From c4aba9545430ed0f842d0833072f990a42da90f0 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Fri, 29 Apr 2016 13:14:42 +0100 Subject: [PATCH] Btrfs: pin log earlier when renaming We were pinning the log right after the first step in the rename operation (inserting inode ref for the new name in the destination directory) instead of doing it before. This behaviour was introduced in 2009 for some reason that was not mentioned neither on the changelog nor any comment, with the drawback of a small time window where concurrent log writers can end up logging the new inode reference for the inode we are renaming while the rename operation is in progress (so that we can end up with a log containing both the new and old references). As of today there's no reason to not pin the log before that first step anymore, so just fix this. Signed-off-by: Filipe Manana --- fs/btrfs/inode.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 4594a26..422833e 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -9479,6 +9479,8 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry, /* force full log commit if subvolume involved. */ btrfs_set_log_full_commit(root->fs_info, trans); } else { + btrfs_pin_log_trans(root); + log_pinned = true; ret = btrfs_insert_inode_ref(trans, dest, new_dentry->d_name.name, new_dentry->d_name.len, @@ -9486,15 +9488,6 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry, btrfs_ino(new_dir), index); if (ret) goto out_fail; - /* - * this is an ugly little race, but the rename is required - * to make sure that if we crash, the inode is either at the - * old name or the new one. pinning the log transaction lets - * us make sure we don't allow a log commit to come in after - * we unlink the name but before we add the new name back in. - */ - btrfs_pin_log_trans(root); - log_pinned = true; } inode_inc_iversion(old_dir); -- 2.7.4