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1048 lines
32 KiB
1048 lines
32 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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#ifndef _BCACHE_H |
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#define _BCACHE_H |
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|
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/* |
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* SOME HIGH LEVEL CODE DOCUMENTATION: |
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* |
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* Bcache mostly works with cache sets, cache devices, and backing devices. |
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* |
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* Support for multiple cache devices hasn't quite been finished off yet, but |
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* it's about 95% plumbed through. A cache set and its cache devices is sort of |
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* like a md raid array and its component devices. Most of the code doesn't care |
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* about individual cache devices, the main abstraction is the cache set. |
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* |
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* Multiple cache devices is intended to give us the ability to mirror dirty |
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* cached data and metadata, without mirroring clean cached data. |
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* |
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* Backing devices are different, in that they have a lifetime independent of a |
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* cache set. When you register a newly formatted backing device it'll come up |
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* in passthrough mode, and then you can attach and detach a backing device from |
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* a cache set at runtime - while it's mounted and in use. Detaching implicitly |
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* invalidates any cached data for that backing device. |
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* |
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* A cache set can have multiple (many) backing devices attached to it. |
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* |
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* There's also flash only volumes - this is the reason for the distinction |
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* between struct cached_dev and struct bcache_device. A flash only volume |
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* works much like a bcache device that has a backing device, except the |
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* "cached" data is always dirty. The end result is that we get thin |
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* provisioning with very little additional code. |
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* |
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* Flash only volumes work but they're not production ready because the moving |
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* garbage collector needs more work. More on that later. |
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* |
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* BUCKETS/ALLOCATION: |
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* |
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* Bcache is primarily designed for caching, which means that in normal |
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* operation all of our available space will be allocated. Thus, we need an |
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* efficient way of deleting things from the cache so we can write new things to |
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* it. |
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* |
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* To do this, we first divide the cache device up into buckets. A bucket is the |
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* unit of allocation; they're typically around 1 mb - anywhere from 128k to 2M+ |
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* works efficiently. |
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* |
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* Each bucket has a 16 bit priority, and an 8 bit generation associated with |
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* it. The gens and priorities for all the buckets are stored contiguously and |
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* packed on disk (in a linked list of buckets - aside from the superblock, all |
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* of bcache's metadata is stored in buckets). |
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* |
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* The priority is used to implement an LRU. We reset a bucket's priority when |
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* we allocate it or on cache it, and every so often we decrement the priority |
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* of each bucket. It could be used to implement something more sophisticated, |
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* if anyone ever gets around to it. |
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* |
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* The generation is used for invalidating buckets. Each pointer also has an 8 |
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* bit generation embedded in it; for a pointer to be considered valid, its gen |
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* must match the gen of the bucket it points into. Thus, to reuse a bucket all |
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* we have to do is increment its gen (and write its new gen to disk; we batch |
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* this up). |
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* |
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* Bcache is entirely COW - we never write twice to a bucket, even buckets that |
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* contain metadata (including btree nodes). |
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* |
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* THE BTREE: |
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* |
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* Bcache is in large part design around the btree. |
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* |
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* At a high level, the btree is just an index of key -> ptr tuples. |
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* |
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* Keys represent extents, and thus have a size field. Keys also have a variable |
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* number of pointers attached to them (potentially zero, which is handy for |
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* invalidating the cache). |
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* |
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* The key itself is an inode:offset pair. The inode number corresponds to a |
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* backing device or a flash only volume. The offset is the ending offset of the |
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* extent within the inode - not the starting offset; this makes lookups |
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* slightly more convenient. |
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* |
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* Pointers contain the cache device id, the offset on that device, and an 8 bit |
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* generation number. More on the gen later. |
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* |
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* Index lookups are not fully abstracted - cache lookups in particular are |
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* still somewhat mixed in with the btree code, but things are headed in that |
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* direction. |
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* |
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* Updates are fairly well abstracted, though. There are two different ways of |
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* updating the btree; insert and replace. |
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* |
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* BTREE_INSERT will just take a list of keys and insert them into the btree - |
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* overwriting (possibly only partially) any extents they overlap with. This is |
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* used to update the index after a write. |
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* |
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* BTREE_REPLACE is really cmpxchg(); it inserts a key into the btree iff it is |
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* overwriting a key that matches another given key. This is used for inserting |
