[PATCH v2 2/3] xfs: clean up xfs_bui_item_recover iget/trans_alloc/ilock ordering

From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: linux-xfs@vger.kernel.org, david@fromorbit.com
Subject: [PATCH v2 2/3] xfs: clean up xfs_bui_item_recover iget/trans_alloc/ilock ordering
Date: Thu, 17 Sep 2020 00:08:02 -0700	[thread overview]
Message-ID: <20200917070802.GW7955@magnolia> (raw)
In-Reply-To: <160031337657.3624582.4680281255744277782.stgit@magnolia>

From: Darrick J. Wong <darrick.wong@oracle.com>

In most places in XFS, we have a specific order in which we gather
resources: grab the inode, allocate a transaction, then lock the inode.
xfs_bui_item_recover doesn't do it in that order, so fix it to be more
consistent.  This also makes the error bailout code a bit less weird.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
v2: fix the error-out paths to free the BUI if the BUD hasn't been
created
---
 fs/xfs/xfs_bmap_item.c |   49 +++++++++++++++++++++++++-----------------------
 1 file changed, 26 insertions(+), 23 deletions(-)

diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c
index 4e5aa29f75b7..f088cfd495bd 100644
--- a/fs/xfs/xfs_bmap_item.c
+++ b/fs/xfs/xfs_bmap_item.c
@@ -432,7 +432,7 @@ xfs_bui_item_recover(
 	struct xfs_inode		*ip = NULL;
 	struct xfs_mount		*mp = lip->li_mountp;
 	struct xfs_map_extent		*bmap;
-	struct xfs_bud_log_item		*budp;
+	struct xfs_bud_log_item		*budp = NULL;
 	xfs_fsblock_t			startblock_fsb;
 	xfs_fsblock_t			inode_fsb;
 	xfs_filblks_t			count;
@@ -475,27 +475,26 @@ xfs_bui_item_recover(
 	    (bmap->me_flags & ~XFS_BMAP_EXTENT_FLAGS))
 		goto garbage;
 
-	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate,
-			XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK), 0, 0, &tp);
-	if (error) {
-		xfs_bui_release(buip);
-		return error;
-	}
-
-	budp = xfs_trans_get_bud(tp, buip);
-
 	/* Grab the inode. */
-	error = xfs_iget(mp, tp, bmap->me_owner, 0, XFS_ILOCK_EXCL, &ip);
+	error = xfs_iget(mp, NULL, bmap->me_owner, 0, 0, &ip);
 	if (error)
-		goto err_inode;
+		goto err_bui;
 
-	error = xfs_qm_dqattach_locked(ip, false);
+	error = xfs_qm_dqattach(ip);
 	if (error)
-		goto err_inode;
+		goto err_rele;
 
 	if (VFS_I(ip)->i_nlink == 0)
 		xfs_iflags_set(ip, XFS_IRECOVERY);
 
+	/* Allocate transaction and do the work. */
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate,
+			XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK), 0, 0, &tp);
+	if (error)
+		goto err_rele;
+
+	budp = xfs_trans_get_bud(tp, buip);
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
 	xfs_trans_ijoin(tp, ip, 0);
 
 	count = bmap->me_len;
@@ -503,7 +502,7 @@ xfs_bui_item_recover(
 			whichfork, bmap->me_startoff, bmap->me_startblock,
 			&count, state);
 	if (error)
-		goto err_inode;
+		goto err_cancel;
 
 	if (count > 0) {
 		ASSERT(bui_type == XFS_BMAP_UNMAP);
@@ -514,17 +513,21 @@ xfs_bui_item_recover(
 		xfs_bmap_unmap_extent(tp, ip, &irec);
 	}
 
+	/* Commit transaction, which frees tp. */
 	error = xlog_recover_trans_commit(tp, dfcp);
+	if (error)
+		goto err_unlock;
+	return 0;
+
+err_cancel:
+	xfs_trans_cancel(tp);
+err_unlock:
 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+err_rele:
 	xfs_irele(ip);
-	return error;
-
-err_inode:
-	xfs_trans_cancel(tp);
-	if (ip) {
-		xfs_iunlock(ip, XFS_ILOCK_EXCL);
-		xfs_irele(ip);
-	}
+err_bui:
+	if (!budp)
+		xfs_bui_release(buip);
 	return error;
 garbage:
 	xfs_bui_release(buip);
