diff options
Diffstat (limited to 'fs/xfs/xfs_buf_item.c')
| -rw-r--r-- | fs/xfs/xfs_buf_item.c | 97 |
1 files changed, 42 insertions, 55 deletions
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c index fb69879e4b2b..2828ce45b701 100644 --- a/fs/xfs/xfs_buf_item.c +++ b/fs/xfs/xfs_buf_item.c @@ -74,14 +74,12 @@ xfs_buf_item_straddle( } /* - * This returns the number of log iovecs needed to log the - * given buf log item. + * Return the number of log iovecs and space needed to log the given buf log + * item segment. * - * It calculates this as 1 iovec for the buf log format structure - * and 1 for each stretch of non-contiguous chunks to be logged. - * Contiguous chunks are logged in a single iovec. - * - * If the XFS_BLI_STALE flag has been set, then log nothing. + * It calculates this as 1 iovec for the buf log format structure and 1 for each + * stretch of non-contiguous chunks to be logged. Contiguous chunks are logged + * in a single iovec. */ STATIC void xfs_buf_item_size_segment( @@ -168,11 +166,8 @@ slow_scan: } /* - * This returns the number of log iovecs needed to log the given buf log item. - * - * It calculates this as 1 iovec for the buf log format structure and 1 for each - * stretch of non-contiguous chunks to be logged. Contiguous chunks are logged - * in a single iovec. + * Return the number of log iovecs and space needed to log the given buf log + * item. * * Discontiguous buffers need a format structure per region that is being * logged. This makes the changes in the buffer appear to log recovery as though @@ -182,7 +177,11 @@ slow_scan: * what ends up on disk. * * If the XFS_BLI_STALE flag has been set, then log nothing but the buf log - * format structures. + * format structures. If the item has previously been logged and has dirty + * regions, we do not relog them in stale buffers. This has the effect of + * reducing the size of the relogged item by the amount of dirty data tracked + * by the log item. This can result in the committing transaction reducing the + * amount of space being consumed by the CIL. */ STATIC void xfs_buf_item_size( @@ -199,9 +198,9 @@ xfs_buf_item_size( ASSERT(atomic_read(&bip->bli_refcount) > 0); if (bip->bli_flags & XFS_BLI_STALE) { /* - * The buffer is stale, so all we need to log - * is the buf log format structure with the - * cancel flag in it. + * The buffer is stale, so all we need to log is the buf log + * format structure with the cancel flag in it as we are never + * going to replay the changes tracked in the log item. */ trace_xfs_buf_item_size_stale(bip); ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL); @@ -216,9 +215,9 @@ xfs_buf_item_size( 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. + * 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); *nvecs = XFS_LOG_VEC_ORDERED; @@ -475,17 +474,8 @@ xfs_buf_item_pin( } /* - * This is called to unpin the buffer associated with the buf log - * item which was previously pinned with a call to xfs_buf_item_pin(). - * - * Also drop the reference to the buf item for the current transaction. - * If the XFS_BLI_STALE flag is set and we are the last reference, - * then free up the buf log item and unlock the buffer. - * - * If the remove flag is set we are called from uncommit in the - * forced-shutdown path. If that is true and the reference count on - * the log item is going to drop to zero we need to free the item's - * descriptor in the transaction. + * This is called to unpin the buffer associated with the buf log item which + * was previously pinned with a call to xfs_buf_item_pin(). */ STATIC void xfs_buf_item_unpin( @@ -502,38 +492,35 @@ xfs_buf_item_unpin( trace_xfs_buf_item_unpin(bip); + /* + * Drop the bli ref associated with the pin and grab the hold required + * for the I/O simulation failure in the abort case. We have to do this + * before the pin count drops because the AIL doesn't acquire a bli + * reference. Therefore if the refcount drops to zero, the bli could + * still be AIL resident and the buffer submitted for I/O (and freed on + * completion) at any point before we return. This can be removed once + * the AIL properly holds a reference on the bli. + */ freed = atomic_dec_and_test(&bip->bli_refcount); - + if (freed && !stale && remove) + xfs_buf_hold(bp); if (atomic_dec_and_test(&bp->b_pin_count)) wake_up_all(&bp->b_waiters); - if (freed && stale) { + /* nothing to do but drop the pin count if the bli is active */ + if (!freed) + return; + + if (stale) { ASSERT(bip->bli_flags & XFS_BLI_STALE); ASSERT(xfs_buf_islocked(bp)); ASSERT(bp->b_flags & XBF_STALE); ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL); + ASSERT(list_empty(&lip->li_trans)); + ASSERT(!bp->b_transp); trace_xfs_buf_item_unpin_stale(bip); - if (remove) { - /* - * If we are in a transaction context, we have to - * remove the log item from the transaction as we are - * about to release our reference to the buffer. If we - * don't, the unlock that occurs later in - * xfs_trans_uncommit() will try to reference the - * buffer which we no longer have a hold on. - */ - if (!list_empty(&lip->li_trans)) - xfs_trans_del_item(lip); - - /* - * Since the transaction no longer refers to the buffer, - * the buffer should no longer refer to the transaction. - */ - bp->b_transp = NULL; - } - /* * If we get called here because of an IO error, we may or may * not have the item on the AIL. xfs_trans_ail_delete() will @@ -550,13 +537,13 @@ xfs_buf_item_unpin( ASSERT(bp->b_log_item == NULL); } xfs_buf_relse(bp); - } else if (freed && remove) { + } else if (remove) { /* * The buffer must be locked and held by the caller to simulate - * an async I/O failure. + * an async I/O failure. We acquired the hold for this case + * before the buffer was unpinned. */ xfs_buf_lock(bp); - xfs_buf_hold(bp); bp->b_flags |= XBF_ASYNC; xfs_buf_ioend_fail(bp); } @@ -714,7 +701,7 @@ xfs_buf_item_release( STATIC void xfs_buf_item_committing( struct xfs_log_item *lip, - xfs_lsn_t commit_lsn) + xfs_csn_t seq) { return xfs_buf_item_release(lip); } |