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VFS: introduce end_creating_keep()

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Occasionally the caller of end_creating() wants to keep using the dentry.
Rather then requiring them to dget() the dentry (when not an error)
before calling end_creating(), provide end_creating_keep() which does
this.

cachefiles and overlayfs make use of this.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-16-neilb@ownmail.net
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
NeilBrown
2025-11-13 11:18:38 +11:00
committed by Christian Brauner
parent fe497f0759
commit cf296b294c
4 changed files with 28 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
fs/cachefiles/namei.c
View File

@@ -155,8 +155,7 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
/* Tell rmdir() it's not allowed to delete the subdir */
inode_lock(d_inode(subdir));
dget(subdir);
end_creating(subdir);
end_creating_keep(subdir);
if (!__cachefiles_mark_inode_in_use(NULL, d_inode(subdir))) {
pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n",

8
fs/overlayfs/dir.c
View File

@@ -251,10 +251,7 @@ struct dentry *ovl_create_temp(struct ovl_fs *ofs, struct dentry *workdir,
if (IS_ERR(ret))
return ret;
ret = ovl_create_real(ofs, workdir, ret, attr);
if (!IS_ERR(ret))
dget(ret);
end_creating(ret);
return ret;
return end_creating_keep(ret);
}
static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper,
@@ -364,8 +361,7 @@ static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
if (IS_ERR(newdentry))
return PTR_ERR(newdentry);
dget(newdentry);
end_creating(newdentry);
end_creating_keep(newdentry);
if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry) &&
!ovl_allow_offline_changes(ofs)) {

11
fs/overlayfs/super.c
View File

@@ -319,8 +319,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
};
if (work->d_inode) {
dget(work);
end_creating(work);
end_creating_keep(work);
if (persist)
return work;
err = -EEXIST;
@@ -336,9 +335,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
}
work = ovl_do_mkdir(ofs, dir, work, attr.ia_mode);
if (!IS_ERR(work))
dget(work);
end_creating(work);
end_creating_keep(work);
err = PTR_ERR(work);
if (IS_ERR(work))
goto out_err;
@@ -630,9 +627,7 @@ static struct dentry *ovl_lookup_or_create(struct ovl_fs *ofs,
if (!child->d_inode)
child = ovl_create_real(ofs, parent, child,
OVL_CATTR(mode));
if (!IS_ERR(child))
dget(child);
end_creating(child);
end_creating_keep(child);
}
dput(parent);

22
include/linux/namei.h
View File

@@ -125,6 +125,28 @@ static inline void end_creating(struct dentry *child)
end_dirop(child);
}
/* end_creating_keep - finish action started with start_creating() and return result
* @child: dentry returned by start_creating() or vfs_mkdir()
*
* Unlock and return the child. This can be called after
* start_creating() whether that function succeeded or not,
* but it is not needed on failure.
*
* If vfs_mkdir() was called then the value returned from that function
* should be given for @child rather than the original dentry, as vfs_mkdir()
* may have provided a new dentry.
*
* Returns: @child, which may be a dentry or an error.
*
*/
static inline struct dentry *end_creating_keep(struct dentry *child)
{
if (!IS_ERR(child))
dget(child);
end_dirop(child);
return child;
}
/**
* end_removing - finish action started with start_removing
* @child: dentry returned by start_removing()