On Thu, Jun 22, 2017 at 09:51:47AM -0400, jeffm@xxxxxxxx wrote:
> From: Jeff Mahoney <jeffm@xxxxxxxx>
>
> In a heavy write scenario, we can end up with a large number of pinned bytes.
> This can translate into (very) premature ENOSPC because pinned bytes
> must be accounted for when allowing a reservation but aren't accounted for
> when deciding whether to create a new chunk.
>
> This patch adds the accounting to should_alloc_chunk so that we can
> create the chunk.
Hey, Jeff,
Does this fix your ENOSPC problem on a fresh filesystem? I just tracked
down an ENOSPC issue someone here reported when doing a btrfs send to a
fresh filesystem and it sounds a lot like your issue: metadata
bytes_may_use shoots up but we don't allocate any chunks for it. I'm not
seeing how including bytes_pinned will help for this case. We won't have
any pinned bytes when populating a new fs, right?
I don't have a good solution. Allocating chunks based on bytes_may_use
is going to way over-allocate because of our worst-case estimations. I'm
double-checking now that the flusher is doing the right thing and not
missing anything. I'll keep digging, just wanted to know if you had any
thoughts.
> Signed-off-by: Jeff Mahoney <jeffm@xxxxxxxx>
> ---
> fs/btrfs/extent-tree.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index 33d979e9ea2a..88b04742beea 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -4377,7 +4377,7 @@ static int should_alloc_chunk(struct btrfs_fs_info *fs_info,
> {
> struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
> u64 num_bytes = sinfo->total_bytes - sinfo->bytes_readonly;
> - u64 num_allocated = sinfo->bytes_used + sinfo->bytes_reserved;
> + u64 num_allocated = sinfo->bytes_used + sinfo->bytes_reserved + sinfo->bytes_pinned;
> u64 thresh;
>
> if (force == CHUNK_ALLOC_FORCE)
> --
> 2.11.0
>
> --
> 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
