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>

diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 38c236e38cef85cbf15696351475ea576235d2af..b62cd3e9a18e4ceab514ac7e67e9b755309d844f 100644 (file)
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -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 */

diff --git a/fs/cachefiles/key.c b/fs/cachefiles/key.c
index bf935e25bdbeb8493d129e6347bf4f69a611cef0..4927b533b9aea17c49a1208680e284d149573e67 100644 (file)
--- a/fs/cachefiles/key.c
+++ b/fs/cachefiles/key.c
@@ -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;
 }

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 14d0cc89400019c5ebc6b5926d0e04376a309b1c..aecfc5c37b49aaa666b9a92a06ec32c2d0d5342e 100644 (file)
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -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 @@ try_again:
                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))