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btrfs-progs: Add delayed refs infrastructure

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This commit pulls those portions of the kernel implementation of
delayed refs which are necessary to have them working in user-space.
I've done the following modifications:

1. Replaced all kmem_cache_alloc calls to kmalloc.

2. Removed all locking-related code, since we are single threaded in
   userspace.

3. Removed code which deals with data refs - delayed refs in user space
   are going to be used only for cowonly trees.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Nikolay Borisov 2018-06-08 17:53:29 +03:00 committed by David Sterba
parent 3c8faad5cf
commit c6039704c5
7 changed files with 1058 additions and 1 deletions
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3
Makefile
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@ -116,7 +116,8 @@ objects = ctree.o disk-io.o kernel-lib/radix-tree.o extent-tree.o print-tree.o \
qgroup.o free-space-cache.o kernel-lib/list_sort.o props.o \
kernel-shared/ulist.o qgroup-verify.o backref.o string-table.o task-utils.o \
inode.o file.o find-root.o free-space-tree.o help.o send-dump.o \
fsfeatures.o kernel-lib/tables.o kernel-lib/raid56.o transaction.o
fsfeatures.o kernel-lib/tables.o kernel-lib/raid56.o transaction.o \
delayed-ref.o
cmds_objects = cmds-subvolume.o cmds-filesystem.o cmds-device.o cmds-scrub.o \
cmds-inspect.o cmds-balance.o cmds-send.o cmds-receive.o \
cmds-quota.o cmds-qgroup.o cmds-replace.o check/main.o \

3
ctree.h
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@ -2790,4 +2790,7 @@ int btrfs_punch_hole(struct btrfs_trans_handle *trans,
int btrfs_read_file(struct btrfs_root *root, u64 ino, u64 start, int len,
char *dest);
/* extent-tree.c */
int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, unsigned long nr);
#endif

607
delayed-ref.c Normal file
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@ -0,0 +1,607 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2009 Oracle. All rights reserved.
*/
#include "ctree.h"
#include "btrfs-list.h"
#include "delayed-ref.h"
#include "transaction.h"
/*
* delayed back reference update tracking. For subvolume trees
* we queue up extent allocations and backref maintenance for
* delayed processing. This avoids deep call chains where we
* add extents in the middle of btrfs_search_slot, and it allows
* us to buffer up frequently modified backrefs in an rb tree instead
* of hammering updates on the extent allocation tree.
*/
/*
* compare two delayed tree backrefs with same bytenr and type
*/
static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref1,
struct btrfs_delayed_tree_ref *ref2)
{
if (ref1->node.type == BTRFS_TREE_BLOCK_REF_KEY) {
if (ref1->root < ref2->root)
return -1;
if (ref1->root > ref2->root)
return 1;
} else {
if (ref1->parent < ref2->parent)
return -1;
if (ref1->parent > ref2->parent)
return 1;
}
return 0;
}
static int comp_refs(struct btrfs_delayed_ref_node *ref1,
struct btrfs_delayed_ref_node *ref2,
bool check_seq)
{
int ret = 0;
if (ref1->type < ref2->type)
return -1;
if (ref1->type > ref2->type)
return 1;
if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY ||
ref1->type == BTRFS_SHARED_BLOCK_REF_KEY)
ret = comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref1),
btrfs_delayed_node_to_tree_ref(ref2));
else
BUG();
if (ret)
return ret;
