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 BB04340243B; Tue, 25 Aug 2026 13:39:41 +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=1787665183; cv=none; b=VQbxS46UIyAMxPU4U0BLNDwF9L4rJRN2cOs6bI28WKweb3g9imvPnEG5LsaF3OMZI+oB4aMWF9EV6O5ofJ3x4ywtKfulLUOss1DU8X8A7wL0lPfiprCMjXJNSgoGhnyq9QerxxUo5a+G3ktZrViYdu3eIbsmNpPyhpdKMxl+0v8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787665183; c=relaxed/simple; bh=GmGAJRwSW9CDld9Y+uk2SMEup7Ul1tjaIh4CsAIoIBw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tkJTsAykfR8B6Td7I0O3ijOUgryU6lCl30UR/ZjlXeXSJPrula+uTy70K6iBGPFD8i7qiv6FD5t8KZRYqGcO+nGDZSFem29tPUgAlGiygo2YMNYNa5KkuNmz+SkKSH1P/1Ore1rHl3Kf1iMz025Fsrz/11CNlcDIWpfJFrr+hPc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2bJBljoF; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="2bJBljoF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10C9E1F000E9; Tue, 25 Aug 2026 13:39:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787665181; bh=PlZYac1G3aextxs2O+Zn+uknGSRn5XDh+ZyK1wt6fC0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=2bJBljoFG92SCwyhd/BxRkpionLdXtN7ZZbH0/2NjgIlWyvxSQlq0jXpI0GBQ8vk/ rV2+LEhPv5/QnyfNeM9U2jdv+fwZVEt3QO8dubh7kEmmfVBL0KSDxwDYKa15by7pa8 6jUUVmmFdeYnMITTBn9i7Ts2rOcdaARXyxMP4EcA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Darrick J. Wong" , Christoph Hellwig , Carlos Maiolino , Sasha Levin Subject: [PATCH 6.18 07/94] xfs: dont livelock in scrub on a circular unlinked list Date: Tue, 25 Aug 2026 15:25:03 +0200 Message-ID: <20260825132542.180803413@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260825132541.887883084@linuxfoundation.org> References: <20260825132541.887883084@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ 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 Signed-off-by: Greg Kroah-Hartman --- fs/xfs/scrub/agheader.c | 44 +++++++++++++++++++++++++++++++++-------- fs/xfs/scrub/agheader_repair.c | 17 +++++++++++++-- 2 files changed, 51 insertions(+), 10 deletions(-) --- 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; } + ret = 1; - return 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: --- 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. */