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Patch "xfs: log recovery should replay deferred ops in order" has been added to the 4.14-stable tree

PATCH [email protected] 1 participant 1 message Feb 1, 2018

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This is a note to let you know that I've just added the patch titled

xfs: log recovery should replay deferred ops in order

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
xfs-log-recovery-should-replay-deferred-ops-in-order.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From foo@baz Thu Feb 1 13:45:42 CET 2018

From: "Darrick J. Wong" <[email protected]>
Date: Tue, 21 Nov 2017 20:53:02 -0800
Subject: xfs: log recovery should replay deferred ops in order

From: "Darrick J. Wong" <[email protected]>

[ Upstream commit 509955823cc9cc225c05673b1b83d70ca70c5c60 ]

As part of testing log recovery with dm_log_writes, Amir Goldstein discovered an error in the deferred ops recovery that lead to corruption of the filesystem metadata if a reflink+rmap filesystem happened to shut down midway through a CoW remap:

"This is what happens [after failed log recovery]:

"Phase 1 - find and verify superblock...
"Phase 2 - using internal log

"        - zero log...
"        - scan filesystem freespace and inode maps...
"        - found root inode chunk
"Phase 3 - for each AG...
"        - scan (but don't clear) agi unlinked lists...
"        - process known inodes and perform inode discovery...
"        - agno = 0

"data fork in regular inode 134 claims CoW block 376 "correcting nextents for inode 134
"bad data fork in inode 134
"would have cleared inode 134"

Hou Tao dissected the log contents of exactly such a crash:

"According to the implementation of xfs_defer_finish(), these ops should be completed in the following sequence:

"Have been done:
"(1) CUI: Oper (160)
"(2) BUI: Oper (161)
"(3) CUD: Oper (194), for CUI Oper (160)
"(4) RUI A: Oper (197), free rmap [0x155, 2, -9]

"Should be done:
"(5) BUD: for BUI Oper (161)
"(6) RUI B: add rmap [0x155, 2, 137]
"(7) RUD: for RUI A
"(8) RUD: for RUI B

"Actually be done by xlog_recover_process_intents() "(5) BUD: for BUI Oper (161)
"(6) RUI B: add rmap [0x155, 2, 137]
"(7) RUD: for RUI B
"(8) RUD: for RUI A

"So the rmap entry [0x155, 2, -9] for COW should be freed firstly, then a new rmap entry [0x155, 2, 137] will be added. However, as we can see from the log record in post_mount.log (generated after umount) and the trace print, the new rmap entry [0x155, 2, 137] are added firstly, then the rmap entry [0x155, 2, -9] are freed."

When reconstructing the internal log state from the log items found on disk, it's required that deferred ops replay in exactly the same order that they would have had the filesystem not gone down. However, replaying unfinished deferred ops can create /more/ deferred ops. These new deferred ops are finished in the wrong order. This causes fs corruption and replay crashes, so let's create a single defer_ops to handle the subsequent ops created during replay, then use one single transaction at the end of log recovery to ensure that everything is replayed in the same order as they're supposed to be.

---
 fs/xfs/xfs_bmap_item.c     |   23 ++++---------
 fs/xfs/xfs_bmap_item.h     |    3 +
 fs/xfs/xfs_log_recover.c   |   75 ++++++++++++++++++++++++++++++++++++++++-----
 fs/xfs/xfs_refcount_item.c |   21 ++++--------
 fs/xfs/xfs_refcount_item.h |    3 +
 5 files changed, 85 insertions(+), 40 deletions(-)
fs/xfs/xfs_bmap_item.c +7 -16
@@ -389,7 +389,8 @@ xfs_bud_init(
 int
 xfs_bui_recover(
 	struct xfs_mount		*mp,
-	struct xfs_bui_log_item		*buip)
+	struct xfs_bui_log_item		*buip,
+	struct xfs_defer_ops		*dfops)
 {
 	int				error = 0;
 	unsigned int			bui_type;
@@ -404,9 +405,7 @@ xfs_bui_recover(
 	xfs_exntst_t			state;
 	struct xfs_trans		*tp;
 	struct xfs_inode		*ip = NULL;
-	struct xfs_defer_ops		dfops;
 	struct xfs_bmbt_irec		irec;
-	xfs_fsblock_t			firstfsb;
 
