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Date: Tue, 15 Mar 2016 09:49:33 +1100
From: Daniel Axtens <dja@...ens.net>
To: Miklos Szeredi <miklos@...redi.hu>
Cc: Theodore Ts'o <tytso@....edu>, linux-kernel@...r.kernel.org,
linux-ext4@...r.kernel.org, viro@...iv.linux.org.uk,
linux-unionfs@...r.kernel.org
Subject: Re: ext4_file_open: Inconsistent encryption contexts (commit ff978b09f973) breaking Docker
Hi Miklos,
> Could you please try the below patch?
>
> It's actually three patches rolled into one:
>
> 1) ext4: use dget_parent() in ext4_file_open()
>
> Even with dget_parent() we don't hold i_mutex on directory and so the file
> could be moved in the mean time. Not sure if it's a problem. Ted?
>
> 2) vfs: add file_dentry()
>
> Posted here:
> http://marc.info/?l=linux-fsdevel&m=145745197615687&w=2
>
> 3) ext4: use file_dentry()
>
> s/\([a-z_]*\)->f_path\.dentry/file_dentry(\1)/
That works! Many thanks to you and Ted.
Feel free to let me know if you'd like my Tested-by on any of these patches.
Regards,
Daniel
>
> Thanks,
> Miklos
>
>
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 4cd318f31cbe..38847f38b34a 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -335,7 +335,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
> struct super_block *sb = inode->i_sb;
> struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> struct vfsmount *mnt = filp->f_path.mnt;
> - struct inode *dir = filp->f_path.dentry->d_parent->d_inode;
> + struct dentry *dir;
> struct path path;
> char buf[64], *cp;
> int ret;
> @@ -379,14 +379,18 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
> if (ext4_encryption_info(inode) == NULL)
> return -ENOKEY;
> }
> - if (ext4_encrypted_inode(dir) &&
> - !ext4_is_child_context_consistent_with_parent(dir, inode)) {
> +
> + dir = dget_parent(file_dentry(filp));
> + if (ext4_encrypted_inode(d_inode(dir)) &&
> + !ext4_is_child_context_consistent_with_parent(d_inode(dir), inode)) {
> ext4_warning(inode->i_sb,
> "Inconsistent encryption contexts: %lu/%lu\n",
> - (unsigned long) dir->i_ino,
> + (unsigned long) d_inode(dir)->i_ino,
> (unsigned long) inode->i_ino);
> + dput(dir);
> return -EPERM;
> }
> + dput(dir);
> /*
> * Set up the jbd2_inode if we are opening the inode for
> * writing and the journal is present
> diff --git a/fs/open.c b/fs/open.c
> index 55bdc75e2172..6326c11eda78 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -831,6 +831,17 @@ char *file_path(struct file *filp, char *buf, int buflen)
> }
> EXPORT_SYMBOL(file_path);
>
> +struct dentry *file_dentry(const struct file *file)
> +{
> + struct dentry *dentry = file->f_path.dentry;
> +
> + if (likely(d_inode(dentry) == file_inode(file)))
> + return dentry;
> + else
> + return dentry->d_op->d_native_dentry(dentry, file_inode(file));
> +}
> +EXPORT_SYMBOL(file_dentry);
> +
> /**
> * vfs_open - open the file at the given path
> * @path: path to open
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 619ad4b016d2..5142aa2034c4 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -336,14 +336,30 @@ static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
> return ret;
> }
>
> +static struct dentry *ovl_d_native_dentry(struct dentry *dentry,
> + struct inode *inode)
> +{
> + struct ovl_entry *oe = dentry->d_fsdata;
> + struct dentry *realentry = ovl_upperdentry_dereference(oe);
> +
> + if (realentry && inode == d_inode(realentry))
> + return realentry;
> + realentry = __ovl_dentry_lower(oe);
> + if (realentry && inode == d_inode(realentry))
> + return realentry;
> + BUG();
> +}
> +
> static const struct dentry_operations ovl_dentry_operations = {
> .d_release = ovl_dentry_release,
> .d_select_inode = ovl_d_select_inode,
> + .d_native_dentry = ovl_d_native_dentry,
> };
>
> static const struct dentry_operations ovl_reval_dentry_operations = {
> .d_release = ovl_dentry_release,
> .d_select_inode = ovl_d_select_inode,
> + .d_native_dentry = ovl_d_native_dentry,
> .d_revalidate = ovl_dentry_revalidate,
> .d_weak_revalidate = ovl_dentry_weak_revalidate,
> };
> diff --git a/include/linux/dcache.h b/include/linux/dcache.h
> index c4b5f4b3f8f8..99ecb6de636c 100644
> --- a/include/linux/dcache.h
> +++ b/include/linux/dcache.h
> @@ -161,6 +161,7 @@ struct dentry_operations {
> struct vfsmount *(*d_automount)(struct path *);
> int (*d_manage)(struct dentry *, bool);
> struct inode *(*d_select_inode)(struct dentry *, unsigned);
> + struct dentry *(*d_native_dentry)(struct dentry *, struct inode *);
> } ____cacheline_aligned;
>
> /*
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index ae681002100a..1091d9f43271 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1234,6 +1234,8 @@ static inline struct inode *file_inode(const struct file *f)
> return f->f_inode;
> }
>
> +extern struct dentry *file_dentry(const struct file *file);
> +
> static inline int locks_lock_file_wait(struct file *filp, struct file_lock *fl)
> {
> return locks_lock_inode_wait(file_inode(filp), fl);
--
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