xfs: implement lazy removal for the dquot freelist

Do not remove dquots from the freelist when we grab a reference to them in
xfs_qm_dqlookup, but leave them on the freelist util scanning notices that
they have a reference.  This speeds up the lookup fastpath, and greatly
simplifies the lock ordering constraints.  Note that the same scheme is
used by the VFS inode and dentry caches.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 1 insertions, 3 deletions

diff --git a/fs/xfs/xfs_quota.h b/fs/xfs/xfs_quota.h
index cbafdee8b98a..487653ddbef0 100644
--- a/fs/xfs/xfs_quota.h
+++ b/fs/xfs/xfs_quota.h
@@ -87,7 +87,6 @@ typedef struct xfs_dqblk {
 #define XFS_DQ_PROJ             0x0002          /* project quota */
 #define XFS_DQ_GROUP            0x0004          /* a group quota */
 #define XFS_DQ_DIRTY            0x0008          /* dquot is dirty */
-#define XFS_DQ_WANT             0x0010          /* for lookup/reclaim race */
 
 #define XFS_DQ_ALLTYPES         (XFS_DQ_USER|XFS_DQ_PROJ|XFS_DQ_GROUP)
 
@@ -95,8 +94,7 @@ typedef struct xfs_dqblk {
         { XFS_DQ_USER,          "USER" }, \
         { XFS_DQ_PROJ,          "PROJ" }, \
         { XFS_DQ_GROUP,         "GROUP" }, \
-        { XFS_DQ_DIRTY,         "DIRTY" }, \
-        { XFS_DQ_WANT,          "WANT" }
+        { XFS_DQ_DIRTY,         "DIRTY" }
 
 /*
  * In the worst case, when both user and group quotas are on,