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drbd: debugfs: add in_flight_summary data
To help diagnosing "high latency" or "hung" IO situations on DRBD,
present per drbd resource group a summary of operations currently in progress.
First item is a list of oldest drbd_request objects
waiting for various things:
* still being prepared
* waiting for activity log transaction
* waiting for local disk
* waiting to be sent
* waiting for peer acknowledgement ("receive ack", "write ack")
* waiting for peer epoch acknowledgement ("barrier ack")
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Lars Ellenberg
Philipp Reisner
parent
4d3d5aa83a
commit
db1866ffee
@ -2,7 +2,9 @@
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/debugfs.h>
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#include <linux/seq_file.h>
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#include <linux/stat.h>
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#include <linux/jiffies.h>
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#include <linux/list.h>
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#include "drbd_int.h"
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@ -13,6 +15,194 @@ static struct dentry *drbd_debugfs_root;
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static struct dentry *drbd_debugfs_resources;
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static struct dentry *drbd_debugfs_minors;
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static void seq_print_age_or_dash(struct seq_file *m, bool valid, unsigned long dt)
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{
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if (valid)
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seq_printf(m, "\t%d", jiffies_to_msecs(dt));
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else
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seq_printf(m, "\t-");
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}
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static void seq_print_rq_state_bit(struct seq_file *m,
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bool is_set, char *sep, const char *name)
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{
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if (!is_set)
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return;
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seq_putc(m, *sep);
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seq_puts(m, name);
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*sep = '|';
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}
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/* pretty print enum drbd_req_state_bits req->rq_state */
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static void seq_print_request_state(struct seq_file *m, struct drbd_request *req)
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{
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unsigned int s = req->rq_state;
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char sep = ' ';
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seq_printf(m, "\t0x%08x", s);
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seq_printf(m, "\tmaster: %s", req->master_bio ? "pending" : "completed");
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/* RQ_WRITE ignored, already reported */
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seq_puts(m, "\tlocal:");
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seq_print_rq_state_bit(m, s & RQ_IN_ACT_LOG, &sep, "in-AL");
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seq_print_rq_state_bit(m, s & RQ_POSTPONED, &sep, "postponed");
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seq_print_rq_state_bit(m, s & RQ_COMPLETION_SUSP, &sep, "suspended");
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sep = ' ';
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seq_print_rq_state_bit(m, s & RQ_LOCAL_PENDING, &sep, "pending");
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seq_print_rq_state_bit(m, s & RQ_LOCAL_COMPLETED, &sep, "completed");
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seq_print_rq_state_bit(m, s & RQ_LOCAL_ABORTED, &sep, "aborted");
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seq_print_rq_state_bit(m, s & RQ_LOCAL_OK, &sep, "ok");
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if (sep == ' ')
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seq_puts(m, " -");
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/* for_each_connection ... */
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seq_printf(m, "\tnet:");
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sep = ' ';
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seq_print_rq_state_bit(m, s & RQ_NET_PENDING, &sep, "pending");
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seq_print_rq_state_bit(m, s & RQ_NET_QUEUED, &sep, "queued");
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seq_print_rq_state_bit(m, s & RQ_NET_SENT, &sep, "sent");
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seq_print_rq_state_bit(m, s & RQ_NET_DONE, &sep, "done");
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seq_print_rq_state_bit(m, s & RQ_NET_SIS, &sep, "sis");
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seq_print_rq_state_bit(m, s & RQ_NET_OK, &sep, "ok");
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if (sep == ' ')
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seq_puts(m, " -");
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seq_printf(m, " :");
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sep = ' ';
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seq_print_rq_state_bit(m, s & RQ_EXP_RECEIVE_ACK, &sep, "B");
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seq_print_rq_state_bit(m, s & RQ_EXP_WRITE_ACK, &sep, "C");
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seq_print_rq_state_bit(m, s & RQ_EXP_BARR_ACK, &sep, "barr");
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if (sep == ' ')
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seq_puts(m, " -");
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seq_printf(m, "\n");
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}
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static void seq_print_one_request(struct seq_file *m, struct drbd_request *req, unsigned long now)
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{
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/* change anything here, fixup header below! */
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unsigned int s = req->rq_state;
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#define RQ_HDR_1 "epoch\tsector\tsize\trw"
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seq_printf(m, "0x%x\t%llu\t%u\t%s",
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req->epoch,
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(unsigned long long)req->i.sector, req->i.size >> 9,
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(s & RQ_WRITE) ? "W" : "R");
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#define RQ_HDR_2 "\tstart\tin AL\tsubmit"
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seq_printf(m, "\t%d", jiffies_to_msecs(now - req->start_jif));
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seq_print_age_or_dash(m, s & RQ_IN_ACT_LOG, now - req->in_actlog_jif);
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seq_print_age_or_dash(m, s & RQ_LOCAL_PENDING, now - req->pre_submit_jif);
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#define RQ_HDR_3 "\tsent\tacked\tdone"
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seq_print_age_or_dash(m, s & RQ_NET_SENT, now - req->pre_send_jif);
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seq_print_age_or_dash(m, (s & RQ_NET_SENT) && !(s & RQ_NET_PENDING), now - req->acked_jif);
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seq_print_age_or_dash(m, s & RQ_NET_DONE, now - req->net_done_jif);
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#define RQ_HDR_4 "\tstate\n"
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seq_print_request_state(m, req);
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}
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#define RQ_HDR RQ_HDR_1 RQ_HDR_2 RQ_HDR_3 RQ_HDR_4
