fs: add a kerneldoc header over lookup_fast

The lookup_fast helper in fs/namei.c has some subtlety in how dentries
are returned. Document them.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20240802-openfast-v1-2-a1cff2a33063@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Jeff Layton 2024-08-02 17:45:03 -04:00 committed by Christian Brauner
parent 45fab40d34
commit 46460c1d42

View File

@ -1639,6 +1639,20 @@ struct dentry *lookup_one_qstr_excl(const struct qstr *name,
}
EXPORT_SYMBOL(lookup_one_qstr_excl);
/**
* lookup_fast - do fast lockless (but racy) lookup of a dentry
* @nd: current nameidata
*
* Do a fast, but racy lookup in the dcache for the given dentry, and
* revalidate it. Returns a valid dentry pointer or NULL if one wasn't
* found. On error, an ERR_PTR will be returned.
*
* If this function returns a valid dentry and the walk is no longer
* lazy, the dentry will carry a reference that must later be put. If
* RCU mode is still in force, then this is not the case and the dentry
* must be legitimized before use. If this returns NULL, then the walk
* will no longer be in RCU mode.
*/
static struct dentry *lookup_fast(struct nameidata *nd)
{
struct dentry *dentry, *parent = nd->path.dentry;