This is a note to let you know that I've just added the patch titled
Btrfs: fix stale entries in readdir
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: btrfs-fix-stale-entries-in-readdir.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From e4fd493c0541d36953f7b9d3bfced67a1321792f Mon Sep 17 00:00:00 2001
From: Josef Bacik jbacik@fb.com Date: Tue, 23 Jan 2018 15:17:05 -0500 Subject: Btrfs: fix stale entries in readdir
From: Josef Bacik jbacik@fb.com
commit e4fd493c0541d36953f7b9d3bfced67a1321792f upstream.
In fixing the readdir+pagefault deadlock I accidentally introduced a stale entry regression in readdir. If we get close to full for the temporary buffer, and then skip a few delayed deletions, and then try to add another entry that won't fit, we will emit the entries we found and retry. Unfortunately we delete entries from our del_list as we find them, assuming we won't need them. However our pos will be with whatever our last entry was, which could be before the delayed deletions we skipped, so the next search will add the deleted entries back into our readdir buffer. So instead don't delete entries we find in our del_list so we can make sure we always find our delayed deletions. This is a slight perf hit for readdir with lots of pending deletions, but hopefully this isn't a common occurrence. If it is we can revist this and optimize it.
Fixes: 23b5ec74943f ("btrfs: fix readdir deadlock with pagefault") Signed-off-by: Josef Bacik jbacik@fb.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/delayed-inode.c | 26 ++++++++------------------ 1 file changed, 8 insertions(+), 18 deletions(-)
--- a/fs/btrfs/delayed-inode.c +++ b/fs/btrfs/delayed-inode.c @@ -1677,28 +1677,18 @@ void btrfs_readdir_put_delayed_items(str int btrfs_should_delete_dir_index(struct list_head *del_list, u64 index) { - struct btrfs_delayed_item *curr, *next; - int ret; + struct btrfs_delayed_item *curr; + int ret = 0;
- if (list_empty(del_list)) - return 0; - - list_for_each_entry_safe(curr, next, del_list, readdir_list) { + list_for_each_entry(curr, del_list, readdir_list) { if (curr->key.offset > index) break; - - list_del(&curr->readdir_list); - ret = (curr->key.offset == index); - - if (refcount_dec_and_test(&curr->refs)) - kfree(curr); - - if (ret) - return 1; - else - continue; + if (curr->key.offset == index) { + ret = 1; + break; + } } - return 0; + return ret; }
/*
Patches currently in stable-queue which might be from jbacik@fb.com are
queue-4.14/btrfs-fix-stale-entries-in-readdir.patch