[PATCH 18/43] btrfs: hold a ref on the root in btrfs_search_path_in_tree_user

Josef Bacik
2020-01-17T21:26:41Z

We can wander into a different root, so grab a ref on the root we look
up. Later on we make root = fs_info->tree_root so we need this separate
out label to make sure we do the right cleanup only in the case we're
looking up a different root.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
fs/btrfs/ioctl.c | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index c721b4fce1c0..5fffa1b6f685 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2432,6 +2432,10 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
ret = PTR_ERR(root);
goto out;
}
+ if (!btrfs_grab_fs_root(root)) {
+ ret = -ENOENT;
+ goto out;
+ }

key.objectid = dirid;
key.type = BTRFS_INODE_REF_KEY;
@@ -2439,15 +2443,15 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
while (1) {
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0) {
- goto out;
+ goto out_put;
} else if (ret > 0) {
ret = btrfs_previous_item(root, path, dirid,
BTRFS_INODE_REF_KEY);
if (ret < 0) {
- goto out;
+ goto out_put;
} else if (ret > 0) {
ret = -ENOENT;
- goto out;
+ goto out_put;
}
}

@@ -2461,7 +2465,7 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
total_len += len + 1;
if (ptr < args->path) {
ret = -ENAMETOOLONG;
- goto out;
+ goto out_put;
}

*(ptr + len) = '/';
@@ -2472,10 +2476,10 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
ret = btrfs_previous_item(root, path, dirid,
BTRFS_INODE_ITEM_KEY);
if (ret < 0) {
- goto out;
+ goto out_put;
} else if (ret > 0) {
ret = -ENOENT;
- goto out;
+ goto out_put;
}

leaf = path->nodes[0];
@@ -2483,26 +2487,26 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
btrfs_item_key_to_cpu(leaf, &key2, slot);
if (key2.objectid != dirid) {
ret = -ENOENT;
- goto out;
+ goto out_put;
}

temp_inode = btrfs_iget(sb, &key2, root);
if (IS_ERR(temp_inode)) {
ret = PTR_ERR(temp_inode);
- goto out;
+ goto out_put;
}
ret = inode_permission(temp_inode, MAY_READ | MAY_EXEC);
iput(temp_inode);
if (ret) {
ret = -EACCES;
- goto out;
+ goto out_put;
}

if (key.offset == upper_limit.objectid)
break;
if (key.objectid == BTRFS_FIRST_FREE_OBJECTID) {
ret = -EACCES;
- goto out;
+ goto out_put;
}

btrfs_release_path(path);
@@ -2513,6 +2517,7 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,

memmove(args->path, ptr, total_len);
args->path[total_len] = '\0';
+ btrfs_put_fs_root(root);
btrfs_release_path(path);
}

@@ -2551,6 +2556,9 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
out:
btrfs_free_path(path);
return ret;
+out_put:
+ btrfs_put_fs_root(root);
+ goto out;
}

static noinline int btrfs_ioctl_ino_lookup(struct file *file,
--
2.24.1