From 2fd26cc07e9f8050e29bf314cbf1bcb64dbe088c Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Thu, 14 Jul 2022 11:46:43 +1000 Subject: xfs: double link the unlinked inode list Now we have forwards traversal via the incore inode in place, we now need to add back pointers to the incore inode to entirely replace the back reference cache. We use the same lookup semantics and constraints as for the forwards pointer lookups during unlinks, and so we can look up any inode in the unlinked list directly and update the list pointers, forwards or backwards, at any time. The only wrinkle in converting the unlinked list manipulations to use in-core previous pointers is that log recovery doesn't have the incore inode state built up so it can't just read in an inode and release it to finish off the unlink. Hence we need to modify the traversal in recovery to read one inode ahead before we release the inode at the head of the list. This populates the next->prev relationship sufficient to be able to replay the unlinked list and hence greatly simplify the runtime code. This recovery algorithm also requires that we actually remove inodes from the unlinked list one at a time as background inode inactivation will result in unlinked list removal racing with the building of the in-memory unlinked list state. We could serialise this by holding the AGI buffer lock when constructing the in memory state, but all that does is lockstep background processing with list building. It is much simpler to flush the inodegc immediately after releasing the inode so that it is unlinked immediately and there is no races present at all. Signed-off-by: Dave Chinner Reviewed-by: Darrick J. Wong Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_icache.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/xfs/xfs_icache.c') diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c index 2609825d53ee..7f4cc341aacc 100644 --- a/fs/xfs/xfs_icache.c +++ b/fs/xfs/xfs_icache.c @@ -111,6 +111,8 @@ xfs_inode_alloc( INIT_WORK(&ip->i_ioend_work, xfs_end_io); INIT_LIST_HEAD(&ip->i_ioend_list); spin_lock_init(&ip->i_ioend_lock); + ip->i_next_unlinked = NULLAGINO; + ip->i_prev_unlinked = NULLAGINO; return ip; } -- cgit v1.2.3