if (check_seq) {
if (ref1->seq < ref2->seq)
return -1;
if (ref1->seq > ref2->seq)
return 1;
}
return 0;
}
/* insert a new ref to head ref rbtree */
static struct btrfs_delayed_ref_head *htree_insert(struct rb_root *root,
struct rb_node *node)
{
struct rb_node **p = &root->rb_node;
struct rb_node *parent_node = NULL;
struct btrfs_delayed_ref_head *entry;
struct btrfs_delayed_ref_head *ins;
u64 bytenr;
ins = rb_entry(node, struct btrfs_delayed_ref_head, href_node);
bytenr = ins->bytenr;
while (*p) {
parent_node = *p;
entry = rb_entry(parent_node, struct btrfs_delayed_ref_head,
href_node);
if (bytenr < entry->bytenr)
p = &(*p)->rb_left;
else if (bytenr > entry->bytenr)
p = &(*p)->rb_right;
else
return entry;
}
rb_link_node(node, parent_node, p);
rb_insert_color(node, root);
return NULL;
}
static struct btrfs_delayed_ref_node* tree_insert(struct rb_root *root,
struct btrfs_delayed_ref_node *ins)
{
struct rb_node **p = &root->rb_node;
struct rb_node *node = &ins->ref_node;
struct rb_node *parent_node = NULL;
struct btrfs_delayed_ref_node *entry;
while (*p) {
int comp;
parent_node = *p;
entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,
ref_node);
comp = comp_refs(ins, entry, true);
if (comp < 0)
p = &(*p)->rb_left;
else if (comp > 0)
p = &(*p)->rb_right;
else
return entry;
}
rb_link_node(node, parent_node, p);
rb_insert_color(node, root);
return NULL;
}
/*
* find an head entry based on bytenr. This returns the delayed ref
* head if it was able to find one, or NULL if nothing was in that spot.
* If return_bigger is given, the next bigger entry is returned if no exact
* match is found.
*/
static struct btrfs_delayed_ref_head *
find_ref_head(struct rb_root *root, u64 bytenr,
int return_bigger)
{
struct rb_node *n;
struct btrfs_delayed_ref_head *entry;
n = root->rb_node;
entry = NULL;
while (n) {
entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
if (bytenr < entry->bytenr)
n = n->rb_left;
else if (bytenr > entry->bytenr)
n = n->rb_right;
else
return entry;
}
if (entry && return_bigger) {
if (bytenr > entry->bytenr) {
n = rb_next(&entry->href_node);
if (!n)
n = rb_first(root);
entry = rb_entry(n, struct btrfs_delayed_ref_head,
href_node);
return entry;
}
return entry;
}
return NULL;
}
static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_delayed_ref_head *head,
struct btrfs_delayed_ref_node *ref)
{
rb_erase(&ref->ref_node, &head->ref_tree);
RB_CLEAR_NODE(&ref->ref_node);
if (!list_empty(&ref->add_list))
list_del(&ref->add_list);
ref->in_tree = 0;
btrfs_put_delayed_ref(ref);
if (trans->delayed_ref_updates)
trans->delayed_ref_updates--;
}
static bool merge_ref(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_delayed_ref_head *head,
struct btrfs_delayed_ref_node *ref,
u64 seq)
{
struct btrfs_delayed_ref_node *next;
struct rb_node *node = rb_next(&ref->ref_node);
bool done = false;
while (!done && node) {
int mod;
next = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
node = rb_next(node);
if (seq && next->seq >= seq)
break;
if (comp_refs(ref, next, false))
break;
if (ref->action == next->action) {
mod = next->ref_mod;
} else {
if (ref->ref_mod < next->ref_mod) {
swap(ref, next);
done = true;
}
mod = -next->ref_mod;
}
drop_delayed_ref(trans, delayed_refs, head, next);
ref->ref_mod += mod;
if (ref->ref_mod == 0) {
drop_delayed_ref(trans, delayed_refs, head, ref);
done = true;
} else {
/*
* Can't have multiples of the same ref on a tree block.
