From 5f6bed76c0c85cb4d04885a5de00b629deee550b Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Thu, 27 Jun 2013 16:04:52 +1000 Subject: 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 Reviewed-by: Mark Tinguely Signed-off-by: Ben Myers --- fs/xfs/xfs_buf_item.c | 75 ++++++++++++++++++++++++++++++++------------------- 1 file changed, 48 insertions(+), 27 deletions(-) (limited to 'fs/xfs/xfs_buf_item.c') diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c index 4ec43177704..61f68768ee8 100644 --- a/fs/xfs/xfs_buf_item.c +++ b/fs/xfs/xfs_buf_item.c @@ -140,6 +140,16 @@ xfs_buf_item_size( ASSERT(bip->bli_flags & XFS_BLI_LOGGED); + if (bip->bli_flags & XFS_BLI_ORDERED) { + /* + * The buffer has been logged just to order it. + * It is not being included in the transaction + * commit, so no vectors are used at all. + */ + trace_xfs_buf_item_size_ordered(bip); + return XFS_LOG_VEC_ORDERED; + } + /* * the vector count is based on the number of buffer vectors we have * dirty bits in. This will only be greater than one when we have a @@ -212,6 +222,7 @@ xfs_buf_item_format_segment( goto out; } + /* * Fill in an iovec for each set of contiguous chunks. */ @@ -311,6 +322,16 @@ xfs_buf_item_format( bip->bli_flags &= ~XFS_BLI_INODE_BUF; } + if ((bip->bli_flags & (XFS_BLI_ORDERED|XFS_BLI_STALE)) == + XFS_BLI_ORDERED) { + /* + * The buffer has been logged just to order it. It is not being + * included in the transaction commit, so don't format it. + */ + trace_xfs_buf_item_format_ordered(bip); + return; + } + for (i = 0; i < bip->bli_format_count; i++) { vecp = xfs_buf_item_format_segment(bip, vecp, offset, &bip->bli_formats[i]); @@ -340,6 +361,7 @@ xfs_buf_item_pin( ASSERT(atomic_read(&bip->bli_refcount) > 0); ASSERT((bip->bli_flags & XFS_BLI_LOGGED) || + (bip->bli_flags & XFS_BLI_ORDERED) || (bip->bli_flags & XFS_BLI_STALE)); trace_xfs_buf_item_pin(bip); @@ -512,8 +534,9 @@ xfs_buf_item_unlock( { struct xfs_buf_log_item *bip = BUF_ITEM(lip); struct xfs_buf *bp = bip->bli_buf; - int aborted, clean, i; - uint hold; + bool clean; + bool aborted; + int flags; /* Clear the buffer's association with this transaction. */ bp->b_transp = NULL; @@ -524,23 +547,21 @@ xfs_buf_item_unlock( * (cancelled) buffers at unpin time, but we'll never go through the * pin/unpin cycle if we abort inside commit. */ - aborted = (lip->li_flags & XFS_LI_ABORTED) != 0; - + aborted = (lip->li_flags & XFS_LI_ABORTED) ? true : false; /* - * Before possibly freeing the buf item, determine if we should - * release the buffer at the end of this routine. + * Before possibly freeing the buf item, copy the per-transaction state + * so we can reference it safely later after clearing it from the + * buffer log item. */ - hold = bip->bli_flags & XFS_BLI_HOLD; - - /* Clear the per transaction state. */ - bip->bli_flags &= ~(XFS_BLI_LOGGED | XFS_BLI_HOLD); + flags = bip->bli_flags; + bip->bli_flags &= ~(XFS_BLI_LOGGED | XFS_BLI_HOLD | XFS_BLI_ORDERED); /* * If the buf item is marked stale, then don't do anything. We'll * unlock the buffer and free the buf item when the buffer is unpinned * for the last time. */ - if (bip->bli_flags & XFS_BLI_STALE) { + if (flags & XFS_BLI_STALE) { trace_xfs_buf_item_unlock_stale(bip); ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL); if (!aborted) { @@ -557,13 +578,19 @@ xfs_buf_item_unlock( * be the only reference to the buf item, so we free it anyway * regardless of whether it is dirty or not. A dirty abort implies a * shutdown, anyway. + * + * Ordered buffers are dirty but may have no recorded changes, so ensure + * we only release clean items here. */ - clean = 1; - for (i = 0; i < bip->bli_format_count; i++) { - if (!xfs_bitmap_empty(bip->bli_formats[i].blf_data_map, - bip->bli_formats[i].blf_map_size)) { - clean = 0; - break; + clean = (flags & XFS_BLI_DIRTY) ? false : true; + if (clean) { + int i; + for (i = 0; i < bip->bli_format_count; i++) { + if (!xfs_bitmap_empty(bip->bli_formats[i].blf_data_map, + bip->bli_formats[i].blf_map_size)) { + clean = false; + break; + } } } if (clean) @@ -576,7 +603,7 @@ xfs_buf_item_unlock( } else atomic_dec(&bip->bli_refcount); - if (!hold) + if (!(flags & XFS_BLI_HOLD)) xfs_buf_relse(bp); } @@ -841,12 +868,6 @@ xfs_buf_item_log( uint end; struct xfs_buf *bp = bip->bli_buf; - /* - * Mark the item as having some dirty data for - * quick reference in xfs_buf_item_dirty. - */ - bip->bli_flags |= XFS_BLI_DIRTY; - /* * walk each buffer segment and mark them dirty appropriately. */ @@ -873,7 +894,7 @@ xfs_buf_item_log( /* - * Return 1 if the buffer has some data that has been logged (at any + * Return 1 if the buffer has been logged or ordered in a transaction (at any * point, not just the current transaction) and 0 if not. */ uint @@ -907,11 +928,11 @@ void xfs_buf_item_relse( xfs_buf_t *bp) { - xfs_buf_log_item_t *bip; + xfs_buf_log_item_t *bip = bp->b_fspriv; trace_xfs_buf_item_relse(bp, _RET_IP_); + ASSERT(!(bip->bli_item.li_flags & XFS_LI_IN_AIL)); - bip = bp->b_fspriv; bp->b_fspriv = bip->bli_item.li_bio_list; if (bp->b_fspriv == NULL) bp->b_iodone = NULL; -- cgit v1.2.3-18-g5258