[020/197] xfs: reclaim all inodes by background tree walks
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From: Greg KH on 22 Apr 2010 16:50 2.6.32-stable review patch. If anyone has any objections, please let us know. ------------------ From: Dave Chinner <david(a)fromorbit.com> commit 57817c68229984818fea9e614d6f95249c3fb098 upstream We cannot do direct inode reclaim without taking the flush lock to ensure that we do not reclaim an inode under IO. We check the inode is clean before doing direct reclaim, but this is not good enough because the inode flush code marks the inode clean once it has copied the in-core dirty state to the backing buffer. It is the flush lock that determines whether the inode is still under IO, even though it is marked clean, and the inode is still required at IO completion so we can't reclaim it even though it is clean in core. Hence the requirement that we need to take the flush lock even on clean inodes because this guarantees that the inode writeback IO has completed and it is safe to reclaim the inode. With delayed write inode flushing, we could end up waiting a long time on the flush lock even for a clean inode. The background reclaim already handles this efficiently, so avoid all the problems by killing the direct reclaim path altogether. Signed-off-by: Dave Chinner <david(a)fromorbit.com> Reviewed-by: Christoph Hellwig <hch(a)lst.de> Signed-off-by: Alex Elder <aelder(a)sgi.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de> --- fs/xfs/linux-2.6/xfs_super.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) --- a/fs/xfs/linux-2.6/xfs_super.c +++ b/fs/xfs/linux-2.6/xfs_super.c @@ -953,16 +953,14 @@ xfs_fs_destroy_inode( ASSERT_ALWAYS(!xfs_iflags_test(ip, XFS_IRECLAIM)); /* - * If we have nothing to flush with this inode then complete the - * teardown now, otherwise delay the flush operation. + * We always use background reclaim here because even if the + * inode is clean, it still may be under IO and hence we have + * to take the flush lock. The background reclaim path handles + * this more efficiently than we can here, so simply let background + * reclaim tear down all inodes. */ - if (!xfs_inode_clean(ip)) { - xfs_inode_set_reclaim_tag(ip); - return; - } - out_reclaim: - xfs_ireclaim(ip); + xfs_inode_set_reclaim_tag(ip); } /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |