On 10.05.2018 09:21, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@xxxxxx>
>
> The truncate loop in btrfs_evict_inode() does two things at once:
>
> - It refills the temporary block reserve, potentially stealing from the
> global reserve or committing
> - It calls btrfs_truncate_inode_items()
>
> The tangle of continues hides the fact that these two steps are actually
> separate. Split the first step out into a separate function both for
> clarity and so that we can reuse it in a later patch.
>
> Signed-off-by: Omar Sandoval <osandov@xxxxxx>
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
> ---
> fs/btrfs/inode.c | 113 ++++++++++++++++++-----------------------------
> 1 file changed, 42 insertions(+), 71 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 9a6a4e626e01..348dc57920f5 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -5224,13 +5224,52 @@ static void evict_inode_truncate_pages(struct inode *inode)
> spin_unlock(&io_tree->lock);
> }
>
> +static struct btrfs_trans_handle *evict_refill_and_join(struct btrfs_root *root,
> + struct btrfs_block_rsv *rsv,
> + u64 min_size)
> +{
> + struct btrfs_fs_info *fs_info = root->fs_info;
> + struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
> + int failures = 0;
> +
> + for (;;) {
> + struct btrfs_trans_handle *trans;
> + int ret;
> +
> + ret = btrfs_block_rsv_refill(root, rsv, min_size,
> + BTRFS_RESERVE_FLUSH_LIMIT);
> +
> + if (ret && ++failures > 2) {
> + btrfs_warn(fs_info,
> + "could not allocate space for a delete; will truncate on mount");
> + return ERR_PTR(-ENOSPC);
> + }
> +
> + trans = btrfs_join_transaction(root);
> + if (IS_ERR(trans) || !ret)
> + return trans;
> +
> + /*
> + * Try to steal from the global reserve if there is space for
> + * it.
> + */
> + if (!btrfs_check_space_for_delayed_refs(trans, fs_info) &&
> + !btrfs_block_rsv_migrate(global_rsv, rsv, min_size, 0))
> + return trans;
> +
> + /* If not, commit and try again. */
> + ret = btrfs_commit_transaction(trans);
> + if (ret)
> + return ERR_PTR(ret);
> + }
> +}
> +
> void btrfs_evict_inode(struct inode *inode)
> {
> struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
> struct btrfs_trans_handle *trans;
> struct btrfs_root *root = BTRFS_I(inode)->root;
> - struct btrfs_block_rsv *rsv, *global_rsv;
> - int steal_from_global = 0;
> + struct btrfs_block_rsv *rsv;
> u64 min_size;
> int ret;
>
> @@ -5286,85 +5325,17 @@ void btrfs_evict_inode(struct inode *inode)
> }
> rsv->size = min_size;
> rsv->failfast = 1;
> - global_rsv = &fs_info->global_block_rsv;
>
> btrfs_i_size_write(BTRFS_I(inode), 0);
>
> - /*
> - * This is a bit simpler than btrfs_truncate since we've already
> - * reserved our space for our orphan item in the unlink, so we just
> - * need to reserve some slack space in case we add bytes and update
> - * inode item when doing the truncate.
> - */
> while (1) {
> - ret = btrfs_block_rsv_refill(root, rsv, min_size,
> - BTRFS_RESERVE_FLUSH_LIMIT);
> -
> - /*
> - * Try and steal from the global reserve since we will
> - * likely not use this space anyway, we want to try as
> - * hard as possible to get this to work.
> - */
> - if (ret)
> - steal_from_global++;
> - else
> - steal_from_global = 0;
> - ret = 0;
> -
> - /*
> - * steal_from_global == 0: we reserved stuff, hooray!
> - * steal_from_global == 1: we didn't reserve stuff, boo!
> - * steal_from_global == 2: we've committed, still not a lot of
> - * room but maybe we'll have room in the global reserve this
> - * time.
> - * steal_from_global == 3: abandon all hope!
> - */
> - if (steal_from_global > 2) {
> - btrfs_warn(fs_info,
> - "Could not get space for a delete, will truncate on mount %d",
> - ret);
> - btrfs_orphan_del(NULL, BTRFS_I(inode));
> - btrfs_free_block_rsv(fs_info, rsv);
> - goto no_delete;
> - }
> -
> - trans = btrfs_join_transaction(root);
> + trans = evict_refill_and_join(root, rsv, min_size);
> if (IS_ERR(trans)) {
> btrfs_orphan_del(NULL, BTRFS_I(inode));
> btrfs_free_block_rsv(fs_info, rsv);
> goto no_delete;
> }
>
> - /*
> - * We can't just steal from the global reserve, we need to make
> - * sure there is room to do it, if not we need to commit and try
> - * again.
> - */
> - if (steal_from_global) {
> - if (!btrfs_check_space_for_delayed_refs(trans, fs_info))
> - ret = btrfs_block_rsv_migrate(global_rsv, rsv,
> - min_size, 0);
> - else
> - ret = -ENOSPC;
> - }
> -
> - /*
> - * Couldn't steal from the global reserve, we have too much
> - * pending stuff built up, commit the transaction and try it
> - * again.
> - */
> - if (ret) {
> - ret = btrfs_commit_transaction(trans);
> - if (ret) {
> - btrfs_orphan_del(NULL, BTRFS_I(inode));
> - btrfs_free_block_rsv(fs_info, rsv);
> - goto no_delete;
> - }
> - continue;
> - } else {
> - steal_from_global = 0;
> - }
> -
> trans->block_rsv = rsv;
>
> ret = btrfs_truncate_inode_items(trans, root, inode, 0, 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
