jbd2: do not try to recover wiped journal

If a journal is wiped, we will set journal->j_tail to 0. However if
'write' argument is not set (as it happens for read-only device or for
ocfs2), the on-disk superblock is not updated accordingly and thus
jbd2_journal_recover() cat try to recover the wiped journal. Fix the
check in jbd2_journal_recover() to use journal->j_tail for checking
empty journal instead.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250206094657.20865-4-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index 38a89a3310b245fee9253613d5380072e0aaa759..c271a050b7e6f2815b3b43d4b8bd029d0ff92621 100644 (file)
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -282,19 +282,20 @@ static int fc_do_one_pass(journal_t *journal,
 int jbd2_journal_recover(journal_t *journal)
 {
        int                     err, err2;
-       journal_superblock_t *  sb;
-
        struct recovery_info    info;
 
        memset(&info, 0, sizeof(info));
-       sb = journal->j_superblock;
 
        /*
         * The journal superblock's s_start field (the current log head)
         * is always zero if, and only if, the journal was cleanly
-        * unmounted.
+        * unmounted. We use its in-memory version j_tail here because
+        * jbd2_journal_wipe() could have updated it without updating journal
+        * superblock.
         */
-       if (!sb->s_start) {
+       if (!journal->j_tail) {
+               journal_superblock_t *sb = journal->j_superblock;
+
                jbd2_debug(1, "No recovery required, last transaction %d, head block %u\n",
                          be32_to_cpu(sb->s_sequence), be32_to_cpu(sb->s_head));
                journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;