*/
WARN_ON(ref->type == BTRFS_TREE_BLOCK_REF_KEY ||
ref->type == BTRFS_SHARED_BLOCK_REF_KEY);
}
}
return done;
}
void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_delayed_ref_head *head)
{
struct btrfs_delayed_ref_node *ref;
struct rb_node *node;
if (RB_EMPTY_ROOT(&head->ref_tree))
return;
/* We don't have too many refs to merge for data. */
if (head->is_data)
return;
again:
for (node = rb_first(&head->ref_tree); node; node = rb_next(node)) {
ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);
if (merge_ref(trans, delayed_refs, head, ref, 0))
goto again;
}
}
struct btrfs_delayed_ref_head *
btrfs_select_ref_head(struct btrfs_trans_handle *trans)
{
struct btrfs_delayed_ref_root *delayed_refs;
struct btrfs_delayed_ref_head *head;
u64 start;
bool loop = false;
delayed_refs = &trans->delayed_refs;
again:
start = delayed_refs->run_delayed_start;
head = find_ref_head(&delayed_refs->href_root, start, 1);
if (!head && !loop) {
delayed_refs->run_delayed_start = 0;
start = 0;
loop = true;
head = find_ref_head(&delayed_refs->href_root, start, 1);
if (!head)
return NULL;
} else if (!head && loop) {
return NULL;
}
while (head->processing) {
struct rb_node *node;
node = rb_next(&head->href_node);
if (!node) {
if (loop)
return NULL;
delayed_refs->run_delayed_start = 0;
start = 0;
loop = true;
goto again;
}
head = rb_entry(node, struct btrfs_delayed_ref_head,
href_node);
}
head->processing = 1;
WARN_ON(delayed_refs->num_heads_ready == 0);
delayed_refs->num_heads_ready--;
delayed_refs->run_delayed_start = head->bytenr +
head->num_bytes;
return head;
}
/*
* Helper to insert the ref_node to the tail or merge with tail.
*
* Return 0 for insert.
* Return >0 for merge.
*/
static int insert_delayed_ref(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_root *root,
struct btrfs_delayed_ref_head *href,
struct btrfs_delayed_ref_node *ref)
{
struct btrfs_delayed_ref_node *exist;
int mod;
int ret = 0;
exist = tree_insert(&href->ref_tree, ref);
if (!exist)
goto inserted;
/* Now we are sure we can merge */
ret = 1;
if (exist->action == ref->action) {
mod = ref->ref_mod;
} else {
/* Need to change action */
if (exist->ref_mod < ref->ref_mod) {
exist->action = ref->action;
mod = -exist->ref_mod;
exist->ref_mod = ref->ref_mod;
if (ref->action == BTRFS_ADD_DELAYED_REF)
list_add_tail(&exist->add_list,
&href->ref_add_list);
else if (ref->action == BTRFS_DROP_DELAYED_REF) {
ASSERT(!list_empty(&exist->add_list));
list_del(&exist->add_list);
} else {
ASSERT(0);
}
} else
mod = -ref->ref_mod;
}
exist->ref_mod += mod;
/* remove existing tail if its ref_mod is zero */
if (exist->ref_mod == 0)
drop_delayed_ref(trans, root, href, exist);
return ret;
inserted:
if (ref->action == BTRFS_ADD_DELAYED_REF)
list_add_tail(&ref->add_list, &href->ref_add_list);
trans->delayed_ref_updates++;
return ret;
}
/*
* helper function to update the accounting in the head ref
* existing and update must have the same bytenr
*/
static noinline void
update_existing_head_ref(struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_delayed_ref_head *existing,
struct btrfs_delayed_ref_head *update,
int *old_ref_mod_ret)
{
int old_ref_mod;
BUG_ON(existing->is_data != update->is_data);
if (update->must_insert_reserved) {
/* if the extent was freed and then
* reallocated before the delayed ref
* entries were processed, we can end up
* with an existing head ref without
* the must_insert_reserved flag set.
* Set it again here
*/
existing->must_insert_reserved = update->must_insert_reserved;
/*
* update the num_bytes so we make sure the accounting
* is done correctly
*/
existing->num_bytes = update->num_bytes;
}
if (update->extent_op) {
if (!existing->extent_op) {
existing->extent_op = update->extent_op;
} else {
if (update->extent_op->update_key) {
memcpy(&existing->extent_op->key,
&update->extent_op->key,
sizeof(update->extent_op->key));
existing->extent_op->update_key = true;
}
if (update->extent_op->update_flags) {
existing->extent_op->flags_to_set |=
update->extent_op->flags_to_set;
existing->extent_op->update_flags = true;
}
btrfs_free_delayed_extent_op(update->extent_op);
}
}
/*
* update the reference mod on the head to reflect this new operation,
* only need the lock for this case cause we could be processing it
* currently, for refs we just added we know we're a-ok.
