From: Liu Bo <bo.li.liu@oracle.com>
Date: Thu, 25 Jan 2018 11:02:56 -0700
Subject: Btrfs: fix unexpected -EEXIST when creating new inode
Git-commit: 900c9981680067573671ecc5cbfa7c5770be3a40
Patch-mainline: v4.16-rc2
References: bsc#1083000

The highest objectid, which is assigned to new inode, is decided at
the time of initializing fs roots.  However, in cases where log replay
gets processed, the btree which fs root owns might be changed, so we
have to search it again for the highest objectid, otherwise creating
new inode would end up with -EEXIST.

cc: <stable@vger.kernel.org> v4.4-rc6+
Fixes: f32e48e92596 ("Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots")
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/tree-log.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 79af4ae042ae..61f20c367aaf 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -28,6 +28,7 @@
 #include "hash.h"
 #include "compression.h"
 #include "qgroup.h"
+#include "inode-map.h"
 
 /* magic values for the inode_only field in btrfs_log_inode:
  *
@@ -5685,6 +5686,23 @@ int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
 						      path);
 		}
 
+		if (!ret && wc.stage == LOG_WALK_REPLAY_ALL) {
+			struct btrfs_root *root = wc.replay_dest;
+
+			btrfs_release_path(path);
+
+			/*
+			 * We have just replayed everything, and the highest
+			 * objectid of fs roots probably has changed in case
+			 * some inode_item's got replayed.
+			 *
+			 * root->objectid_mutex is not acquired as log replay
+			 * could only happen during mount.
+			 */
+			ret = btrfs_find_highest_objectid(root,
+						  &root->highest_objectid);
+		}
+
 		key.offset = found_key.offset - 1;
 		wc.replay_dest->log_root = NULL;
 		free_extent_buffer(log->node);