Re: [PATCH v7 07/12] kernfs: hold kernfs_iattr_rwsem when initializing a new inode
flat view
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2026-10-16 14:50:01
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On Fri, Oct 16, 2026 at 04:38:01PM +0200, Jori Koolstra wrote:
kernfs_refresh_inode() copies the uid, gid, timestamps and nlink of a
kernfs_node into its VFS inode. Since commit 9caf69614225 ("kernfs:
Introduce separate rwsem to protect inode attributes.") these are
protected by kernfs_iattr_rwsem.
kernfs_init_inode() calls kernfs_refresh_inode(), but was not converted.
Its callers in turn hold kernfs_rwsem (kernfs_iop_lookup(),
kernfs_fill_super()) or no lock at all (__kernfs_fh_to_dentry()),
neither of which excludes a concurrent
kernfs_setattr()/kernfs_iop_setattr().
Take kernfs_iattr_rwsem for reading around the refresh in
kernfs_init_inode(). This nests inside kernfs_rwsem, which matches
kernfs_link_sibling() and kernfs_unlink_sibling().
Also, kernfs_get_inode() then does not need to hold kernfs_rwsem, so
drop it from kernfs_fill_super().Oh, nice, this fixes the issue of kernfs not keeping the inode like we talked about at LPC? Can't argue with this tiny patch, nice work! Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>