> +#define ESHAREDENIED 258 /* File is locked with a sharelock */
Have you prepared C library patches to match this ?
(and why not just use EPERM, it has the meaning you want already)
> + * Check to see if there's a share_reservation conflict. LOCK_READ/LOCK_WRITE
> + * tell us whether the reservation allows other readers and writers.
> + */
> +static int
> +locks_mand_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
> +{
Shouldn't this also check for CAP_SYS_DAC or some similar permission so
that root can override such a mess (eg to fix full disks in an
emergency) ?
> +
> + /*
> + * For sharelock mounts if a file was created but not opened, we need
> + * to keep parent i_mutex until we finish the open to prevent races when
> + * somebody opens newly created by us file and locks it with a sharelock
> + * before we open it.
> + */
> + if (IS_SHARELOCK(dir->d_inode) && error > 0 && *opened & FILE_CREATED) {
> + /* Don't check for write permission, don't truncate */
> + open_flag &= ~O_TRUNC;
> + will_truncate = false;
> + acc_mode = MAY_OPEN;
> + path_to_nameidata(path, nd);
> +
> + error = may_open(&nd->path, acc_mode, open_flag);
> + if (error) {
> + mutex_unlock(&dir->d_inode->i_mutex);
> + goto out;
> + }
> + file->f_path.mnt = nd->path.mnt;
> + error = finish_open(file, nd->path.dentry, NULL, opened);
> + if (error) {
> + mutex_unlock(&dir->d_inode->i_mutex);
> + if (error == -EOPENSTALE)
> + goto stale_open;
> + goto out;
> + }
> + error = sharelock_lock_file(file);
> + mutex_unlock(&dir->d_inode->i_mutex);
> + if (error)
> + goto exit_fput;
> + goto opened;
> + }
> +
> mutex_unlock(&dir->d_inode->i_mutex);
What stops the file system changing mount flags via a remount between
these two ?
>
> if (error <= 0) {
> @@ -3034,6 +3073,18 @@ finish_open_created:
> goto stale_open;
> goto out;
> }
> +
> + if (IS_SHARELOCK(dir->d_inode)) {
> + /*
> + * Lock parent i_mutex to prevent races with sharelocks on
> + * newly created files.
> + */
> + mutex_lock(&dir->d_inode->i_mutex);
> + error = sharelock_lock_file(file);
> + mutex_unlock(&dir->d_inode->i_mutex);
> + if (error)
> + goto exit_fput;
> + }
> opened:
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