Merge tag 'xfs-6.3-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull xfs fixes from Darrick Wong:

 - Fix a crash if mount time quotacheck fails when there are inodes
   queued for garbage collection.

 - Fix an off by one error when discarding folios after writeback
   failure.

* tag 'xfs-6.3-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: fix off-by-one-block in xfs_discard_folio()
  xfs: quotacheck failure can race with background inode inactivation

Author: torvalds

fs/xfs/xfs_aops.c

@@ -449,15 +449,17 @@ xfs_prepare_ioend(
 }
 
 /*
- * If the page has delalloc blocks on it, we need to punch them out before we
- * invalidate the page.  If we don't, we leave a stale delalloc mapping on the
- * inode that can trip up a later direct I/O read operation on the same region.
+ * If the folio has delalloc blocks on it, the caller is asking us to punch them
+ * out. If we don't, we can leave a stale delalloc mapping covered by a clean
+ * page that needs to be dirtied again before the delalloc mapping can be
+ * converted. This stale delalloc mapping can trip up a later direct I/O read
+ * operation on the same region.
  *
- * We prevent this by truncating away the delalloc regions on the page.  Because
+ * We prevent this by truncating away the delalloc regions on the folio. Because
  * they are delalloc, we can do this without needing a transaction. Indeed - if
  * we get ENOSPC errors, we have to be able to do this truncation without a
- * transaction as there is no space left for block reservation (typically why we
- * see a ENOSPC in writeback).
+ * transaction as there is no space left for block reservation (typically why
+ * we see a ENOSPC in writeback).
  */
 static void
 xfs_discard_folio(
@@ -475,8 +477,13 @@ xfs_discard_folio(
 		"page discard on page "PTR_FMT", inode 0x%llx, pos %llu.",
 			folio, ip->i_ino, pos);
 
+	/*
+	 * The end of the punch range is always the offset of the the first
+	 * byte of the next folio. Hence the end offset is only dependent on the
+	 * folio itself and not the start offset that is passed in.
+	 */
 	error = xfs_bmap_punch_delalloc_range(ip, pos,
-			round_up(pos, folio_size(folio)));
+				folio_pos(folio) + folio_size(folio));
 
 	if (error && !xfs_is_shutdown(mp))
 		xfs_alert(mp, "page discard unable to remove delalloc mapping.");

fs/xfs/xfs_qm.c

@@ -1321,15 +1321,14 @@ xfs_qm_quotacheck(
 
 	error = xfs_iwalk_threaded(mp, 0, 0, xfs_qm_dqusage_adjust, 0, true,
 			NULL);
-	if (error) {
-		/*
-		 * The inode walk may have partially populated the dquot
-		 * caches.  We must purge them before disabling quota and
-		 * tearing down the quotainfo, or else the dquots will leak.
-		 */
-		xfs_qm_dqpurge_all(mp);
-		goto error_return;
-	}
+
+	/*
+	 * On error, the inode walk may have partially populated the dquot
+	 * caches.  We must purge them before disabling quota and tearing down
+	 * the quotainfo, or else the dquots will leak.
+	 */
+	if (error)
+		goto error_purge;
 
 	/*
 	 * We've made all the changes that we need to make incore.  Flush them
@@ -1363,10 +1362,8 @@ xfs_qm_quotacheck(
 	 * and turn quotaoff. The dquots won't be attached to any of the inodes
 	 * at this point (because we intentionally didn't in dqget_noattach).
 	 */
-	if (error) {
-		xfs_qm_dqpurge_all(mp);
-		goto error_return;
-	}
+	if (error)
+		goto error_purge;
 
 	/*
 	 * If one type of quotas is off, then it will lose its
@@ -1376,7 +1373,7 @@ xfs_qm_quotacheck(
 	mp->m_qflags &= ~XFS_ALL_QUOTA_CHKD;
 	mp->m_qflags |= flags;
 
- error_return:
+error_return:
 	xfs_buf_delwri_cancel(&buffer_list);
 
 	if (error) {
@@ -1395,6 +1392,21 @@ xfs_qm_quotacheck(
 	} else
 		xfs_notice(mp, "Quotacheck: Done.");
 	return error;
+
+error_purge:
+	/*
+	 * On error, we may have inodes queued for inactivation. This may try
+	 * to attach dquots to the inode before running cleanup operations on
+	 * the inode and this can race with the xfs_qm_destroy_quotainfo() call
+	 * below that frees mp->m_quotainfo. To avoid this race, flush all the
+	 * pending inodegc operations before we purge the dquots from memory,
+	 * ensuring that background inactivation is idle whilst we turn off
+	 * quotas.
+	 */
+	xfs_inodegc_flush(mp);
+	xfs_qm_dqpurge_all(mp);
+	goto error_return;
+
 }
 
 /*