*/
old_ref_mod = existing->total_ref_mod;
if (old_ref_mod_ret)
*old_ref_mod_ret = old_ref_mod;
existing->ref_mod += update->ref_mod;
existing->total_ref_mod += update->ref_mod;
}
static void init_delayed_ref_head(struct btrfs_delayed_ref_head *head_ref,
void *qrecord,
u64 bytenr, u64 num_bytes, u64 ref_root,
u64 reserved, int action, bool is_data,
bool is_system)
{
int count_mod = 1;
int must_insert_reserved = 0;
/* If reserved is provided, it must be a data extent. */
BUG_ON(!is_data && reserved);
/*
* The head node stores the sum of all the mods, so dropping a ref
* should drop the sum in the head node by one.
*/
if (action == BTRFS_UPDATE_DELAYED_HEAD)
count_mod = 0;
else if (action == BTRFS_DROP_DELAYED_REF)
count_mod = -1;
/*
* BTRFS_ADD_DELAYED_EXTENT means that we need to update the reserved
* accounting when the extent is finally added, or if a later
* modification deletes the delayed ref without ever inserting the
* extent into the extent allocation tree. ref->must_insert_reserved
* is the flag used to record that accounting mods are required.
*
* Once we record must_insert_reserved, switch the action to
* BTRFS_ADD_DELAYED_REF because other special casing is not required.
*/
if (action == BTRFS_ADD_DELAYED_EXTENT)
must_insert_reserved = 1;
else
must_insert_reserved = 0;
head_ref->refs = 1;
head_ref->bytenr = bytenr;
head_ref->num_bytes = num_bytes;
head_ref->ref_mod = count_mod;
head_ref->must_insert_reserved = must_insert_reserved;
head_ref->is_data = is_data;
head_ref->is_system = is_system;
head_ref->ref_tree = RB_ROOT;
INIT_LIST_HEAD(&head_ref->ref_add_list);
RB_CLEAR_NODE(&head_ref->href_node);
head_ref->processing = 0;
head_ref->total_ref_mod = count_mod;
}
/*
* helper function to actually insert a head node into the rbtree.
* this does all the dirty work in terms of maintaining the correct
* overall modification count.
*/
static noinline struct btrfs_delayed_ref_head *
add_delayed_ref_head(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_head *head_ref,
void *qrecord,
int action, int *qrecord_inserted_ret,
int *old_ref_mod, int *new_ref_mod)
{
struct btrfs_delayed_ref_head *existing;
struct btrfs_delayed_ref_root *delayed_refs;
delayed_refs = &trans->delayed_refs;
existing = htree_insert(&delayed_refs->href_root, &head_ref->href_node);
if (existing) {
update_existing_head_ref(delayed_refs, existing, head_ref, old_ref_mod);
/*
* we've updated the existing ref, free the newly
* allocated ref
*/
kfree(head_ref);
head_ref = existing;
} else {
if (old_ref_mod)
*old_ref_mod = 0;
delayed_refs->num_heads++;
delayed_refs->num_heads_ready++;
trans->delayed_ref_updates++;
}
if (new_ref_mod)
*new_ref_mod = head_ref->total_ref_mod;
return head_ref;
}
/*
* init_delayed_ref_common - Initialize the structure which represents a
* modification to a an extent.
*
* @fs_info: Internal to the mounted filesystem mount structure.
*
* @ref: The structure which is going to be initialized.
*
* @bytenr: The logical address of the extent for which a modification is
* going to be recorded.
*
* @num_bytes: Size of the extent whose modification is being recorded.
*
* @ref_root: The id of the root where this modification has originated, this
* can be either one of the well-known metadata trees or the
* subvolume id which references this extent.
