ext4: correct behavior under errors=remount-ro mode

And after commit 95257987a638 ("ext4: drop EXT4_MF_FS_ABORTED flag") in
v6.6-rc1, the EXT4_FLAGS_SHUTDOWN bit is set in ext4_handle_error() under
errors=remount-ro mode. This causes the read to fail even when the error
is triggered in errors=remount-ro mode.

To correct the behavior under errors=remount-ro, EXT4_FLAGS_SHUTDOWN is
replaced by the newly introduced EXT4_FLAGS_EMERGENCY_RO. This new flag
only prevents writes, matching the previous behavior with SB_RDONLY.

Fixes: 95257987a638 ("ext4: drop EXT4_MF_FS_ABORTED flag")
Closes: https://lore.kernel.org/all/22d652f6-cb3c-43f5-b2fe-0a4bb6516a04@huawei.com/
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250122114130.229709-6-libaokun@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 4cf0ff217481127e760a35d98b2305700201a58c..94bd351fd2b19314ba738f7c07d49dfb3bcabaa3 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -693,11 +693,8 @@ static void ext4_handle_error(struct super_block *sb, bool force_ro, int error,
        if (test_opt(sb, WARN_ON_ERROR))
                WARN_ON_ONCE(1);
 
-       if (!continue_fs && !sb_rdonly(sb)) {
-               set_bit(EXT4_FLAGS_SHUTDOWN, &EXT4_SB(sb)->s_ext4_flags);
-               if (journal)
-                       jbd2_journal_abort(journal, -EIO);
-       }
+       if (!continue_fs && !ext4_emergency_ro(sb) && journal)
+               jbd2_journal_abort(journal, -EIO);
 
        if (!bdev_read_only(sb->s_bdev)) {
                save_error_info(sb, error, ino, block, func, line);
@@ -723,17 +720,17 @@ static void ext4_handle_error(struct super_block *sb, bool force_ro, int error,
                        sb->s_id);
        }
 
-       if (sb_rdonly(sb) || continue_fs)
+       if (ext4_emergency_ro(sb) || continue_fs)
                return;
 
        ext4_msg(sb, KERN_CRIT, "Remounting filesystem read-only");
        /*
-        * EXT4_FLAGS_SHUTDOWN was set which stops all filesystem
-        * modifications. We don't set SB_RDONLY because that requires
-        * sb->s_umount semaphore and setting it without proper remount
-        * procedure is confusing code such as freeze_super() leading to
-        * deadlocks and other problems.
+        * We don't set SB_RDONLY because that requires sb->s_umount
+        * semaphore and setting it without proper remount procedure is
+        * confusing code such as freeze_super() leading to deadlocks
+        * and other problems.
         */
+       set_bit(EXT4_FLAGS_EMERGENCY_RO, &EXT4_SB(sb)->s_ext4_flags);
 }
 
 static void update_super_work(struct work_struct *work)