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sunrpc: add helpers to count and snapshot pending cache requests

Add sunrpc_cache_requests_count() and sunrpc_cache_requests_snapshot() to allow callers to count and snapshot the pending upcall request list without exposing struct cache_request outside of cache.c. Both functions skip entries that no longer have CACHE_PENDING set. The snapshot function takes a cache_get() reference on each item so the caller can safely use them after the queue_lock is released. These will be used by the nfsd generic netlink dumpit handler for svc_export upcall requests.

Jeff Layton committed 7 months ago

Commit c13ecd41 parent d52db762 files · +67 −0Browse files

Unified · Split

2 files
  1. include/linux/sunrpc/cache.h +6 −0
  2. net/sunrpc/cache.c +61 −0
include/linux/sunrpc/cache.h+6−0
@@ -251,6 +251,12 @@ extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *, · 250 unmodified lines
251extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);251extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
252extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);252extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
253 253
254int sunrpc_cache_requests_count(struct cache_detail *cd);
255int sunrpc_cache_requests_snapshot(struct cache_detail *cd,
256 struct cache_head **items,
257 u64 *seqnos, int max,
258 u64 min_seqno);
259
254/* Must store cache_detail in seq_file->private if using next three functions */260/* Must store cache_detail in seq_file->private if using next three functions */
255extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);261extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
256extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);262extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
net/sunrpc/cache.c+61−0
@@ -1902,3 +1902,64 @@ void sunrpc_cache_unhash(struct cache_detail *cd, struct cache_head *h) · 1901 unmodified lines
1902 spin_unlock(&cd->hash_lock);1902 spin_unlock(&cd->hash_lock);
1903}1903}
1904EXPORT_SYMBOL_GPL(sunrpc_cache_unhash);1904EXPORT_SYMBOL_GPL(sunrpc_cache_unhash);
1905
1906/**
1907 * sunrpc_cache_requests_count - count pending upcall requests
1908 * @cd: cache_detail to query
1909 *
1910 * Returns the number of requests on the cache's request list that
1911 * still have CACHE_PENDING set.
1912 */
1913int sunrpc_cache_requests_count(struct cache_detail *cd)
1914{
1915 struct cache_request *crq;
1916 int cnt = 0;
1917
1918 spin_lock(&cd->queue_lock);
1919 list_for_each_entry(crq, &cd->requests, list) {
1920 if (test_bit(CACHE_PENDING, &crq->item->flags))
1921 cnt++;
1922 }
1923 spin_unlock(&cd->queue_lock);
1924 return cnt;
1925}
1926EXPORT_SYMBOL_GPL(sunrpc_cache_requests_count);
1927
1928/**
1929 * sunrpc_cache_requests_snapshot - snapshot pending upcall requests
1930 * @cd: cache_detail to query
1931 * @items: array to fill with cache_head pointers (caller-allocated)
1932 * @seqnos: array to fill with sequence numbers (caller-allocated)
1933 * @max: size of the arrays
1934 * @min_seqno: only include entries with seqno > min_seqno (0 for all)
1935 *
1936 * Only entries with CACHE_PENDING set are included. Takes a reference
1937 * on each cache_head via cache_get(). Caller must call cache_put()
1938 * on each returned item when done.
1939 *
1940 * Returns the number of entries filled.
1941 */
1942int sunrpc_cache_requests_snapshot(struct cache_detail *cd,
1943 struct cache_head **items,
1944 u64 *seqnos, int max,
1945 u64 min_seqno)
1946{
1947 struct cache_request *crq;
1948 int i = 0;
1949
1950 spin_lock(&cd->queue_lock);
1951 list_for_each_entry(crq, &cd->requests, list) {
1952 if (i >= max)
1953 break;
1954 if (!test_bit(CACHE_PENDING, &crq->item->flags))
1955 continue;
1956 if (crq->seqno <= min_seqno)
1957 continue;
1958 items[i] = cache_get(crq->item);
1959 seqnos[i] = crq->seqno;
1960 i++;
1961 }
1962 spin_unlock(&cd->queue_lock);
1963 return i;
1964}
1965EXPORT_SYMBOL_GPL(sunrpc_cache_requests_snapshot);