Merge v6.12.34

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 16 insertions, 1 deletions

diff --git a/fs/xfs/xfs_discard.c b/fs/xfs/xfs_discard.c
index d8c4a5dcca7a..0b343776da8c 100644
--- a/fs/xfs/xfs_discard.c
+++ b/fs/xfs/xfs_discard.c
@@ -146,6 +146,14 @@ xfs_discard_extents(
 	return error;
 }
 
+/*
+ * Care must be taken setting up the trim cursor as the perags may not have been
+ * initialised when the cursor is initialised. e.g. a clean mount which hasn't
+ * read in AGFs and the first operation run on the mounted fs is a trim. This
+ * can result in perag fields that aren't initialised until
+ * xfs_trim_gather_extents() calls xfs_alloc_read_agf() to lock down the AG for
+ * the free space search.
+ */
 struct xfs_trim_cur {
 	xfs_agblock_t	start;
 	xfs_extlen_t	count;
@@ -183,6 +191,14 @@ xfs_trim_gather_extents(
 	if (error)
 		goto out_trans_cancel;
 
+	/*
+	 * First time through tcur->count will not have been initialised as
+	 * pag->pagf_longest is not guaranteed to be valid before we read
+	 * the AGF buffer above.
+	 */
+	if (!tcur->count)
+		tcur->count = pag->pagf_longest;
+
 	if (tcur->by_bno) {
 		/* sub-AG discard request always starts at tcur->start */
 		cur = xfs_bnobt_init_cursor(mp, tp, agbp, pag);
@@ -329,7 +345,6 @@ xfs_trim_perag_extents(
 {
 	struct xfs_trim_cur	tcur = {
 		.start		= start,
-		.count		= pag->pagf_longest,
 		.end		= end,
 		.minlen		= minlen,
 	};