Qu Wenruo
2014-Apr-22 09:13 UTC
[PATCH] btrfs: Add check to avoid cleanup roots already in fs_info->dead_roots.
Current btrfs_orphan_cleanup will also cleanup roots which is already in
fs_info->dead_roots without protection.
This will have conditional race with fs_info->cleaner_kthread.
This patch will use refs in root->root_item to detect roots in
dead_roots and avoid conflicts.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
fs/btrfs/disk-io.c | 37 ++++++++++++++++++++++++++++++-------
1 file changed, 30 insertions(+), 7 deletions(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 029d46c..ddfec98 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3533,28 +3533,51 @@ int btrfs_cleanup_fs_roots(struct btrfs_fs_info
*fs_info)
{
u64 root_objectid = 0;
struct btrfs_root *gang[8];
- int i;
- int ret;
+ int i = 0;
+ int err = 0;
+ unsigned int ret = 0;
+ int index;
while (1) {
+ index = srcu_read_lock(&fs_info->subvol_srcu);
ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
(void **)gang, root_objectid,
ARRAY_SIZE(gang));
- if (!ret)
+ if (!ret) {
+ srcu_read_unlock(&fs_info->subvol_srcu, index);
break;
-
+ }
root_objectid = gang[ret - 1]->root_key.objectid + 1;
+
for (i = 0; i < ret; i++) {
- int err;
+ /* Avoid to grab roots in dead_roots */
+ if (btrfs_root_refs(&gang[i]->root_item) == 0) {
+ gang[i] = NULL;
+ continue;
+ }
+ /* grab all the search result for later use */
+ gang[i] = btrfs_grab_fs_root(gang[i]);
+ }
+ srcu_read_unlock(&fs_info->subvol_srcu, index);
+ for (i = 0; i < ret; i++) {
+ if (!gang[i])
+ continue;
root_objectid = gang[i]->root_key.objectid;
err = btrfs_orphan_cleanup(gang[i]);
if (err)
- return err;
+ break;
+ btrfs_put_fs_root(gang[i]);
}
root_objectid++;
}
- return 0;
+
+ /* release the uncleaned roots due to error */
+ for (; i < ret; i++) {
+ if (gang[i])
+ btrfs_put_fs_root(gang[i]);
+ }
+ return err;
}
int btrfs_commit_super(struct btrfs_root *root)
--
1.9.2
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