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cachefiles: Use lookup_one() rather than lookup_one_len() 

cachefiles uses some VFS interfaces (such as vfs_mkdir) which take an
explicit mnt_idmap, and it passes &nop_mnt_idmap as cachefiles doesn't
yet support idmapped mounts.

It also uses the lookup_one_len() family of functions which implicitly
use &nop_mnt_idmap.  This mixture of implicit and explicit could be
confusing.  When we eventually update cachefiles to support idmap mounts it
would be best if all places which need an idmap determined from the
mount point were similar and easily found.

So this patch changes cachefiles to use lookup_one(), lookup_one_unlocked(),
and lookup_one_positive_unlocked(), passing &nop_mnt_idmap.

This has the benefit of removing the remaining user of the
lookup_one_len functions where permission checking is actually needed.
Other callers don't care about permission checking and using these
function only where permission checking is needed is a valuable
simplification.

This requires passing the name in a qstr.  This is easily done with
QSTR() as the name is always nul terminated, and often strlen is used
anyway.  ->d_name_len is removed as no longer useful.

Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20250319031545.2999807-4-neil@brown.name
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
NeilBrown 2025-03-19 14:01:34 +11:00 committed by Christian Brauner
parent 8ad9248471
commit 2011067c64
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
3 changed files with 7 additions and 9 deletions
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1
fs/cachefiles/internal.h
View File

@ -71,7 +71,6 @@ struct cachefiles_object {
int debug_id;
spinlock_t lock;
refcount_t ref;
u8 d_name_len; /* Length of filename */
enum cachefiles_content content_info:8; /* Info about content presence */
unsigned long flags;
#define CACHEFILES_OBJECT_USING_TMPFILE 0 /* Have an unlinked tmpfile */

1
fs/cachefiles/key.c
View File

@ -132,7 +132,6 @@ bool cachefiles_cook_key(struct cachefiles_object *object)
success:
name[len] = 0;
object->d_name = name;
object->d_name_len = len;
_leave(" = %s", object->d_name);
return true;
}

14
fs/cachefiles/namei.c
View File

@ -98,7 +98,7 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
retry:
ret = cachefiles_inject_read_error();
if (ret == 0)
subdir = lookup_one_len(dirname, dir, strlen(dirname));
subdir = lookup_one(&nop_mnt_idmap, &QSTR(dirname), dir);
else
subdir = ERR_PTR(ret);
trace_cachefiles_lookup(NULL, dir, subdir);
@ -338,7 +338,7 @@ int cachefiles_bury_object(struct cachefiles_cache *cache,
return -EIO;
}
grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
grave = lookup_one(&nop_mnt_idmap, &QSTR(nbuffer), cache->graveyard);
if (IS_ERR(grave)) {
unlock_rename(cache->graveyard, dir);
trace_cachefiles_vfs_error(object, d_inode(cache->graveyard),
@ -630,8 +630,8 @@ bool cachefiles_look_up_object(struct cachefiles_object *object)
/* Look up path "cache/vol/fanout/file". */
ret = cachefiles_inject_read_error();
if (ret == 0)
dentry = lookup_positive_unlocked(object->d_name, fan,
object->d_name_len);
dentry = lookup_one_positive_unlocked(&nop_mnt_idmap,
&QSTR(object->d_name), fan);
else
dentry = ERR_PTR(ret);
trace_cachefiles_lookup(object, fan, dentry);
@ -683,7 +683,7 @@ bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache,
inode_lock_nested(d_inode(fan), I_MUTEX_PARENT);
ret = cachefiles_inject_read_error();
if (ret == 0)
dentry = lookup_one_len(object->d_name, fan, object->d_name_len);
dentry = lookup_one(&nop_mnt_idmap, &QSTR(object->d_name), fan);
else
dentry = ERR_PTR(ret);
if (IS_ERR(dentry)) {
@ -702,7 +702,7 @@ bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache,
dput(dentry);
ret = cachefiles_inject_read_error();
if (ret == 0)
dentry = lookup_one_len(object->d_name, fan, object->d_name_len);
dentry = lookup_one(&nop_mnt_idmap, &QSTR(object->d_name), fan);
else
dentry = ERR_PTR(ret);
if (IS_ERR(dentry)) {
@ -751,7 +751,7 @@ static struct dentry *cachefiles_lookup_for_cull(struct cachefiles_cache *cache,
inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
victim = lookup_one_len(filename, dir, strlen(filename));
victim = lookup_one(&nop_mnt_idmap, &QSTR(filename), dir);
if (IS_ERR(victim))
goto lookup_error;
if (d_is_negative(victim))