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* data into the cache after a cache miss, and for background writeback, and for |
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* the moving garbage collector. |
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* |
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* There is no "delete" operation; deleting things from the index is |
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* accomplished by either by invalidating pointers (by incrementing a bucket's |
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* gen) or by inserting a key with 0 pointers - which will overwrite anything |
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* previously present at that location in the index. |
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* |
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* This means that there are always stale/invalid keys in the btree. They're |
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* filtered out by the code that iterates through a btree node, and removed when |
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* a btree node is rewritten. |
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* |
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* BTREE NODES: |
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* |
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* Our unit of allocation is a bucket, and we can't arbitrarily allocate and |
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* free smaller than a bucket - so, that's how big our btree nodes are. |
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* |
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* (If buckets are really big we'll only use part of the bucket for a btree node |
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* - no less than 1/4th - but a bucket still contains no more than a single |
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* btree node. I'd actually like to change this, but for now we rely on the |
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* bucket's gen for deleting btree nodes when we rewrite/split a node.) |
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* |
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* Anyways, btree nodes are big - big enough to be inefficient with a textbook |
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* btree implementation. |
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* |
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* The way this is solved is that btree nodes are internally log structured; we |
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* can append new keys to an existing btree node without rewriting it. This |
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* means each set of keys we write is sorted, but the node is not. |
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* |
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* We maintain this log structure in memory - keeping 1Mb of keys sorted would |
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* be expensive, and we have to distinguish between the keys we have written and |
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* the keys we haven't. So to do a lookup in a btree node, we have to search |
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* each sorted set. But we do merge written sets together lazily, so the cost of |
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* these extra searches is quite low (normally most of the keys in a btree node |
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* will be in one big set, and then there'll be one or two sets that are much |
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* smaller). |
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* |
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* This log structure makes bcache's btree more of a hybrid between a |
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* conventional btree and a compacting data structure, with some of the |
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* advantages of both. |
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* |
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* GARBAGE COLLECTION: |
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* |
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* We can't just invalidate any bucket - it might contain dirty data or |
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* metadata. If it once contained dirty data, other writes might overwrite it |
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* later, leaving no valid pointers into that bucket in the index. |
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* |
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* Thus, the primary purpose of garbage collection is to find buckets to reuse. |
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* It also counts how much valid data it each bucket currently contains, so that |
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* allocation can reuse buckets sooner when they've been mostly overwritten. |
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* |
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* It also does some things that are really internal to the btree |
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* implementation. If a btree node contains pointers that are stale by more than |
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* some threshold, it rewrites the btree node to avoid the bucket's generation |
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* wrapping around. It also merges adjacent btree nodes if they're empty enough. |
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* |
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* THE JOURNAL: |
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* |
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* Bcache's journal is not necessary for consistency; we always strictly |
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* order metadata writes so that the btree and everything else is consistent on |
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* disk in the event of an unclean shutdown, and in fact bcache had writeback |
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* caching (with recovery from unclean shutdown) before journalling was |
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* implemented. |
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* |
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* Rather, the journal is purely a performance optimization; we can't complete a |
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* write until we've updated the index on disk, otherwise the cache would be |
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* inconsistent in the event of an unclean shutdown. This means that without the |
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* journal, on random write workloads we constantly have to update all the leaf |
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* nodes in the btree, and those writes will be mostly empty (appending at most |
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* a few keys each) - highly inefficient in terms of amount of metadata writes, |
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* and it puts more strain on the various btree resorting/compacting code. |
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* |
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* The journal is just a log of keys we've inserted; on startup we just reinsert |
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* all the keys in the open journal entries. That means that when we're updating |
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* a node in the btree, we can wait until a 4k block of keys fills up before |
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* writing them out. |
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* |
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* For simplicity, we only journal updates to leaf nodes; updates to parent |
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* nodes are rare enough (since our leaf nodes are huge) that it wasn't worth |
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* the complexity to deal with journalling them (in particular, journal replay) |
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* - updates to non leaf nodes just happen synchronously (see btree_split()). |
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*/ |
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|
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#define pr_fmt(fmt) "bcache: %s() " fmt, __func__ |
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#include <linux/bio.h> |
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#include <linux/kobject.h> |
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#include <linux/list.h> |
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#include <linux/mutex.h> |
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#include <linux/rbtree.h> |
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#include <linux/rwsem.h> |
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#include <linux/refcount.h> |
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#include <linux/types.h> |
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#include <linux/workqueue.h> |
