On Fri, Apr 13, 2018 at 1:28 PM, Josef Bacik <josef@xxxxxxxxxxxxxx> wrote:
> From: Josef Bacik <jbacik@xxxxxx>
>
> Since we're allocating under atomic we could every easily enomem, so if
> that's the case and we can block then loop around and try to allocate
> the prealloc not under a lock.
>
> We also saw this happen during try_to_release_page in production, in
> which case it's completely valid to return ENOMEM so we can tell
> try_to_release_page that we can't release this page.
>
> Signed-off-by: Josef Bacik <jbacik@xxxxxx>
> ---
> fs/btrfs/extent_io.c | 28 ++++++++++++++++++++++++----
> 1 file changed, 24 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index fb32394fd830..1054dc0158b5 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -593,8 +593,9 @@ int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
> struct extent_state *prealloc = NULL;
> struct rb_node *node;
> u64 last_end;
> - int err;
> + int err = 0;
> int clear = 0;
> + bool need_prealloc = false;
>
> btrfs_debug_check_extent_io_range(tree, start, end);
>
> @@ -617,6 +618,9 @@ int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
> * If we end up needing a new extent state we allocate it later.
> */
> prealloc = alloc_extent_state(mask);
> + if (!prealloc && need_prealloc)
> + return -ENOMEM;
> + need_prealloc = false;
> }
>
> spin_lock(&tree->lock);
> @@ -676,7 +680,15 @@ int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
>
> if (state->start < start) {
> prealloc = alloc_extent_state_atomic(prealloc);
> - BUG_ON(!prealloc);
> + if (!prealloc) {
> + if (gfpflags_allow_blocking(mask)) {
> + need_prealloc = true;
> + spin_unlock(&tree->lock);
> + goto again;
Could we simply 'goto search_again;' ?
thanks,
liubo
> + }
> + err = -ENOMEM;
> + goto out;
> + }
> err = split_state(tree, state, prealloc, start);
> if (err)
> extent_io_tree_panic(tree, err);
> @@ -699,7 +711,15 @@ int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
> */
> if (state->start <= end && state->end > end) {
> prealloc = alloc_extent_state_atomic(prealloc);
> - BUG_ON(!prealloc);
> + if (!prealloc) {
> + if (gfpflags_allow_blocking(mask)) {
> + need_prealloc = true;
> + spin_unlock(&tree->lock);
> + goto again;
> + }
> + err = -ENOMEM;
> + goto out;
> + }
> err = split_state(tree, state, prealloc, end + 1);
> if (err)
> extent_io_tree_panic(tree, err);
> @@ -734,7 +754,7 @@ int __clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
> if (prealloc)
> free_extent_state(prealloc);
>
> - return 0;
> + return err;
>
> }
>
> --
> 2.14.3
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
