Merge tag 'fix-fix-iunlink-6.6_2023-09-25' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.6-fixesB

xfs: fix reloading the last iunlink item

It's not a good idea to be trying to send bug fixes to the mailing list
while also trying to take a vacation.  Dave sent some review comments
about the iunlink reloading patches, I changed them in djwong-dev, and
forgot to backport those changes to my -fixes tree.

As a result, the patch is missing some important pieces.  Perhaps
manually copying code diffs between email and two separate git trees
is archaic and stupid^W^W^W^Wisn't really a good idea?

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'fix-fix-iunlink-6.6_2023-09-25' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: fix reloading entire unlinked bucket lists

Author: Chandan Babu R

fs/xfs/xfs_export.c

@@ -146,10 +146,18 @@ xfs_nfs_get_inode(
 		return ERR_PTR(error);
 	}
 
-	error = xfs_inode_reload_unlinked(ip);
-	if (error) {
-		xfs_irele(ip);
-		return ERR_PTR(error);
+	/*
+	 * Reload the incore unlinked list to avoid failure in inodegc.
+	 * Use an unlocked check here because unrecovered unlinked inodes
+	 * should be somewhat rare.
+	 */
+	if (xfs_inode_unlinked_incomplete(ip)) {
+		error = xfs_inode_reload_unlinked(ip);
+		if (error) {
+			xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+			xfs_irele(ip);
+			return ERR_PTR(error);
+		}
 	}
 
 	if (VFS_I(ip)->i_generation != generation) {

fs/xfs/xfs_inode.c

@@ -1743,6 +1743,14 @@ xfs_inactive(
 		truncate = 1;
 
 	if (xfs_iflags_test(ip, XFS_IQUOTAUNCHECKED)) {
+		/*
+		 * If this inode is being inactivated during a quotacheck and
+		 * has not yet been scanned by quotacheck, we /must/ remove
+		 * the dquots from the inode before inactivation changes the
+		 * block and inode counts.  Most probably this is a result of
+		 * reloading the incore iunlinked list to purge unrecovered
+		 * unlinked inodes.
+		 */
 		xfs_qm_dqdetach(ip);
 	} else {
 		error = xfs_qm_dqattach(ip);
@@ -3641,6 +3649,16 @@ xfs_inode_reload_unlinked_bucket(
 	if (error)
 		return error;
 
+	/*
+	 * We've taken ILOCK_SHARED and the AGI buffer lock to stabilize the
+	 * incore unlinked list pointers for this inode.  Check once more to
+	 * see if we raced with anyone else to reload the unlinked list.
+	 */
+	if (!xfs_inode_unlinked_incomplete(ip)) {
+		foundit = true;
+		goto out_agibp;
+	}
+
 	bucket = agino % XFS_AGI_UNLINKED_BUCKETS;
 	agi = agibp->b_addr;
 
@@ -3655,36 +3673,40 @@ xfs_inode_reload_unlinked_bucket(
 	while (next_agino != NULLAGINO) {
 		struct xfs_inode	*next_ip = NULL;
 
+		/* Found this caller's inode, set its backlink. */
 		if (next_agino == agino) {
-			/* Found this inode, set its backlink. */
 			next_ip = ip;
 			next_ip->i_prev_unlinked = prev_agino;
 			foundit = true;
+			goto next_inode;
 		}
-		if (!next_ip) {
-			/* Inode already in memory. */
-			next_ip = xfs_iunlink_lookup(pag, next_agino);
-		}
-		if (!next_ip) {
-			/* Inode not in memory, reload. */
-			error = xfs_iunlink_reload_next(tp, agibp, prev_agino,
-					next_agino);
-			if (error)
-				break;
 
-			next_ip = xfs_iunlink_lookup(pag, next_agino);
-		}
+		/* Try in-memory lookup first. */
+		next_ip = xfs_iunlink_lookup(pag, next_agino);
+		if (next_ip)
+			goto next_inode;
+
+		/* Inode not in memory, try reloading it. */
+		error = xfs_iunlink_reload_next(tp, agibp, prev_agino,
+				next_agino);
+		if (error)
+			break;
+
+		/* Grab the reloaded inode. */
+		next_ip = xfs_iunlink_lookup(pag, next_agino);
 		if (!next_ip) {
 			/* No incore inode at all?  We reloaded it... */
 			ASSERT(next_ip != NULL);
 			error = -EFSCORRUPTED;
 			break;
 		}
 
+next_inode:
 		prev_agino = next_agino;
 		next_agino = next_ip->i_next_unlinked;
 	}
 
+out_agibp:
 	xfs_trans_brelse(tp, agibp);
 	/* Should have found this inode somewhere in the iunlinked bucket. */
 	if (!error && !foundit)

fs/xfs/xfs_itable.c

@@ -80,10 +80,12 @@ xfs_bulkstat_one_int(
 	if (error)
 		goto out;
 
+	/* Reload the incore unlinked list to avoid failure in inodegc. */
 	if (xfs_inode_unlinked_incomplete(ip)) {
 		error = xfs_inode_reload_unlinked_bucket(tp, ip);
 		if (error) {
 			xfs_iunlock(ip, XFS_ILOCK_SHARED);
+			xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
 			xfs_irele(ip);
 			return error;
 		}

fs/xfs/xfs_qm.c

@@ -1160,9 +1160,18 @@ xfs_qm_dqusage_adjust(
 	if (error)
 		return error;
 
-	error = xfs_inode_reload_unlinked(ip);
-	if (error)
-		goto error0;
+	/*
+	 * Reload the incore unlinked list to avoid failure in inodegc.
+	 * Use an unlocked check here because unrecovered unlinked inodes
+	 * should be somewhat rare.
+	 */
+	if (xfs_inode_unlinked_incomplete(ip)) {
+		error = xfs_inode_reload_unlinked(ip);
+		if (error) {
+			xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+			goto error0;
+		}
+	}
 
 	ASSERT(ip->i_delayed_blks == 0);