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linux-next/fs/netfs/internal.h
David Howells b4f239c91f
netfs: Change the read result collector to only use one work item 
Change the way netfslib collects read results to do all the collection for
a particular read request using a single work item that walks along the
subrequest queue as subrequests make progress or complete, unlocking folios
progressively rather than doing the unlock in parallel as parallel requests
come in.

The code is remodelled to be more like the write-side code, though only
using a single stream.  This makes it more directly comparable and thus
easier to duplicate fixes between the two sides.

This has a number of advantages:

 (1) It's simpler.  There doesn't need to be a complex donation mechanism
     to handle mismatches between the size and alignment of subrequests and
     folios.  The collector unlocks folios as the subrequests covering each
     complete.

 (2) It should cause less scheduler overhead as there's a single work item
     in play unlocking pages in parallel when a read gets split up into a
     lot of subrequests instead of one per subrequest.

     Whilst the parallellism is nice in theory, in practice, the vast
     majority of loads are sequential reads of the whole file, so
     committing a bunch of threads to unlocking folios out of order doesn't
     help in those cases.

 (3) It should make it easier to implement content decryption.  A folio
     cannot be decrypted until all the requests that contribute to it have
     completed - and, again, most loads are sequential and so, most of the
     time, we want to begin decryption sequentially (though it's great if
     the decryption can happen in parallel).

There is a disadvantage in that we're losing the ability to decrypt and
unlock things on an as-things-arrive basis which may affect some
applications.

Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241108173236.1382366-29-dhowells@redhat.com
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-12-02 11:21:23 +01:00

