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scoutfs: add item saving and restoring

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Add item cache functions for saving and restoring items.  This lets
callers more easily undo changes while they have transactions pinned.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2018-03-15 09:23:57 -07:00
committed by Zach Brown
parent 4dad03a3dd
commit acfc4b357b
2 changed files with 124 additions and 0 deletions
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kmod/src/item.c
+118
View File
@@ -1558,6 +1558,124 @@ int scoutfs_item_delete_force(struct super_block *sb,
become_deletion_item(sb, cac, item);
spin_unlock_irqrestore(&cac->lock, flags);
return ret;
}
/*
* Delete an item and give it to the caller so that they can restore it
* later.
*
* The deleted items can be dirty or not.. we maintain an accurate dirty
* count as we remove the deleted items and leave their dirty flag set
* so that restore can mark them dirty again.
*
* Returns -ENOENT if the item didn't exist and couldn't be deleted.
*/
int scoutfs_item_delete_save(struct super_block *sb,
struct scoutfs_key_buf *key,
struct list_head *list,
struct scoutfs_lock *lock)
{
struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
struct item_cache *cac = sbi->item_cache;
struct cached_item *item;
struct cached_item *del;
unsigned long flags;
bool was_dirty;
int ret;
if (WARN_ON_ONCE(!lock_coverage(lock, key, DLM_LOCK_EX)))
return -EINVAL;
del = alloc_item(sb, key, NULL);
if (!del)
return -ENOMEM;
do {
spin_lock_irqsave(&cac->lock, flags);
item = find_item(sb, &cac->items, key);
if (item) {
was_dirty = item_is_dirty(item);
unlink_item(sb, cac, item);
list_add_tail(&item->entry, list);
if (was_dirty)
item->dirty |= ITEM_DIRTY;
ret = insert_item(sb, cac, del, false, false);
BUG_ON(ret);
become_deletion_item(sb, cac, del);
del = NULL;
ret = 0;
} else if (check_range(sb, &cac->ranges, key, NULL)) {
ret = -ENOENT;
} else {
ret = -ENODATA;
}
spin_unlock_irqrestore(&cac->lock, flags);
} while (ret == -ENODATA &&
(ret = scoutfs_manifest_read_items(sb, key, lock->end)) == 0);
free_item(sb, del);
return ret;
}
/*
* Restore a set of previousl saved items. They're returned to the
* cached and marked dirty if they were dirty when they were saved.
* Restored items completely overwrite any existing cached items.
*
* The caller must have held locks covering the save and restore so that
* the cached ranges still exist.
*/
int scoutfs_item_restore(struct super_block *sb, struct list_head *list,
struct scoutfs_lock *lock)
{
struct scoutfs_sb_info *sbi = SCOUTFS_SB(sb);
struct item_cache *cac = sbi->item_cache;
struct cached_item *existing;
struct cached_item *item;
struct cached_item *tmp;
unsigned long flags;
bool was_dirty;
int mode;
int ret;
if (list_empty(list))
return 0;
spin_lock_irqsave(&cac->lock, flags);
/* make sure all the items are locked and cached */
list_for_each_entry(item, list, entry) {
mode = item_is_dirty(item) ? DLM_LOCK_EX : DLM_LOCK_PR;
if (WARN_ON_ONCE(!lock_coverage(lock, item->key, mode)) ||
WARN_ON_ONCE(!check_range(sb, &cac->ranges, item->key,
NULL))) {
ret = -EINVAL;
goto out;
}
}
list_for_each_entry_safe(item, tmp, list, entry) {
was_dirty = item_is_dirty(item);
item->dirty &= ~ITEM_DIRTY;
list_del_init(&item->entry);
existing = find_item(sb, &cac->items, item->key);
if (existing)
erase_item(sb, cac, existing);
insert_item(sb, cac, item, false, false);
if (was_dirty)
mark_item_dirty(sb, cac, item);
}
ret = 0;
out:
spin_unlock_irqrestore(&cac->lock, flags);
return ret;
}
kmod/src/item.h
+6
View File
@@ -46,6 +46,12 @@ int scoutfs_item_delete(struct super_block *sb, struct scoutfs_key_buf *key,
int scoutfs_item_delete_force(struct super_block *sb,
struct scoutfs_key_buf *key,
struct scoutfs_lock *lock);
int scoutfs_item_delete_save(struct super_block *sb,
struct scoutfs_key_buf *key,
struct list_head *list,
struct scoutfs_lock *lock);
int scoutfs_item_restore(struct super_block *sb, struct list_head *list,
struct scoutfs_lock *lock);
int scoutfs_item_add_batch(struct super_block *sb, struct list_head *list,
struct scoutfs_key_buf *key, struct kvec *val);