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Subject[PATCH v2 3/6] Btrfs: clean up error handling in mount_subvol()
Date
In preparation for new functionality in mount_subvol(), give it
ownership of subvol_name and tidy up the error paths.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
---
fs/btrfs/super.c | 61 ++++++++++++++++++++++++++++++--------------------------
1 file changed, 33 insertions(+), 28 deletions(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index bac3c9a..ab100e5 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1167,55 +1167,61 @@ static struct dentry *mount_subvol(const char *subvol_name, int flags,
const char *device_name, char *data)
{
struct dentry *root;
- struct vfsmount *mnt;
+ struct vfsmount *mnt = NULL;
char *newargs;
+ int ret;

newargs = setup_root_args(data);
- if (!newargs)
- return ERR_PTR(-ENOMEM);
- mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name,
- newargs);
+ if (!newargs) {
+ root = ERR_PTR(-ENOMEM);
+ goto out;
+ }

- if (PTR_RET(mnt) == -EBUSY) {
+ mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name, newargs);
+ if (PTR_ERR_OR_ZERO(mnt) == -EBUSY) {
if (flags & MS_RDONLY) {
- mnt = vfs_kern_mount(&btrfs_fs_type, flags & ~MS_RDONLY, device_name,
- newargs);
+ mnt = vfs_kern_mount(&btrfs_fs_type, flags & ~MS_RDONLY,
+ device_name, newargs);
} else {
- int r;
- mnt = vfs_kern_mount(&btrfs_fs_type, flags | MS_RDONLY, device_name,
- newargs);
+ mnt = vfs_kern_mount(&btrfs_fs_type, flags | MS_RDONLY,
+ device_name, newargs);
if (IS_ERR(mnt)) {
- kfree(newargs);
- return ERR_CAST(mnt);
+ root = ERR_CAST(mnt);
+ mnt = NULL;
+ goto out;
}

down_write(&mnt->mnt_sb->s_umount);
- r = btrfs_remount(mnt->mnt_sb, &flags, NULL);
+ ret = btrfs_remount(mnt->mnt_sb, &flags, NULL);
up_write(&mnt->mnt_sb->s_umount);
- if (r < 0) {
- /* FIXME: release vfsmount mnt ??*/
- kfree(newargs);
- return ERR_PTR(r);
+ if (ret < 0) {
+ root = ERR_PTR(ret);
+ goto out;
}
}
}
-
- kfree(newargs);
-
- if (IS_ERR(mnt))
- return ERR_CAST(mnt);
+ if (IS_ERR(mnt)) {
+ root = ERR_CAST(mnt);
+ mnt = NULL;
+ goto out;
+ }

root = mount_subtree(mnt, subvol_name);
+ /* mount_subtree() drops our reference on the vfsmount. */
+ mnt = NULL;

if (!IS_ERR(root) && !is_subvolume_inode(root->d_inode)) {
struct super_block *s = root->d_sb;
dput(root);
root = ERR_PTR(-EINVAL);
deactivate_locked_super(s);
- printk(KERN_ERR "BTRFS: '%s' is not a valid subvolume\n",
- subvol_name);
+ pr_err("BTRFS: '%s' is not a valid subvolume\n", subvol_name);
}

+out:
+ mntput(mnt);
+ kfree(newargs);
+ kfree(subvol_name);
return root;
}

@@ -1301,9 +1307,8 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
}

if (subvol_name) {
- root = mount_subvol(subvol_name, flags, device_name, data);
- kfree(subvol_name);
- return root;
+ /* mount_subvol() will free subvol_name. */
+ return mount_subvol(subvol_name, flags, device_name, data);
}

security_init_mnt_opts(&new_sec_opts);
--
2.3.5


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