From: "Darrick J. Wong" darrick.wong@oracle.com
commit 93293bcbde93567efaf4e6bcd58cad270e1fcbf5 upstream.
[Slightly edit fs/xfs/xfs_bmap_item.c & fs/xfs/xfs_refcount_item.c to resolve merge conflicts]
During a code inspection, I found a serious bug in the log intent item recovery code when an intent item cannot complete all the work and decides to requeue itself to get that done. When this happens, the item recovery creates a new incore deferred op representing the remaining work and attaches it to the transaction that it allocated. At the end of _item_recover, it moves the entire chain of deferred ops to the dummy parent_tp that xlog_recover_process_intents passed to it, but fail to log a new intent item for the remaining work before committing the transaction for the single unit of work.
xlog_finish_defer_ops logs those new intent items once recovery has finished dealing with the intent items that it recovered, but this isn't sufficient. If the log is forced to disk after a recovered log item decides to requeue itself and the system goes down before we call xlog_finish_defer_ops, the second log recovery will never see the new intent item and therefore has no idea that there was more work to do. It will finish recovery leaving the filesystem in a corrupted state.
The same logic applies to /any/ deferred ops added during intent item recovery, not just the one handling the remaining work.
Signed-off-by: Darrick J. Wong darrick.wong@oracle.com Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Dave Chinner dchinner@redhat.com Signed-off-by: Chandan Babu R chandan.babu@oracle.com Acked-by: Darrick J. Wong djwong@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/xfs/libxfs/xfs_defer.c | 26 ++++++++++++++++++++++++-- fs/xfs/libxfs/xfs_defer.h | 6 ++++++ fs/xfs/xfs_bmap_item.c | 2 +- fs/xfs/xfs_refcount_item.c | 2 +- 4 files changed, 32 insertions(+), 4 deletions(-)
--- a/fs/xfs/libxfs/xfs_defer.c +++ b/fs/xfs/libxfs/xfs_defer.c @@ -186,8 +186,9 @@ xfs_defer_create_intent( { const struct xfs_defer_op_type *ops = defer_op_types[dfp->dfp_type];
- dfp->dfp_intent = ops->create_intent(tp, &dfp->dfp_work, - dfp->dfp_count, sort); + if (!dfp->dfp_intent) + dfp->dfp_intent = ops->create_intent(tp, &dfp->dfp_work, + dfp->dfp_count, sort); }
/* @@ -390,6 +391,7 @@ xfs_defer_finish_one( list_add(li, &dfp->dfp_work); dfp->dfp_count++; dfp->dfp_done = NULL; + dfp->dfp_intent = NULL; xfs_defer_create_intent(tp, dfp, false); }
@@ -552,3 +554,23 @@ xfs_defer_move(
xfs_defer_reset(stp); } + +/* + * Prepare a chain of fresh deferred ops work items to be completed later. Log + * recovery requires the ability to put off until later the actual finishing + * work so that it can process unfinished items recovered from the log in + * correct order. + * + * Create and log intent items for all the work that we're capturing so that we + * can be assured that the items will get replayed if the system goes down + * before log recovery gets a chance to finish the work it put off. Then we + * move the chain from stp to dtp. + */ +void +xfs_defer_capture( + struct xfs_trans *dtp, + struct xfs_trans *stp) +{ + xfs_defer_create_intents(stp); + xfs_defer_move(dtp, stp); +} --- a/fs/xfs/libxfs/xfs_defer.h +++ b/fs/xfs/libxfs/xfs_defer.h @@ -61,4 +61,10 @@ extern const struct xfs_defer_op_type xf extern const struct xfs_defer_op_type xfs_extent_free_defer_type; extern const struct xfs_defer_op_type xfs_agfl_free_defer_type;
+/* + * Functions to capture a chain of deferred operations and continue them later. + * This doesn't normally happen except log recovery. + */ +void xfs_defer_capture(struct xfs_trans *dtp, struct xfs_trans *stp); + #endif /* __XFS_DEFER_H__ */ --- a/fs/xfs/xfs_bmap_item.c +++ b/fs/xfs/xfs_bmap_item.c @@ -541,7 +541,7 @@ xfs_bui_recover( }
set_bit(XFS_BUI_RECOVERED, &buip->bui_flags); - xfs_defer_move(parent_tp, tp); + xfs_defer_capture(parent_tp, tp); error = xfs_trans_commit(tp); xfs_iunlock(ip, XFS_ILOCK_EXCL); xfs_irele(ip); --- a/fs/xfs/xfs_refcount_item.c +++ b/fs/xfs/xfs_refcount_item.c @@ -574,7 +574,7 @@ xfs_cui_recover(
xfs_refcount_finish_one_cleanup(tp, rcur, error); set_bit(XFS_CUI_RECOVERED, &cuip->cui_flags); - xfs_defer_move(parent_tp, tp); + xfs_defer_capture(parent_tp, tp); error = xfs_trans_commit(tp); return error;