diff options
Diffstat (limited to 'Documentation/filesystems/vfs.rst')
| -rw-r--r-- | Documentation/filesystems/vfs.rst | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst index 0b18af3f954e..31eea688609a 100644 --- a/Documentation/filesystems/vfs.rst +++ b/Documentation/filesystems/vfs.rst @@ -1251,7 +1251,8 @@ defined: .. code-block:: c struct dentry_operations { - int (*d_revalidate)(struct dentry *, unsigned int); + int (*d_revalidate)(struct inode *, const struct qstr *, + struct dentry *, unsigned int); int (*d_weak_revalidate)(struct dentry *, unsigned int); int (*d_hash)(const struct dentry *, struct qstr *); int (*d_compare)(const struct dentry *, @@ -1264,6 +1265,8 @@ defined: struct vfsmount *(*d_automount)(struct path *); int (*d_manage)(const struct path *, bool); struct dentry *(*d_real)(struct dentry *, enum d_real_type type); + bool (*d_unalias_trylock)(const struct dentry *); + void (*d_unalias_unlock)(const struct dentry *); }; ``d_revalidate`` @@ -1427,6 +1430,25 @@ defined: For non-regular files, the 'dentry' argument is returned. +``d_unalias_trylock`` + if present, will be called by d_splice_alias() before moving a + preexisting attached alias. Returning false prevents __d_move(), + making d_splice_alias() fail with -ESTALE. + + Rationale: setting FS_RENAME_DOES_D_MOVE will prevent d_move() + and d_exchange() calls from the outside of filesystem methods; + however, it does not guarantee that attached dentries won't + be renamed or moved by d_splice_alias() finding a preexisting + alias for a directory inode. Normally we would not care; + however, something that wants to stabilize the entire path to + root over a blocking operation might need that. See 9p for one + (and hopefully only) example. + +``d_unalias_unlock`` + should be paired with ``d_unalias_trylock``; that one is called after + __d_move() call in __d_unalias(). + + Each dentry has a pointer to its parent dentry, as well as a hash list of child dentries. Child dentries are basically like files in a directory. |