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linux/fs/cachefiles/internal.h
Xin Yin 1122f40072 cachefiles: make on-demand request distribution fairer 
For now, enqueuing and dequeuing on-demand requests all start from
idx 0, this makes request distribution unfair. In the weighty
concurrent I/O scenario, the request stored in higher idx will starve.

Searching requests cyclically in cachefiles_ondemand_daemon_read,
makes distribution fairer.

Fixes: c838305450 ("cachefiles: notify the user daemon when looking up cookie")
Reported-by: Yongqing Li <liyongqing@bytedance.com>
Signed-off-by: Xin Yin <yinxin.x@bytedance.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220817065200.11543-1-yinxin.x@bytedance.com/ # v1
Link: https://lore.kernel.org/r/20220825020945.2293-1-yinxin.x@bytedance.com/ # v2
2022-08-31 16:41:10 +01:00

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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* General netfs cache on cache files internal defs
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#ifdef pr_fmt
#undef pr_fmt
#endif
#define pr_fmt(fmt) "CacheFiles: " fmt
#include <linux/fscache-cache.h>
#include <linux/cred.h>
#include <linux/security.h>
#include <linux/xarray.h>
#include <linux/cachefiles.h>
#define CACHEFILES_DIO_BLOCK_SIZE 4096
struct cachefiles_cache;
struct cachefiles_object;
enum cachefiles_content {
/* These values are saved on disk */
CACHEFILES_CONTENT_NO_DATA = 0, /* No content stored */
CACHEFILES_CONTENT_SINGLE = 1, /* Content is monolithic, all is present */
CACHEFILES_CONTENT_ALL = 2, /* Content is all present, no map */
CACHEFILES_CONTENT_BACKFS_MAP = 3, /* Content is piecemeal, mapped through backing fs */
CACHEFILES_CONTENT_DIRTY = 4, /* Content is dirty (only seen on disk) */
nr__cachefiles_content
};
/*
* Cached volume representation.
*/
struct cachefiles_volume {
struct cachefiles_cache *cache;
struct list_head cache_link; /* Link in cache->volumes */
struct fscache_volume *vcookie; /* The netfs's representation */
struct dentry *dentry; /* The volume dentry */
struct dentry *fanout[256]; /* Fanout subdirs */
};
/*
* Backing file state.
*/
struct cachefiles_object {
struct fscache_cookie *cookie; /* Netfs data storage object cookie */
struct cachefiles_volume *volume; /* Cache volume that holds this object */
struct list_head cache_link; /* Link in cache->*_list */
struct file *file; /* The file representing this object */
char *d_name; /* Backing file name */
int debug_id;
spinlock_t lock;
refcount_t ref;
u8 d_name_len; /* Length of filename */
enum cachefiles_content content_info:8; /* Info about content presence */
unsigned long flags;
#define CACHEFILES_OBJECT_USING_TMPFILE 0 /* Have an unlinked tmpfile */
#ifdef CONFIG_CACHEFILES_ONDEMAND
int ondemand_id;
#endif
};
#define CACHEFILES_ONDEMAND_ID_CLOSED -1
/*
* Cache files cache definition
*/
struct cachefiles_cache {
struct fscache_cache *cache; /* Cache cookie */
struct vfsmount *mnt; /* mountpoint holding the cache */
struct dentry *store; /* Directory into which live objects go */
struct dentry *graveyard; /* directory into which dead objects go */
struct file *cachefilesd; /* manager daemon handle */
struct list_head volumes; /* List of volume objects */
struct list_head object_list; /* List of active objects */
spinlock_t object_list_lock; /* Lock for volumes and object_list */
const struct cred *cache_cred; /* security override for accessing cache */
struct mutex daemon_mutex; /* command serialisation mutex */
wait_queue_head_t daemon_pollwq; /* poll waitqueue for daemon */
atomic_t gravecounter; /* graveyard uniquifier */
atomic_t f_released; /* number of objects released lately */
atomic_long_t b_released; /* number of blocks released lately */
atomic_long_t b_writing; /* Number of blocks being written */
unsigned frun_percent; /* when to stop culling (% files) */
unsigned fcull_percent; /* when to start culling (% files) */
unsigned fstop_percent; /* when to stop allocating (% files) */
unsigned brun_percent; /* when to stop culling (% blocks) */
unsigned bcull_percent; /* when to start culling (% blocks) */
unsigned bstop_percent; /* when to stop allocating (% blocks) */
unsigned bsize; /* cache's block size */
unsigned bshift; /* ilog2(bsize) */
uint64_t frun; /* when to stop culling */
uint64_t fcull; /* when to start culling */
