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linux/fs/netfs/internal.h
David Howells ee4cdf7ba8
netfs: Speed up buffered reading 
Improve the efficiency of buffered reads in a number of ways:

 (1) Overhaul the algorithm in general so that it's a lot more compact and
     split the read submission code between buffered and unbuffered
     versions.  The unbuffered version can be vastly simplified.

 (2) Read-result collection is handed off to a work queue rather than being
     done in the I/O thread.  Multiple subrequests can be processes
     simultaneously.

 (3) When a subrequest is collected, any folios it fully spans are
     collected and "spare" data on either side is donated to either the
     previous or the next subrequest in the sequence.

Notes:

 (*) Readahead expansion is massively slows down fio, presumably because it
     causes a load of extra allocations, both folio and xarray, up front
     before RPC requests can be transmitted.

 (*) RDMA with cifs does appear to work, both with SIW and RXE.

 (*) PG_private_2-based reading and copy-to-cache is split out into its own
     file and altered to use folio_queue.  Note that the copy to the cache
     now creates a new write transaction against the cache and adds the
     folios to be copied into it.  This allows it to use part of the
     writeback I/O code.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20240814203850.2240469-20-dhowells@redhat.com/ # v2
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-09-12 12:20:41 +02:00

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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
*/
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
*/
int netfs_buffer_append_folio(struct netfs_io_request *rreq, struct folio *folio,
bool needs_put);
struct folio_queue *netfs_delete_buffer_head(struct netfs_io_request *wreq);
void netfs_clear_buffer(struct netfs_io_request *rreq);
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);
}
/*
* read_collect.c
*/
void netfs_read_termination_worker(struct work_struct *work);
void netfs_rreq_terminated(struct netfs_io_request *rreq, bool was_async);
/*
* read_pgpriv2.c
*/
void netfs_pgpriv2_mark_copy_to_cache(struct netfs_io_subrequest *subreq,
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_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);
int 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);
/*
* 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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