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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Internal definitions for network filesystem support
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/folio_queue.h>
#include <linux/netfs.h>
#include <linux/fscache.h>
#include <linux/fscache-cache.h>
#include <trace/events/netfs.h>
#include <trace/events/fscache.h>
#ifdef pr_fmt
#undef pr_fmt
#endif
#define pr_fmt(fmt) "netfs: " fmt
/*
* buffered_read.c
*/
void netfs_cache_read_terminated(void *priv, ssize_t transferred_or_error, bool was_async);
int netfs_prefetch_for_write(struct file *file, struct folio *folio,
size_t offset, size_t len);
/*
* main.c
*/
extern unsigned int netfs_debug;
extern struct list_head netfs_io_requests;
extern spinlock_t netfs_proc_lock;
extern mempool_t netfs_request_pool;
extern mempool_t netfs_subrequest_pool;
#ifdef CONFIG_PROC_FS
static inline void netfs_proc_add_rreq(struct netfs_io_request *rreq)
{
spin_lock(&netfs_proc_lock);
list_add_tail_rcu(&rreq->proc_link, &netfs_io_requests);
spin_unlock(&netfs_proc_lock);
}
static inline void netfs_proc_del_rreq(struct netfs_io_request *rreq)
{
if (!list_empty(&rreq->proc_link)) {
spin_lock(&netfs_proc_lock);
list_del_rcu(&rreq->proc_link);
spin_unlock(&netfs_proc_lock);
}
}
#else
static inline void netfs_proc_add_rreq(struct netfs_io_request *rreq) {}
static inline void netfs_proc_del_rreq(struct netfs_io_request *rreq) {}
#endif
/*
* misc.c
*/
struct folio_queue *netfs_buffer_make_space(struct netfs_io_request *rreq,
enum netfs_folioq_trace trace);
void netfs_reset_iter(struct netfs_io_subrequest *subreq);
/*
* objects.c
*/
struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
struct file *file,
loff_t start, size_t len,
enum netfs_io_origin origin);
void netfs_get_request(struct netfs_io_request *rreq, enum netfs_rreq_ref_trace what);
void netfs_clear_subrequests(struct netfs_io_request *rreq, bool was_async);
void netfs_put_request(struct netfs_io_request *rreq, bool was_async,
enum netfs_rreq_ref_trace what);
struct netfs_io_subrequest *netfs_alloc_subrequest(struct netfs_io_request *rreq);
static inline void netfs_see_request(struct netfs_io_request *rreq,
enum netfs_rreq_ref_trace what)
{
trace_netfs_rreq_ref(rreq->debug_id, refcount_read(&rreq->ref), what);
}
static inline void netfs_see_subrequest(struct netfs_io_subrequest *subreq,
enum netfs_sreq_ref_trace what)
{
trace_netfs_sreq_ref(subreq->rreq->debug_id, subreq->debug_index,
refcount_read(&subreq->ref), what);
}
/*
* read_collect.c
*/
void netfs_read_collection_worker(struct work_struct *work);
void netfs_wake_read_collector(struct netfs_io_request *rreq);
void netfs_cache_read_terminated(void *priv, ssize_t transferred_or_error, bool was_async);
ssize_t netfs_wait_for_read(struct netfs_io_request *rreq);
/*
* read_pgpriv2.c
*/
void netfs_pgpriv2_mark_copy_to_cache(struct netfs_io_request *rreq,
struct folio_queue *folioq,
int slot);
void netfs_pgpriv2_write_to_the_cache(struct netfs_io_request *rreq);
bool netfs_pgpriv2_unlock_copied_folios(struct netfs_io_request *wreq);
/*
* read_retry.c
*/
void netfs_retry_reads(struct netfs_io_request *rreq);
void netfs_unlock_abandoned_read_pages(struct netfs_io_request *rreq);
/*
* stats.c
*/
#ifdef CONFIG_NETFS_STATS
extern atomic_t netfs_n_rh_dio_read;
extern atomic_t netfs_n_rh_readahead;
extern atomic_t netfs_n_rh_read_folio;
extern atomic_t netfs_n_rh_read_single;
extern atomic_t netfs_n_rh_rreq;
extern atomic_t netfs_n_rh_sreq;
extern atomic_t netfs_n_rh_download;
extern atomic_t netfs_n_rh_download_done;
extern atomic_t netfs_n_rh_download_failed;
extern atomic_t netfs_n_rh_download_instead;
extern atomic_t netfs_n_rh_read;
extern atomic_t netfs_n_rh_read_done;
extern atomic_t netfs_n_rh_read_failed;
extern atomic_t netfs_n_rh_zero;
extern atomic_t netfs_n_rh_short_read;
extern atomic_t netfs_n_rh_write;
extern atomic_t netfs_n_rh_write_begin;
extern atomic_t netfs_n_rh_write_done;
extern atomic_t netfs_n_rh_write_failed;
extern atomic_t netfs_n_rh_write_zskip;
extern atomic_t netfs_n_wh_buffered_write;
extern atomic_t netfs_n_wh_writethrough;
extern atomic_t netfs_n_wh_dio_write;
extern atomic_t netfs_n_wh_writepages;
