netfs: Add a procfile to list in-progress requests

Add a procfile, /proc/fs/netfs/requests, to list in-progress netfslib I/O
requests.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org

diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
index 3f6e222294339e54b780908859ec52501edb525f..4708fb15446bdaa7d381c8b2ed491e14e2bbda5e 100644 (file)
--- a/fs/netfs/internal.h
+++ b/fs/netfs/internal.h
@@ -33,6 +33,28 @@ int netfs_begin_read(struct netfs_io_request *rreq, bool sync);
  * main.c
  */
 extern unsigned int netfs_debug;
+extern struct list_head netfs_io_requests;
+extern spinlock_t netfs_proc_lock;
+
+#ifdef CONFIG_PROC_FS
+static inline void netfs_proc_add_rreq(struct netfs_io_request *rreq)
+{
+       spin_lock(&netfs_proc_lock);
+       list_add_tail_rcu(&rreq->proc_link, &netfs_io_requests);
+       spin_unlock(&netfs_proc_lock);
+}
+static inline void netfs_proc_del_rreq(struct netfs_io_request *rreq)
+{
+       if (!list_empty(&rreq->proc_link)) {
+               spin_lock(&netfs_proc_lock);
+               list_del_rcu(&rreq->proc_link);
+               spin_unlock(&netfs_proc_lock);
+       }
+}
+#else
+static inline void netfs_proc_add_rreq(struct netfs_io_request *rreq) {}
+static inline void netfs_proc_del_rreq(struct netfs_io_request *rreq) {}
+#endif
 
 /*
  * objects.c

diff --git a/fs/netfs/main.c b/fs/netfs/main.c
index c9af6e0896d31c480c05ab46caacbe52d65264e2..97ce1436615b725eb12747db03b643975830e077 100644 (file)
--- a/fs/netfs/main.c
+++ b/fs/netfs/main.c
@@ -21,13 +21,80 @@ unsigned netfs_debug;
 module_param_named(debug, netfs_debug, uint, S_IWUSR | S_IRUGO);
 MODULE_PARM_DESC(netfs_debug, "Netfs support debugging mask");
 
+#ifdef CONFIG_PROC_FS
+LIST_HEAD(netfs_io_requests);
+DEFINE_SPINLOCK(netfs_proc_lock);
+
+static const char *netfs_origins[] = {
+       [NETFS_READAHEAD]       = "RA",
+       [NETFS_READPAGE]        = "RP",
+       [NETFS_READ_FOR_WRITE]  = "RW",
+};
+
+/*
+ * Generate a list of I/O requests in /proc/fs/netfs/requests
+ */
+static int netfs_requests_seq_show(struct seq_file *m, void *v)
+{
+       struct netfs_io_request *rreq;
+
+       if (v == &netfs_io_requests) {
+               seq_puts(m,
+                        "REQUEST  OR REF FL ERR  OPS COVERAGE\n"
+                        "======== == === == ==== === =========\n"
+                        );
+               return 0;
+       }
+
+       rreq = list_entry(v, struct netfs_io_request, proc_link);
+       seq_printf(m,
+                  "%08x %s %3d %2lx %4d %3d @%04llx %zx/%zx",
+                  rreq->debug_id,
+                  netfs_origins[rreq->origin],
+                  refcount_read(&rreq->ref),
+                  rreq->flags,
+                  rreq->error,
+                  atomic_read(&rreq->nr_outstanding),
+                  rreq->start, rreq->submitted, rreq->len);
+       seq_putc(m, '\n');
+       return 0;
+}
+
+static void *netfs_requests_seq_start(struct seq_file *m, loff_t *_pos)
+       __acquires(rcu)
+{
+       rcu_read_lock();
+       return seq_list_start_head(&netfs_io_requests, *_pos);
+}
+
+static void *netfs_requests_seq_next(struct seq_file *m, void *v, loff_t *_pos)
+{
+       return seq_list_next(v, &netfs_io_requests, _pos);
+}
+
+static void netfs_requests_seq_stop(struct seq_file *m, void *v)
+       __releases(rcu)
+{
+       rcu_read_unlock();
+}
+
+static const struct seq_operations netfs_requests_seq_ops = {
+       .start  = netfs_requests_seq_start,
+       .next   = netfs_requests_seq_next,
+       .stop   = netfs_requests_seq_stop,
+       .show   = netfs_requests_seq_show,
+};
+#endif /* CONFIG_PROC_FS */
+
 static int __init netfs_init(void)
 {
        int ret = -ENOMEM;
 
        if (!proc_mkdir("fs/netfs", NULL))
                goto error;
-
+       if (!proc_create_seq("fs/netfs/requests", S_IFREG | 0444, NULL,
+                            &netfs_requests_seq_ops))
+               goto error_proc;
 #ifdef CONFIG_FSCACHE_STATS
        if (!proc_create_single("fs/netfs/stats", S_IFREG | 0444, NULL,
                                netfs_stats_show))

diff --git a/fs/netfs/objects.c b/fs/netfs/objects.c
index e17cdf53f6a7883a3459c47d5695554e516f4c51..85f428fc52e6fb33db3f28136c16332ffa2ab12d 100644 (file)
--- a/fs/netfs/objects.c
+++ b/fs/netfs/objects.c
@@ -45,6 +45,7 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
                }
        }
 
+       netfs_proc_add_rreq(rreq);
        netfs_stat(&netfs_n_rh_rreq);
        return rreq;
 }
@@ -76,12 +77,13 @@ static void netfs_free_request(struct work_struct *work)
                container_of(work, struct netfs_io_request, work);
 
        trace_netfs_rreq(rreq, netfs_rreq_trace_free);
+       netfs_proc_del_rreq(rreq);
        netfs_clear_subrequests(rreq, false);
        if (rreq->netfs_ops->free_request)
                rreq->netfs_ops->free_request(rreq);
        if (rreq->cache_resources.ops)
                rreq->cache_resources.ops->end_operation(&rreq->cache_resources);
-       kfree(rreq);
+       kfree_rcu(rreq, rcu);
        netfs_stat_d(&netfs_n_rh_rreq);
 }
 

diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 32faf6c897029a64caca737194726998b0d971ca..7244ddebd974cc3d30c0bf6031f5fa7eeb0316ac 100644 (file)
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -175,10 +175,14 @@ enum netfs_io_origin {
  * operations to a variety of data stores and then stitch the result together.
  */
 struct netfs_io_request {
-       struct work_struct      work;
+       union {
+               struct work_struct work;
+               struct rcu_head rcu;
+       };
        struct inode            *inode;         /* The file being accessed */
        struct address_space    *mapping;       /* The mapping being accessed */
        struct netfs_cache_resources cache_resources;
+       struct list_head        proc_link;      /* Link in netfs_iorequests */
        struct list_head        subrequests;    /* Contributory I/O operations */
        void                    *netfs_priv;    /* Private data for the netfs */
        unsigned int            debug_id;