On Mon, 2007-12-10 at 19:57 +0100, Andi Kleen wrote: > > Hi Andi, > > > > Does the attached patch fix the Oops? > > Nope, got that a few hours after boot again: > > -Andi
Hi Andi, I appear to have misread d_find_alias(). It would seem that the only way to ensure that a mountpoint won't be found is to remove it altogether from the inode->i_dentry list. AFAICS that should be largely harmless since the nfs sb->s_root is never visible to users, and is never part of a dentry tree. Cheers Trond
--- Begin Message ---Ensure that the dummy 'root dentry' is invisible to d_find_alias(). If not, then it may be spliced into the tree if a parent directory from the same filesystem gets mounted at a later time. Signed-off-by: Trond Myklebust <[EMAIL PROTECTED]> --- fs/nfs/getroot.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c index 0ee4384..e6242cd 100644 --- a/fs/nfs/getroot.c +++ b/fs/nfs/getroot.c @@ -57,6 +57,17 @@ static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *i } /* Circumvent igrab(): we know the inode is not being freed */ atomic_inc(&inode->i_count); + /* + * Ensure that this dentry is invisible to d_find_alias(). + * Otherwise, it may be spliced into the tree by + * d_materialise_unique if a parent directory from the same + * filesystem gets mounted at a later time. + * This again causes shrink_dcache_for_umount_subtree() to + * Oops, since the test for IS_ROOT() will fail. + */ + spin_lock(&dcache_lock); + list_del_init(&sb->s_root->d_alias); + spin_unlock(&dcache_lock); } return 0; }
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