On 10/24/2012 06:45 PM, Jan Schmidt wrote:
> get_old_root needs its lock on the root node only to clone that buffer.
> However, when we call read_tree_block, we know already that we're not
> going to clone the root node. Thus we can safely unlock before, to avoid
> issues where read_tree_block makes potentially sleeping allocations.
>
I tested this for 20 times, it's no more blocked.
So you can add
Reviewed-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
Tested-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
thanks,
liubo
> Signed-off-by: Jan Schmidt <list.btrfs@xxxxxxxxxxxxx>
> ---
> Thanks for pointing that out, liubo!
>
> I added this additional patch on top of my patch staple at:
>
> git://git.jan-o-sch.net/btrfs-unstable for-chris
>
> I also made a second branch, because this last commit actually fixes
> that's introduced by one of the patches in the patch set. So I folded
> it into the respective commit:
>
> git://git.jan-o-sch.net/btrfs-unstable for-chris-fixed
>
> I made sure that the resulting code is the same.
>
> Chris: please pull either one for rc3.
>
> -Jan
>
> ---
> fs/btrfs/ctree.c | 9 +++++++--
> 1 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
> index c608b3c..eba44b0 100644
> --- a/fs/btrfs/ctree.c
> +++ b/fs/btrfs/ctree.c
> @@ -1261,6 +1261,8 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
>
> tm = tree_mod_log_search(root->fs_info, logical, time_seq);
> if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
> + btrfs_tree_read_unlock(root->node);
> + free_extent_buffer(root->node);
> blocksize = btrfs_level_size(root, old_root->level);
> eb = read_tree_block(root, logical, blocksize, 0);
> if (!eb) {
> @@ -1271,12 +1273,15 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
> eb = btrfs_clone_extent_buffer(eb);
> }
> } else if (old_root) {
> + btrfs_tree_read_unlock(root->node);
> + free_extent_buffer(root->node);
> eb = alloc_dummy_extent_buffer(logical, root->nodesize);
> } else {
> eb = btrfs_clone_extent_buffer(root->node);
> + btrfs_tree_read_unlock(root->node);
> + free_extent_buffer(root->node);
> }
> - btrfs_tree_read_unlock(root->node);
> - free_extent_buffer(root->node);
> +
> if (!eb)
> return NULL;
> extent_buffer_get(eb);
>
--
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