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#include <linux/kthread.h> |
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#include "bcache_ondisk.h" |
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#include "bset.h" |
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#include "util.h" |
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#include "closure.h" |
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struct bucket { |
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atomic_t pin; |
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uint16_t prio; |
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uint8_t gen; |
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uint8_t last_gc; /* Most out of date gen in the btree */ |
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uint16_t gc_mark; /* Bitfield used by GC. See below for field */ |
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}; |
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/* |
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* I'd use bitfields for these, but I don't trust the compiler not to screw me |
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* as multiple threads touch struct bucket without locking |
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*/ |
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BITMASK(GC_MARK, struct bucket, gc_mark, 0, 2); |
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#define GC_MARK_RECLAIMABLE 1 |
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#define GC_MARK_DIRTY 2 |
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#define GC_MARK_METADATA 3 |
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#define GC_SECTORS_USED_SIZE 13 |
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#define MAX_GC_SECTORS_USED (~(~0ULL << GC_SECTORS_USED_SIZE)) |
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BITMASK(GC_SECTORS_USED, struct bucket, gc_mark, 2, GC_SECTORS_USED_SIZE); |
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BITMASK(GC_MOVE, struct bucket, gc_mark, 15, 1); |
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#include "journal.h" |
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#include "stats.h" |
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struct search; |
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struct btree; |
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struct keybuf; |
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struct keybuf_key { |
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struct rb_node node; |
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BKEY_PADDED(key); |
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void *private; |
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}; |
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struct keybuf { |
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struct bkey last_scanned; |
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spinlock_t lock; |
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|
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/* |
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* Beginning and end of range in rb tree - so that we can skip taking |
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* lock and checking the rb tree when we need to check for overlapping |
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* keys. |
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*/ |
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struct bkey start; |
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struct bkey end; |
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struct rb_root keys; |
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#define KEYBUF_NR 500 |
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DECLARE_ARRAY_ALLOCATOR(struct keybuf_key, freelist, KEYBUF_NR); |
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}; |
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struct bcache_device { |
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struct closure cl; |
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struct kobject kobj; |
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struct cache_set *c; |
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unsigned int id; |
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#define BCACHEDEVNAME_SIZE 12 |
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char name[BCACHEDEVNAME_SIZE]; |
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struct gendisk *disk; |
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unsigned long flags; |
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#define BCACHE_DEV_CLOSING 0 |
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#define BCACHE_DEV_DETACHING 1 |
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#define BCACHE_DEV_UNLINK_DONE 2 |
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#define BCACHE_DEV_WB_RUNNING 3 |
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#define BCACHE_DEV_RATE_DW_RUNNING 4 |
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int nr_stripes; |
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unsigned int stripe_size; |
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atomic_t *stripe_sectors_dirty; |
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unsigned long *full_dirty_stripes; |
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struct bio_set bio_split; |
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unsigned int data_csum:1; |
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int (*cache_miss)(struct btree *b, struct search *s, |
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struct bio *bio, unsigned int sectors); |
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int (*ioctl)(struct bcache_device *d, fmode_t mode, |
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unsigned int cmd, unsigned long arg); |
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}; |
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struct io { |
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/* Used to track sequential IO so it can be skipped */ |
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struct hlist_node hash; |
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struct list_head lru; |
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unsigned long jiffies; |
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unsigned int sequential; |
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sector_t last; |
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}; |
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enum stop_on_failure { |
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BCH_CACHED_DEV_STOP_AUTO = 0, |
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BCH_CACHED_DEV_STOP_ALWAYS, |
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BCH_CACHED_DEV_STOP_MODE_MAX, |
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}; |
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struct cached_dev { |
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struct list_head list; |
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struct bcache_device disk; |
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struct block_device *bdev; |
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struct cache_sb sb; |
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struct cache_sb_disk *sb_disk; |
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struct bio sb_bio; |
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struct bio_vec sb_bv[1]; |
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struct closure sb_write; |
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struct semaphore sb_write_mutex; |
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/* Refcount on the cache set. Always nonzero when we're caching. */ |
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refcount_t count; |
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struct work_struct detach; |
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/* |
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* Device might not be running if it's dirty and the cache set hasn't |
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* showed up yet. |
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*/ |
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atomic_t running; |
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/* |
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* Writes take a shared lock from start to finish; scanning for dirty |
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* data to refill the rb tree requires an exclusive lock. |
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*/ |
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struct rw_semaphore writeback_lock; |
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|
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/* |
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* Nonzero, and writeback has a refcount (d->count), iff there is dirty |
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* data in the cache. Protected by writeback_lock; must have an |
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* shared lock to set and exclusive lock to clear. |
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*/ |
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atomic_t has_dirty; |
