Re: [PATCH V11 09/11] fs: Lift XFS_IDONTCACHE to the VFS layer

Darrick J. Wong
2020-04-28T20:06:26Z

On Mon, Apr 27, 2020 at 05:21:40PM -0700, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
>
> 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@zeniv.linux.org.uk>
> Reviewed-by: Dave Chinner <dchinner@redhat.com>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>

Looks ok to me,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

>
> ---
> Changes from V9:
> Fix misspelling in commit subject
> move XFS_IEOFBLOCKS to '9'
>
> Changes from V8:
> Remove XFS_IDONTCACHE
> ---
> fs/xfs/xfs_icache.c | 4 ++--
> fs/xfs/xfs_inode.h | 3 +--
> fs/xfs/xfs_super.c | 2 +-
> include/linux/fs.h | 6 +++++-
> 4 files changed, 9 insertions(+), 6 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..d8ce3eaa246e 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -218,8 +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 */
> -#define XFS_IEOFBLOCKS (1 << 10)/* has the preallocblocks tag set */
> +#define XFS_IEOFBLOCKS (1 << 9) /* has the preallocblocks tag set */
> /*
> * If this unlinked inode is in the middle of recovery, don't let drop_inode
> * truncate and free the inode. This can happen if we iget the inode during
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index e80bd2c4c279..6f91c13fb6ea 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -737,7 +737,7 @@ 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
>