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    Subject[patch 093/114] ext4: Fix lockdep warning

    2.6.28-stable review patch. If anyone has any objections, please let us know.

    ------------------

    From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

    (cherry picked from commit ba4439165f0f0d25b2fe065cf0c1ff8130b802eb)

    We should not call ext4_mb_add_n_trim while holding alloc_semp.

    =============================================
    [ INFO: possible recursive locking detected ]
    2.6.29-rc4-git1-dirty #124
    ---------------------------------------------
    ffsb/3116 is trying to acquire lock:
    (&meta_group_info[i]->alloc_sem){----}, at: [<ffffffff8035a6e8>]
    ext4_mb_load_buddy+0xd2/0x343

    but task is already holding lock:
    (&meta_group_info[i]->alloc_sem){----}, at: [<ffffffff8035a6e8>]
    ext4_mb_load_buddy+0xd2/0x343

    http://bugzilla.kernel.org/show_bug.cgi?id=12672

    Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    fs/ext4/mballoc.c | 29 ++++++++++++++++-------------
    1 file changed, 16 insertions(+), 13 deletions(-)

    --- a/fs/ext4/mballoc.c
    +++ b/fs/ext4/mballoc.c
    @@ -4456,23 +4456,26 @@ static int ext4_mb_release_context(struc
    pa->pa_free -= ac->ac_b_ex.fe_len;
    pa->pa_len -= ac->ac_b_ex.fe_len;
    spin_unlock(&pa->pa_lock);
    - /*
    - * We want to add the pa to the right bucket.
    - * Remove it from the list and while adding
    - * make sure the list to which we are adding
    - * doesn't grow big.
    - */
    - if (likely(pa->pa_free)) {
    - spin_lock(pa->pa_obj_lock);
    - list_del_rcu(&pa->pa_inode_list);
    - spin_unlock(pa->pa_obj_lock);
    - ext4_mb_add_n_trim(ac);
    - }
    }
    - ext4_mb_put_pa(ac, ac->ac_sb, pa);
    }
    if (ac->alloc_semp)
    up_read(ac->alloc_semp);
    + if (pa) {
    + /*
    + * We want to add the pa to the right bucket.
    + * Remove it from the list and while adding
    + * make sure the list to which we are adding
    + * doesn't grow big. We need to release
    + * alloc_semp before calling ext4_mb_add_n_trim()
    + */
    + if (pa->pa_linear && likely(pa->pa_free)) {
    + spin_lock(pa->pa_obj_lock);
    + list_del_rcu(&pa->pa_inode_list);
    + spin_unlock(pa->pa_obj_lock);
    + ext4_mb_add_n_trim(ac);
    + }
    + ext4_mb_put_pa(ac, ac->ac_sb, pa);
    + }
    if (ac->ac_bitmap_page)
    page_cache_release(ac->ac_bitmap_page);
    if (ac->ac_buddy_page)



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