From c7bc6319c59cc791743cf1b6e98f86be69444495 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Mon, 3 Nov 2014 14:12:57 +0000 Subject: [PATCH] Btrfs: avoid premature -ENOMEM in clear_extent_bit() We try to allocate an extent state structure before acquiring the extent state tree's spinlock as we might need a new one later and therefore avoid doing later an atomic allocation while holding the tree's spinlock. However we returned -ENOMEM if that initial non-atomic allocation failed, which is a bit excessive since we might end up not needing the pre-allocated extent state at all - for the case where the tree doesn't have any extent states that cover the input range and cover too any other range. Therefore don't return -ENOMEM if that pre-allocation fails. Signed-off-by: Filipe Manana Signed-off-by: Chris Mason --- fs/btrfs/extent_io.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 654ed3de0054..4ebabd237153 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -595,9 +595,14 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, clear = 1; again: if (!prealloc && (mask & __GFP_WAIT)) { + /* + * Don't care for allocation failure here because we might end + * up not needing the pre-allocated extent state at all, which + * is the case if we only have in the tree extent states that + * cover our input range and don't cover too any other range. + * If we end up needing a new extent state we allocate it later. + */ prealloc = alloc_extent_state(mask); - if (!prealloc) - return -ENOMEM; } spin_lock(&tree->lock); -- 2.39.5