 	ASSERT(!test_bit(XFS_BUI_RECOVERED, &buip->bui_flags));
 
@@ -464,7 +463,6 @@ xfs_bui_recover(
 
 	if (VFS_I(ip)->i_nlink == 0)
 		xfs_iflags_set(ip, XFS_IRECOVERY);
-	xfs_defer_init(&dfops, &firstfsb);
 
 	/* Process deferred bmap item. */
 	state = (bmap->me_flags & XFS_BMAP_EXTENT_UNWRITTEN) ?
@@ -479,16 +477,16 @@ xfs_bui_recover(
 		break;
 	default:
 		error = -EFSCORRUPTED;
-		goto err_dfops;
+		goto err_inode;
 	}
 	xfs_trans_ijoin(tp, ip, 0);
 
 	count = bmap->me_len;
-	error = xfs_trans_log_finish_bmap_update(tp, budp, &dfops, type,
+	error = xfs_trans_log_finish_bmap_update(tp, budp, dfops, type,
 			ip, whichfork, bmap->me_startoff,
 			bmap->me_startblock, &count, state);
 	if (error)
-		goto err_dfops;
+		goto err_inode;
 
 	if (count > 0) {
 		ASSERT(type == XFS_BMAP_UNMAP);
@@ -496,16 +494,11 @@ xfs_bui_recover(
 		irec.br_blockcount = count;
 		irec.br_startoff = bmap->me_startoff;
 		irec.br_state = state;
-		error = xfs_bmap_unmap_extent(tp->t_mountp, &dfops, ip, &irec);
+		error = xfs_bmap_unmap_extent(tp->t_mountp, dfops, ip, &irec);
 		if (error)
-			goto err_dfops;
+			goto err_inode;
 	}
 
-	/* Finish transaction, free inodes. */
-	error = xfs_defer_finish(&tp, &dfops);
-	if (error)
-		goto err_dfops;
-
 	set_bit(XFS_BUI_RECOVERED, &buip->bui_flags);
 	error = xfs_trans_commit(tp);
 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
@@ -513,8 +506,6 @@ xfs_bui_recover(
 
 	return error;
 
-err_dfops:
-	xfs_defer_cancel(&dfops);
 err_inode:
 	xfs_trans_cancel(tp);
 	if (ip) {
fs/xfs/xfs_bmap_item.h +2 -1
@@ -93,6 +93,7 @@ struct xfs_bud_log_item *xfs_bud_init(st
 		struct xfs_bui_log_item *);
 void xfs_bui_item_free(struct xfs_bui_log_item *);
 void xfs_bui_release(struct xfs_bui_log_item *);
-int xfs_bui_recover(struct xfs_mount *mp, struct xfs_bui_log_item *buip);
+int xfs_bui_recover(struct xfs_mount *mp, struct xfs_bui_log_item *buip,
+		struct xfs_defer_ops *dfops);
 
 #endif	/* __XFS_BMAP_ITEM_H__ */
fs/xfs/xfs_log_recover.c +67 -8

145 lines not on this page · raw message

fs/xfs/xfs_refcount_item.c +7 -14
@@ -393,7 +393,8 @@ xfs_cud_init(
 int
 xfs_cui_recover(
 	struct xfs_mount		*mp,
-	struct xfs_cui_log_item		*cuip)
+	struct xfs_cui_log_item		*cuip,
+	struct xfs_defer_ops		*dfops)
 {
 	int				i;
 	int				error = 0;
@@ -405,11 +406,9 @@ xfs_cui_recover(
 	struct xfs_trans		*tp;
 	struct xfs_btree_cur		*rcur = NULL;
 	enum xfs_refcount_intent_type	type;
-	xfs_fsblock_t			firstfsb;
 	xfs_fsblock_t			new_fsb;
 	xfs_extlen_t			new_len;
 	struct xfs_bmbt_irec		irec;
-	struct xfs_defer_ops		dfops;
 	bool				requeue_only = false;
 
