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Btrfs: fix qgroup rescan resume on mount

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When called during mount, we cannot start the rescan worker thread until
open_ctree is done. This commit restuctures the qgroup rescan internals to
enable a clean deferral of the rescan resume operation.

First of all, the struct qgroup_rescan is removed, saving us a malloc and
some initialization synchronizations problems. Its only element (the worker
struct) now lives within fs_info just as the rest of the rescan code.

Then setting up a rescan worker is split into several reusable stages.
Currently we have three different rescan startup scenarios:
	(A) rescan ioctl
	(B) rescan resume by mount
	(C) rescan by quota enable

Each case needs its own combination of the four following steps:
	(1) set the progress [A, C: zero; B: state of umount]
	(2) commit the transaction [A]
	(3) set the counters [A, C: zero; B: state of umount]
	(4) start worker [A, B, C]

qgroup_rescan_init does step (1). There's no extra function added to commit
a transaction, we've got that already. qgroup_rescan_zero_tracking does
step (3). Step (4) is nothing more than a call to the generic
btrfs_queue_worker.

We also get rid of a double check for the rescan progress during
btrfs_qgroup_account_ref, which is no longer required due to having step 2
from the list above.

As a side effect, this commit prepares to move the rescan start code from
btrfs_run_qgroups (which is run during commit) to a less time critical
section.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
This commit is contained in:
Jan Schmidt 2013-05-28 15:47:24 +00:00 committed by Josef Bacik
parent eb1716af88
commit b382a324b6
3 changed files with 126 additions and 70 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
fs/btrfs/ctree.h
View file

@ -1609,6 +1609,7 @@ struct btrfs_fs_info {
struct btrfs_key qgroup_rescan_progress;
struct btrfs_workers qgroup_rescan_workers;
struct completion qgroup_rescan_completion;
struct btrfs_work qgroup_rescan_work;
/* filesystem state */
unsigned long fs_state;
@ -3858,6 +3859,7 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
int btrfs_quota_disable(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info);
int btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info);
void btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info);
int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info);
int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info, u64 src, u64 dst);

2
fs/btrfs/disk-io.c
View file

@ -2879,6 +2879,8 @@ retry_root_backup:
return ret;
}
btrfs_qgroup_rescan_resume(fs_info);
return 0;
fail_qgroup:

