linux-kernel - [PATCH AUTOSEL 5.5 002/106] gfs2: clear ail1 list when gfs2 withdraws

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Date:   Wed, 15 Apr 2020 07:40:42 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Bob Peterson <rpeterso@...hat.com>,
        Andreas Gruenbacher <agruenba@...hat.com>,
        Sasha Levin <sashal@...nel.org>, cluster-devel@...hat.com
Subject: [PATCH AUTOSEL 5.5 002/106] gfs2: clear ail1 list when gfs2 withdraws

From: Bob Peterson <rpeterso@...hat.com>

[ Upstream commit 30fe70a85a909a23dcbc2c628ca6655b2c85e7a1 ]

This patch fixes a bug in which function gfs2_log_flush can get into
an infinite loop when a gfs2 file system is withdrawn. The problem
is the infinite loop "for (;;)" in gfs2_log_flush which would never
finish because the io error and subsequent withdraw prevented the
items from being taken off the ail list.

This patch tries to clean up the mess by allowing withdraw situations
to move not-in-flight buffer_heads to the ail2 list, where they will
be dealt with later.

Signed-off-by: Bob Peterson <rpeterso@...hat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/gfs2/log.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index eb3f2e7b80856..a62e03ebc0ec8 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -107,16 +107,22 @@ __acquires(&sdp->sd_ail_lock)
 		gfs2_assert(sdp, bd->bd_tr == tr);
 
 		if (!buffer_busy(bh)) {
-			if (!buffer_uptodate(bh) &&
-			    !test_and_set_bit(SDF_AIL1_IO_ERROR,
+			if (buffer_uptodate(bh)) {
+				list_move(&bd->bd_ail_st_list,
+					  &tr->tr_ail2_list);
+				continue;
+			}
+			if (!test_and_set_bit(SDF_AIL1_IO_ERROR,
 					      &sdp->sd_flags)) {
 				gfs2_io_error_bh(sdp, bh);
 				*withdraw = true;
 			}
-			list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
-			continue;
 		}
 
+		if (gfs2_withdrawn(sdp)) {
+			gfs2_remove_from_ail(bd);
+			continue;
+		}
 		if (!buffer_dirty(bh))
 			continue;
 		if (gl == bd->bd_gl)
@@ -866,6 +872,8 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags)
 				if (gfs2_ail1_empty(sdp))
 					break;
 			}
+			if (gfs2_withdrawn(sdp))
+				goto out;
 			atomic_dec(&sdp->sd_log_blks_free); /* Adjust for unreserved buffer */
 			trace_gfs2_log_blocks(sdp, -1);
 			log_write_header(sdp, flags);
@@ -878,6 +886,7 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags)
 			atomic_set(&sdp->sd_freeze_state, SFS_FROZEN);
 	}
 
+out:
 	trace_gfs2_log_flush(sdp, 0, flags);
 	up_write(&sdp->sd_log_flush_lock);
 
-- 
2.20.1