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static void seq_print_minor_vnr_req(struct seq_file *m, struct drbd_request *req, unsigned long now)
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{
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seq_printf(m, "%u\t%u\t", req->device->minor, req->device->vnr);
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seq_print_one_request(m, req, now);
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}
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static void seq_print_resource_transfer_log_summary(struct seq_file *m,
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struct drbd_resource *resource,
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struct drbd_connection *connection,
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unsigned long now)
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{
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struct drbd_request *req;
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unsigned int count = 0;
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unsigned int show_state = 0;
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seq_puts(m, "n\tdevice\tvnr\t" RQ_HDR);
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spin_lock_irq(&resource->req_lock);
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list_for_each_entry(req, &connection->transfer_log, tl_requests) {
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unsigned int tmp = 0;
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unsigned int s;
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++count;
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/* don't disable irq "forever" */
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if (!(count & 0x1ff)) {
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struct drbd_request *req_next;
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kref_get(&req->kref);
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spin_unlock_irq(&resource->req_lock);
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cond_resched();
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spin_lock_irq(&resource->req_lock);
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req_next = list_next_entry(req, tl_requests);
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if (kref_put(&req->kref, drbd_req_destroy))
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req = req_next;
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if (&req->tl_requests == &connection->transfer_log)
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break;
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}
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s = req->rq_state;
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/* This is meant to summarize timing issues, to be able to tell
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* local disk problems from network problems.
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* Skip requests, if we have shown an even older request with
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* similar aspects already. */
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if (req->master_bio == NULL)
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tmp |= 1;
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if ((s & RQ_LOCAL_MASK) && (s & RQ_LOCAL_PENDING))
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tmp |= 2;
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if (s & RQ_NET_MASK) {
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if (!(s & RQ_NET_SENT))
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tmp |= 4;
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if (s & RQ_NET_PENDING)
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tmp |= 8;
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if (!(s & RQ_NET_DONE))
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tmp |= 16;
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}
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if ((tmp & show_state) == tmp)
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continue;
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show_state |= tmp;
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seq_printf(m, "%u\t", count);
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seq_print_minor_vnr_req(m, req, now);
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if (show_state == 0x1f)
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break;
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}
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spin_unlock_irq(&resource->req_lock);
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}
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/* TODO: transfer_log and friends should be moved to resource */
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static int in_flight_summary_show(struct seq_file *m, void *pos)
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{
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struct drbd_resource *resource = m->private;
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struct drbd_connection *connection;
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unsigned long jif = jiffies;
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connection = first_connection(resource);
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/* This does not happen, actually.
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* But be robust and prepare for future code changes. */
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if (!connection)
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return 0;
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seq_puts(m, "oldest application requests\n");
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seq_print_resource_transfer_log_summary(m, resource, connection, jif);
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seq_putc(m, '\n');
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jif = jiffies - jif;
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if (jif)
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seq_printf(m, "generated in %d ms\n", jiffies_to_msecs(jif));
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return 0;
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}
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static int in_flight_summary_open(struct inode *inode, struct file *file)
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{
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return single_open(file, in_flight_summary_show, inode->i_private);
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}
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static const struct file_operations in_flight_summary_fops = {
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.owner = THIS_MODULE,
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.open = in_flight_summary_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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void drbd_debugfs_resource_add(struct drbd_resource *resource)
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{
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struct dentry *dentry;
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@ -34,6 +224,12 @@ void drbd_debugfs_resource_add(struct drbd_resource *resource)
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goto fail;
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resource->debugfs_res_connections = dentry;
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dentry = debugfs_create_file("in_flight_summary", S_IRUSR|S_IRGRP,
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resource->debugfs_res, resource,
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&in_flight_summary_fops);
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if (IS_ERR_OR_NULL(dentry))
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goto fail;
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resource->debugfs_res_in_flight_summary = dentry;
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return;
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fail:
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