On Sun, Nov 20, 2011 at 10:32:41AM -0500, Christoph Hellwig wrote:
> On Wed, Nov 16, 2011 at 11:56:43AM -0800, Simon Kirby wrote:
> > Sorry for the delay in testing.
> >
> > Yes, everything looks fine even with the xfs_log_force line from your
> > patch commented out. So, the changes in xfs_reclaim_inode() are just the
> > set_bit(XBT_FORCE_FLUSH) and wake_up_process(), relative to 3.1.
>
> Dave pointed out that we can do better than the big hammer, and the
> patch below should fix your issue, too. Can you test it?
Yes, seems to be fine. No hung task warnings, tested for ~5 days.
Simon-
> ---
> From: Christoph Hellwig <hch@xxxxxx>
> Subject: xfs: force buffer writeback before blocking on the ilock in inode reclaim
>
> If we are doing synchronous inode reclaim we block the VM from making
> progress in memory reclaim. So if we encouter a flush locked inode
> promote it in the delwri list and wake up xfsbufd to write it out now.
> Without this we can get hangs of up to 30 seconds during workloads hitting
> synchronous inode reclaim.
>
> The scheme is copied from what we do for dquot reclaims.
>
> Reported-by: Simon Kirby <sim@xxxxxxxxxx>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
>
> Index: xfs/fs/xfs/xfs_sync.c
> ===================================================================
> --- xfs.orig/fs/xfs/xfs_sync.c 2011-11-20 12:48:36.664765032 +0100
> +++ xfs/fs/xfs/xfs_sync.c 2011-11-20 13:51:55.594184465 +0100
> @@ -770,6 +770,17 @@ restart:
> if (!xfs_iflock_nowait(ip)) {
> if (!(sync_mode & SYNC_WAIT))
> goto out;
> +
> + /*
> + * If we only have a single dirty inode in a cluster there is
> + * a fair chance that the AIL push may have pushed it into
> + * the buffer, but xfsbufd won't touch it until 30 seconds
> + * from now, and thus we will lock up here.
> + *
> + * Promote the inode buffer to the front of the delwri list
> + * and wake up xfsbufd now.
> + */
> + xfs_promote_inode(ip);
> xfs_iflock(ip);
> }
>
> Index: xfs/fs/xfs/xfs_inode.c
> ===================================================================
> --- xfs.orig/fs/xfs/xfs_inode.c 2011-11-20 13:50:51.457865253 +0100
> +++ xfs/fs/xfs/xfs_inode.c 2011-11-20 13:52:30.420662460 +0100
> @@ -2835,6 +2835,27 @@ corrupt_out:
> return XFS_ERROR(EFSCORRUPTED);
> }
>
> +void
> +xfs_promote_inode(
> + struct xfs_inode *ip)
> +{
> + struct xfs_buf *bp;
> +
> + ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
> +
> + bp = xfs_incore(ip->i_mount->m_ddev_targp, ip->i_imap.im_blkno,
> + ip->i_imap.im_len, XBF_TRYLOCK);
> + if (!bp)
> + return;
> +
> + if (XFS_BUF_ISDELAYWRITE(bp)) {
> + xfs_buf_delwri_promote(bp);
> + wake_up_process(ip->i_mount->m_ddev_targp->bt_task);
> + }
> +
> + xfs_buf_relse(bp);
> +}
> +
> /*
> * Return a pointer to the extent record at file index idx.
> */
> Index: xfs/fs/xfs/xfs_inode.h
> ===================================================================
> --- xfs.orig/fs/xfs/xfs_inode.h 2011-11-20 13:50:51.487865091 +0100
> +++ xfs/fs/xfs/xfs_inode.h 2011-11-20 13:51:39.224273148 +0100
> @@ -498,6 +498,7 @@ int xfs_iunlink(struct xfs_trans *, xfs
> void xfs_iext_realloc(xfs_inode_t *, int, int);
> void xfs_iunpin_wait(xfs_inode_t *);
> int xfs_iflush(xfs_inode_t *, uint);
> +void xfs_promote_inode(struct xfs_inode *);
> void xfs_lock_inodes(xfs_inode_t **, int, uint);
> void xfs_lock_two_inodes(xfs_inode_t *, xfs_inode_t *, uint);
>
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