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fscache, cachefiles: Display stats of no-space events 

Add stat counters of no-space events that caused caching not to happen and
display in /proc/fs/fscache/stats.

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/163819653216.215744.17210522251617386509.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906958369.143852.7257100711818401748.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967166917.1823006.14842444049198947892.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021566184.640689.4417328329632709265.stgit@warthog.procyon.org.uk/ # v4
This commit is contained in:
David Howells 2021-10-21 21:58:29 +01:00
parent ecd1a5f62e
commit 3929eca769
7 changed files with 48 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
fs/cachefiles/cache.c
View File

@ -147,7 +147,7 @@ int cachefiles_add_cache(struct cachefiles_cache *cache)
pr_info("File cache on %s registered\n", cache_cookie->name);
/* check how much space the cache has */
cachefiles_has_space(cache, 0, 0);
cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check);
cachefiles_end_secure(cache, saved_cred);
_leave(" = 0 [%px]", cache->cache);
return 0;
@ -175,7 +175,8 @@ int cachefiles_add_cache(struct cachefiles_cache *cache)
* cache
*/
int cachefiles_has_space(struct cachefiles_cache *cache,
unsigned fnr, unsigned bnr)
unsigned fnr, unsigned bnr,
enum cachefiles_has_space_for reason)
{
struct kstatfs stats;
u64 b_avail, b_writing;
@ -233,7 +234,7 @@ int cachefiles_has_space(struct cachefiles_cache *cache,
ret = -ENOBUFS;
if (stats.f_ffree < cache->fstop ||
b_avail < cache->bstop)
goto begin_cull;
goto stop_and_begin_cull;
ret = 0;
if (stats.f_ffree < cache->fcull ||
@ -252,6 +253,17 @@ int cachefiles_has_space(struct cachefiles_cache *cache,
//_leave(" = 0");
return 0;
stop_and_begin_cull:
switch (reason) {
case cachefiles_has_space_for_write:
fscache_count_no_write_space();
break;
case cachefiles_has_space_for_create:
fscache_count_no_create_space();
break;
default:
break;
}
begin_cull:
if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
_debug("### CULL CACHE ###");

2
fs/cachefiles/daemon.c
View File

@ -170,7 +170,7 @@ static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
return 0;
/* check how much space the cache has */
cachefiles_has_space(cache, 0, 0);
cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check);
/* summarise */
f_released = atomic_xchg(&cache->f_released, 0);

11
fs/cachefiles/internal.h
View File

@ -130,10 +130,17 @@ static inline void cachefiles_state_changed(struct cachefiles_cache *cache)
* cache.c
*/
extern int cachefiles_add_cache(struct cachefiles_cache *cache);
extern int cachefiles_has_space(struct cachefiles_cache *cache,
unsigned fnr, unsigned bnr);
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
*/

7
fs/cachefiles/io.c
View File

@ -468,7 +468,8 @@ static int __cachefiles_prepare_write(struct netfs_cache_resources *cres,
* space, we need to see if it's fully allocated. If it's not, we may
* want to cull it.
*/
if (cachefiles_has_space(cache, 0, *_len / PAGE_SIZE) == 0)
if (cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
cachefiles_has_space_check) == 0)
return 0; /* Enough space to simply overwrite the whole block */
pos = cachefiles_inject_read_error();
@ -483,6 +484,7 @@ static int __cachefiles_prepare_write(struct netfs_cache_resources *cres,
return 0; /* Fully allocated */
/* Partially allocated, but insufficient space: cull. */
fscache_count_no_write_space();
ret = cachefiles_inject_remove_error();
if (ret == 0)
ret = vfs_fallocate(file, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
@ -498,7 +500,8 @@ static int __cachefiles_prepare_write(struct netfs_cache_resources *cres,
return ret;
check_space:
return cachefiles_has_space(cache, 0, *_len / PAGE_SIZE);
return cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
cachefiles_has_space_for_write);
}
static int cachefiles_prepare_write(struct netfs_cache_resources *cres,

6
fs/cachefiles/namei.c
View File

@ -115,7 +115,8 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
/* we need to create the subdir if it doesn't exist yet */
if (d_is_negative(subdir)) {
ret = cachefiles_has_space(cache, 1, 0);
ret = cachefiles_has_space(cache, 1, 0,
cachefiles_has_space_for_create);
if (ret < 0)
goto mkdir_error;
@ -513,7 +514,8 @@ static bool cachefiles_create_file(struct cachefiles_object *object)
struct file *file;
int ret;
ret = cachefiles_has_space(object->volume->cache, 1, 0);
ret = cachefiles_has_space(object->volume->cache, 1, 0,
cachefiles_has_space_for_create);
if (ret < 0)
return false;

8
fs/fscache/stats.c
View File

@ -42,6 +42,10 @@ atomic_t fscache_n_read;
EXPORT_SYMBOL(fscache_n_read);
atomic_t fscache_n_write;
EXPORT_SYMBOL(fscache_n_write);
atomic_t fscache_n_no_write_space;
EXPORT_SYMBOL(fscache_n_no_write_space);
atomic_t fscache_n_no_create_space;
EXPORT_SYMBOL(fscache_n_no_create_space);
/*
* display the general statistics
@ -82,6 +86,10 @@ int fscache_stats_show(struct seq_file *m, void *v)
atomic_read(&fscache_n_relinquishes_retire),
atomic_read(&fscache_n_relinquishes_dropped));
seq_printf(m, "NoSpace: nwr=%u ncr=%u\n",
atomic_read(&fscache_n_no_write_space),
atomic_read(&fscache_n_no_create_space));
seq_printf(m, "IO : rd=%u wr=%u\n",
atomic_read(&fscache_n_read),
atomic_read(&fscache_n_write));

6
include/linux/fscache-cache.h
View File

@ -186,11 +186,17 @@ static inline void fscache_wait_for_objects(struct fscache_cache *cache)
#ifdef CONFIG_FSCACHE_STATS
extern atomic_t fscache_n_read;
extern atomic_t fscache_n_write;
extern atomic_t fscache_n_no_write_space;
extern atomic_t fscache_n_no_create_space;
#define fscache_count_read() atomic_inc(&fscache_n_read)
#define fscache_count_write() atomic_inc(&fscache_n_write)
#define fscache_count_no_write_space() atomic_inc(&fscache_n_no_write_space)
#define fscache_count_no_create_space() atomic_inc(&fscache_n_no_create_space)
#else
#define fscache_count_read() do {} while(0)
#define fscache_count_write() do {} while(0)
#define fscache_count_no_write_space() do {} while(0)
#define fscache_count_no_create_space() do {} while(0)
#endif
#endif /* _LINUX_FSCACHE_CACHE_H */