uint64_t fstop; /* when to stop allocating */
sector_t brun; /* when to stop culling */
sector_t bcull; /* when to start culling */
sector_t bstop; /* when to stop allocating */
unsigned long flags;
#define CACHEFILES_READY 0 /* T if cache prepared */
#define CACHEFILES_DEAD 1 /* T if cache dead */
#define CACHEFILES_CULLING 2 /* T if cull engaged */
#define CACHEFILES_STATE_CHANGED 3 /* T if state changed (poll trigger) */
#define CACHEFILES_ONDEMAND_MODE 4 /* T if in on-demand read mode */
char *rootdirname; /* name of cache root directory */
char *secctx; /* LSM security context */
char *tag; /* cache binding tag */
refcount_t unbind_pincount;/* refcount to do daemon unbind */
struct xarray reqs; /* xarray of pending on-demand requests */
unsigned long req_id_next;
struct xarray ondemand_ids; /* xarray for ondemand_id allocation */
u32 ondemand_id_next;
};
static inline bool cachefiles_in_ondemand_mode(struct cachefiles_cache *cache)
{
return IS_ENABLED(CONFIG_CACHEFILES_ONDEMAND) &&
test_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags);
}
struct cachefiles_req {
struct cachefiles_object *object;
struct completion done;
int error;
struct cachefiles_msg msg;
};
#define CACHEFILES_REQ_NEW XA_MARK_1
#include <trace/events/cachefiles.h>
static inline
struct file *cachefiles_cres_file(struct netfs_cache_resources *cres)
{
return cres->cache_priv2;
}
static inline
struct cachefiles_object *cachefiles_cres_object(struct netfs_cache_resources *cres)
{
return fscache_cres_cookie(cres)->cache_priv;
}
/*
* note change of state for daemon
*/
static inline void cachefiles_state_changed(struct cachefiles_cache *cache)
{
set_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
wake_up_all(&cache->daemon_pollwq);
}
/*
* cache.c
*/
extern int cachefiles_add_cache(struct cachefiles_cache *cache);
extern void cachefiles_withdraw_cache(struct cachefiles_cache *cache);
enum cachefiles_has_space_for {
cachefiles_has_space_check,
cachefiles_has_space_for_write,
cachefiles_has_space_for_create,
};
extern int cachefiles_has_space(struct cachefiles_cache *cache,
unsigned fnr, unsigned bnr,
enum cachefiles_has_space_for reason);
/*
* daemon.c
*/
extern const struct file_operations cachefiles_daemon_fops;
extern void cachefiles_get_unbind_pincount(struct cachefiles_cache *cache);
extern void cachefiles_put_unbind_pincount(struct cachefiles_cache *cache);
/*
* error_inject.c
*/
#ifdef CONFIG_CACHEFILES_ERROR_INJECTION
extern unsigned int cachefiles_error_injection_state;
extern int cachefiles_register_error_injection(void);
extern void cachefiles_unregister_error_injection(void);
#else
#define cachefiles_error_injection_state 0
static inline int cachefiles_register_error_injection(void)
{
return 0;
}
static inline void cachefiles_unregister_error_injection(void)
{
}
#endif
static inline int cachefiles_inject_read_error(void)
{
return cachefiles_error_injection_state & 2 ? -EIO : 0;
}
static inline int cachefiles_inject_write_error(void)
{
return cachefiles_error_injection_state & 2 ? -EIO :
cachefiles_error_injection_state & 1 ? -ENOSPC :
0;
}
static inline int cachefiles_inject_remove_error(void)
{
return cachefiles_error_injection_state & 2 ? -EIO : 0;
}
/*
* interface.c
*/
extern const struct fscache_cache_ops cachefiles_cache_ops;
extern void cachefiles_see_object(struct cachefiles_object *object,
enum cachefiles_obj_ref_trace why);
extern struct cachefiles_object *cachefiles_grab_object(struct cachefiles_object *object,
enum cachefiles_obj_ref_trace why);
extern void cachefiles_put_object(struct cachefiles_object *object,
enum cachefiles_obj_ref_trace why);
/*
* io.c
*/
extern bool cachefiles_begin_operation(struct netfs_cache_resources *cres,
enum fscache_want_state want_state);
extern int __cachefiles_prepare_write(struct cachefiles_object *object,
struct file *file,
loff_t *_start, size_t *_len,
bool no_space_allocated_yet);
extern int __cachefiles_write(struct cachefiles_object *object,
struct file *file,
loff_t start_pos,
struct iov_iter *iter,
netfs_io_terminated_t term_func,
void *term_func_priv);
/*
* key.c
*/
extern bool cachefiles_cook_key(struct cachefiles_object *object);
/*
* main.c
*/
extern struct kmem_cache *cachefiles_object_jar;
/*
* namei.c
*/
extern void cachefiles_unmark_inode_in_use(struct cachefiles_object *object,
struct file *file);
extern int cachefiles_bury_object(struct cachefiles_cache *cache,
