Btrfs: rescan for qgroups
If qgroup tracking is out of sync, a rescan operation can be started. It
iterates the complete extent tree and recalculates all qgroup tracking data.
This is an expensive operation and should not be used unless required.
A filesystem under rescan can still be umounted. The rescan continues on the
next mount. Status information is provided with a separate ioctl while a
rescan operation is in progress.
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 1fb7d8d..da84583 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -31,13 +31,13 @@
#include "locking.h"
#include "ulist.h"
#include "backref.h"
+#include "extent_io.h"
/* TODO XXX FIXME
* - subvol delete -> delete when ref goes to 0? delete limits also?
* - reorganize keys
* - compressed
* - sync
- * - rescan
* - copy also limits on subvol creation
* - limit
* - caches fuer ulists
@@ -98,6 +98,14 @@
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);
+
/* must be called with qgroup_ioctl_lock held */
static struct btrfs_qgroup *find_qgroup_rb(struct btrfs_fs_info *fs_info,
u64 qgroupid)
@@ -298,7 +306,20 @@
}
fs_info->qgroup_flags = btrfs_qgroup_status_flags(l,
ptr);
- /* FIXME read scan element */
+ 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);
+ }
goto next1;
}
@@ -719,7 +740,8 @@
ptr = btrfs_item_ptr(l, slot, struct btrfs_qgroup_status_item);
btrfs_set_qgroup_status_flags(l, ptr, fs_info->qgroup_flags);
btrfs_set_qgroup_status_generation(l, ptr, trans->transid);
- /* XXX scan */
+ btrfs_set_qgroup_status_rescan(l, ptr,
+ fs_info->qgroup_rescan_progress.objectid);
btrfs_mark_buffer_dirty(l);
@@ -830,7 +852,7 @@
fs_info->qgroup_flags = BTRFS_QGROUP_STATUS_FLAG_ON |
BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
btrfs_set_qgroup_status_flags(leaf, ptr, fs_info->qgroup_flags);
- btrfs_set_qgroup_status_scan(leaf, ptr, 0);
+ btrfs_set_qgroup_status_rescan(leaf, ptr, 0);
btrfs_mark_buffer_dirty(leaf);
@@ -944,10 +966,11 @@
return ret;
}
-int btrfs_quota_rescan(struct btrfs_fs_info *fs_info)
+static void qgroup_dirty(struct btrfs_fs_info *fs_info,
+ struct btrfs_qgroup *qgroup)
{
- /* FIXME */
- return 0;
+ if (list_empty(&qgroup->dirty))
+ list_add(&qgroup->dirty, &fs_info->dirty_qgroups);
}
int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans,
@@ -1155,13 +1178,6 @@
return ret;
}
-static void qgroup_dirty(struct btrfs_fs_info *fs_info,
- struct btrfs_qgroup *qgroup)
-{
- if (list_empty(&qgroup->dirty))
- list_add(&qgroup->dirty, &fs_info->dirty_qgroups);
-}
-
/*
* btrfs_qgroup_record_ref is called when the ref is added or deleted. it puts
* the modification into a list that's later used by btrfs_end_transaction to
@@ -1390,6 +1406,15 @@
BUG();
}
+ mutex_lock(&fs_info->qgroup_rescan_lock);
+ if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
+ if (fs_info->qgroup_rescan_progress.objectid <= node->bytenr) {
+ mutex_unlock(&fs_info->qgroup_rescan_lock);
+ return 0;
+ }
+ }
+ mutex_unlock(&fs_info->qgroup_rescan_lock);
+
/*
* the delayed ref sequence number we pass depends on the direction of
* the operation. for add operations, we pass
@@ -1403,7 +1428,15 @@
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)
goto unlock;
@@ -1445,6 +1478,7 @@
unlock:
spin_unlock(&fs_info->qgroup_lock);
+ mutex_unlock(&fs_info->qgroup_rescan_lock);
ulist_free(roots);
ulist_free(tmp);
@@ -1823,3 +1857,259 @@
(u32)trans->delayed_ref_elem.seq);
BUG();
}
+
+/*
+ * returns < 0 on error, 0 when more leafs are to be scanned.
+ * 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,
+ 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;
+ struct seq_list tree_mod_seq_elem = {};
+ u64 seq;
+ int slot;
+ int ret;
+
+ path->leave_spinning = 1;
+ mutex_lock(&fs_info->qgroup_rescan_lock);
+ ret = btrfs_search_slot_for_read(fs_info->extent_root,
+ &fs_info->qgroup_rescan_progress,
+ path, 1, 0);
+
+ pr_debug("current progress key (%llu %u %llu), search_slot ret %d\n",
+ (unsigned long long)fs_info->qgroup_rescan_progress.objectid,
+ fs_info->qgroup_rescan_progress.type,
+ (unsigned long long)fs_info->qgroup_rescan_progress.offset,
+ ret);
+
+ if (ret) {
+ /*
+ * The rescan is about to end, we will not be scanning any
+ * further blocks. We cannot unset the RESCAN flag here, because
+ * we want to commit the transaction if everything went well.
+ * To make the live accounting work in this phase, we set our
+ * scan progress pointer such that every real extent objectid
+ * will be smaller.