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|
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#define BCH_CACHE_READA_ALL 0 |
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#define BCH_CACHE_READA_META_ONLY 1 |
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unsigned int cache_readahead_policy; |
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struct bch_ratelimit writeback_rate; |
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struct delayed_work writeback_rate_update; |
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|
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/* Limit number of writeback bios in flight */ |
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struct semaphore in_flight; |
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struct task_struct *writeback_thread; |
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struct workqueue_struct *writeback_write_wq; |
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struct keybuf writeback_keys; |
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struct task_struct *status_update_thread; |
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/* |
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* Order the write-half of writeback operations strongly in dispatch |
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* order. (Maintain LBA order; don't allow reads completing out of |
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* order to re-order the writes...) |
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*/ |
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struct closure_waitlist writeback_ordering_wait; |
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atomic_t writeback_sequence_next; |
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|
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/* For tracking sequential IO */ |
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#define RECENT_IO_BITS 7 |
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#define RECENT_IO (1 << RECENT_IO_BITS) |
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struct io io[RECENT_IO]; |
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struct hlist_head io_hash[RECENT_IO + 1]; |
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struct list_head io_lru; |
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spinlock_t io_lock; |
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struct cache_accounting accounting; |
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|
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/* The rest of this all shows up in sysfs */ |
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unsigned int sequential_cutoff; |
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|
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unsigned int io_disable:1; |
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unsigned int verify:1; |
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unsigned int bypass_torture_test:1; |
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unsigned int partial_stripes_expensive:1; |
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unsigned int writeback_metadata:1; |
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unsigned int writeback_running:1; |
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unsigned int writeback_consider_fragment:1; |
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unsigned char writeback_percent; |
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unsigned int writeback_delay; |
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uint64_t writeback_rate_target; |
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int64_t writeback_rate_proportional; |
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int64_t writeback_rate_integral; |
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int64_t writeback_rate_integral_scaled; |
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int32_t writeback_rate_change; |
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unsigned int writeback_rate_update_seconds; |
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unsigned int writeback_rate_i_term_inverse; |
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unsigned int writeback_rate_p_term_inverse; |
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unsigned int writeback_rate_fp_term_low; |
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unsigned int writeback_rate_fp_term_mid; |
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unsigned int writeback_rate_fp_term_high; |
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unsigned int writeback_rate_minimum; |
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enum stop_on_failure stop_when_cache_set_failed; |
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#define DEFAULT_CACHED_DEV_ERROR_LIMIT 64 |
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atomic_t io_errors; |
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unsigned int error_limit; |
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unsigned int offline_seconds; |
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|
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/* |
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* Retry to update writeback_rate if contention happens for |
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* down_read(dc->writeback_lock) in update_writeback_rate() |
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*/ |
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#define BCH_WBRATE_UPDATE_MAX_SKIPS 15 |
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unsigned int rate_update_retry; |
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}; |
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|
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enum alloc_reserve { |
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RESERVE_BTREE, |
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RESERVE_PRIO, |
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RESERVE_MOVINGGC, |
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RESERVE_NONE, |
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RESERVE_NR, |
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}; |
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struct cache { |
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struct cache_set *set; |
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struct cache_sb sb; |
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struct cache_sb_disk *sb_disk; |
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struct bio sb_bio; |
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struct bio_vec sb_bv[1]; |
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|
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struct kobject kobj; |
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struct block_device *bdev; |
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struct task_struct *alloc_thread; |
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|
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struct closure prio; |
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struct prio_set *disk_buckets; |
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|
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/* |
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* When allocating new buckets, prio_write() gets first dibs - since we |
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* may not be allocate at all without writing priorities and gens. |
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* prio_last_buckets[] contains the last buckets we wrote priorities to |
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* (so gc can mark them as metadata), prio_buckets[] contains the |
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* buckets allocated for the next prio write. |
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*/ |
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uint64_t *prio_buckets; |
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uint64_t *prio_last_buckets; |
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|
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/* |
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* free: Buckets that are ready to be used |
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* |
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* free_inc: Incoming buckets - these are buckets that currently have |
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* cached data in them, and we can't reuse them until after we write |
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* their new gen to disk. After prio_write() finishes writing the new |
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* gens/prios, they'll be moved to the free list (and possibly discarded |
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* in the process) |
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*/ |
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DECLARE_FIFO(long, free)[RESERVE_NR]; |
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DECLARE_FIFO(long, free_inc); |
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|
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size_t fifo_last_bucket; |
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|
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/* Allocation stuff: */ |
