On Sun 12-04-20 22:40:44, ira.weiny@xxxxxxxxx wrote:
> From: Ira Weiny <ira.weiny@xxxxxxxxx>
>
> DAX effective mode changes (setting of S_DAX) require inode eviction.
>
> Define a flag which can be set to inform the VFS layer that inodes
> should not be cached. This will expedite the eviction of those nodes
> requiring reload.
>
> Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
This inode flag will have a limited impact because usually dentry will
still hold inode reference. So until dentry is evicted, inode stays as
well. So I think we'd need something like DCACHE_DONTCACHE flag as well to
discard a dentry whenever dentry usecount hits zero (which will be
generally on last file close). What do you think?
And I'd note that checking for I_DONTCACHE flag in dput() isn't
straightforward because of locking so that's why I suggest separate dentry
flag.
Honza
> ---
> include/linux/fs.h | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index a818ced22961..e2db71d150c3 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2151,6 +2151,8 @@ 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 Do not cache the inode
> + *
> * Q: What is the difference between I_WILL_FREE and I_FREEING?
> */
> #define I_DIRTY_SYNC (1 << 0)
> @@ -2173,6 +2175,7 @@ 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)
> @@ -3042,7 +3045,8 @@ 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
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