+ */
+ fs_info->qgroup_rescan_progress.objectid = (u64)-1;
+ btrfs_release_path(path);
+ mutex_unlock(&fs_info->qgroup_rescan_lock);
+ return ret;
+ }
+
+ btrfs_item_key_to_cpu(path->nodes[0], &found,
+ btrfs_header_nritems(path->nodes[0]) - 1);
+ fs_info->qgroup_rescan_progress.objectid = found.objectid + 1;
+
+ btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
+ memcpy(scratch_leaf, path->nodes[0], sizeof(*scratch_leaf));
+ slot = path->slots[0];
+ btrfs_release_path(path);
+ mutex_unlock(&fs_info->qgroup_rescan_lock);
+
+ for (; slot < btrfs_header_nritems(scratch_leaf); ++slot) {
+ btrfs_item_key_to_cpu(scratch_leaf, &found, slot);
+ if (found.type != BTRFS_EXTENT_ITEM_KEY)
+ continue;
+ ret = btrfs_find_all_roots(trans, fs_info, found.objectid,
+ tree_mod_seq_elem.seq, &roots);
+ if (ret < 0)
+ goto out;
+ spin_lock(&fs_info->qgroup_lock);
+ seq = fs_info->qgroup_seq;
+ fs_info->qgroup_seq += roots->nnodes + 1; /* max refcnt */
+
+ ret = qgroup_account_ref_step1(fs_info, roots, tmp, seq);
+ if (ret) {
+ spin_unlock(&fs_info->qgroup_lock);
+ ulist_free(roots);
+ goto out;
+ }
+
+ /*
+ * step2 of btrfs_qgroup_account_ref works from a single root,
+ * we're doing all at once here.
+ */
+ ulist_reinit(tmp);
+ ULIST_ITER_INIT(&uiter);
+ while ((unode = ulist_next(roots, &uiter))) {
+ struct btrfs_qgroup *qg;
+
+ qg = find_qgroup_rb(fs_info, unode->val);
+ if (!qg)
+ continue;
+
+ ret = ulist_add(tmp, qg->qgroupid, (uintptr_t)qg,
+ GFP_ATOMIC);
+ if (ret < 0) {
+ spin_unlock(&fs_info->qgroup_lock);
+ ulist_free(roots);
+ goto out;
+ }
+ }
+
+ /* this loop is similar to step 2 of btrfs_qgroup_account_ref */
+ ULIST_ITER_INIT(&uiter);
+ while ((unode = ulist_next(tmp, &uiter))) {
+ struct btrfs_qgroup *qg;
+ struct btrfs_qgroup_list *glist;
+
+ qg = (struct btrfs_qgroup *)(uintptr_t) unode->aux;
+ qg->rfer += found.offset;
+ qg->rfer_cmpr += found.offset;
+ WARN_ON(qg->tag >= seq);
+ if (qg->refcnt - seq == roots->nnodes) {
+ qg->excl += found.offset;
+ qg->excl_cmpr += found.offset;
+ }
+ qgroup_dirty(fs_info, qg);
+
+ list_for_each_entry(glist, &qg->groups, next_group) {
+ ret = ulist_add(tmp, glist->group->qgroupid,
+ (uintptr_t)glist->group,
+ GFP_ATOMIC);
+ if (ret < 0) {
+ spin_unlock(&fs_info->qgroup_lock);
+ ulist_free(roots);
+ goto out;
+ }
+ }
+ }
+
+ spin_unlock(&fs_info->qgroup_lock);
+ ulist_free(roots);
+ ret = 0;
+ }
+
+out:
+ btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
+
+ return ret;
+}
+
+static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
+{
+ struct qgroup_rescan *qscan = container_of(work, struct 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;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ goto out;
+ tmp = ulist_alloc(GFP_NOFS);
+ if (!tmp)
+ goto out;
+ scratch_leaf = kmalloc(sizeof(*scratch_leaf), GFP_NOFS);
+ if (!scratch_leaf)
+ goto out;
+
+ err = 0;
+ while (!err) {
+ trans = btrfs_start_transaction(fs_info->fs_root, 0);
+ if (IS_ERR(trans)) {
+ err = PTR_ERR(trans);
+ break;
+ }
+ if (!fs_info->quota_enabled) {
+ err = -EINTR;
+ } else {
+ err = qgroup_rescan_leaf(qscan, path, trans,
+ tmp, scratch_leaf);
+ }
+ if (err > 0)
+ btrfs_commit_transaction(trans, fs_info->fs_root);
+ else
+ btrfs_end_transaction(trans, fs_info->fs_root);
+ }
+
+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;
+
+ if (err == 2 &&
+ fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT) {
+ fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
+ } else if (err < 0) {
+ fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
+ }
+ mutex_unlock(&fs_info->qgroup_rescan_lock);
+
+ if (err >= 0) {
+ pr_info("btrfs: qgroup scan completed%s\n",
+ err == 2 ? " (inconsistency flag cleared)" : "");
+ } else {
+ pr_err("btrfs: qgroup scan failed with %d\n", err);
+ }
+}
+
+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)
+{
+ int ret = 0;
+ struct rb_node *n;
+ struct btrfs_qgroup *qgroup;
+ struct qgroup_rescan *qscan = kmalloc(sizeof(*qscan), GFP_NOFS);
+
+ if (!qscan)
+ return -ENOMEM;
+
+ 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 (ret) {
+ spin_unlock(&fs_info->qgroup_lock);
+ mutex_unlock(&fs_info->qgroup_rescan_lock);
+ kfree(qscan);
+ return ret;
+ }
+
+ fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_RESCAN;
+ memset(&fs_info->qgroup_rescan_progress, 0,
+ sizeof(fs_info->qgroup_rescan_progress));
+
+ /* 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);
+ qgroup->rfer = 0;
+ qgroup->rfer_cmpr = 0;
+ qgroup->excl = 0;
+ qgroup->excl_cmpr = 0;
+ }
+ spin_unlock(&fs_info->qgroup_lock);
+ mutex_unlock(&fs_info->qgroup_rescan_lock);
+
+ qgroup_rescan_start(fs_info, qscan);
+
+ return 0;
+}