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-rw-r--r--fs/xfs/xfs_log_recover.c65
1 files changed, 58 insertions, 7 deletions
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index d6204d1..83088d9 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -1599,10 +1599,43 @@ xlog_recover_add_to_trans(
}
/*
- * Sort the log items in the transaction. Cancelled buffers need
- * to be put first so they are processed before any items that might
- * modify the buffers. If they are cancelled, then the modifications
- * don't need to be replayed.
+ * Sort the log items in the transaction.
+ *
+ * The ordering constraints are defined by the inode allocation and unlink
+ * behaviour. The rules are:
+ *
+ * 1. Every item is only logged once in a given transaction. Hence it
+ * represents the last logged state of the item. Hence ordering is
+ * dependent on the order in which operations need to be performed so
+ * required initial conditions are always met.
+ *
+ * 2. Cancelled buffers are recorded in pass 1 in a separate table and
+ * there's nothing to replay from them so we can simply cull them
+ * from the transaction. However, we can't do that until after we've
+ * replayed all the other items because they may be dependent on the
+ * cancelled buffer and replaying the cancelled buffer can remove it
+ * form the cancelled buffer table. Hence they have tobe done last.
+ *
+ * 3. Inode allocation buffers must be replayed before inode items that
+ * read the buffer and replay changes into it.
+ *
+ * 4. Inode unlink buffers must be replayed after inode items are replayed.
+ * This ensures that inodes are completely flushed to the inode buffer
+ * in a "free" state before we remove the unlinked inode list pointer.
+ *
+ * Hence the ordering needs to be inode allocation buffers first, inode items
+ * second, inode unlink buffers third and cancelled buffers last.
+ *
+ * But there's a problem with that - we can't tell an inode allocation buffer
+ * apart from a regular buffer, so we can't separate them. We can, however,
+ * tell an inode unlink buffer from the others, and so we can separate them out
+ * from all the other buffers and move them to last.
+ *
+ * Hence, 4 lists, in order from head to tail:
+ * - buffer_list for all buffers except cancelled/inode unlink buffers
+ * - item_list for all non-buffer items
+ * - inode_buffer_list for inode unlink buffers
+ * - cancel_list for the cancelled buffers
*/
STATIC int
xlog_recover_reorder_trans(
@@ -1612,6 +1645,10 @@ xlog_recover_reorder_trans(
{
xlog_recover_item_t *item, *n;
LIST_HEAD(sort_list);
+ LIST_HEAD(cancel_list);
+ LIST_HEAD(buffer_list);
+ LIST_HEAD(inode_buffer_list);
+ LIST_HEAD(inode_list);
list_splice_init(&trans->r_itemq, &sort_list);
list_for_each_entry_safe(item, n, &sort_list, ri_list) {
@@ -1619,12 +1656,18 @@ xlog_recover_reorder_trans(
switch (ITEM_TYPE(item)) {
case XFS_LI_BUF:
- if (!(buf_f->blf_flags & XFS_BLF_CANCEL)) {
+ if (buf_f->blf_flags & XFS_BLF_CANCEL) {
trace_xfs_log_recover_item_reorder_head(log,
trans, item, pass);
- list_move(&item->ri_list, &trans->r_itemq);
+ list_move(&item->ri_list, &cancel_list);
break;
}
+ if (buf_f->blf_flags & XFS_BLF_INODE_BUF) {
+ list_move(&item->ri_list, &inode_buffer_list);
+ break;
+ }
+ list_move_tail(&item->ri_list, &buffer_list);
+ break;
case XFS_LI_INODE:
case XFS_LI_DQUOT:
case XFS_LI_QUOTAOFF:
@@ -1632,7 +1675,7 @@ xlog_recover_reorder_trans(
case XFS_LI_EFI:
trace_xfs_log_recover_item_reorder_tail(log,
trans, item, pass);
- list_move_tail(&item->ri_list, &trans->r_itemq);
+ list_move_tail(&item->ri_list, &inode_list);
break;
default:
xfs_warn(log->l_mp,
@@ -1643,6 +1686,14 @@ xlog_recover_reorder_trans(
}
}
ASSERT(list_empty(&sort_list));
+ if (!list_empty(&buffer_list))
+ list_splice(&buffer_list, &trans->r_itemq);
+ if (!list_empty(&inode_list))
+ list_splice_tail(&inode_list, &trans->r_itemq);
+ if (!list_empty(&inode_buffer_list))
+ list_splice_tail(&inode_buffer_list, &trans->r_itemq);
+ if (!list_empty(&cancel_list))
+ list_splice_tail(&cancel_list, &trans->r_itemq);
return 0;
}
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