This is quite ugly compared to the previous version but looks correct
enough to me. One problem is that the first filesystem registered will
get an far over-proportional number of shrink requests, which the simple
patch to pass private data to the shrinker would get around easily.
Anyway, we need a fix, so:
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
On Wed, Apr 28, 2010 at 02:34:08PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> On low memory boxes or those with highmem, kernel can OOM before the
> background reclaims inodes via xfssyncd. Add a shrinker to run inode
> reclaim so that it inode reclaim is expedited when memory is low.
>
> This is more complex than it needs to be because the VM folk don't
> want a context added to the shrinker infrastructure. Hence we need
> to add a global list of XFS mount structures so the shrinker can
> traverse them.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
> fs/xfs/linux-2.6/xfs_super.c | 5 ++
> fs/xfs/linux-2.6/xfs_sync.c | 112 +++++++++++++++++++++++++++++++++++++---
> fs/xfs/linux-2.6/xfs_sync.h | 7 ++-
> fs/xfs/quota/xfs_qm_syscalls.c | 3 +-
> fs/xfs/xfs_ag.h | 1 +
> fs/xfs/xfs_mount.h | 1 +
> 6 files changed, 120 insertions(+), 9 deletions(-)
>
> diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
> index 1abcacc..a43d09e 100644
> --- a/fs/xfs/linux-2.6/xfs_super.c
> +++ b/fs/xfs/linux-2.6/xfs_super.c
> @@ -1210,6 +1210,7 @@ xfs_fs_put_super(
>
> xfs_unmountfs(mp);
> xfs_freesb(mp);
> + xfs_inode_shrinker_unregister(mp);
> xfs_icsb_destroy_counters(mp);
> xfs_close_devices(mp);
> xfs_dmops_put(mp);
> @@ -1623,6 +1624,8 @@ xfs_fs_fill_super(
> if (error)
> goto fail_vnrele;
>
> + xfs_inode_shrinker_register(mp);
> +
> kfree(mtpt);
> return 0;
>
> @@ -1868,6 +1871,7 @@ init_xfs_fs(void)
> goto out_cleanup_procfs;
>
> vfs_initquota();
> + xfs_inode_shrinker_init();
>
> error = register_filesystem(&xfs_fs_type);
> if (error)
> @@ -1895,6 +1899,7 @@ exit_xfs_fs(void)
> {
> vfs_exitquota();
> unregister_filesystem(&xfs_fs_type);
> + xfs_inode_shrinker_destroy();
> xfs_sysctl_unregister();
> xfs_cleanup_procfs();
> xfs_buf_terminate();
> diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
> index 3a64179..3884e20 100644
> --- a/fs/xfs/linux-2.6/xfs_sync.c
> +++ b/fs/xfs/linux-2.6/xfs_sync.c
> @@ -95,7 +95,8 @@ xfs_inode_ag_walk(
> struct xfs_perag *pag, int flags),
> int flags,
> int tag,
> - int exclusive)
> + int exclusive,
> + int *nr_to_scan)
> {
> uint32_t first_index;
> int last_error = 0;
> @@ -134,7 +135,7 @@ restart:
> if (error == EFSCORRUPTED)
> break;
>
> - } while (1);
> + } while ((*nr_to_scan)--);
>
> if (skipped) {
> delay(1);
> @@ -150,12 +151,15 @@ xfs_inode_ag_iterator(
> struct xfs_perag *pag, int flags),
> int flags,
> int tag,
> - int exclusive)
> + int exclusive,
> + int *nr_to_scan)
> {
> int error = 0;
> int last_error = 0;
> xfs_agnumber_t ag;
> + int nr;
>
> + nr = nr_to_scan ? *nr_to_scan : INT_MAX;
> for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
> struct xfs_perag *pag;
