[RFC][PATCH v2 01/34] do_add_mount(): lift lock_mount/unlock_mount into callers

Al Viro
2020-02-23T01:16:37Z

preparation to finish_automount() fix (next commit)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/namespace.c | 47 ++++++++++++++++++++++++-----------------------
1 file changed, 24 insertions(+), 23 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 85b5f7bea82e..dcd015fafe01 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2697,45 +2697,32 @@ static int do_move_mount_old(struct path *path, const char *old_name)
/*
* add a mount into a namespace's mount tree
*/
-static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags)
+static int do_add_mount(struct mount *newmnt, struct mountpoint *mp,
+ struct path *path, int mnt_flags)
{
- struct mountpoint *mp;
- struct mount *parent;
- int err;
+ struct mount *parent = real_mount(path->mnt);

mnt_flags &= ~MNT_INTERNAL_FLAGS;

- mp = lock_mount(path);
- if (IS_ERR(mp))
- return PTR_ERR(mp);
-
- parent = real_mount(path->mnt);
- err = -EINVAL;
if (unlikely(!check_mnt(parent))) {
/* that's acceptable only for automounts done in private ns */
if (!(mnt_flags & MNT_SHRINKABLE))
- goto unlock;
+ return -EINVAL;
/* ... and for those we'd better have mountpoint still alive */
if (!parent->mnt_ns)
- goto unlock;
+ return -EINVAL;
}

/* Refuse the same filesystem on the same mount point */
- err = -EBUSY;
if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb &&
path->mnt->mnt_root == path->dentry)
- goto unlock;
+ return -EBUSY;

- err = -EINVAL;
if (d_is_symlink(newmnt->mnt.mnt_root))
- goto unlock;
+ return -EINVAL;

newmnt->mnt.mnt_flags = mnt_flags;
- err = graft_tree(newmnt, parent, mp);
-
-unlock:
- unlock_mount(mp);
- return err;
+ return graft_tree(newmnt, parent, mp);
}

static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags);
@@ -2748,6 +2735,7 @@ static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint,
unsigned int mnt_flags)
{
struct vfsmount *mnt;
+ struct mountpoint *mp;
struct super_block *sb = fc->root->d_sb;
int error;

@@ -2768,7 +2756,13 @@ static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint,

mnt_warn_timestamp_expiry(mountpoint, mnt);

- error = do_add_mount(real_mount(mnt), mountpoint, mnt_flags);
+ mp = lock_mount(mountpoint);
+ if (IS_ERR(mp)) {
+ mntput(mnt);
+ return PTR_ERR(mp);
+ }
+ error = do_add_mount(real_mount(mnt), mp, mountpoint, mnt_flags);
+ unlock_mount(mp);
if (error < 0)
mntput(mnt);
return error;
@@ -2830,6 +2824,7 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags,
int finish_automount(struct vfsmount *m, struct path *path)
{
struct mount *mnt = real_mount(m);
+ struct mountpoint *mp;
int err;
/* The new mount record should have at least 2 refs to prevent it being
* expired before we get a chance to add it
@@ -2842,7 +2837,13 @@ int finish_automount(struct vfsmount *m, struct path *path)
goto fail;
}

- err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
+ mp = lock_mount(path);
+ if (IS_ERR(mp)) {
+ err = PTR_ERR(mp);
+ goto fail;
+ }
+ err = do_add_mount(mnt, mp, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
+ unlock_mount(mp);
if (!err)
return 0;
fail:
--
2.11.0