[PATCH 33/44] btrfs: hold a ref on the root in btrfs_ioctl_send

Josef Bacik
2019-12-06T14:46:41Z

We lookup all the clone roots and the parent root for send, so we need
to hold refs on all of these roots while we're processing them.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
fs/btrfs/send.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 73e2e350f4a1..a82201e6979e 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -7206,11 +7206,17 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
ret = PTR_ERR(clone_root);
goto out;
}
+ if (!btrfs_grab_fs_root(clone_root)) {
+ srcu_read_unlock(&fs_info->subvol_srcu, index);
+ ret = -ENOENT;
+ goto out;
+ }
spin_lock(&clone_root->root_item_lock);
if (!btrfs_root_readonly(clone_root) ||
btrfs_root_dead(clone_root)) {
spin_unlock(&clone_root->root_item_lock);
srcu_read_unlock(&fs_info->subvol_srcu, index);
+ btrfs_put_fs_root(clone_root);
ret = -EPERM;
goto out;
}
@@ -7218,6 +7224,7 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
dedupe_in_progress_warn(clone_root);
spin_unlock(&clone_root->root_item_lock);
srcu_read_unlock(&fs_info->subvol_srcu, index);
+ btrfs_put_fs_root(clone_root);
ret = -EAGAIN;
goto out;
}
@@ -7245,6 +7252,12 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
ret = PTR_ERR(sctx->parent_root);
goto out;
}
+ if (!btrfs_grab_fs_root(sctx->parent_root)) {
+ srcu_read_unlock(&fs_info->subvol_srcu, index);
+ ret = -ENOENT;
+ sctx->parent_root = ERR_PTR(ret);
+ goto out;
+ }

spin_lock(&sctx->parent_root->root_item_lock);
sctx->parent_root->send_in_progress++;
@@ -7272,7 +7285,8 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
* is behind the current send position. This is checked while searching
* for possible clone sources.
*/
- sctx->clone_roots[sctx->clone_roots_cnt++].root = sctx->send_root;
+ sctx->clone_roots[sctx->clone_roots_cnt++].root =
+ btrfs_grab_fs_root(sctx->send_root);

/* We do a bsearch later */
sort(sctx->clone_roots, sctx->clone_roots_cnt,
@@ -7357,18 +7371,24 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
}

if (sort_clone_roots) {
- for (i = 0; i < sctx->clone_roots_cnt; i++)
+ for (i = 0; i < sctx->clone_roots_cnt; i++) {
btrfs_root_dec_send_in_progress(
sctx->clone_roots[i].root);
+ btrfs_put_fs_root(sctx->clone_roots[i].root);
+ }
} else {
- for (i = 0; sctx && i < clone_sources_to_rollback; i++)
+ for (i = 0; sctx && i < clone_sources_to_rollback; i++) {
btrfs_root_dec_send_in_progress(
sctx->clone_roots[i].root);
+ btrfs_put_fs_root(sctx->clone_roots[i].root);
+ }

btrfs_root_dec_send_in_progress(send_root);
}
- if (sctx && !IS_ERR_OR_NULL(sctx->parent_root))
+ if (sctx && !IS_ERR_OR_NULL(sctx->parent_root)) {
btrfs_root_dec_send_in_progress(sctx->parent_root);
+ btrfs_put_fs_root(sctx->parent_root);
+ }

kvfree(clone_sources_tmp);

--
2.23.0