On Wed, 2005-05-18 at 14:56, Andrew Morton wrote:

Badari Pulavarty [off-list ref] wrote:

quoted

Does anyone know what this page-flag is used for ? I see some
references to this in AFS. 

Is it possible for me to use this for my own use in ext3 ? 
(like delayed allocations ?) Any generic routines/VM stuff
expects me to use this only for a specific purpose ?

#define PG_fs_misc               9      /* Filesystem specific bit */

It's identical to PG_checked, added by David Howells'
provide-a-filesystem-specific-syncable-page-bit.patch

IIRC we decided to expand the definition of PG_checked to mean
"a_ops-private, fs-defined page flag".  I guess if/when that patch is
merged we'll do a kernel-wide s/PG_checked/PG_fs_misc/.

And ext3 is already using that flag.

:(

Is it possible to get yet another PG_fs_specific flag ? 
Reasons for it are:

	- I need this for supporting delayed allocation on ext3. Me, Ted
	  and Suparna thought about it for a while to see we can 
	  workaround it. So far, I haven't found a clean way.

	- useful for other folks currently overloading page->private
	  for this purpose. May be then, we can make most filesystems
	  use mpage routines (since they assume page->private is for
	  bufferheads ?)

Thanks,
Badari


--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"aart@kvack.org"> aart@kvack.org </a>