 	ASSERT(!test_bit(XFS_CUI_RECOVERED, &cuip->cui_flags));
@@ -465,7 +464,6 @@ xfs_cui_recover(
 		return error;
 	cudp = xfs_trans_get_cud(tp, cuip);
 
-	xfs_defer_init(&dfops, &firstfsb);
 	for (i = 0; i < cuip->cui_format.cui_nextents; i++) {
 		refc = &cuip->cui_format.cui_extents[i];
 		refc_type = refc->pe_flags & XFS_REFCOUNT_EXTENT_TYPE_MASK;
@@ -485,7 +483,7 @@ xfs_cui_recover(
 			new_len = refc->pe_len;
 		} else
 			error = xfs_trans_log_finish_refcount_update(tp, cudp,
-				&dfops, type, refc->pe_startblock, refc->pe_len,
+				dfops, type, refc->pe_startblock, refc->pe_len,
 				&new_fsb, &new_len, &rcur);
 		if (error)
 			goto abort_error;
@@ -497,21 +495,21 @@ xfs_cui_recover(
 			switch (type) {
 			case XFS_REFCOUNT_INCREASE:
 				error = xfs_refcount_increase_extent(
-						tp->t_mountp, &dfops, &irec);
+						tp->t_mountp, dfops, &irec);
 				break;
 			case XFS_REFCOUNT_DECREASE:
 				error = xfs_refcount_decrease_extent(
-						tp->t_mountp, &dfops, &irec);
+						tp->t_mountp, dfops, &irec);
 				break;
 			case XFS_REFCOUNT_ALLOC_COW:
 				error = xfs_refcount_alloc_cow_extent(
-						tp->t_mountp, &dfops,
+						tp->t_mountp, dfops,
 						irec.br_startblock,
 						irec.br_blockcount);
 				break;
 			case XFS_REFCOUNT_FREE_COW:
 				error = xfs_refcount_free_cow_extent(
-						tp->t_mountp, &dfops,
+						tp->t_mountp, dfops,
 						irec.br_startblock,
 						irec.br_blockcount);
 				break;
@@ -525,17 +523,12 @@ xfs_cui_recover(
 	}
 
 	xfs_refcount_finish_one_cleanup(tp, rcur, error);
-	error = xfs_defer_finish(&tp, &dfops);
-	if (error)
-		goto abort_defer;
 	set_bit(XFS_CUI_RECOVERED, &cuip->cui_flags);
 	error = xfs_trans_commit(tp);
 	return error;
 
 abort_error:
 	xfs_refcount_finish_one_cleanup(tp, rcur, error);
-abort_defer:
-	xfs_defer_cancel(&dfops);
 	xfs_trans_cancel(tp);
 	return error;
 }
fs/xfs/xfs_refcount_item.h +2 -1
@@ -96,6 +96,7 @@ struct xfs_cud_log_item *xfs_cud_init(st
 		struct xfs_cui_log_item *);
 void xfs_cui_item_free(struct xfs_cui_log_item *);
 void xfs_cui_release(struct xfs_cui_log_item *);
-int xfs_cui_recover(struct xfs_mount *mp, struct xfs_cui_log_item *cuip);
+int xfs_cui_recover(struct xfs_mount *mp, struct xfs_cui_log_item *cuip,
+		struct xfs_defer_ops *dfops);
 
 #endif	/* __XFS_REFCOUNT_ITEM_H__ */

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/xfs-always-free-inline-data-before-resetting-inode-fork-during-ifree.patch queue-4.14/xfs-log-recovery-should-replay-deferred-ops-in-order.patch queue-4.14/xfs-ubsan-fixes.patch queue-4.14/xfs-fortify-xfs_alloc_buftarg-error-handling.patch queue-4.14/xfs-properly-retry-failed-dquot-items-in-case-of-error-during-buffer-writeback.patch