*
* @action: Can be one of BTRFS_ADD_DELAYED_REF/BTRFS_DROP_DELAYED_REF or
* BTRFS_ADD_DELAYED_EXTENT
*
* @ref_type: Holds the type of the extent which is being recorded, can be
* one of BTRFS_SHARED_BLOCK_REF_KEY/BTRFS_TREE_BLOCK_REF_KEY
* when recording a metadata extent or BTRFS_SHARED_DATA_REF_KEY/
* BTRFS_EXTENT_DATA_REF_KEY when recording data extent
*/
static void init_delayed_ref_common(struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_node *ref,
u64 bytenr, u64 num_bytes, u64 ref_root,
int action, u8 ref_type)
{
if (action == BTRFS_ADD_DELAYED_EXTENT)
action = BTRFS_ADD_DELAYED_REF;
ref->refs = 1;
ref->bytenr = bytenr;
ref->num_bytes = num_bytes;
ref->ref_mod = 1;
ref->action = action;
ref->is_head = 0;
ref->in_tree = 1;
ref->seq = 0;
ref->type = ref_type;
RB_CLEAR_NODE(&ref->ref_node);
INIT_LIST_HEAD(&ref->add_list);
}
/*
* add a delayed tree ref. This does all of the accounting required
* to make sure the delayed ref is eventually processed before this
* transaction commits.
*/
int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes, u64 parent,
u64 ref_root, int level, int action,
struct btrfs_delayed_extent_op *extent_op,
int *old_ref_mod, int *new_ref_mod)
{
struct btrfs_delayed_tree_ref *ref;
struct btrfs_delayed_ref_head *head_ref;
struct btrfs_delayed_ref_root *delayed_refs;
bool is_system = (ref_root == BTRFS_CHUNK_TREE_OBJECTID);
int ret;
u8 ref_type;
BUG_ON(extent_op && extent_op->is_data);
ref = kmalloc(sizeof(*ref), GFP_NOFS);
if (!ref)
return -ENOMEM;
if (parent)
ref_type = BTRFS_SHARED_BLOCK_REF_KEY;
else
ref_type = BTRFS_TREE_BLOCK_REF_KEY;
init_delayed_ref_common(fs_info, &ref->node, bytenr, num_bytes,
ref_root, action, ref_type);
ref->root = ref_root;
ref->parent = parent;
ref->level = level;
head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
if (!head_ref)
goto free_ref;
init_delayed_ref_head(head_ref, NULL, bytenr, num_bytes,
ref_root, 0, action, false, is_system);
head_ref->extent_op = extent_op;
delayed_refs = &trans->delayed_refs;
head_ref = add_delayed_ref_head(trans, head_ref, NULL, action, NULL,
old_ref_mod, new_ref_mod);
ret = insert_delayed_ref(trans, delayed_refs, head_ref, &ref->node);
if (ret > 0)
kfree(ref);
return 0;
free_ref:
kfree(ref);
return -ENOMEM;
}

208
delayed-ref.h Normal file
View File

@ -0,0 +1,208 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2008 Oracle. All rights reserved.
*/
#ifndef BTRFS_DELAYED_REF_H
#define BTRFS_DELAYED_REF_H
#include "kerncompat.h"
/* these are the possible values of struct btrfs_delayed_ref_node->action */
#define BTRFS_ADD_DELAYED_REF 1 /* add one backref to the tree */
#define BTRFS_DROP_DELAYED_REF 2 /* delete one backref from the tree */
#define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */
#define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */
struct btrfs_delayed_ref_node {
struct rb_node ref_node;
/*
* If action is BTRFS_ADD_DELAYED_REF, also link this node to
* ref_head->ref_add_list, then we do not need to iterate the
* whole ref_head->ref_list to find BTRFS_ADD_DELAYED_REF nodes.
*/
struct list_head add_list;
/* the starting bytenr of the extent */
u64 bytenr;
/* the size of the extent */
u64 num_bytes;
/* seq number to keep track of insertion order */
u64 seq;
/* ref count on this data structure */
u64 refs;
/*
* how many refs is this entry adding or deleting. For
* head refs, this may be a negative number because it is keeping
* track of the total mods done to the reference count.
