[Devel] [PATCH v2 vz10] ext4: avoid remount errors with 'abort' mount option

[Vasileios Almpanis]

From: Jan Kara <jack at suse.cz>

When we remount filesystem with 'abort' mount option while changing
other mount options as well (as is LTP test doing), we can return error
from the system call after commit d3476f3dad4a ("ext4: don't set
SB_RDONLY after filesystem errors") because the application of mount
option changes detects shutdown filesystem and refuses to do anything.
The behavior of application of other mount options in presence of
'abort' mount option is currently rather arbitary as some mount option
changes are handled before 'abort' and some after it.

Move aborting of the filesystem to the end of remount handling so all
requested changes are properly applied before the filesystem is shutdown
to have a reasonably consistent behavior.

https://virtuozzo.atlassian.net/browse/VSTOR-120065

Fixes: d3476f3dad4a ("ext4: don't set SB_RDONLY after filesystem errors")
Reported-by: Jan Stancek <jstancek at redhat.com>
Link: https://lore.kernel.org/all/Zvp6L+oFnfASaoHl@t14s
Signed-off-by: Jan Kara <jack at suse.cz>
Tested-by: Jan Stancek <jstancek at redhat.com>
Link: https://patch.msgid.link/20241004221556.19222-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso at mit.edu>
Signed-off-by: Vasileios Almpanis <vasileios.almpanis at virtuozzo.com>

Feature: ext4 fixes

v2:
- Adds bug id in commit message
- Adds feature in commit message

---
 fs/ext4/super.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 6cc6c408cf94..a810dcaa135c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -6635,9 +6635,6 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb)
 		goto restore_opts;
 	}
 
-	if (test_opt2(sb, ABORT))
-		ext4_abort(sb, ESHUTDOWN, "Abort forced by user");
-
 	sb->s_flags = (sb->s_flags & ~SB_POSIXACL) |
 		(test_opt(sb, POSIX_ACL) ? SB_POSIXACL : 0);
 
@@ -6809,6 +6806,14 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb)
 	if (!ext4_has_feature_mmp(sb) || sb_rdonly(sb))
 		ext4_stop_mmpd(sbi);
 
+	/*
+	 * Handle aborting the filesystem as the last thing during remount to
+	 * avoid obsure errors during remount when some option changes fail to
+	 * apply due to shutdown filesystem.
+	 */
+	if (test_opt2(sb, ABORT))
+		ext4_abort(sb, ESHUTDOWN, "Abort forced by user");
+
 	return 0;
 
 restore_opts:
-- 
2.43.0