment will be permitted to proceed.
> + */
> +static inline void fscache_unuse_cookie(struct fscache_cookie *cookie,
> + const void *aux_data,
> + const loff_t *object_size)
> +{
> + if (fscache_cookie_valid(cookie))
> + __fscache_unuse_cookie(cookie, aux_data, object_size);
> +}
> +
> /**
> * fscache_relinquish_cookie - Return the cookie to the cache, maybe discarding
> * it
> @@ -248,4 +286,46 @@ void fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
> __fscache_relinquish_cookie(cookie, retire);
> }
>
> +/*
> + * Find the auxiliary data on a cookie.
> + */
> +static inline void *fscache_get_aux(struct fscache_cookie *cookie)
> +{
> + if (cookie->aux_len <= sizeof(cookie->inline_aux))
> + return cookie->inline_aux;
> + else
> + return cookie->aux;
> +}
> +
> +/*
> + * Update the auxiliary data on a cookie.
> + */
> +static inline
> +void fscache_update_aux(struct fscache_cookie *cookie,
> + const void *aux_data, const loff_t *object_size)
> +{
> + void *p = fscache_get_aux(cookie);
> +
> + if (aux_data && p)
> + memcpy(p, aux_data, cookie->aux_len);
> + if (object_size)
> + cookie->object_size = *object_size;
> +}
> +
> +#ifdef CONFIG_FSCACHE_STATS
> +extern atomic_t fscache_n_updates;
> +#endif
> +
> +static inline
> +void __fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data,
> + const loff_t *object_size)
> +{
> +#ifdef CONFIG_FSCACHE_STATS
> + atomic_inc(&fscache_n_updates);
> +#endif
> + fscache_update_aux(cookie, aux_data, object_size);
> + smp_wmb();
> + set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);
> +}
> +
> #endif /* _LINUX_FSCACHE_H */
> diff --git a/include/trace/events/fscache.h b/include/trace/events/fscache.h
> index 030c97bb9c8b..b0409b1fad23 100644
> --- a/include/trace/events/fscache.h
> +++ b/include/trace/events/fscache.h
> @@ -51,13 +51,18 @@ enum fscache_cookie_trace {
> fscache_cookie_discard,
> fscache_cookie_get_end_access,
> fscache_cookie_get_hash_collision,
> + fscache_cookie_get_lru,
> + fscache_cookie_get_use_work,
> fscache_cookie_new_acquire,
> fscache_cookie_put_hash_collision,
> + fscache_cookie_put_lru,
> fscache_cookie_put_over_queued,
> fscache_cookie_put_relinquish,
> fscache_cookie_put_withdrawn,
> fscache_cookie_put_work,
> fscache_cookie_see_active,
> + fscache_cookie_see_lru_discard,
> + fscache_cookie_see_lru_do_one,
> fscache_cookie_see_relinquish,
> fscache_cookie_see_withdraw,
> fscache_cookie_see_work,
> @@ -68,6 +73,7 @@ enum fscache_access_trace {
> fscache_access_acquire_volume_end,
> fscache_access_cache_pin,
> fscache_access_cache_unpin,
> + fscache_access_lookup_cookie,
> fscache_access_lookup_cookie_end,
> fscache_access_lookup_cookie_end_failed,
> fscache_access_relinquish_volume,
> @@ -110,13 +116,18 @@ 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_lru, "GET lru ") \
> + EM(fscache_cookie_get_use_work, "GQ use ") \
> EM(fscache_cookie_new_acquire, "NEW acq ") \
> EM(fscache_cookie_put_hash_collision, "PUT hcoll") \
> + EM(fscache_cookie_put_lru, "PUT lru ") \
> EM(fscache_cookie_put_over_queued, "PQ overq") \
> EM(fscache_cookie_put_relinquish, "PUT relnq") \
> EM(fscache_cookie_put_withdrawn, "PUT wthdn") \
> EM(fscache_cookie_put_work, "PQ work ") \
> EM(fscache_cookie_see_active, "- activ") \
> + EM(fscache_cookie_see_lru_discard, "- x-lru") \
> + EM(fscache_cookie_see_lru_do_one, "- lrudo") \
> EM(fscache_cookie_see_relinquish, "- x-rlq") \
> EM(fscache_cookie_see_withdraw, "- x-wth") \
> E_(fscache_cookie_see_work, "- work ")
> @@ -126,6 +137,7 @@ 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_lookup_cookie, "BEGIN lookup ") \
> EM(fscache_access_lookup_cookie_end, "END lookup ") \
> EM(fscache_access_lookup_cookie_end_failed,"END lookupf") \
> EM(fscache_access_relinquish_volume, "BEGIN rlq_vol") \
>
>

--
Jeff Layton <jlayton@kernel.org>

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