Commit 3929eca7 authored by David Howells's avatar David Howells
Browse files

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: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarJeff 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
parent ecd1a5f6

fs/cachefiles/cache.c

+15 −3
Original line number Diff line number Diff line
@@ -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 ###");

fs/cachefiles/daemon.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

fs/cachefiles/internal.h

+9 −2
Original line number Diff line number Diff line
@@ -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

 */

fs/cachefiles/io.c

+5 −2
Original line number Diff line number Diff line
@@ -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,

fs/cachefiles/namei.c

+4 −2
Original line number Diff line number Diff line
@@ -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;