[RFC PATCH v2 1/3] xfs: arrange all unlinked inodes into one list

[Gao Xiang <hsiangkao@redhat.com>]

There is no need to keep old multiple short unlink inode buckets
since we have an in-memory double linked list for all unlinked
inodes.

Apart from the perspective of the necessity, the main advantage
is the log and AGI update can be reduced since each AG has the
only one head now, which is implemented in the following patches.

Therefore, this patch applies the new way in xfs_iunlink() and
keep the old approach in xfs_iunlink_remove_inode() path as
well so inode eviction can still work properly in recovery.

Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
---
 fs/xfs/xfs_inode.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index ab288424764c..4994398373df 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -33,6 +33,7 @@
 #include "xfs_symlink.h"
 #include "xfs_trans_priv.h"
 #include "xfs_log.h"
+#include "xfs_log_priv.h"
 #include "xfs_bmap_btree.h"
 #include "xfs_reflink.h"
 #include "xfs_iunlink_item.h"
@@ -2001,14 +2002,13 @@ xfs_iunlink_insert_inode(
 	xfs_agino_t		agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
 	xfs_agino_t		agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
 	xfs_agino_t		next_agino;
-	short			bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
 
 	/*
 	 * Get the index into the agi hash table for the list this inode will
 	 * go on.  Make sure the pointer isn't garbage and that this inode
 	 * isn't already on the list.
 	 */
-	next_agino = be32_to_cpu(agi->agi_unlinked[bucket_index]);
+	next_agino = be32_to_cpu(agi->agi_unlinked[0]);
 	if (next_agino == agino ||
 	    !xfs_verify_agino_or_null(mp, agno, next_agino)) {
 		xfs_buf_mark_corrupt(agibp);
@@ -2036,7 +2036,7 @@ xfs_iunlink_insert_inode(
 	}
 
 	/* Point the head of the list to point to this inode. */
-	return xfs_iunlink_update_bucket(tp, agno, agibp, bucket_index, agino);
+	return xfs_iunlink_update_bucket(tp, agno, agibp, 0, agino);
 }
 
 /*
@@ -2055,10 +2055,17 @@ xfs_iunlink_remove_inode(
 	xfs_agino_t		agno = XFS_INO_TO_AGNO(mp, ip->i_ino);
 	xfs_agino_t		agino = XFS_INO_TO_AGINO(mp, ip->i_ino);
 	xfs_agino_t		next_agino = ip->i_next_unlinked;
-	short			bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
 	int			error;
 
 	if (ip->i_prev_unlinked == NULLAGINO) {
+		struct xlog	*log = mp->m_log;
+		short		bucket_index = 0;
+
+		/* During recovery, the old multiple bucket can be applied */
+		if ((!log || log->l_flags & XLOG_RECOVERY_NEEDED) &&
+		    be32_to_cpu(agi->agi_unlinked[0]) != agino)
+			bucket_index = agino % XFS_AGI_UNLINKED_BUCKETS;
+
 		/* remove from head of list */
 		if (be32_to_cpu(agi->agi_unlinked[bucket_index]) != agino) {
 			xfs_buf_mark_corrupt(agibp);
-- 
2.18.1