Commit b3276c1f authored by Chuck Lever's avatar Chuck Lever
Browse files

NFSD: Flesh out a documenting comment for filecache.c 



Record what we've learned recently about the NFSD filecache in a
documenting comment so our future selves don't forget what all this
is for.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
parent 4d1ea845

fs/nfsd/filecache.c

+24 −0
Original line number Diff line number Diff line
@@ -2,6 +2,30 @@ 
 * Open file cache.

 *

 * (c) 2015 - Jeff Layton <jeff.layton@primarydata.com>

 *

 * An nfsd_file object is a per-file collection of open state that binds

 * together:

 *   - a struct file *

 *   - a user credential

 *   - a network namespace

 *   - a read-ahead context

 *   - monitoring for writeback errors

 *

 * nfsd_file objects are reference-counted. Consumers acquire a new

 * object via the nfsd_file_acquire API. They manage their interest in

 * the acquired object, and hence the object's reference count, via

 * nfsd_file_get and nfsd_file_put. There are two varieties of nfsd_file

 * object:

 *

 *  * non-garbage-collected: When a consumer wants to precisely control

 *    the lifetime of a file's open state, it acquires a non-garbage-

 *    collected nfsd_file. The final nfsd_file_put releases the open

 *    state immediately.

 *

 *  * garbage-collected: When a consumer does not control the lifetime

 *    of open state, it acquires a garbage-collected nfsd_file. The

 *    final nfsd_file_put allows the open state to linger for a period

 *    during which it may be re-used.

 */



#include <linux/hash.h>