From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B8BA42E3FE for ; Mon, 24 Aug 2026 00:09:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787530176; cv=none; b=tQATHZ3gG73YovEbtTj3w0B76S48D+YcBayTrRqMPY2PS0pxckoiX5EW0cQbBcMqRo5nscg7jqIl6s5jA6Gl3YNveNVkiLCDoalBjG4T123p4UZFH0GV4/+l6AoK/JRg6F5Oj4ZF1Dl2TpOuRX72CaPtZHi+ERsMTQs9NUgTuRU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787530176; c=relaxed/simple; bh=+QMjj+Ryvh4j9XLLaCkCxqTHqPrx6K+Nflc22UogVzo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IYcbSmfzT/oIBvo5vJp/LeFO2Y3HXl3iAntT1Lvkk45NdogXk8DsJfNAbOStG3yMsXGKVX4aYGRiz8FA2FcQT9pTdgCyNJ8yTwA9D9QUv4oC5aKMA2Ux/Q20PCt2qaMVN5f9ksqz6TPdykzb/c0Pu9fXRMfYs8TsnW3x3GqCqtY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=U6MeDZ7q; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="U6MeDZ7q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C20DB1F00A3A; Mon, 24 Aug 2026 00:09:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787530175; bh=BUGndJ+0BcpFrqc7WqCDnWqmx6zpSXa1dn/J8GmWvZQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=U6MeDZ7qF6JJckptcYSnSKrEY48ZXbZJcgFVSrha7AzmJPm0aPfd+J4aerq6foO4n HvdlZxxJyDVp54e38dy8BU4aYZX66aCwSu+YfbQ7jSUSBbystZnGxUij02duaIzKSS Vdb9HilO2jOxGviYhiiW4IOugFUM7qRqf6EbHU1jHsTP6a4rMTyFEQ73SeWaFqSbS5 UGrJQYzk/ZVfT57O3spRYysXhsXT+ENb6BFPJeFAFyQiGDKb67IUTUS4JX3v70rxOP s7Tvt0ewzidHGDqLnRMQrNKJv74Hof+59iSJTUyzwdx9Bvm2twEny8urjjhNXDo47k dl1QtbOrYL59w== From: Sasha Levin To: stable@vger.kernel.org Cc: "Darrick J. Wong" , Christoph Hellwig , Carlos Maiolino , Sasha Levin Subject: [PATCH 6.18.y 2/2] xfs: don't livelock in scrub on a circular unlinked list Date: Sun, 23 Aug 2026 20:09:32 -0400 Message-ID: <20260824000932.2649491-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260824000932.2649491-1-sashal@kernel.org> References: <2026082043-rely-pentagram-07de@gregkh> <20260824000932.2649491-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Darrick J. Wong" [ Upstream commit 527eaaefddb6ec5c83a06c9a1559960dd6361753 ] LOLLM points out that online fsck can livelock if an unlinked inode list contains a loop. Use a bitmap to detect cycles. Cc: stable@vger.kernel.org # v4.15 Fixes: a12890aebb8959 ("xfs: scrub the AGI") Signed-off-by: Darrick J. Wong Assisted-by: LOLLM # finding obvious bugs Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino Signed-off-by: Sasha Levin --- fs/xfs/scrub/agheader.c | 46 +++++++++++++++++++++++++++------- fs/xfs/scrub/agheader_repair.c | 17 +++++++++++-- 2 files changed, 52 insertions(+), 11 deletions(-) diff --git a/fs/xfs/scrub/agheader.c b/fs/xfs/scrub/agheader.c index 7c44ea7a26c95..fb403a7bf4310 100644 --- a/fs/xfs/scrub/agheader.c +++ b/fs/xfs/scrub/agheader.c @@ -18,6 +18,8 @@ #include "xfs_inode.h" #include "scrub/scrub.h" #include "scrub/common.h" +#include "scrub/bitmap.h" +#include "scrub/agino_bitmap.h" int xchk_setup_agheader( @@ -935,7 +937,8 @@ xchk_agi_xref( /* * Walk the incore unlinked list for a particular AGI bucket to construct * the unlinked inode bitmap for later reconstruction of the unlinked list. - * Returns 1 if we should keep checking, or 0 to stop