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Btrfs: avoid premature -ENOMEM in clear_extent_bit()

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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 <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Filipe Manana 2014-11-03 14:12:57 +00:00 committed by Chris Mason
parent 7e33fd993a
commit c7bc6319c5
1 changed files with 7 additions and 2 deletions
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9
fs/btrfs/extent_io.c
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@ -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);