From 9a9d575074e72f58a4aba80fd6078c6d98072af8 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Tue, 20 Oct 2015 13:33:43 -0400 Subject: [PATCH] nfsd: keep some rudimentary stats on nfsd_file cache Per chain count and max length, protected by the per-chain spinlock. When the file is read, we walk the array of buckets and fetch the count from each. Signed-off-by: Jeff Layton Signed-off-by: J. Bruce Fields --- fs/nfsd/filecache.c | 40 ++++++++++++++++++++++++++++++++++++++++ fs/nfsd/filecache.h | 1 + fs/nfsd/nfsctl.c | 10 ++++++++++ 3 files changed, 51 insertions(+) diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index 2cbdf9889993..aca3c3c638ec 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -11,6 +11,7 @@ #include #include #include +#include #include "vfs.h" #include "nfsd.h" @@ -30,6 +31,8 @@ struct nfsd_fcache_bucket { struct hlist_head nfb_head; spinlock_t nfb_lock; + unsigned int nfb_count; + unsigned int nfb_maxcount; }; static struct kmem_cache *nfsd_file_slab; @@ -171,6 +174,7 @@ nfsd_file_unhash(struct nfsd_file *nf) trace_nfsd_file_unhash(nf); if (test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) { + --nfsd_file_hashtbl[nf->nf_hashval].nfb_count; clear_bit(NFSD_FILE_HASHED, &nf->nf_flags); hlist_del_rcu(&nf->nf_node); list_lru_del(&nfsd_file_lru, &nf->nf_lru); @@ -587,6 +591,9 @@ retry: list_lru_add(&nfsd_file_lru, &new->nf_lru); hlist_add_head_rcu(&new->nf_node, &nfsd_file_hashtbl[hashval].nfb_head); + ++nfsd_file_hashtbl[hashval].nfb_count; + nfsd_file_hashtbl[hashval].nfb_maxcount = max(nfsd_file_hashtbl[hashval].nfb_maxcount, + nfsd_file_hashtbl[hashval].nfb_count); spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock); nf = new; new = NULL; @@ -669,3 +676,36 @@ open_file: wake_up_bit(&nf->nf_flags, NFSD_FILE_PENDING); goto out; } + +/* + * Note that fields may be added, removed or reordered in the future. Programs + * scraping this file for info should test the labels to ensure they're + * getting the correct field. + */ +static int nfsd_file_cache_stats_show(struct seq_file *m, void *v) +{ + unsigned int i, count = 0, longest = 0; + + /* + * No need for spinlocks here since we're not terribly interested in + * accuracy. We do take the nfsd_mutex simply to ensure that we + * don't end up racing with server shutdown + */ + mutex_lock(&nfsd_mutex); + if (nfsd_file_hashtbl) { + for (i = 0; i < NFSD_FILE_HASH_SIZE; i++) { + count += nfsd_file_hashtbl[i].nfb_count; + longest = max(longest, nfsd_file_hashtbl[i].nfb_count); + } + } + mutex_unlock(&nfsd_mutex); + + seq_printf(m, "total entries: %u\n", count); + seq_printf(m, "longest chain: %u\n", longest); + return 0; +} + +int nfsd_file_cache_stats_open(struct inode *inode, struct file *file) +{ + return single_open(file, nfsd_file_cache_stats_show, NULL); +} diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h index a045c7fe3655..756aea5431da 100644 --- a/fs/nfsd/filecache.h +++ b/fs/nfsd/filecache.h @@ -40,4 +40,5 @@ struct nfsd_file *nfsd_file_get(struct nfsd_file *nf); void nfsd_file_close_inode_sync(struct inode *inode); __be32 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, unsigned int may_flags, struct nfsd_file **nfp); +int nfsd_file_cache_stats_open(struct inode *, struct file *); #endif /* _FS_NFSD_FILECACHE_H */ diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 9690cb4dd588..eff44a277f70 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -22,6 +22,7 @@ #include "state.h" #include "netns.h" #include "pnfs.h" +#include "filecache.h" /* * We have a single directory with several nodes in it. @@ -36,6 +37,7 @@ enum { NFSD_Threads, NFSD_Pool_Threads, NFSD_Pool_Stats, + NFSD_File_Cache_Stats, NFSD_Reply_Cache_Stats, NFSD_Versions, NFSD_Ports, @@ -220,6 +222,13 @@ static const struct file_operations pool_stats_operations = { .owner = THIS_MODULE, }; +static struct file_operations file_cache_stats_operations = { + .open = nfsd_file_cache_stats_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + static struct file_operations reply_cache_stats_operations = { .open = nfsd_reply_cache_stats_open, .read = seq_read, @@ -1138,6 +1147,7 @@ static int nfsd_fill_super(struct super_block * sb, void * data, int silent) [NFSD_Threads] = {"threads", &transaction_ops, S_IWUSR|S_IRUSR}, [NFSD_Pool_Threads] = {"pool_threads", &transaction_ops, S_IWUSR|S_IRUSR}, [NFSD_Pool_Stats] = {"pool_stats", &pool_stats_operations, S_IRUGO}, + [NFSD_File_Cache_Stats] = {"file_cache_stats", &file_cache_stats_operations, S_IRUGO}, [NFSD_Reply_Cache_Stats] = {"reply_cache_stats", &reply_cache_stats_operations, S_IRUGO}, [NFSD_Versions] = {"versions", &transaction_ops, S_IWUSR|S_IRUSR}, [NFSD_Ports] = {"portlist", &transaction_ops, S_IWUSR|S_IRUGO}, -- 2.39.5