From d6125af095c9553f38cba0696f15158f5abe4ecc Mon Sep 17 00:00:00 2001
From: Kamil Dudka <kdudka@redhat.com>
Date: Wed, 30 Jun 2021 17:53:22 +0200
Subject: [PATCH] df: fix duplicated remote entries due to bind mounts

As originally reported in <https://bugzilla.redhat.com/1962515>,
df invoked without -a printed duplicated entries for NFS mounts
of bind mounts.  This is a regression from commit v8.25-54-g1c17f61ef99,
which introduced the use of a hash table.

The proposed patch makes sure that the devlist entry seen the last time
is used for comparison when eliminating duplicated mount entries.  This
way it worked before introducing the hash table.

Patch co-authored by Roberto Bergantinos.

* src/ls.c (struct devlist): Introduce the seen_last pointer.
(devlist_for_dev): Return the devlist entry seen the last time if found.
(filter_mount_list): Remember the devlist entry seen the last time for
each hashed item.
* NEWS: Mention the bug fix.
Fixes https://bugs.gnu.org/49298

Reference: https://github.com/coreutils/coreutils/commit/d6125af095c9553f38cba0696f15158f5abe4ecc
Conflict: NEWS Context adaptation 

---
 NEWS     |  3 +++
 src/df.c | 15 +++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index fc8ff16..bae6ced 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,9 @@ GNU coreutils NEWS                                    -*- outline -*-
 
 ** Bug fixes
 
+  df no longer outputs duplicate remote mounts in the presence of bind mounts.
+  [bug introduced in coreutils-8.26]
+
   'sort -g' no longer infloops when given multiple NaNs on platforms
   like x86-64 where 'long double' has padding bits in memory.
   Although the fix alters sort -g's NaN ordering, that ordering has
diff --git a/src/df.c b/src/df.c
index 7e01839..3e9247f 100644
--- a/src/df.c
+++ b/src/df.c
@@ -54,6 +54,7 @@ struct devlist
   dev_t dev_num;
   struct mount_entry *me;
   struct devlist *next;
+  struct devlist *seen_last; /* valid for hashed devlist entries only */
 };
 
 /* Filled with device numbers of examined file systems to avoid
@@ -689,7 +690,13 @@ devlist_for_dev (dev_t dev)
     return NULL;
   struct devlist dev_entry;
   dev_entry.dev_num = dev;
-  return hash_lookup (devlist_table, &dev_entry);
+
+  struct devlist *found = hash_lookup (devlist_table, &dev_entry);
+  if (found == NULL)
+    return NULL;
+
+  /* Return the last devlist entry we have seen with this dev_num */
+  return found->seen_last;
 }
 
 static void
@@ -807,8 +814,12 @@ filter_mount_list (bool devices_only)
           devlist->dev_num = buf.st_dev;
           devlist->next = device_list;
           device_list = devlist;
-          if (hash_insert (devlist_table, devlist) == NULL)
+
+          struct devlist *hash_entry = hash_insert (devlist_table, devlist);
+          if (hash_entry == NULL)
             xalloc_die ();
+          /* Ensure lookups use this latest devlist.  */
+          hash_entry->seen_last = devlist;
 
           me = me->me_next;
         }
-- 
2.27.0

