From 4b9d7b59bfcb62a7d438876eac5a054db32904dd Mon Sep 17 00:00:00 2001 From: Omar Sandoval Date: Fri, 11 May 2018 13:13:36 -0700 Subject: [PATCH] Btrfs: refactor btrfs_evict_inode() reserve refill dance 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. Reviewed-by: Nikolay Borisov Signed-off-by: Omar Sandoval Signed-off-by: David Sterba --- 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 73783492a0d1..f70284acb6ac 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5452,13 +5452,52 @@ 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; @@ -5511,85 +5550,17 @@ 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); -- 2.11.0