struct cachefiles_object *object,
struct dentry *dir,
struct dentry *rep,
enum fscache_why_object_killed why);
extern int cachefiles_delete_object(struct cachefiles_object *object,
enum fscache_why_object_killed why);
extern bool cachefiles_look_up_object(struct cachefiles_object *object);
extern struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
struct dentry *dir,
const char *name,
bool *_is_new);
extern void cachefiles_put_directory(struct dentry *dir);
extern int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
char *filename);
extern int cachefiles_check_in_use(struct cachefiles_cache *cache,
struct dentry *dir, char *filename);
extern struct file *cachefiles_create_tmpfile(struct cachefiles_object *object);
extern bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache,
struct cachefiles_object *object);
/*
* ondemand.c
*/
#ifdef CONFIG_CACHEFILES_ONDEMAND
extern ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
char __user *_buffer, size_t buflen);
extern int cachefiles_ondemand_copen(struct cachefiles_cache *cache,
char *args);
extern int cachefiles_ondemand_init_object(struct cachefiles_object *object);
extern void cachefiles_ondemand_clean_object(struct cachefiles_object *object);
extern int cachefiles_ondemand_read(struct cachefiles_object *object,
loff_t pos, size_t len);
#else
static inline ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
char __user *_buffer, size_t buflen)
{
return -EOPNOTSUPP;
}
static inline int cachefiles_ondemand_init_object(struct cachefiles_object *object)
{
return 0;
}
static inline void cachefiles_ondemand_clean_object(struct cachefiles_object *object)
{
}
static inline int cachefiles_ondemand_read(struct cachefiles_object *object,
loff_t pos, size_t len)
{
return -EOPNOTSUPP;
}
#endif
/*
* security.c
*/
extern int cachefiles_get_security_ID(struct cachefiles_cache *cache);
extern int cachefiles_determine_cache_security(struct cachefiles_cache *cache,
struct dentry *root,
const struct cred **_saved_cred);
static inline void cachefiles_begin_secure(struct cachefiles_cache *cache,
const struct cred **_saved_cred)
{
*_saved_cred = override_creds(cache->cache_cred);
}
static inline void cachefiles_end_secure(struct cachefiles_cache *cache,
const struct cred *saved_cred)
{
revert_creds(saved_cred);
}
/*
* volume.c
*/
void cachefiles_acquire_volume(struct fscache_volume *volume);
void cachefiles_free_volume(struct fscache_volume *volume);
void cachefiles_withdraw_volume(struct cachefiles_volume *volume);
/*
* xattr.c
*/
extern int cachefiles_set_object_xattr(struct cachefiles_object *object);
extern int cachefiles_check_auxdata(struct cachefiles_object *object,
struct file *file);
extern int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
struct cachefiles_object *object,
struct dentry *dentry);
extern void cachefiles_prepare_to_write(struct fscache_cookie *cookie);
extern bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume);
extern int cachefiles_check_volume_xattr(struct cachefiles_volume *volume);
/*
* Error handling
*/
#define cachefiles_io_error(___cache, FMT, ...) \
do { \
pr_err("I/O Error: " FMT"\n", ##__VA_ARGS__); \
fscache_io_error((___cache)->cache); \
set_bit(CACHEFILES_DEAD, &(___cache)->flags); \
} while (0)
#define cachefiles_io_error_obj(object, FMT, ...) \
do { \
struct cachefiles_cache *___cache; \
\
___cache = (object)->volume->cache; \
cachefiles_io_error(___cache, FMT " [o=%08x]", ##__VA_ARGS__, \
(object)->debug_id); \
} while (0)
/*
* Debug tracing
*/
extern unsigned cachefiles_debug;
#define CACHEFILES_DEBUG_KENTER 1
#define CACHEFILES_DEBUG_KLEAVE 2
#define CACHEFILES_DEBUG_KDEBUG 4
#define dbgprintk(FMT, ...) \
printk(KERN_DEBUG "[%-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__)
#if defined(__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_CACHEFILES_DEBUG)
#define _enter(FMT, ...) \
do { \
if (cachefiles_debug & CACHEFILES_DEBUG_KENTER) \
kenter(FMT, ##__VA_ARGS__); \
} while (0)
#define _leave(FMT, ...) \
do { \
if (cachefiles_debug & CACHEFILES_DEBUG_KLEAVE) \
kleave(FMT, ##__VA_ARGS__); \
} while (0)
#define _debug(FMT, ...) \
do { \
if (cachefiles_debug & CACHEFILES_DEBUG_KDEBUG) \
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
#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
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