* For individual refs, this will always be a positive number
*
* It may be more than one, since it is possible for a single
* parent to have more than one ref on an extent
*/
int ref_mod;
unsigned int action:8;
unsigned int type:8;
/* is this node still in the rbtree? */
unsigned int is_head:1;
unsigned int in_tree:1;
};
struct btrfs_delayed_extent_op {
struct btrfs_disk_key key;
u8 level;
bool update_key;
bool update_flags;
bool is_data;
u64 flags_to_set;
};
/*
* the head refs are used to hold a lock on a given extent, which allows us
* to make sure that only one process is running the delayed refs
* at a time for a single extent. They also store the sum of all the
* reference count modifications we've queued up.
*/
struct btrfs_delayed_ref_head {
u64 bytenr;
u64 num_bytes;
u64 refs;
struct rb_root ref_tree;
/* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
struct list_head ref_add_list;
struct rb_node href_node;
struct btrfs_delayed_extent_op *extent_op;
/*
* This is used to track the final ref_mod from all the refs associated
* with this head ref, this is not adjusted as delayed refs are run,
* this is meant to track if we need to do the csum accounting or not.
*/
int total_ref_mod;
/*
* This is the current outstanding mod references for this bytenr. This
* is used with lookup_extent_info to get an accurate reference count
* for a bytenr, so it is adjusted as delayed refs are run so that any
* on disk reference count + ref_mod is accurate.
*/
int ref_mod;
/*
* when a new extent is allocated, it is just reserved in memory
* The actual extent isn't inserted into the extent allocation tree
* until the delayed ref is processed. must_insert_reserved is
* used to flag a delayed ref so the accounting can be updated
* when a full insert is done.
*
* It is possible the extent will be freed before it is ever
* inserted into the extent allocation tree. In this case
* we need to update the in ram accounting to properly reflect
* the free has happened.
*/
unsigned int must_insert_reserved:1;
unsigned int is_data:1;
unsigned int is_system:1;
unsigned int processing:1;
};
struct btrfs_delayed_tree_ref {
struct btrfs_delayed_ref_node node;
u64 root;
u64 parent;
int level;
};
struct btrfs_delayed_ref_root {
/* head ref rbtree */
struct rb_root href_root;
/* dirty extent records */
struct rb_root dirty_extent_root;
/* total number of head nodes in tree */
unsigned long num_heads;
/* total number of head nodes ready for processing */
unsigned long num_heads_ready;
/*
* set when the tree is flushing before a transaction commit,
* used by the throttling code to decide if new updates need
* to be run right away
*/
int flushing;
u64 run_delayed_start;
};
static inline struct btrfs_delayed_extent_op *
btrfs_alloc_delayed_extent_op(void)
{
return kmalloc(sizeof(struct btrfs_delayed_extent_op), GFP_KERNEL);
}
static inline void
btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
{
if (op)
kfree(op);
}
static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
{
WARN_ON(ref->refs == 0);
if (--ref->refs) {
WARN_ON(ref->in_tree);
switch (ref->type) {
case BTRFS_TREE_BLOCK_REF_KEY:
case BTRFS_SHARED_BLOCK_REF_KEY:
kfree(ref);
break;
case BTRFS_EXTENT_DATA_REF_KEY:
case BTRFS_SHARED_DATA_REF_KEY:
kfree(ref);
break;
default:
BUG();
}
}
}
static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head)
{
if (--head->refs)
kfree(head);
}
int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes, u64 parent,
u64 ref_root, int level, int action,
struct btrfs_delayed_extent_op *extent_op,
int *old_ref_mod, int *new_ref_mod);
void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_delayed_ref_head *head);
struct btrfs_delayed_ref_head *
btrfs_select_ref_head(struct btrfs_trans_handle *trans);
/*
* helper functions to cast a node into its container
*/
static inline struct btrfs_delayed_tree_ref *
btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
{
return container_of(node, struct btrfs_delayed_tree_ref, node);
}
#endif

226
extent-tree.c
View File

@ -4219,3 +4219,229 @@ u64 add_new_free_space(struct btrfs_block_group_cache *block_group,
return total_added;
}
static void cleanup_extent_op(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_head *head)
{
struct btrfs_delayed_extent_op *extent_op = head->extent_op;
if (!extent_op)
return;
head->extent_op = NULL;
btrfs_free_delayed_extent_op(extent_op);
}
static void unselect_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
struct btrfs_delayed_ref_head *head)
{
head->processing = 0;
delayed_refs->num_heads_ready++;
}
static int cleanup_ref_head(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_head *head)
{
struct btrfs_delayed_ref_root *delayed_refs;
delayed_refs = &trans->delayed_refs;
cleanup_extent_op(trans, fs_info, head);
/*
* Need to drop our head ref lock and re-acquire the delayed ref lock
* and then re-check to make sure nobody got added.