>
> @@ -165,14 +169,18 @@ xfs_inode_ag_iterator(
> continue;
> }
> error = xfs_inode_ag_walk(mp, pag, execute, flags, tag,
> - exclusive);
> + exclusive, &nr);
> xfs_perag_put(pag);
> if (error) {
> last_error = error;
> if (error == EFSCORRUPTED)
> break;
> }
> + if (nr <= 0)
> + break;
> }
> + if (nr_to_scan)
> + *nr_to_scan = nr;
> return XFS_ERROR(last_error);
> }
>
> @@ -291,7 +299,7 @@ xfs_sync_data(
> ASSERT((flags & ~(SYNC_TRYLOCK|SYNC_WAIT)) == 0);
>
> error = xfs_inode_ag_iterator(mp, xfs_sync_inode_data, flags,
> - XFS_ICI_NO_TAG, 0);
> + XFS_ICI_NO_TAG, 0, NULL);
> if (error)
> return XFS_ERROR(error);
>
> @@ -310,7 +318,7 @@ xfs_sync_attr(
> ASSERT((flags & ~SYNC_WAIT) == 0);
>
> return xfs_inode_ag_iterator(mp, xfs_sync_inode_attr, flags,
> - XFS_ICI_NO_TAG, 0);
> + XFS_ICI_NO_TAG, 0, NULL);
> }
>
> STATIC int
> @@ -636,6 +644,7 @@ __xfs_inode_set_reclaim_tag(
> radix_tree_tag_set(&pag->pag_ici_root,
> XFS_INO_TO_AGINO(ip->i_mount, ip->i_ino),
> XFS_ICI_RECLAIM_TAG);
> + pag->pag_ici_reclaimable++;
> }
>
> /*
> @@ -668,6 +677,7 @@ __xfs_inode_clear_reclaim_tag(
> {
> radix_tree_tag_clear(&pag->pag_ici_root,
> XFS_INO_TO_AGINO(mp, ip->i_ino), XFS_ICI_RECLAIM_TAG);
> + pag->pag_ici_reclaimable--;
> }
>
> /*
> @@ -817,5 +827,93 @@ xfs_reclaim_inodes(
> int mode)
> {
> return xfs_inode_ag_iterator(mp, xfs_reclaim_inode, mode,
> - XFS_ICI_RECLAIM_TAG, 1);
> + XFS_ICI_RECLAIM_TAG, 1, NULL);
> +}
> +
> +/*
> + * Shrinker infrastructure.
> + *
> + * This is all far more complex than it needs to be. It adds a global list of
> + * mounts because the shrinkers can only call a global context. We need to make
> + * the shrinkers pass a context to avoid the need for global state.
> + */
> +static LIST_HEAD(xfs_mount_list);
> +static struct rw_semaphore xfs_mount_list_lock;
> +
> +static int
> +xfs_reclaim_inode_shrink(
> + int nr_to_scan,
> + gfp_t gfp_mask)
> +{
> + struct xfs_mount *mp;
> + struct xfs_perag *pag;
> + xfs_agnumber_t ag;
> + int reclaimable = 0;
> +
> + if (nr_to_scan) {
> + if (!(gfp_mask & __GFP_FS))
> + return -1;
> +
> + down_read(&xfs_mount_list_lock);
> + list_for_each_entry(mp, &xfs_mount_list, m_mplist) {
> + xfs_inode_ag_iterator(mp, xfs_reclaim_inode, 0,
> + XFS_ICI_RECLAIM_TAG, 1, &nr_to_scan);
> + if (nr_to_scan <= 0)
> + break;
> + }
> + up_read(&xfs_mount_list_lock);
> + }
> +
> + down_read(&xfs_mount_list_lock);
> + list_for_each_entry(mp, &xfs_mount_list, m_mplist) {
> + for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
> +
> + pag = xfs_perag_get(mp, ag);
> + if (!pag->pag_ici_init) {
> + xfs_perag_put(pag);
> + continue;
> + }
> + reclaimable += pag->pag_ici_reclaimable;
> + xfs_perag_put(pag);
> + }
> + }
> + up_read(&xfs_mount_list_lock);
> + return reclaimable;
> +}
> +
> +static struct shrinker xfs_inode_shrinker = {
> + .shrink = xfs_reclaim_inode_shrink,
> + .seeks = DEFAULT_SEEKS,
> +};
> +
> +void __init
> +xfs_inode_shrinker_init(void)
> +{
> + init_rwsem(&xfs_mount_list_lock);
> + register_shrinker(&xfs_inode_shrinker);