extern atomic_t netfs_n_wh_copy_to_cache;
extern atomic_t netfs_n_wh_wstream_conflict;
extern atomic_t netfs_n_wh_upload;
extern atomic_t netfs_n_wh_upload_done;
extern atomic_t netfs_n_wh_upload_failed;
extern atomic_t netfs_n_wh_write;
extern atomic_t netfs_n_wh_write_done;
extern atomic_t netfs_n_wh_write_failed;
extern atomic_t netfs_n_wb_lock_skip;
extern atomic_t netfs_n_wb_lock_wait;
extern atomic_t netfs_n_folioq;
int netfs_stats_show(struct seq_file *m, void *v);
static inline void netfs_stat(atomic_t *stat)
{
atomic_inc(stat);
}
static inline void netfs_stat_d(atomic_t *stat)
{
atomic_dec(stat);
}
#else
#define netfs_stat(x) do {} while(0)
#define netfs_stat_d(x) do {} while(0)
#endif
/*
* write_collect.c
*/
int netfs_folio_written_back(struct folio *folio);
void netfs_write_collection_worker(struct work_struct *work);
void netfs_wake_write_collector(struct netfs_io_request *wreq, bool was_async);
/*
* write_issue.c
*/
struct netfs_io_request *netfs_create_write_req(struct address_space *mapping,
struct file *file,
loff_t start,
enum netfs_io_origin origin);
void netfs_reissue_write(struct netfs_io_stream *stream,
struct netfs_io_subrequest *subreq,
struct iov_iter *source);
void netfs_issue_write(struct netfs_io_request *wreq,
struct netfs_io_stream *stream);
size_t netfs_advance_write(struct netfs_io_request *wreq,
struct netfs_io_stream *stream,
loff_t start, size_t len, bool to_eof);
struct netfs_io_request *netfs_begin_writethrough(struct kiocb *iocb, size_t len);
int netfs_advance_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
struct folio *folio, size_t copied, bool to_page_end,
struct folio **writethrough_cache);
int netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_control *wbc,
struct folio *writethrough_cache);
int netfs_unbuffered_write(struct netfs_io_request *wreq, bool may_wait, size_t len);
/*
* write_retry.c
*/
void netfs_retry_writes(struct netfs_io_request *wreq);
/*
* Miscellaneous functions.
*/
static inline bool netfs_is_cache_enabled(struct netfs_inode *ctx)
{
#if IS_ENABLED(CONFIG_FSCACHE)
struct fscache_cookie *cookie = ctx->cache;
return fscache_cookie_valid(cookie) && cookie->cache_priv &&
fscache_cookie_enabled(cookie);
#else
return false;
#endif
}
/*
* Get a ref on a netfs group attached to a dirty page (e.g. a ceph snap).
*/
static inline struct netfs_group *netfs_get_group(struct netfs_group *netfs_group)
{
if (netfs_group && netfs_group != NETFS_FOLIO_COPY_TO_CACHE)
refcount_inc(&netfs_group->ref);
return netfs_group;
}
/*
* Dispose of a netfs group attached to a dirty page (e.g. a ceph snap).
*/
static inline void netfs_put_group(struct netfs_group *netfs_group)
{
if (netfs_group &&
netfs_group != NETFS_FOLIO_COPY_TO_CACHE &&
refcount_dec_and_test(&netfs_group->ref))
netfs_group->free(netfs_group);
}
/*
* Dispose of a netfs group attached to a dirty page (e.g. a ceph snap).
*/
static inline void netfs_put_group_many(struct netfs_group *netfs_group, int nr)
{
if (netfs_group &&
netfs_group != NETFS_FOLIO_COPY_TO_CACHE &&
refcount_sub_and_test(nr, &netfs_group->ref))
netfs_group->free(netfs_group);
}
/*
* fscache-cache.c
*/
#ifdef CONFIG_PROC_FS
extern const struct seq_operations fscache_caches_seq_ops;
#endif
bool fscache_begin_cache_access(struct fscache_cache *cache, enum fscache_access_trace why);
void fscache_end_cache_access(struct fscache_cache *cache, enum fscache_access_trace why);
struct fscache_cache *fscache_lookup_cache(const char *name, bool is_cache);
void fscache_put_cache(struct fscache_cache *cache, enum fscache_cache_trace where);
static inline enum fscache_cache_state fscache_cache_state(const struct fscache_cache *cache)
{
return smp_load_acquire(&cache->state);
}
static inline bool fscache_cache_is_live(const struct fscache_cache *cache)
{
return fscache_cache_state(cache) == FSCACHE_CACHE_IS_ACTIVE;
}
static inline void fscache_set_cache_state(struct fscache_cache *cache,
enum fscache_cache_state new_state)
{
smp_store_release(&cache->state, new_state);
}
static inline bool fscache_set_cache_state_maybe(struct fscache_cache *cache,
enum fscache_cache_state old_state,
enum fscache_cache_state new_state)
{
return try_cmpxchg_release(&cache->state, &old_state, new_state);