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struct bucket *buckets; |
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|
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DECLARE_HEAP(struct bucket *, heap); |
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|
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/* |
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* If nonzero, we know we aren't going to find any buckets to invalidate |
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* until a gc finishes - otherwise we could pointlessly burn a ton of |
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* cpu |
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*/ |
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unsigned int invalidate_needs_gc; |
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|
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bool discard; /* Get rid of? */ |
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|
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struct journal_device journal; |
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|
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/* The rest of this all shows up in sysfs */ |
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#define IO_ERROR_SHIFT 20 |
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atomic_t io_errors; |
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atomic_t io_count; |
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|
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atomic_long_t meta_sectors_written; |
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atomic_long_t btree_sectors_written; |
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atomic_long_t sectors_written; |
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}; |
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|
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struct gc_stat { |
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size_t nodes; |
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size_t nodes_pre; |
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size_t key_bytes; |
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|
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size_t nkeys; |
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uint64_t data; /* sectors */ |
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unsigned int in_use; /* percent */ |
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}; |
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|
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/* |
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* Flag bits, for how the cache set is shutting down, and what phase it's at: |
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* |
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* CACHE_SET_UNREGISTERING means we're not just shutting down, we're detaching |
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* all the backing devices first (their cached data gets invalidated, and they |
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* won't automatically reattach). |
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* |
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* CACHE_SET_STOPPING always gets set first when we're closing down a cache set; |
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* we'll continue to run normally for awhile with CACHE_SET_STOPPING set (i.e. |
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* flushing dirty data). |
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* |
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* CACHE_SET_RUNNING means all cache devices have been registered and journal |
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* replay is complete. |
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* |
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* CACHE_SET_IO_DISABLE is set when bcache is stopping the whold cache set, all |
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* external and internal I/O should be denied when this flag is set. |
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* |
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*/ |
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#define CACHE_SET_UNREGISTERING 0 |
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#define CACHE_SET_STOPPING 1 |
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#define CACHE_SET_RUNNING 2 |
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#define CACHE_SET_IO_DISABLE 3 |
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|
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struct cache_set { |
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struct closure cl; |
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|
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struct list_head list; |
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struct kobject kobj; |
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struct kobject internal; |
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struct dentry *debug; |
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struct cache_accounting accounting; |
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|
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unsigned long flags; |
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atomic_t idle_counter; |
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atomic_t at_max_writeback_rate; |
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|
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struct cache *cache; |
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|
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struct bcache_device **devices; |
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unsigned int devices_max_used; |
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atomic_t attached_dev_nr; |
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struct list_head cached_devs; |
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uint64_t cached_dev_sectors; |
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atomic_long_t flash_dev_dirty_sectors; |
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struct closure caching; |
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|
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struct closure sb_write; |
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struct semaphore sb_write_mutex; |
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|
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mempool_t search; |
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mempool_t bio_meta; |
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struct bio_set bio_split; |
|
|
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/* For the btree cache */ |
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struct shrinker shrink; |
|
|
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/* For the btree cache and anything allocation related */ |
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struct mutex bucket_lock; |
|
|
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/* log2(bucket_size), in sectors */ |
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unsigned short bucket_bits; |
|
|
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/* log2(block_size), in sectors */ |
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unsigned short block_bits; |
|
|
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/* |
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* Default number of pages for a new btree node - may be less than a |
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* full bucket |
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*/ |
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unsigned int btree_pages; |
|
|
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/* |
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* Lists of struct btrees; lru is the list for structs that have memory |
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* allocated for actual btree node, freed is for structs that do not. |
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* |
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* We never free a struct btree, except on shutdown - we just put it on |
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* the btree_cache_freed list and reuse it later. This simplifies the |
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* code, and it doesn't cost us much memory as the memory usage is |
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* dominated by buffers that hold the actual btree node data and those |
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* can be freed - and the number of struct btrees allocated is |
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* effectively bounded. |
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* |
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* btree_cache_freeable effectively is a small cache - we use it because |
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* high order page allocations can be rather expensive, and it's quite |
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* common to delete and allocate btree nodes in quick succession. It |
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* should never grow past ~2-3 nodes in practice. |
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*/ |