> +}
> +
> +void
> +xfs_inode_shrinker_destroy(void)
> +{
> + ASSERT(list_empty(&xfs_mount_list));
> + unregister_shrinker(&xfs_inode_shrinker);
> +}
> +
> +void
> +xfs_inode_shrinker_register(
> + struct xfs_mount *mp)
> +{
> + down_write(&xfs_mount_list_lock);
> + list_add_tail(&mp->m_mplist, &xfs_mount_list);
> + up_write(&xfs_mount_list_lock);
> +}
> +
> +void
> +xfs_inode_shrinker_unregister(
> + struct xfs_mount *mp)
> +{
> + down_write(&xfs_mount_list_lock);
> + list_del(&mp->m_mplist);
> + up_write(&xfs_mount_list_lock);
> }
> diff --git a/fs/xfs/linux-2.6/xfs_sync.h b/fs/xfs/linux-2.6/xfs_sync.h
> index d480c34..cdcbaac 100644
> --- a/fs/xfs/linux-2.6/xfs_sync.h
> +++ b/fs/xfs/linux-2.6/xfs_sync.h
> @@ -53,6 +53,11 @@ void __xfs_inode_clear_reclaim_tag(struct xfs_mount *mp, struct xfs_perag *pag,
> int xfs_sync_inode_valid(struct xfs_inode *ip, struct xfs_perag *pag);
> int xfs_inode_ag_iterator(struct xfs_mount *mp,
> int (*execute)(struct xfs_inode *ip, struct xfs_perag *pag, int flags),
> - int flags, int tag, int write_lock);
> + int flags, int tag, int write_lock, int *nr_to_scan);
> +
> +void xfs_inode_shrinker_init(void);
> +void xfs_inode_shrinker_destroy(void);
> +void xfs_inode_shrinker_register(struct xfs_mount *mp);
> +void xfs_inode_shrinker_unregister(struct xfs_mount *mp);
>
> #endif
> diff --git a/fs/xfs/quota/xfs_qm_syscalls.c b/fs/xfs/quota/xfs_qm_syscalls.c
> index f14408e..26fa431 100644
> --- a/fs/xfs/quota/xfs_qm_syscalls.c
> +++ b/fs/xfs/quota/xfs_qm_syscalls.c
> @@ -889,7 +889,8 @@ xfs_qm_dqrele_all_inodes(
> uint flags)
> {
> ASSERT(mp->m_quotainfo);
> - xfs_inode_ag_iterator(mp, xfs_dqrele_inode, flags, XFS_ICI_NO_TAG, 0);
> + xfs_inode_ag_iterator(mp, xfs_dqrele_inode, flags,
> + XFS_ICI_NO_TAG, 0, NULL);
> }
>
> /*------------------------------------------------------------------------*/
> diff --git a/fs/xfs/xfs_ag.h b/fs/xfs/xfs_ag.h
> index b1a5a1f..abb8222 100644
> --- a/fs/xfs/xfs_ag.h
> +++ b/fs/xfs/xfs_ag.h
> @@ -223,6 +223,7 @@ typedef struct xfs_perag {
> int pag_ici_init; /* incore inode cache initialised */
> rwlock_t pag_ici_lock; /* incore inode lock */
> struct radix_tree_root pag_ici_root; /* incore inode cache root */
> + int pag_ici_reclaimable; /* reclaimable inodes */
> #endif
> int pagb_count; /* pagb slots in use */
> xfs_perag_busy_t pagb_list[XFS_PAGB_NUM_SLOTS]; /* unstable blocks */
> diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
> index 4fa0bc7..9ff48a1 100644
> --- a/fs/xfs/xfs_mount.h
> +++ b/fs/xfs/xfs_mount.h
> @@ -259,6 +259,7 @@ typedef struct xfs_mount {
> wait_queue_head_t m_wait_single_sync_task;
> __int64_t m_update_flags; /* sb flags we need to update
> on the next remount,rw */
> + struct list_head m_mplist; /* inode shrinker mount list */
> } xfs_mount_t;
>
> /*
> --
> 1.5.6.5
>
> _______________________________________________
> xfs mailing list
> xfs@xxxxxxxxxxx
> http://oss.sgi.com/mailman/listinfo/xfs
---end quoted text---
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>