[PATCH V9 08/11] fs: Lift XFS_IDONTCACNE to the VFS layer

[ira . weiny]

From: Ira Weiny <ira.weiny@xxxxxxxxx>

DAX effective mode (S_DAX) changes requires inode eviction.

XFS has an advisory flag (XFS_IDONTCACHE) to prevent caching of the
inode if no other additional references are taken.  We lift this flag to
the VFS layer and change the behavior slightly by allowing the flag to
remain even if multiple references are taken.

This will expedite the eviction of inodes to change S_DAX.

Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>

---
Changes from V8:
	Remove XFS_IDONTCACHE
---
 fs/xfs/xfs_icache.c | 4 ++--
 fs/xfs/xfs_inode.h  | 2 +-
 fs/xfs/xfs_super.c  | 2 +-
 include/linux/fs.h  | 6 +++++-
 4 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 17a0b86fe701..de76f7f60695 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -477,7 +477,7 @@ xfs_iget_cache_hit(
 		xfs_ilock(ip, lock_flags);
 
 	if (!(flags & XFS_IGET_INCORE))
-		xfs_iflags_clear(ip, XFS_ISTALE | XFS_IDONTCACHE);
+		xfs_iflags_clear(ip, XFS_ISTALE);
 	XFS_STATS_INC(mp, xs_ig_found);
 
 	return 0;
@@ -559,7 +559,7 @@ xfs_iget_cache_miss(
 	 */
 	iflags = XFS_INEW;
 	if (flags & XFS_IGET_DONTCACHE)
-		iflags |= XFS_IDONTCACHE;
+		VFS_I(ip)->i_state |= I_DONTCACHE;
 	ip->i_udquot = NULL;
 	ip->i_gdquot = NULL;
 	ip->i_pdquot = NULL;
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 83073c883fbf..52b8ee21a0b1 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -218,7 +218,7 @@ static inline bool xfs_inode_has_cow_data(struct xfs_inode *ip)
 #define XFS_IFLOCK		(1 << __XFS_IFLOCK_BIT)
 #define __XFS_IPINNED_BIT	8	 /* wakeup key for zero pin count */
 #define XFS_IPINNED		(1 << __XFS_IPINNED_BIT)
-#define XFS_IDONTCACHE		(1 << 9) /* don't cache the inode long term */
+/* Was XFS_IDONTCACHE 9 */
 #define XFS_IEOFBLOCKS		(1 << 10)/* has the preallocblocks tag set */
 /*
  * If this unlinked inode is in the middle of recovery, don't let drop_inode
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 0d0f74786799..2e165e226e15 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -742,7 +742,7 @@ xfs_fs_drop_inode(
 		return 0;
 	}
 
-	return generic_drop_inode(inode) || (ip->i_flags & XFS_IDONTCACHE);
+	return generic_drop_inode(inode);
 }
 
 static void
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a87cc5845a02..44bd45af760f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2156,6 +2156,8 @@ static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src,
  *
  * I_CREATING		New object's inode in the middle of setting up.
  *
+ * I_DONTCACHE		Evict inode as soon as it is not used anymore.
+ *
  * Q: What is the difference between I_WILL_FREE and I_FREEING?
  */
 #define I_DIRTY_SYNC		(1 << 0)
@@ -2178,6 +2180,7 @@ static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src,
 #define I_WB_SWITCH		(1 << 13)
 #define I_OVL_INUSE		(1 << 14)
 #define I_CREATING		(1 << 15)
+#define I_DONTCACHE		(1 << 16)
 
 #define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)
 #define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES)
@@ -3049,7 +3052,8 @@ extern int inode_needs_sync(struct inode *inode);
 extern int generic_delete_inode(struct inode *inode);
 static inline int generic_drop_inode(struct inode *inode)
 {
-	return !inode->i_nlink || inode_unhashed(inode);
+	return !inode->i_nlink || inode_unhashed(inode) ||
+		(inode->i_state & I_DONTCACHE);
 }
 
 extern struct inode *ilookup5_nowait(struct super_block *sb,
-- 
2.25.1