192
fs/btrfs/qgroup.c
View file

@ -98,13 +98,10 @@ struct btrfs_qgroup_list {
struct btrfs_qgroup *member;
};
struct qgroup_rescan {
struct btrfs_work work;
struct btrfs_fs_info *fs_info;
};
static void qgroup_rescan_start(struct btrfs_fs_info *fs_info,
struct qgroup_rescan *qscan);
static int
qgroup_rescan_init(struct btrfs_fs_info *fs_info, u64 progress_objectid,
int init_flags);
static void qgroup_rescan_zero_tracking(struct btrfs_fs_info *fs_info);
/* must be called with qgroup_ioctl_lock held */
static struct btrfs_qgroup *find_qgroup_rb(struct btrfs_fs_info *fs_info,
@ -255,6 +252,7 @@ int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info)
int slot;
int ret = 0;
u64 flags = 0;
u64 rescan_progress = 0;
if (!fs_info->quota_enabled)
return 0;
@ -312,20 +310,7 @@ int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info)
}
fs_info->qgroup_flags = btrfs_qgroup_status_flags(l,
ptr);
fs_info->qgroup_rescan_progress.objectid =
btrfs_qgroup_status_rescan(l, ptr);
if (fs_info->qgroup_flags &
BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
struct qgroup_rescan *qscan =
kmalloc(sizeof(*qscan), GFP_NOFS);
if (!qscan) {
ret = -ENOMEM;
goto out;
}
fs_info->qgroup_rescan_progress.type = 0;
fs_info->qgroup_rescan_progress.offset = 0;
qgroup_rescan_start(fs_info, qscan);
}
rescan_progress = btrfs_qgroup_status_rescan(l, ptr);
goto next1;
}
@ -427,12 +412,16 @@ out:
if (!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON)) {
fs_info->quota_enabled = 0;
fs_info->pending_quota_state = 0;
} else if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN &&
ret >= 0) {
ret = qgroup_rescan_init(fs_info, rescan_progress, 0);
}
btrfs_free_path(path);
if (ret < 0) {
ulist_free(fs_info->qgroup_ulist);
fs_info->qgroup_ulist = NULL;
fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
}
return ret < 0 ? ret : 0;
@ -1449,14 +1438,7 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle *trans,
if (ret < 0)
return ret;
mutex_lock(&fs_info->qgroup_rescan_lock);
spin_lock(&fs_info->qgroup_lock);
if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
if (fs_info->qgroup_rescan_progress.objectid <= node->bytenr) {
ret = 0;
goto unlock;
}
}
quota_root = fs_info->quota_root;
if (!quota_root)
@ -1496,7 +1478,6 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle *trans,
unlock:
spin_unlock(&fs_info->qgroup_lock);
mutex_unlock(&fs_info->qgroup_rescan_lock);
ulist_free(roots);
return ret;
@ -1544,9 +1525,12 @@ int btrfs_run_qgroups(struct btrfs_trans_handle *trans,
fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
if (!ret && start_rescan_worker) {
ret = btrfs_qgroup_rescan(fs_info);
if (ret)
pr_err("btrfs: start rescan quota failed: %d\n", ret);
ret = qgroup_rescan_init(fs_info, 0, 1);
if (!ret) {
qgroup_rescan_zero_tracking(fs_info);
btrfs_queue_worker(&fs_info->qgroup_rescan_workers,
&fs_info->qgroup_rescan_work);
}
ret = 0;
}
@ -1880,12 +1864,11 @@ void assert_qgroups_uptodate(struct btrfs_trans_handle *trans)
* returns 1 when done, 2 when done and FLAG_INCONSISTENT was cleared.
*/
static int
qgroup_rescan_leaf(struct qgroup_rescan *qscan, struct btrfs_path *path,
qgroup_rescan_leaf(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
struct btrfs_trans_handle *trans, struct ulist *tmp,
struct extent_buffer *scratch_leaf)
{
struct btrfs_key found;
struct btrfs_fs_info *fs_info = qscan->fs_info;
struct ulist *roots = NULL;
struct ulist_node *unode;
struct ulist_iterator uiter;
@ -2013,11 +1996,10 @@ out:
static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
{
struct qgroup_rescan *qscan = container_of(work, struct qgroup_rescan,
work);
struct btrfs_fs_info *fs_info = container_of(work, struct btrfs_fs_info,
qgroup_rescan_work);
struct btrfs_path *path;
struct btrfs_trans_handle *trans = NULL;
struct btrfs_fs_info *fs_info = qscan->fs_info;
struct ulist *tmp = NULL;
struct extent_buffer *scratch_leaf = NULL;
int err = -ENOMEM;
@ -2042,7 +2024,7 @@ static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
if (!fs_info->quota_enabled) {
err = -EINTR;
} else {
err = qgroup_rescan_leaf(qscan, path, trans,
err = qgroup_rescan_leaf(fs_info, path, trans,
tmp, scratch_leaf);
}
if (err > 0)
@ -2055,7 +2037,6 @@ out:
kfree(scratch_leaf);
ulist_free(tmp);
btrfs_free_path(path);
kfree(qscan);
mutex_lock(&fs_info->qgroup_rescan_lock);
fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
@ -2078,46 +2059,70 @@ out:
complete_all(&fs_info->qgroup_rescan_completion);
}
static void
qgroup_rescan_start(struct btrfs_fs_info *fs_info, struct qgroup_rescan *qscan)
{
memset(&qscan->work, 0, sizeof(qscan->work));
qscan->work.func = btrfs_qgroup_rescan_worker;
qscan->fs_info = fs_info;
pr_info("btrfs: qgroup scan started\n");
btrfs_queue_worker(&fs_info->qgroup_rescan_workers, &qscan->work);
}
int
btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info)
/*
* Checks that (a) no rescan is running and (b) quota is enabled. Allocates all
* memory required for the rescan context.
*/
static int
qgroup_rescan_init(struct btrfs_fs_info *fs_info, u64 progress_objectid,
int init_flags)
{
int ret = 0;
struct rb_node *n;
struct btrfs_qgroup *qgroup;
struct qgroup_rescan *qscan = kmalloc(sizeof(*qscan), GFP_NOFS);
if (!qscan)
return -ENOMEM;
if (!init_flags &&
(!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) ||
!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON))) {
ret = -EINVAL;
goto err;
}
mutex_lock(&fs_info->qgroup_rescan_lock);
spin_lock(&fs_info->qgroup_lock);
if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN)
ret = -EINPROGRESS;
else if (!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON))
ret = -EINVAL;
if (init_flags) {
if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN)
ret = -EINPROGRESS;
else if (!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON))
ret = -EINVAL;
if (ret) {
spin_unlock(&fs_info->qgroup_lock);
mutex_unlock(&fs_info->qgroup_rescan_lock);
goto err;
}
fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_RESCAN;
}
memset(&fs_info->qgroup_rescan_progress, 0,
sizeof(fs_info->qgroup_rescan_progress));
fs_info->qgroup_rescan_progress.objectid = progress_objectid;
spin_unlock(&fs_info->qgroup_lock);
mutex_unlock(&fs_info->qgroup_rescan_lock);
init_completion(&fs_info->qgroup_rescan_completion);
memset(&fs_info->qgroup_rescan_work, 0,
sizeof(fs_info->qgroup_rescan_work));
fs_info->qgroup_rescan_work.func = btrfs_qgroup_rescan_worker;
if (ret) {
spin_unlock(&fs_info->qgroup_lock);
mutex_unlock(&fs_info->qgroup_rescan_lock);
kfree(qscan);
err:
pr_info("btrfs: qgroup_rescan_init failed with %d\n", ret);
return ret;
}
fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_RESCAN;
memset(&fs_info->qgroup_rescan_progress, 0,
sizeof(fs_info->qgroup_rescan_progress));
init_completion(&fs_info->qgroup_rescan_completion);
return 0;
}
static void
qgroup_rescan_zero_tracking(struct btrfs_fs_info *fs_info)
{
struct rb_node *n;
struct btrfs_qgroup *qgroup;
spin_lock(&fs_info->qgroup_lock);
/* clear all current qgroup tracking information */
for (n = rb_first(&fs_info->qgroup_tree); n; n = rb_next(n)) {
qgroup = rb_entry(n, struct btrfs_qgroup, node);
@ -2127,9 +2132,44 @@ btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info)
qgroup->excl_cmpr = 0;
}
spin_unlock(&fs_info->qgroup_lock);
mutex_unlock(&fs_info->qgroup_rescan_lock);
}
qgroup_rescan_start(fs_info, qscan);
int
btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info)
{
int ret = 0;
struct btrfs_trans_handle *trans;
ret = qgroup_rescan_init(fs_info, 0, 1);
if (ret)
return ret;
/*
* We have set the rescan_progress to 0, which means no more
* delayed refs will be accounted by btrfs_qgroup_account_ref.
* However, btrfs_qgroup_account_ref may be right after its call
* to btrfs_find_all_roots, in which case it would still do the
* accounting.
* To solve this, we're committing the transaction, which will
* ensure we run all delayed refs and only after that, we are
* going to clear all tracking information for a clean start.
*/
trans = btrfs_join_transaction(fs_info->fs_root);
if (IS_ERR(trans)) {
fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
return PTR_ERR(trans);
}
ret = btrfs_commit_transaction(trans, fs_info->fs_root);
if (ret) {
fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
return ret;
}
qgroup_rescan_zero_tracking(fs_info);
btrfs_queue_worker(&fs_info->qgroup_rescan_workers,
&fs_info->qgroup_rescan_work);
return 0;
}
@ -2151,3 +2191,15 @@ int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info)
return ret;
}
/*
* this is only called from open_ctree where we're still single threaded, thus
* locking is omitted here.
*/
void
btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info)
{
if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN)
btrfs_queue_worker(&fs_info->qgroup_rescan_workers,
&fs_info->qgroup_rescan_work);
}