Re: why does fsync() on a tmpfs directory give EINVAL?

[Andrew Morton <akpm@osdl.org>]

Chris Friesen <cfriesen@nortel.com> wrote:
>
> Andrew Morton wrote:
> > Chris Friesen <cfriesen@nortel.com> wrote:
> 
> >>Currently tmpfs reuses the simple_dir_operations from libfs.c.
> >>
> >>Would it make sense to add the empty fsync() function there, and have 
> >>all other users pick it up as well?  Is this likely to break stuff?
> >  
> > Isn't simple_sync_file() suitable?
> 
> I think it would be fine.  The issue is that currently for directories 
> tmpfs doesn't have it's own set of operations--it reuses the 
> simple_dir_operations set of file ops from libfs.
> 
> We could make a tmpfs-specific set of operations that is identical to 
> simple_dir_operations but with the addition of setting the fsync 
> function to simple_sync_file().
> 
> Alternately, if it makes sense for all the users of 
> simple_dir_operations we could modify it directly and all of the other 
> users of simple_dir_operations would get the change for free.  I don't 
> know enough about the other filesystems to know if this makes sense or not.
> 

hm, what a lot of filesystems.

bix:/usr/src/linux-2.6.12-rc6> grep -rl simple_dir_operations .            
./drivers/usb/gadget/inode.c
./drivers/usb/core/inode.c
./drivers/isdn/capi/capifs.c
./drivers/oprofile/oprofilefs.c
./drivers/misc/ibmasm/ibmasmfs.c
./fs/libfs.c
./fs/debugfs/inode.c
./fs/autofs/inode.c
./fs/devpts/inode.c
./fs/hugetlbfs/inode.c
./fs/ramfs/inode.c
./include/linux/fs.h
./net/sunrpc/rpc_pipe.c
./kernel/cpuset.c
./security/selinux/selinuxfs.c
./ipc/mqueue.c
./mm/shmem.c

I can't think of any reason why any of these would want fsync(dir_fd) to
return -EINVAL.