From 6f7ff6d7832c6be13e8c95598884dbc40ad69fb7 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Wed, 2 Jul 2014 20:07:54 +0100 Subject: [PATCH] Btrfs: read lock extent buffer while walking backrefs Before processing the extent buffer, acquire a read lock on it, so that we're safe against concurrent updates on the extent buffer. Signed-off-by: Filipe Manana Signed-off-by: Chris Mason --- fs/btrfs/backref.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index e25564bfcb46..a1efd39ca28a 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -1001,8 +1001,11 @@ again: ret = -EIO; goto out; } + btrfs_tree_read_lock(eb); + btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK); ret = find_extent_in_eb(eb, bytenr, *extent_item_pos, &eie); + btrfs_tree_read_unlock_blocking(eb); free_extent_buffer(eb); if (ret < 0) goto out; -- 2.20.1