*/
if (!RB_EMPTY_ROOT(&head->ref_tree) || head->extent_op)
return 1;
delayed_refs->num_heads--;
rb_erase(&head->href_node, &delayed_refs->href_root);
RB_CLEAR_NODE(&head->href_node);
if (head->must_insert_reserved)
btrfs_pin_extent(fs_info, head->bytenr, head->num_bytes);
btrfs_put_delayed_ref_head(head);
return 0;
}
static inline struct btrfs_delayed_ref_node *
select_delayed_ref(struct btrfs_delayed_ref_head *head)
{
struct btrfs_delayed_ref_node *ref;
if (RB_EMPTY_ROOT(&head->ref_tree))
return NULL;
/*
* Select a delayed ref of type BTRFS_ADD_DELAYED_REF first.
* This is to prevent a ref count from going down to zero, which deletes
* the extent item from the extent tree, when there still are references
* to add, which would fail because they would not find the extent item.
*/
if (!list_empty(&head->ref_add_list))
return list_first_entry(&head->ref_add_list,
struct btrfs_delayed_ref_node,
add_list);
ref = rb_entry(rb_first(&head->ref_tree),
struct btrfs_delayed_ref_node, ref_node);
ASSERT(list_empty(&ref->add_list));
return ref;
}
static int run_delayed_tree_ref(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_node *node,
struct btrfs_delayed_extent_op *extent_op,
int insert_reserved)
{
int ret = 0;
struct btrfs_delayed_tree_ref *ref;
u64 parent = 0;
u64 ref_root = 0;
ref = btrfs_delayed_node_to_tree_ref(node);
if (node->type == BTRFS_SHARED_BLOCK_REF_KEY)
parent = ref->parent;
ref_root = ref->root;
if (node->ref_mod != 1) {
printf("btree block(%llu) has %d references rather than 1: action %d ref_root %llu parent %llu",
node->bytenr, node->ref_mod, node->action, ref_root,
parent);
return -EIO;
}
if (node->action == BTRFS_ADD_DELAYED_REF && insert_reserved) {
BUG_ON(!extent_op || !extent_op->update_flags);
ret = alloc_reserved_tree_block2(trans, node, extent_op);
} else if (node->action == BTRFS_DROP_DELAYED_REF) {
ret = __free_extent2(trans, node, extent_op);
} else {
BUG();
}
return ret;
}
/* helper function to actually process a single delayed ref entry */
static int run_one_delayed_ref(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_delayed_ref_node *node,
struct btrfs_delayed_extent_op *extent_op,
int insert_reserved)
{
int ret = 0;
if (node->type == BTRFS_TREE_BLOCK_REF_KEY ||
node->type == BTRFS_SHARED_BLOCK_REF_KEY) {
ret = run_delayed_tree_ref(trans, fs_info, node, extent_op,
insert_reserved);
} else
BUG();
return ret;
}
int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, unsigned long nr)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_delayed_ref_root *delayed_refs;
struct btrfs_delayed_ref_node *ref;
struct btrfs_delayed_ref_head *locked_ref = NULL;
struct btrfs_delayed_extent_op *extent_op;
int ret;
int must_insert_reserved = 0;
delayed_refs = &trans->delayed_refs;
while (1) {
if (!locked_ref) {
locked_ref = btrfs_select_ref_head(trans);
if (!locked_ref)
break;
}
/*
* We need to try and merge add/drops of the same ref since we
* can run into issues with relocate dropping the implicit ref
* and then it being added back again before the drop can
* finish. If we merged anything we need to re-loop so we can
* get a good ref.
