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authorDave Chinner <david@fromorbit.com>2013-06-27 16:04:52 +1000
committerBen Myers <bpm@sgi.com>2013-06-27 13:33:11 -0500
commit5f6bed76c0c85cb4d04885a5de00b629deee550b (patch)
treed2a39b931b367da3a797472c95d886d9e3b6c989 /fs/xfs/xfs_trans_buf.c
parentfd63875cc4cd60b9e5c609c24d75eaaad3e6d1c4 (diff)
xfs: Introduce an ordered buffer item
If we have a buffer that we have modified but we do not wish to physically log in a transaction (e.g. we've logged a logical change), we still need to ensure that transactional integrity is maintained. Hence we must not move the tail of the log past the transaction that the buffer is associated with before the buffer is written to disk. This means these special buffers still need to be included in the transaction and added to the AIL just like a normal buffer, but we do not want the modifications to the buffer written into the transaction. IOWs, what we want is an "ordered buffer" that maintains the same transactional life cycle as a physically logged buffer, just without the transcribing of the modifications to the log. Hence we need to flag the buffer as an "ordered buffer" to avoid including it in vector size calculations or formatting during the transaction. Once the transaction is committed, the buffer appears for all intents to be the same as a physically logged buffer as it transitions through the log and AIL. Relogging will also work just fine for such an ordered buffer - the logical transaction will be replayed before the subsequent modifications that relog the buffer, so everything will be reconstructed correctly by recovery. Signed-off-by: Dave Chinner <david@fromorbit.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_trans_buf.c')
-rw-r--r--fs/xfs/xfs_trans_buf.c34
1 files changed, 31 insertions, 3 deletions
diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
index 73a5fa457e16..aa5a04b844d6 100644
--- a/fs/xfs/xfs_trans_buf.c
+++ b/fs/xfs/xfs_trans_buf.c
@@ -397,7 +397,6 @@ shutdown_abort:
return XFS_ERROR(EIO);
}
-
/*
* Release the buffer bp which was previously acquired with one of the
* xfs_trans_... buffer allocation routines if the buffer has not
@@ -603,8 +602,14 @@ xfs_trans_log_buf(xfs_trans_t *tp,
tp->t_flags |= XFS_TRANS_DIRTY;
bip->bli_item.li_desc->lid_flags |= XFS_LID_DIRTY;
- bip->bli_flags |= XFS_BLI_LOGGED;
- xfs_buf_item_log(bip, first, last);
+
+ /*
+ * If we have an ordered buffer we are not logging any dirty range but
+ * it still needs to be marked dirty and that it has been logged.
+ */
+ bip->bli_flags |= XFS_BLI_DIRTY | XFS_BLI_LOGGED;
+ if (!(bip->bli_flags & XFS_BLI_ORDERED))
+ xfs_buf_item_log(bip, first, last);
}
@@ -757,6 +762,29 @@ xfs_trans_inode_alloc_buf(
}
/*
+ * Mark the buffer as ordered for this transaction. This means
+ * that the contents of the buffer are not recorded in the transaction
+ * but it is tracked in the AIL as though it was. This allows us
+ * to record logical changes in transactions rather than the physical
+ * changes we make to the buffer without changing writeback ordering
+ * constraints of metadata buffers.
+ */
+void
+xfs_trans_ordered_buf(
+ struct xfs_trans *tp,
+ struct xfs_buf *bp)
+{
+ struct xfs_buf_log_item *bip = bp->b_fspriv;
+
+ ASSERT(bp->b_transp == tp);
+ ASSERT(bip != NULL);
+ ASSERT(atomic_read(&bip->bli_refcount) > 0);
+
+ bip->bli_flags |= XFS_BLI_ORDERED;
+ trace_xfs_buf_item_ordered(bip);
+}
+
+/*
* Set the type of the buffer for log recovery so that it can correctly identify
* and hence attach the correct buffer ops to the buffer after replay.
*/