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    SubjectRe: [PATCH] Change ll_rw_block() calls in JBD
    I have got some crashes due to:

    Assertion failure in __journal_file_buffer():
    "jh->b_transaction == transaction || jh->b_transaction == 0"

    [<a0000002053b44e0>] __journal_file_buffer+0x420/0x7c0 [jbd]
    r32 : e000000161a1f3e0 jh
    r33 : e00000010396a380 transaction
    r34 : 0000000000000008 jlist == BJ_Locked

    *(struct journal_head *) 0xe000000161a1f3e0: // jh
    {
    b_bh = 0xe00000048bb36930,
    b_jcount = 0x0,
    b_jlist = 0x1,
    b_modified = 0x0,
    b_frozen_data = 0x0,
    b_committed_data = 0x0,
    b_transaction = 0xe0000020014adb80, // ->j_running_transaction
    b_next_transaction = 0x0,
    b_tnext = 0xe0000001c17306e0,
    b_tprev = 0xe00000204757e540,
    b_cp_transaction = 0x0,
    b_cpnext = 0x0,
    b_cpprev = 0x0
    }

    *(struct buffer_head *) 0xe00000048bb36930: // jh->b_bh
    {
    b_state = 0x8201d,
    b_this_page = 0xe00000048bb33d88,
    b_page = 0xa07ffffff9201300,
    b_count = {
    counter = 0x2
    },
    b_size = 0x1000,
    b_blocknr = 0xadc001,
    b_data = 0xe000000492a0e000,
    b_bdev = 0xe0000023fe1ca300,
    b_end_io = 0xa000000100630be0,
    b_private = 0xe000000161a1f3e0,
    b_assoc_buffers = {
    next = 0xe00000048bb36978,
    prev = 0xe00000048bb36978
    }

    --- Called from --- :

    journal_submit_data_buffers+0x200/0x660 [jbd]
    r32 : e0000001035ec100 journal
    r33 : e00000010396a380 commit_transaction

    As you can see, the current "jh" has been stolen for the new
    "->j_running_transaction" while we released temporarily "->j_list_lock"
    in the middle of "journal_submit_data_buffers()".

    Therefore the test "jh->b_jlist != BJ_SyncData", i.e. if it is still
    on a (_any_) sync. list is not enough.

    --- linux-2.6.16.20-orig/fs/jbd/commit.c 2006-06-20 17:19:47.000000000 +0200
    +++ linux-2.6.16.20/fs/jbd/commit.c 2006-06-20 17:35:54.000000000 +0200
    @@ -219,15 +219,26 @@
    bufs = 0;
    lock_buffer(bh);
    spin_lock(&journal->j_list_lock);
    + /* Stolen (e.g. for a new transaction) ? */
    + if (jh != commit_transaction->t_sync_datalist) {
    + unlock_buffer(bh);
    + JBUFFER_TRACE(jh, "stolen sync. data");
    + put_bh(bh);
    + continue;
    + }
    /* Someone already cleaned up the buffer? */
    - if (!buffer_jbd(bh)
    - || jh->b_jlist != BJ_SyncData) {
    +
    + // Can this happen???
    +
    + if (!buffer_jbd(bh)) {
    unlock_buffer(bh);
    BUFFER_TRACE(bh, "already cleaned up");
    put_bh(bh);
    continue;
    }
    put_bh(bh);
    + J_ASSERT_JH(jh, jh->b_transaction ==
    + commit_transaction);
    }
    if (test_clear_buffer_dirty(bh)) {
    BUFFER_TRACE(bh, "needs writeout, submitting");
    I am not really sure that the test "!buffer_jbd(bh)" is really useful.
    I left it alone for not introducing a new bug.
    If you can confirm that it is not necessary, I can take it away.

    Thanks,

    Zoltan





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