checking. + * Returns 1 if we should keep checking, 0 to stop checking, or a negative + * errno. */ static int xchk_iunlink_bucket( @@ -943,36 +946,57 @@ xchk_iunlink_bucket( unsigned int bucket, xfs_agino_t agino) { + struct xagino_bitmap seen; + int ret; + + xagino_bitmap_init(&seen); + while (agino != NULLAGINO) { struct xfs_inode *ip; + unsigned int len = 1; if (agino % XFS_AGI_UNLINKED_BUCKETS != bucket) { xchk_block_set_corrupt(sc, sc->sa.agi_bp); - return 0; + goto bad; + } + + if (xagino_bitmap_test(&seen, agino, &len)) { + xchk_block_set_corrupt(sc, sc->sa.agi_bp); + goto bad; } ip = xfs_iunlink_lookup(sc->sa.pag, agino); if (!ip) { xchk_block_set_corrupt(sc, sc->sa.agi_bp); - return 0; + goto bad; } if (!xfs_inode_on_unlinked_list(ip)) { xchk_block_set_corrupt(sc, sc->sa.agi_bp); - return 0; + goto bad; } + ret = xagino_bitmap_set(&seen, agino, 1); + if (ret) + goto out_bitmap; + agino = ip->i_next_unlinked; } - - return 1; + ret = 1; + +out_bitmap: + xagino_bitmap_destroy(&seen); + return ret; +bad: + ret = 0; + goto out_bitmap; } /* * Check the unlinked buckets for links to bad inodes. We hold the AGI, so * there cannot be any threads updating unlinked list pointers in this AG. */ -STATIC void +STATIC int xchk_iunlink( struct xfs_scrub *sc, struct xfs_agi *agi) @@ -985,8 +1009,10 @@ xchk_iunlink( ret = xchk_iunlink_bucket(sc, i, be32_to_cpu(agi->agi_unlinked[i])); if (ret < 1) - return; + return ret; } + + return 0; } /* Scrub the AGI. */ @@ -1073,7 +1099,9 @@ xchk_agi( if (pag->pagi_freecount != be32_to_cpu(agi->agi_freecount)) xchk_block_set_corrupt(sc, sc->sa.agi_bp); - xchk_iunlink(sc, agi); + error = xchk_iunlink(sc, agi); + if (error) + goto out; xchk_agi_xref(sc); out: diff --git a/fs/xfs/scrub/agheader_repair.c b/fs/xfs/scrub/agheader_repair.c index d18944449b3a9..6ed9c6fa52116 100644 --- a/fs/xfs/scrub/agheader_repair.c +++ b/fs/xfs/scrub/agheader_repair.c @@ -1096,18 +1096,22 @@ xrep_iunlink_walk_ondisk_bucket( struct xrep_agi *ragi, unsigned int bucket) { + struct xagino_bitmap seen; struct xfs_scrub *sc = ragi->sc; struct xfs_agi *agi = ragi->agi_bp->b_addr; xfs_agino_t prev_agino = NULLAGINO; xfs_agino_t next_agino; int error = 0; + xagino_bitmap_init(&seen); + next_agino = be32_to_cpu(agi->agi_unlinked[bucket]); while (next_agino != NULLAGINO) { xfs_agino_t agino = next_agino; + unsigned int len = 1; if (xchk_should_terminate(ragi->sc, &error)) - return error; + goto out_bitmap; trace_xrep_iunlink_walk_ondisk_bucket(sc->sa.pag, bucket, prev_agino, agino); @@ -1115,6 +1119,9 @@ xrep_iunlink_walk_ondisk_bucket( if (bucket != agino % XFS_AGI_UNLINKED_BUCKETS) break; + if (xagino_bitmap_test(&seen, agino, &len)) + break; + next_agino = xrep_iunlink_next(sc, agino); if (!next_agino) { error = xrep_iunlink_reload_next(ragi, prev_agino, @@ -1123,10 +1130,16 @@ xrep_iunlink_walk_ondisk_bucket( break; } + error = xagino_bitmap_set(&seen, agino, 1); + if (error) + goto out_bitmap; + prev_agino = agino; } - return 0; +out_bitmap: + xagino_bitmap_destroy(&seen); + return error; } /* Decide if this is an unlinked inode in this AG. */ -- 2.53.0