* Or we can get node references of the same type that weren't
* merged when created due to bumps in the tree mod seq, and
* we need to merge them to prevent adding an inline extent
* backref before dropping it (triggering a BUG_ON at
* insert_inline_extent_backref()).
*/
btrfs_merge_delayed_refs(trans, delayed_refs, locked_ref);
ref = select_delayed_ref(locked_ref);
/*
* We're done processing refs in this ref_head, clean everything
* up and move on to the next ref_head.
*/
if (!ref) {
ret = cleanup_ref_head(trans, fs_info, locked_ref);
if (ret > 0 ) {
/* We dropped our lock, we need to loop. */
ret = 0;
continue;
} else if (ret) {
return ret;
}
locked_ref = NULL;
continue;
}
ref->in_tree = 0;
rb_erase(&ref->ref_node, &locked_ref->ref_tree);
RB_CLEAR_NODE(&ref->ref_node);
if (!list_empty(&ref->add_list))
list_del(&ref->add_list);
/*
* When we play the delayed ref, also correct the ref_mod on
* head
*/
switch (ref->action) {
case BTRFS_ADD_DELAYED_REF:
case BTRFS_ADD_DELAYED_EXTENT:
locked_ref->ref_mod -= ref->ref_mod;
break;
case BTRFS_DROP_DELAYED_REF:
locked_ref->ref_mod += ref->ref_mod;
break;
default:
WARN_ON(1);
}
/*
* Record the must-insert_reserved flag before we drop the spin
* lock.
*/
must_insert_reserved = locked_ref->must_insert_reserved;
locked_ref->must_insert_reserved = 0;
extent_op = locked_ref->extent_op;
locked_ref->extent_op = NULL;
ret = run_one_delayed_ref(trans, fs_info, ref, extent_op,
must_insert_reserved);
btrfs_free_delayed_extent_op(extent_op);
/*
* If we are re-initing extent tree in this transaction
* failure in freeing old roots are expected (because we don't
* have the old extent tree, hence backref resolution will
* return -EIO).
*/
if (ret && (!trans->reinit_extent_tree ||
ref->action != BTRFS_DROP_DELAYED_REF)) {
unselect_delayed_ref_head(delayed_refs, locked_ref);
btrfs_put_delayed_ref(ref);
return ret;
}
btrfs_put_delayed_ref(ref);
}
return 0;
}

8
kerncompat.h
View File

@ -263,6 +263,14 @@ static inline int IS_ERR_OR_NULL(const void *ptr)
return !ptr || IS_ERR(ptr);
}
/**
* swap - swap values of @a and @b
* @a: first value
* @b: second value
*/
#define swap(a, b) \
do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
/*
* This looks more complex than it should be. But we need to
* get the type for the ~ right in round_down (it needs to be

4
transaction.h
View File

@ -21,6 +21,7 @@
#include "kerncompat.h"
#include "ctree.h"
#include "delayed-ref.h"
struct btrfs_trans_handle {
struct btrfs_fs_info *fs_info;
@ -28,9 +29,12 @@ struct btrfs_trans_handle {
u64 alloc_exclude_start;
u64 alloc_exclude_nr;
bool reinit_extent_tree;
u64 delayed_ref_updates;
unsigned long blocks_reserved;
unsigned long blocks_used;
struct btrfs_block_group_cache *block_group;
struct btrfs_delayed_ref_root delayed_refs;
};
struct btrfs_trans_handle* btrfs_start_transaction(struct btrfs_root *root,