File 0062-LU-13985-lustre-seq_file-.next-functions-must-update.patch of Package lustre_2_12

From 817d6c116599639599919bcde7999a7f06b74d2c Mon Sep 17 00:00:00 2001
From: Mr NeilBrown <neilb@suse.de>
Date: Fri, 25 Sep 2020 09:46:24 +1000
Subject: [PATCH] LU-13985 lustre: seq_file .next functions must update *pos

A seq_file .next function must update *pos on EOF to a value which
will cause a subsequent ->start to also return EOF.
If it doesn't the last record of the file can be returned
twice to a 'read()'.  Also the seq_file code will generate
a warning.

This patch fixes various ->next functions to always update
*pos.

Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: Ia0c432cd50550ecde6b308cbc554b316fa03adae
Reviewed-on: https://review.whamcloud.com/40035
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
---
 lnet/klnds/gnilnd/gnilnd_proc.c |    8 ++++----
 lustre/fid/lproc_fid.c          |    1 +
 lustre/fld/lproc_fld.c          |    1 +
 lustre/lov/lov_pool.c           |   28 ++++++++++++++--------------
 lustre/obdclass/lu_ref.c        |    8 ++++----
 lustre/ptlrpc/lproc_ptlrpc.c    |    1 +
 6 files changed, 25 insertions(+), 22 deletions(-)

--- a/lnet/klnds/gnilnd/gnilnd_proc.c
+++ b/lnet/klnds/gnilnd/gnilnd_proc.c
@@ -459,10 +459,10 @@ kgnilnd_mdd_seq_next(struct seq_file *s,
 	loff_t                  next = *pos + 1;
 
 	rc = kgnilnd_mdd_seq_seek(gseq, next);
+	*pos = next;
 	if (rc != 0) {
 		return NULL;
 	}
-	*pos = next;
 	return gseq;
 }
 
@@ -648,11 +648,11 @@ kgnilnd_smsg_seq_next(struct seq_file *s
 	loff_t                  next = *pos + 1;
 
 	rc = kgnilnd_smsg_seq_seek(gseq, next);
+	*pos = next;
 	if (rc != 0) {
 		LIBCFS_FREE(gseq, sizeof(*gseq));
 		return NULL;
 	}
-	*pos = next;
 	return gseq;
 }
 
@@ -864,11 +864,11 @@ kgnilnd_conn_seq_next(struct seq_file *s
 	loff_t                  next = *pos + 1;
 
 	rc = kgnilnd_conn_seq_seek(gseq, next);
+	*pos = next;
 	if (rc != 0) {
 		LIBCFS_FREE(gseq, sizeof(*gseq));
 		return NULL;
 	}
-	*pos = next;
 	return gseq;
 }
 
@@ -1217,11 +1217,11 @@ kgnilnd_peer_seq_next(struct seq_file *s
 	loff_t                  next = *pos + 1;
 
 	rc = kgnilnd_peer_seq_seek(gseq, next);
+	*pos = next;
 	if (rc != 0) {
 		LIBCFS_FREE(gseq, sizeof(*gseq));
 		return NULL;
 	}
-	*pos = next;
 	return gseq;
 }
 
--- a/lustre/fid/lproc_fid.c
+++ b/lustre/fid/lproc_fid.c
@@ -278,6 +278,7 @@ static void *fldb_seq_next(struct seq_fi
 	const struct dt_it_ops	*iops;
 	int			rc;
 
+	++*pos;
 	if (param == NULL || param->fsp_stop)
 		return NULL;
 
--- a/lustre/fld/lproc_fld.c
+++ b/lustre/fld/lproc_fld.c
@@ -210,6 +210,7 @@ static void *fldb_seq_next(struct seq_fi
 	const struct dt_it_ops	*iops;
 	int			rc;
 
+	++*pos;
 	if (param == NULL || param->fsp_stop)
 		return NULL;
 
--- a/lustre/lov/lov_pool.c
+++ b/lustre/lov/lov_pool.c
@@ -170,25 +170,25 @@ struct pool_iterator {
 
 static void *pool_proc_next(struct seq_file *s, void *v, loff_t *pos)
 {
-        struct pool_iterator *iter = (struct pool_iterator *)s->private;
-        int prev_idx;
+	struct pool_iterator *iter = (struct pool_iterator *)s->private;
+	int prev_idx;
 
 	LASSERTF(iter->magic == POOL_IT_MAGIC, "%08X\n", iter->magic);
 
-        /* test if end of file */
-        if (*pos >= pool_tgt_count(iter->pool))
-                return NULL;
+	(*pos)++;
+	/* test if end of file */
+	if (*pos > pool_tgt_count(iter->pool))
+		return NULL;
 
-        /* iterate to find a non empty entry */
-        prev_idx = iter->idx;
-        iter->idx++;
+	/* iterate to find a non empty entry */
+	prev_idx = iter->idx;
+	iter->idx++;
 	if (iter->idx >= pool_tgt_count(iter->pool)) {
-                iter->idx = prev_idx; /* we stay on the last entry */
-                return NULL;
-        }
-        (*pos)++;
-        /* return != NULL to continue */
-        return iter;
+		iter->idx = prev_idx; /* we stay on the last entry */
+		return NULL;
+	}
+	/* return != NULL to continue */
+	return iter;
 }
 
 static void *pool_proc_start(struct seq_file *s, loff_t *pos)
--- a/lustre/obdclass/lu_ref.c
+++ b/lustre/obdclass/lu_ref.c
@@ -309,15 +309,15 @@ static void *lu_ref_seq_next(struct seq_
 	LASSERT(seq->private == p);
 	LASSERT(!list_empty(&ref->lf_linkage));
 
+	(*pos)++;
 	spin_lock(&lu_ref_refs_guard);
 	next = list_entry(ref->lf_linkage.next, struct lu_ref, lf_linkage);
-	if (&next->lf_linkage == &lu_ref_refs) {
+	if (&next->lf_linkage == &lu_ref_refs)
 		p = NULL;
-	} else {
-		(*pos)++;
+	else
 		list_move(&ref->lf_linkage, &next->lf_linkage);
-	}
 	spin_unlock(&lu_ref_refs_guard);
+
 	return p;
 }
 
--- a/lustre/ptlrpc/lproc_ptlrpc.c
+++ b/lustre/ptlrpc/lproc_ptlrpc.c
@@ -946,6 +946,7 @@ ptlrpc_lprocfs_svc_req_history_start(str
 	}
 
 	OBD_FREE(srhi, sizeof(*srhi));
+	++*pos;
 	return NULL;
 }