}
/*
* fscache-cookie.c
*/
extern struct kmem_cache *fscache_cookie_jar;
#ifdef CONFIG_PROC_FS
extern const struct seq_operations fscache_cookies_seq_ops;
#endif
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,
enum fscache_access_trace why);
static inline void fscache_see_cookie(struct fscache_cookie *cookie,
enum fscache_cookie_trace where)
{
trace_fscache_cookie(cookie->debug_id, refcount_read(&cookie->ref),
where);
}
/*
* fscache-main.c
*/
extern unsigned int fscache_hash(unsigned int salt, const void *data, size_t len);
#ifdef CONFIG_FSCACHE
int __init fscache_init(void);
void __exit fscache_exit(void);
#else
static inline int fscache_init(void) { return 0; }
static inline void fscache_exit(void) {}
#endif
/*
* fscache-proc.c
*/
#ifdef CONFIG_PROC_FS
extern int __init fscache_proc_init(void);
extern void fscache_proc_cleanup(void);
#else
#define fscache_proc_init() (0)
#define fscache_proc_cleanup() do {} while (0)
#endif
/*
* fscache-stats.c
*/
#ifdef CONFIG_FSCACHE_STATS
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;
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;
extern atomic_t fscache_n_resizes;
extern atomic_t fscache_n_resizes_null;
static inline void fscache_stat(atomic_t *stat)
{
atomic_inc(stat);
}
static inline void fscache_stat_d(atomic_t *stat)
{
atomic_dec(stat);
}
#define __fscache_stat(stat) (stat)
int fscache_stats_show(struct seq_file *m);
#else
#define __fscache_stat(stat) (NULL)
#define fscache_stat(stat) do {} while (0)
#define fscache_stat_d(stat) do {} while (0)
static inline int fscache_stats_show(struct seq_file *m) { return 0; }
#endif
/*
* fscache-volume.c
*/
#ifdef CONFIG_PROC_FS
extern const struct seq_operations fscache_volumes_seq_ops;
#endif
struct fscache_volume *fscache_get_volume(struct fscache_volume *volume,
enum fscache_volume_trace where);
bool fscache_begin_volume_access(struct fscache_volume *volume,
struct fscache_cookie *cookie,
enum fscache_access_trace why);
void fscache_create_volume(struct fscache_volume *volume, bool wait);
/*****************************************************************************/
/*
* debug tracing
*/
#define dbgprintk(FMT, ...) \
printk("[%-6.6s] "FMT"\n", current->comm, ##__VA_ARGS__)
#define kenter(FMT, ...) dbgprintk("==> %s("FMT")", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) dbgprintk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
#define kdebug(FMT, ...) dbgprintk(FMT, ##__VA_ARGS__)
#ifdef __KDEBUG
#define _enter(FMT, ...) kenter(FMT, ##__VA_ARGS__)
#define _leave(FMT, ...) kleave(FMT, ##__VA_ARGS__)
#define _debug(FMT, ...) kdebug(FMT, ##__VA_ARGS__)
#elif defined(CONFIG_NETFS_DEBUG)
#define _enter(FMT, ...) \
do { \
if (netfs_debug) \
kenter(FMT, ##__VA_ARGS__); \
} while (0)
#define _leave(FMT, ...) \
do { \
if (netfs_debug) \
kleave(FMT, ##__VA_ARGS__); \
} while (0)
#define _debug(FMT, ...) \
do { \
if (netfs_debug) \
kdebug(FMT, ##__VA_ARGS__); \
} while (0)
#else
#define _enter(FMT, ...) no_printk("==> %s("FMT")", __func__, ##__VA_ARGS__)
#define _leave(FMT, ...) no_printk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
#define _debug(FMT, ...) no_printk(FMT, ##__VA_ARGS__)
#endif
/*
* assertions
*/
#if 1 /* defined(__KDEBUGALL) */
#define ASSERT(X) \
do { \
if (unlikely(!(X))) { \
pr_err("\n"); \
pr_err("Assertion failed\n"); \
BUG(); \
} \
} while (0)
#define ASSERTCMP(X, OP, Y) \
do { \
if (unlikely(!((X) OP (Y)))) { \
pr_err("\n"); \
pr_err("Assertion failed\n"); \
pr_err("%lx " #OP " %lx is false\n", \
(unsigned long)(X), (unsigned long)(Y)); \
BUG(); \
} \
} while (0)
#define ASSERTIF(C, X) \
do { \
if (unlikely((C) && !(X))) { \
pr_err("\n"); \
pr_err("Assertion failed\n"); \
BUG(); \
} \
} while (0)
#define ASSERTIFCMP(C, X, OP, Y) \
do { \
if (unlikely((C) && !((X) OP (Y)))) { \
pr_err("\n"); \
pr_err("Assertion failed\n"); \
pr_err("%lx " #OP " %lx is false\n", \
(unsigned long)(X), (unsigned long)(Y)); \
BUG(); \
} \
} while (0)
#else
#define ASSERT(X) do {} while (0)
#define ASSERTCMP(X, OP, Y) do {} while (0)
#define ASSERTIF(C, X) do {} while (0)
#define ASSERTIFCMP(C, X, OP, Y) do {} while (0)
#endif /* assert or not */
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