2013/6/11 Jeff Layton <jlayton@xxxxxxxxxxxxxxx>:
> On Fri, 26 Apr 2013 16:04:16 +0400
> Pavel Shilovsky <piastry@xxxxxxxxxxx> wrote:
>
>> Introduce new LOCK_DELETE flock flag that is suggested to be used
>> internally only to map O_DENYDELETE open flag:
>>
>> !O_DENYDELETE -> LOCK_DELETE | LOCK_MAND.
>>
>> Signed-off-by: Pavel Shilovsky <piastry@xxxxxxxxxxx>
>> ---
>> fs/locks.c | 53 +++++++++++++++++++++++++++++++++-------
>> fs/namei.c | 3 +++
>> include/linux/fs.h | 6 +++++
>> include/uapi/asm-generic/fcntl.h | 1 +
>> 4 files changed, 54 insertions(+), 9 deletions(-)
>>
>> diff --git a/fs/locks.c b/fs/locks.c
>> index dbc5557..1cc68a9 100644
>> --- a/fs/locks.c
>> +++ b/fs/locks.c
>> @@ -269,7 +269,7 @@ EXPORT_SYMBOL(locks_copy_lock);
>>
>> static inline int flock_translate_cmd(int cmd) {
>> if (cmd & LOCK_MAND)
>> - return cmd & (LOCK_MAND | LOCK_RW);
>> + return cmd & (LOCK_MAND | LOCK_RW | LOCK_DELETE);
>> switch (cmd) {
>> case LOCK_SH:
>> return F_RDLCK;
>> @@ -614,6 +614,8 @@ deny_flags_to_cmd(unsigned int flags)
>> cmd |= LOCK_READ;
>> if (!(flags & O_DENYWRITE))
>> cmd |= LOCK_WRITE;
>> + if (!(flags & O_DENYDELETE))
>> + cmd |= LOCK_DELETE;
>>
>> return cmd;
>> }
>> @@ -836,6 +838,31 @@ out:
>> return error;
>> }
>>
>> +int
>> +sharelock_may_delete(struct dentry *dentry)
>> +{
>> + struct file_lock **before;
>> + int rc = 0;
>> +
>> + if (!IS_SHARELOCK(dentry->d_inode))
>> + return rc;
>> +
>> + lock_flocks();
>> + for_each_lock(dentry->d_inode, before) {
>> + struct file_lock *fl = *before;
>> + if (IS_POSIX(fl))
>> + break;
>> + if (IS_LEASE(fl))
>> + continue;
>> + if (fl->fl_type & LOCK_DELETE)
>> + continue;
>
> Are you sure this logic is right? What if I have a normal non-LOCK_MAND
> lock on this file. Won't that prevent me from deleting it with this
> patch?
>
It is a bug, thank you for pointing it out. We need to skip all
non-LOCK_MAND locks here.
--
Best regards,
Pavel Shilovsky.
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