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struct list_head btree_cache; |
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struct list_head btree_cache_freeable; |
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struct list_head btree_cache_freed; |
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|
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/* Number of elements in btree_cache + btree_cache_freeable lists */ |
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unsigned int btree_cache_used; |
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|
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/* |
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* If we need to allocate memory for a new btree node and that |
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* allocation fails, we can cannibalize another node in the btree cache |
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* to satisfy the allocation - lock to guarantee only one thread does |
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* this at a time: |
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*/ |
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wait_queue_head_t btree_cache_wait; |
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struct task_struct *btree_cache_alloc_lock; |
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spinlock_t btree_cannibalize_lock; |
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|
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/* |
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* When we free a btree node, we increment the gen of the bucket the |
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* node is in - but we can't rewrite the prios and gens until we |
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* finished whatever it is we were doing, otherwise after a crash the |
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* btree node would be freed but for say a split, we might not have the |
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* pointers to the new nodes inserted into the btree yet. |
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* |
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* This is a refcount that blocks prio_write() until the new keys are |
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* written. |
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*/ |
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atomic_t prio_blocked; |
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wait_queue_head_t bucket_wait; |
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|
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/* |
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* For any bio we don't skip we subtract the number of sectors from |
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* rescale; when it hits 0 we rescale all the bucket priorities. |
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*/ |
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atomic_t rescale; |
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/* |
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* used for GC, identify if any front side I/Os is inflight |
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*/ |
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atomic_t search_inflight; |
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/* |
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* When we invalidate buckets, we use both the priority and the amount |
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* of good data to determine which buckets to reuse first - to weight |
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* those together consistently we keep track of the smallest nonzero |
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* priority of any bucket. |
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*/ |
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uint16_t min_prio; |
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|
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/* |
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* max(gen - last_gc) for all buckets. When it gets too big we have to |
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* gc to keep gens from wrapping around. |
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*/ |
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uint8_t need_gc; |
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struct gc_stat gc_stats; |
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size_t nbuckets; |
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size_t avail_nbuckets; |
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|
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struct task_struct *gc_thread; |
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/* Where in the btree gc currently is */ |
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struct bkey gc_done; |
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|
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/* |
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* For automatical garbage collection after writeback completed, this |
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* varialbe is used as bit fields, |
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* - 0000 0001b (BCH_ENABLE_AUTO_GC): enable gc after writeback |
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* - 0000 0010b (BCH_DO_AUTO_GC): do gc after writeback |
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* This is an optimization for following write request after writeback |
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* finished, but read hit rate dropped due to clean data on cache is |
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* discarded. Unless user explicitly sets it via sysfs, it won't be |
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* enabled. |
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*/ |
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#define BCH_ENABLE_AUTO_GC 1 |
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#define BCH_DO_AUTO_GC 2 |
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uint8_t gc_after_writeback; |
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|
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/* |
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* The allocation code needs gc_mark in struct bucket to be correct, but |
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* it's not while a gc is in progress. Protected by bucket_lock. |
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*/ |
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int gc_mark_valid; |
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|
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/* Counts how many sectors bio_insert has added to the cache */ |
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atomic_t sectors_to_gc; |
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wait_queue_head_t gc_wait; |
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|
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struct keybuf moving_gc_keys; |
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/* Number of moving GC bios in flight */ |
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struct semaphore moving_in_flight; |
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|
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struct workqueue_struct *moving_gc_wq; |
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|
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struct btree *root; |
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|
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#ifdef CONFIG_BCACHE_DEBUG |
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struct btree *verify_data; |
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struct bset *verify_ondisk; |
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struct mutex verify_lock; |
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#endif |
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|
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uint8_t set_uuid[16]; |
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unsigned int nr_uuids; |
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struct uuid_entry *uuids; |
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BKEY_PADDED(uuid_bucket); |
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struct closure uuid_write; |
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struct semaphore uuid_write_mutex; |
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|
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/* |
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* A btree node on disk could have too many bsets for an iterator to fit |
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* on the stack - have to dynamically allocate them. |
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* bch_cache_set_alloc() will make sure the pool can allocate iterators |
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* equipped with enough room that can host |
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* (sb.bucket_size / sb.block_size) |
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* btree_iter_sets, which is more than static MAX_BSETS. |
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*/ |
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mempool_t fill_iter; |
