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btrfs: Add check to avoid cleanup roots already in fs_info->dead_roots.
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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>
Signed-off-by: Chris Mason <clm@fb.com>
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Qu Wenruo authored and Chris Mason committed Jun 10, 2014
1 parent 21c7e75 commit 65d33fd
Showing 1 changed file with 30 additions and 7 deletions.
37 changes: 30 additions & 7 deletions fs/btrfs/disk-io.c
Original file line number Diff line number Diff line change
Expand Up @@ -3534,28 +3534,51 @@ 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)
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