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Btrfs: refactor btrfs_evict_inode() reserve refill dance

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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 <nborisov@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Omar Sandoval 2018-05-11 13:13:36 -07:00 committed by David Sterba
parent c08db7d8d2
commit 4b9d7b59bf
1 changed files with 42 additions and 71 deletions
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113
fs/btrfs/inode.c
View file

@ -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);