Re: fcntl(2) and other file systems like XFS

From: Stephen C. Tweedie (
Date: Thu Mar 16 2000 - 18:06:58 EST


On Tue, 14 Mar 2000 21:42:40 -0600 (CST), Jim Mostek <>

> XFS has several fcntls for things like preallocating space. This is used
> by some applications who want very large files. This let's a file system
> allocate the space all at once.

> Has the issue of a file_operation callout for fcntl gone around before?
> Anyone opposed to adding this? I don't think this belongs in the
> inode_operations.

It sounds very much like an ioctl() operation to me. Basically, fcntl()
operations usually operate not on the file, but on the file descriptor.
They affect such things as close-on-exec, async IO status and so on.
Anything which affects the inode should probably be an ioctl().

> I think we want to add a few more like F_FATTR_SET, F_FATTR_GET,
> F_FATTR_LIST, and F_FATTR_REMOVE to implement the extended attribute
> capability XFS has.

Definitely ioctl() material. Extending fcntl() would be appropriate for
advanced file-descriptor-specific operations such as defining readahead
properties for the fd, but what you've listed here sounds as if the
existing ioctl pass-through would be both appropriate and sufficient.


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