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kernfs: combine ino/id lookup functions into kernfs_find_and_get_node_by_id()

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kernfs_find_and_get_node_by_ino() looks the kernfs_node matching the
specified ino.  On top of that, kernfs_get_node_by_id() and
kernfs_fh_get_inode() implement full ID matching by testing the rest
of ID.

On surface, confusingly, the two are slightly different in that the
latter uses 0 gen as wildcard while the former doesn't - does it mean
that the latter can't uniquely identify inodes w/ 0 gen?  In practice,
this is a distinction without a difference because generation number
starts at 1.  There are no actual IDs with 0 gen, so it can always
safely used as wildcard.

Let's simplify the code by renaming kernfs_find_and_get_node_by_ino()
to kernfs_find_and_get_node_by_id(), moving all lookup logics into it,
and removing now unnecessary kernfs_get_node_by_id().

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tejun Heo
2019-11-04 15:54:30 -08:00
parent 67c0496e87
commit fe0f726c9f
5 changed files with 18 additions and 32 deletions
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17
fs/kernfs/dir.c
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@@ -696,17 +696,22 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
}
/*
* kernfs_find_and_get_node_by_ino - get kernfs_node from inode number
* kernfs_find_and_get_node_by_id - get kernfs_node from node id
* @root: the kernfs root
* @ino: inode number
* @id: the target node id
*
* @id's lower 32bits encode ino and upper gen. If the gen portion is
* zero, all generations are matched.
*
* RETURNS:
* NULL on failure. Return a kernfs node with reference counter incremented
*/
struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root,
unsigned int ino)
struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root,
u64 id)
{
struct kernfs_node *kn;
ino_t ino = kernfs_id_ino(id);
u32 gen = kernfs_id_gen(id);
spin_lock(&kernfs_idr_lock);
@@ -714,6 +719,10 @@ struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root,
if (!kn)
goto err_unlock;
/* 0 matches all generations */
if (unlikely(gen && kernfs_gen(kn) != gen))
goto err_unlock;
/*
* ACTIVATED is protected with kernfs_mutex but it was clear when
* @kn was added to idr and we just wanna see it set. No need to