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|
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struct bset_sort_state sort; |
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|
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/* List of buckets we're currently writing data to */ |
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struct list_head data_buckets; |
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spinlock_t data_bucket_lock; |
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|
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struct journal journal; |
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|
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#define CONGESTED_MAX 1024 |
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unsigned int congested_last_us; |
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atomic_t congested; |
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|
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/* The rest of this all shows up in sysfs */ |
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unsigned int congested_read_threshold_us; |
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unsigned int congested_write_threshold_us; |
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|
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struct time_stats btree_gc_time; |
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struct time_stats btree_split_time; |
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struct time_stats btree_read_time; |
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|
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atomic_long_t cache_read_races; |
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atomic_long_t writeback_keys_done; |
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atomic_long_t writeback_keys_failed; |
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|
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atomic_long_t reclaim; |
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atomic_long_t reclaimed_journal_buckets; |
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atomic_long_t flush_write; |
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|
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enum { |
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ON_ERROR_UNREGISTER, |
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ON_ERROR_PANIC, |
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} on_error; |
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#define DEFAULT_IO_ERROR_LIMIT 8 |
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unsigned int error_limit; |
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unsigned int error_decay; |
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|
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unsigned short journal_delay_ms; |
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bool expensive_debug_checks; |
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unsigned int verify:1; |
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unsigned int key_merging_disabled:1; |
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unsigned int gc_always_rewrite:1; |
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unsigned int shrinker_disabled:1; |
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unsigned int copy_gc_enabled:1; |
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unsigned int idle_max_writeback_rate_enabled:1; |
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|
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#define BUCKET_HASH_BITS 12 |
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struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS]; |
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}; |
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|
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struct bbio { |
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unsigned int submit_time_us; |
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union { |
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struct bkey key; |
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uint64_t _pad[3]; |
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/* |
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* We only need pad = 3 here because we only ever carry around a |
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* single pointer - i.e. the pointer we're doing io to/from. |
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*/ |
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}; |
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struct bio bio; |
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}; |
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|
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#define BTREE_PRIO USHRT_MAX |
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#define INITIAL_PRIO 32768U |
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|
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#define btree_bytes(c) ((c)->btree_pages * PAGE_SIZE) |
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#define btree_blocks(b) \ |
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((unsigned int) (KEY_SIZE(&b->key) >> (b)->c->block_bits)) |
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|
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#define btree_default_blocks(c) \ |
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((unsigned int) ((PAGE_SECTORS * (c)->btree_pages) >> (c)->block_bits)) |
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|
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#define bucket_bytes(ca) ((ca)->sb.bucket_size << 9) |
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#define block_bytes(ca) ((ca)->sb.block_size << 9) |
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|
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static inline unsigned int meta_bucket_pages(struct cache_sb *sb) |
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{ |
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unsigned int n, max_pages; |
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|
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max_pages = min_t(unsigned int, |
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__rounddown_pow_of_two(USHRT_MAX) / PAGE_SECTORS, |
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MAX_ORDER_NR_PAGES); |
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|
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n = sb->bucket_size / PAGE_SECTORS; |
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if (n > max_pages) |
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n = max_pages; |
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|
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return n; |
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} |
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|
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static inline unsigned int meta_bucket_bytes(struct cache_sb *sb) |
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{ |
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return meta_bucket_pages(sb) << PAGE_SHIFT; |
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} |
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|
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#define prios_per_bucket(ca) \ |
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((meta_bucket_bytes(&(ca)->sb) - sizeof(struct prio_set)) / \ |
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sizeof(struct bucket_disk)) |
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|
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#define prio_buckets(ca) \ |
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DIV_ROUND_UP((size_t) (ca)->sb.nbuckets, prios_per_bucket(ca)) |
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|
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static inline size_t sector_to_bucket(struct cache_set *c, sector_t s) |
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{ |
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return s >> c->bucket_bits; |
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} |
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|
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static inline sector_t bucket_to_sector(struct cache_set *c, size_t b) |
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{ |
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return ((sector_t) b) << c->bucket_bits; |
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} |
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|
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static inline sector_t bucket_remainder(struct cache_set *c, sector_t s) |
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{ |
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return s & (c->cache->sb.bucket_size - 1); |
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} |
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|
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static inline size_t PTR_BUCKET_NR(struct cache_set *c, |
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const struct bkey *k, |
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unsigned int ptr) |
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{ |
