On Mon, Jan 16, 2017 at 6:46 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> Factor out some common vfs bits from do_tmpfile()
> to be used by overlayfs for concurrent copy up.
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/namei.c | 66 +++++++++++++++++++++++++++++++++++-------------------
> include/linux/fs.h | 3 +++
> 2 files changed, 46 insertions(+), 23 deletions(-)
>
> diff --git a/fs/namei.c b/fs/namei.c
> index ad74877..3e7c7a6 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -3353,11 +3353,49 @@ static int do_last(struct nameidata *nd,
> return error;
> }
>
> +struct dentry *vfs_tmpfile(struct inode *dir, struct dentry *dentry,
dir and dentry refer to the same thing; can just pass the dentry.
> + umode_t mode, int open_flag)
> +{
> + static const struct qstr name = QSTR_INIT("/", 1);
> + struct dentry *child = NULL;
> + struct inode *inode;
> + int error;
> +
> + /* we want directory to be writable */
> + error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
This is not in the scope of this patch, but shoudln't we be using
may_create() here? Or at least a variant without the audit thing...
Al?
Thanks,
Miklos
> + if (error)
> + goto out_err;
> + error = -EOPNOTSUPP;
> + if (!dir->i_op->tmpfile)
> + goto out_err;
> + error = -ENOMEM;
> + child = d_alloc(dentry, &name);
> + if (unlikely(!child))
> + goto out_err;
> + error = dir->i_op->tmpfile(dir, child, mode);
> + if (error)
> + goto out_err;
> + error = -ENOENT;
> + inode = child->d_inode;
> + if (unlikely(!inode))
> + goto out_err;
> + if (!(open_flag & O_EXCL)) {
> + spin_lock(&inode->i_lock);
> + inode->i_state |= I_LINKABLE;
> + spin_unlock(&inode->i_lock);
> + }
> + return child;
> +
> +out_err:
> + dput(child);
> + return ERR_PTR(error);
> +}
> +EXPORT_SYMBOL(vfs_tmpfile);
> +
> static int do_tmpfile(struct nameidata *nd, unsigned flags,
> const struct open_flags *op,
> struct file *file, int *opened)
> {
> - static const struct qstr name = QSTR_INIT("/", 1);
> struct dentry *child;
> struct inode *dir;
> struct path path;
> @@ -3368,24 +3406,12 @@ static int do_tmpfile(struct nameidata *nd, unsigned flags,
> if (unlikely(error))
> goto out;
> dir = path.dentry->d_inode;
> - /* we want directory to be writable */
> - error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
> - if (error)
> - goto out2;
> - if (!dir->i_op->tmpfile) {
> - error = -EOPNOTSUPP;
> - goto out2;
> - }
> - child = d_alloc(path.dentry, &name);
> - if (unlikely(!child)) {
> - error = -ENOMEM;
> + child = vfs_tmpfile(dir, path.dentry, op->mode, op->open_flag);
> + error = PTR_ERR(child);
> + if (unlikely(IS_ERR(child)))
> goto out2;
> - }
> dput(path.dentry);
> path.dentry = child;
> - error = dir->i_op->tmpfile(dir, child, op->mode);
> - if (error)
> - goto out2;
> audit_inode(nd->name, child, 0);
> /* Don't check for other permissions, the inode was just created */
> error = may_open(&path, 0, op->open_flag);
> @@ -3396,14 +3422,8 @@ static int do_tmpfile(struct nameidata *nd, unsigned flags,
> if (error)
> goto out2;
> error = open_check_o_direct(file);
> - if (error) {
> + if (error)
> fput(file);
> - } else if (!(op->open_flag & O_EXCL)) {
> - struct inode *inode = file_inode(file);
> - spin_lock(&inode->i_lock);
> - inode->i_state |= I_LINKABLE;
> - spin_unlock(&inode->i_lock);
> - }
> out2:
> mnt_drop_write(path.mnt);
> out:
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 2ba0743..8c7cbcb 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1561,6 +1561,9 @@ extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
> extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **, unsigned int);
> extern int vfs_whiteout(struct inode *, struct dentry *);
>
> +extern struct dentry *vfs_tmpfile(struct inode *dir, struct dentry *dentry,
> + umode_t mode, int open_flag);
> +
> /*
> * VFS file helper functions.
> */
> --
> 2.7.4
>
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