| Message ID | 874kdyh65j.wl-chenli@uniontech.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ramfs: skip mknod if inode already exists. | expand |
On Wed, Jun 16, 2021 at 10:53:12AM +0800, Chen Li wrote: > > It's possible we try to mknod a dentry, which have > already bound to an inode, just skip it. How do you think this could happen?
On Wed, 16 Jun 2021 13:10:25 +0800, Christoph Hellwig wrote: > > On Wed, Jun 16, 2021 at 10:53:12AM +0800, Chen Li wrote: > > > > It's possible we try to mknod a dentry, which have > > already bound to an inode, just skip it. > > How do you think this could happen? > > Sorry, that's my bad. I noticed unionfs used to do this check in 9c5b4452998c6e670cfde0928b277e9c50d9a676, but not sure is it a must.
On Wed, Jun 16, 2021 at 10:53:12AM +0800, Chen Li wrote: > > It's possible we try to mknod a dentry, which have > already bound to an inode, just skip it. Caller should have checked may_create(), which includes EEXIST handling. NAKed-by: Al Viro <viro@zeniv.linux.org.uk> Incidentally, if it ever had been called that way, your variant would leak inode. Not the main problem, though...
On Wed, 16 Jun 2021 20:16:58 +0800, Al Viro wrote: > > On Wed, Jun 16, 2021 at 10:53:12AM +0800, Chen Li wrote: > > > > It's possible we try to mknod a dentry, which have > > already bound to an inode, just skip it. > > Caller should have checked may_create(), which includes EEXIST handling. > NAKed-by: Al Viro <viro@zeniv.linux.org.uk> Don't know may_create before, thanks! > > Incidentally, if it ever had been called that way, your variant would > leak inode. Not the main problem, though... > >
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c index 9ebd17d7befb..6cb1de521142 100644 --- a/fs/ramfs/inode.c +++ b/fs/ramfs/inode.c @@ -106,6 +106,8 @@ ramfs_mknod(struct user_namespace *mnt_userns, struct inode *dir, { struct inode * inode = ramfs_get_inode(dir->i_sb, dir, mode, dev); int error = -ENOSPC; + if (dentry->d_inode) + return -EEXIST; if (inode) { d_instantiate(dentry, inode);
It's possible we try to mknod a dentry, which have already bound to an inode, just skip it. Signed-off-by: Chen Li <chenli@uniontech.com> --- fs/ramfs/inode.c | 2 ++ 1 file changed, 2 insertions(+)