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return sector_to_bucket(c, PTR_OFFSET(k, ptr)); |
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} |
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|
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static inline struct bucket *PTR_BUCKET(struct cache_set *c, |
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const struct bkey *k, |
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unsigned int ptr) |
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{ |
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return c->cache->buckets + PTR_BUCKET_NR(c, k, ptr); |
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} |
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|
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static inline uint8_t gen_after(uint8_t a, uint8_t b) |
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{ |
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uint8_t r = a - b; |
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|
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return r > 128U ? 0 : r; |
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} |
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|
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static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k, |
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unsigned int i) |
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{ |
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return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i)); |
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} |
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|
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static inline bool ptr_available(struct cache_set *c, const struct bkey *k, |
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unsigned int i) |
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{ |
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return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && c->cache; |
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} |
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|
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/* Btree key macros */ |
|
|
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/* |
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* This is used for various on disk data structures - cache_sb, prio_set, bset, |
|
* jset: The checksum is _always_ the first 8 bytes of these structs |
|
*/ |
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#define csum_set(i) \ |
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bch_crc64(((void *) (i)) + sizeof(uint64_t), \ |
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((void *) bset_bkey_last(i)) - \ |
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(((void *) (i)) + sizeof(uint64_t))) |
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|
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/* Error handling macros */ |
|
|
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#define btree_bug(b, ...) \ |
|
do { \ |
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if (bch_cache_set_error((b)->c, __VA_ARGS__)) \ |
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dump_stack(); \ |
|
} while (0) |
|
|
|
#define cache_bug(c, ...) \ |
|
do { \ |
|
if (bch_cache_set_error(c, __VA_ARGS__)) \ |
|
dump_stack(); \ |
|
} while (0) |
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|
|
#define btree_bug_on(cond, b, ...) \ |
|
do { \ |
|
if (cond) \ |
|
btree_bug(b, __VA_ARGS__); \ |
|
} while (0) |
|
|
|
#define cache_bug_on(cond, c, ...) \ |
|
do { \ |
|
if (cond) \ |
|
cache_bug(c, __VA_ARGS__); \ |
|
} while (0) |
|
|
|
#define cache_set_err_on(cond, c, ...) \ |
|
do { \ |
|
if (cond) \ |
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bch_cache_set_error(c, __VA_ARGS__); \ |
|
} while (0) |
|
|
|
/* Looping macros */ |
|
|
|
#define for_each_bucket(b, ca) \ |
|
for (b = (ca)->buckets + (ca)->sb.first_bucket; \ |
|
b < (ca)->buckets + (ca)->sb.nbuckets; b++) |
|
|
|
static inline void cached_dev_put(struct cached_dev *dc) |
|
{ |
|
if (refcount_dec_and_test(&dc->count)) |
|
schedule_work(&dc->detach); |
|
} |
|
|
|
static inline bool cached_dev_get(struct cached_dev *dc) |
|
{ |
|
if (!refcount_inc_not_zero(&dc->count)) |
|
return false; |
|
|
|
/* Paired with the mb in cached_dev_attach */ |
|
smp_mb__after_atomic(); |
|
return true; |
|
} |
|
|
|
/* |
|
* bucket_gc_gen() returns the difference between the bucket's current gen and |
|
* the oldest gen of any pointer into that bucket in the btree (last_gc). |
|
*/ |
|
|
|
static inline uint8_t bucket_gc_gen(struct bucket *b) |
|
{ |
|
return b->gen - b->last_gc; |
|
} |
|
|
|
#define BUCKET_GC_GEN_MAX 96U |
|
|
|
#define kobj_attribute_write(n, fn) \ |
|
static struct kobj_attribute ksysfs_##n = __ATTR(n, 0200, NULL, fn) |
|
|
|
#define kobj_attribute_rw(n, show, store) \ |
|
static struct kobj_attribute ksysfs_##n = \ |
|
__ATTR(n, 0600, show, store) |
|
|
|
static inline void wake_up_allocators(struct cache_set *c) |
|
{ |
|
struct cache *ca = c->cache; |
|
|
|
wake_up_process(ca->alloc_thread); |
|
} |
|
|
|
static inline void closure_bio_submit(struct cache_set *c, |
|
struct bio *bio, |
|
struct closure *cl) |
|
{ |
|
closure_get(cl); |
|
if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) { |
|
bio->bi_status = BLK_STS_IOERR; |
|
bio_endio(bio); |
|
return; |
|
} |
|
submit_bio_noacct(bio); |
|
} |
|
|
|
/* |
|
* Prevent the kthread exits directly, and make sure when kthread_stop() |
|
* is called to stop a kthread, it is still alive. If a kthread might be |
|
* stopped by CACHE_SET_IO_DISABLE bit set, wait_for_kthread_stop() is |
|
* necessary before the kthread returns. |
|
*/ |
|
static inline void wait_for_kthread_stop(void) |
|
{ |
|
while (!kthread_should_stop()) { |
|
set_current_state(TASK_INTERRUPTIBLE); |
|
schedule(); |
|
} |
|
} |
|
|
|
/* Forward declarations */ |
|
|
|
void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio); |
|
void bch_count_io_errors(struct cache *ca, blk_status_t error, |
|
int is_read, const char *m); |
|
void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio, |
|
blk_status_t error, const char *m); |
|
void bch_bbio_endio(struct cache_set *c, struct bio *bio, |
|
blk_status_t error, const char *m); |
|
void bch_bbio_free(struct bio *bio, struct cache_set *c); |
|
struct bio *bch_bbio_alloc(struct cache_set *c); |
|
|
|
void __bch_submit_bbio(struct bio *bio, struct cache_set *c); |
|
void bch_submit_bbio(struct bio *bio, struct cache_set *c, |
|
struct bkey *k, unsigned int ptr); |
|
|
|
uint8_t bch_inc_gen(struct cache *ca, struct bucket *b); |
|
void bch_rescale_priorities(struct cache_set *c, int sectors); |
|
|
|
bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b); |
|
void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b); |
|
|
|
void __bch_bucket_free(struct cache *ca, struct bucket *b); |
|
void bch_bucket_free(struct cache_set *c, struct bkey *k); |
|
|
|
long bch_bucket_alloc(struct cache *ca, unsigned int reserve, bool wait); |
|
int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve, |
|
struct bkey *k, bool wait); |
|
int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve, |
|
struct bkey *k, bool wait); |
|
bool bch_alloc_sectors(struct cache_set *c, struct bkey *k, |
|
unsigned int sectors, unsigned int write_point, |
|
unsigned int write_prio, bool wait); |
|
bool bch_cached_dev_error(struct cached_dev *dc); |
|
|
|
__printf(2, 3) |
|
bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...); |
|
|
|
int bch_prio_write(struct cache *ca, bool wait); |
|
void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent); |
|
|
|
extern struct workqueue_struct *bcache_wq; |
|
extern struct workqueue_struct *bch_journal_wq; |
|
extern struct workqueue_struct *bch_flush_wq; |
|
extern struct mutex bch_register_lock; |
|
extern struct list_head bch_cache_sets; |
|
|
|
extern struct kobj_type bch_cached_dev_ktype; |
|
extern struct kobj_type bch_flash_dev_ktype; |
|
extern struct kobj_type bch_cache_set_ktype; |
|
extern struct kobj_type bch_cache_set_internal_ktype; |
|
extern struct kobj_type bch_cache_ktype; |
|
|
|
void bch_cached_dev_release(struct kobject *kobj); |
|
void bch_flash_dev_release(struct kobject *kobj); |
|
void bch_cache_set_release(struct kobject *kobj); |
|
void bch_cache_release(struct kobject *kobj); |
|
|
|
int bch_uuid_write(struct cache_set *c); |
|
void bcache_write_super(struct cache_set *c); |
|
|
|
int bch_flash_dev_create(struct cache_set *c, uint64_t size); |
|
|
|
int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c, |
|
uint8_t *set_uuid); |
|
void bch_cached_dev_detach(struct cached_dev *dc); |
|
int bch_cached_dev_run(struct cached_dev *dc); |
|
void bcache_device_stop(struct bcache_device *d); |
|
|
|
void bch_cache_set_unregister(struct cache_set *c); |
|
void bch_cache_set_stop(struct cache_set *c); |
|
|
|
struct cache_set *bch_cache_set_alloc(struct cache_sb *sb); |
|
void bch_btree_cache_free(struct cache_set *c); |
|
int bch_btree_cache_alloc(struct cache_set *c); |
|
void bch_moving_init_cache_set(struct cache_set *c); |
|
int bch_open_buckets_alloc(struct cache_set *c); |
|
void bch_open_buckets_free(struct cache_set *c); |
|
|
|
int bch_cache_allocator_start(struct cache *ca); |
|
|
|
void bch_debug_exit(void); |
|
void bch_debug_init(void); |
|
void bch_request_exit(void); |
|
int bch_request_init(void); |
|
void bch_btree_exit(void); |
|
int bch_btree_init(void); |
|
|
|
#endif /* _BCACHE_H */
|
|
|