From: Josef Bacik Date: Wed, 10 Jan 2024 22:14:21 +0000 (-0500) Subject: btrfs: don't unconditionally call folio_start_writeback in subpage X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=1e61b8c672ab2f59b282c8d48a29c14b52c0f5b4;p=linux.git btrfs: don't unconditionally call folio_start_writeback in subpage In the normal case we check if a page is under writeback and skip it before we attempt to begin writeback. The exception is subpage metadata writes, where we know we don't have an eb under writeback and we're doing it one eb at a time. Since b5612c368648 ("mm: return void from folio_start_writeback() and related functions") we now will BUG_ON() if we call folio_start_writeback() on a folio that's already under writeback. Previously folio_start_writeback() would bail if writeback was already started. Fix this in the subpage code by checking if we have writeback set and skipping it if we do. This fixes the panic we were seeing on subpage. Reviewed-by: Qu Wenruo Reviewed-by: Anand Jain Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c index d9a30b93d543b..277dd6d312ee3 100644 --- a/fs/btrfs/subpage.c +++ b/fs/btrfs/subpage.c @@ -475,7 +475,8 @@ void btrfs_subpage_set_writeback(const struct btrfs_fs_info *fs_info, spin_lock_irqsave(&subpage->lock, flags); bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits); - folio_start_writeback(folio); + if (!folio_test_writeback(folio)) + folio_start_writeback(folio); spin_unlock_irqrestore(&subpage->lock, flags); }