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__d_unalias() should refuse to move mountpoints

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-06-08 15:59:33 -04:00
parent e77fb7cef8
commit ee3efa91e2
1 changed files with 5 additions and 4 deletions
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5
fs/dcache.c
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@ -2387,14 +2387,13 @@ static struct dentry *__d_unalias(struct inode *inode,
struct dentry *dentry, struct dentry *alias) struct dentry *dentry, struct dentry *alias)
{ {
struct mutex *m1 = NULL, *m2 = NULL; struct mutex *m1 = NULL, *m2 = NULL;
struct dentry *ret; struct dentry *ret = ERR_PTR(-EBUSY);
/* If alias and dentry share a parent, then no extra locks required */ /* If alias and dentry share a parent, then no extra locks required */
if (alias->d_parent == dentry->d_parent) if (alias->d_parent == dentry->d_parent)
goto out_unalias; goto out_unalias;
/* See lock_rename() */ /* See lock_rename() */
ret = ERR_PTR(-EBUSY);
if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex)) if (!mutex_trylock(&dentry->d_sb->s_vfs_rename_mutex))
goto out_err; goto out_err;
m1 = &dentry->d_sb->s_vfs_rename_mutex; m1 = &dentry->d_sb->s_vfs_rename_mutex;
@ -2402,8 +2401,10 @@ static struct dentry *__d_unalias(struct inode *inode,
goto out_err; goto out_err;
m2 = &alias->d_parent->d_inode->i_mutex; m2 = &alias->d_parent->d_inode->i_mutex;
out_unalias: out_unalias:
if (likely(!d_mountpoint(alias))) {
__d_move(alias, dentry); __d_move(alias, dentry);
ret = alias; ret = alias;
}
out_err: out_err:
spin_unlock(&inode->i_lock); spin_unlock(&inode->i_lock);
if (m2) if (m2)