Messages in this thread |  | | Date | Mon, 20 Jan 2014 14:45:00 +0400 | Subject | Re: [PATCH v7 1/7] VFS: Introduce new O_DENY* open flags | From | Pavel Shilovsky <> |
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2014/1/17 One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>: >> +#define ESHAREDENIED 258 /* File is locked with a sharelock */ > > Have you prepared C library patches to match this ?
I don't have it for now.
> > (and why not just use EPERM, it has the meaning you want already)
We need to determine if we have a share reservation error to map it accurately in file servers and wine.
> > >> + * 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) ?
May be it's better to let root an ability to remount the system without sharelock mount option and then fix 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 ?
Nothing, but it doesn't bring problems here: if the first IS_SHARELOCK condition is true, we don't get into the second (see 'goto opened').
> >> >> 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: > -- > To unsubscribe from this list: send the line "unsubscribe linux-cifs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
-- Best regards, Pavel Shilovsky.
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