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    Subject[PATCH 4.19 094/125] writeback: Protect inode->i_io_list with inode->i_lock
    Date
    From: Jan Kara <jack@suse.cz>

    commit b35250c0816c7cf7d0a8de92f5fafb6a7508a708 upstream.

    Currently, operations on inode->i_io_list are protected by
    wb->list_lock. In the following patches we'll need to maintain
    consistency between inode->i_state and inode->i_io_list so change the
    code so that inode->i_lock protects also all inode's i_io_list handling.

    Reviewed-by: Martijn Coenen <maco@android.com>
    Reviewed-by: Christoph Hellwig <hch@lst.de>
    CC: stable@vger.kernel.org # Prerequisite for "writeback: Avoid skipping inode writeback"
    Signed-off-by: Jan Kara <jack@suse.cz>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/fs-writeback.c | 22 +++++++++++++++++-----
    1 file changed, 17 insertions(+), 5 deletions(-)

    --- a/fs/fs-writeback.c
    +++ b/fs/fs-writeback.c
    @@ -160,6 +160,7 @@ static void inode_io_list_del_locked(str
    struct bdi_writeback *wb)
    {
    assert_spin_locked(&wb->list_lock);
    + assert_spin_locked(&inode->i_lock);

    list_del_init(&inode->i_io_list);
    wb_io_lists_depopulated(wb);
    @@ -1042,7 +1043,9 @@ void inode_io_list_del(struct inode *ino
    struct bdi_writeback *wb;

    wb = inode_to_wb_and_lock_list(inode);
    + spin_lock(&inode->i_lock);
    inode_io_list_del_locked(inode, wb);
    + spin_unlock(&inode->i_lock);
    spin_unlock(&wb->list_lock);
    }

    @@ -1091,8 +1094,10 @@ void sb_clear_inode_writeback(struct ino
    * the case then the inode must have been redirtied while it was being written
    * out and we don't reset its dirtied_when.
    */
    -static void redirty_tail(struct inode *inode, struct bdi_writeback *wb)
    +static void redirty_tail_locked(struct inode *inode, struct bdi_writeback *wb)
    {
    + assert_spin_locked(&inode->i_lock);
    +
    if (!list_empty(&wb->b_dirty)) {
    struct inode *tail;

    @@ -1103,6 +1108,13 @@ static void redirty_tail(struct inode *i
    inode_io_list_move_locked(inode, wb, &wb->b_dirty);
    }

    +static void redirty_tail(struct inode *inode, struct bdi_writeback *wb)
    +{
    + spin_lock(&inode->i_lock);
    + redirty_tail_locked(inode, wb);
    + spin_unlock(&inode->i_lock);
    +}
    +
    /*
    * requeue inode for re-scanning after bdi->b_io list is exhausted.
    */
    @@ -1313,7 +1325,7 @@ static void requeue_inode(struct inode *
    * writeback is not making progress due to locked
    * buffers. Skip this inode for now.
    */
    - redirty_tail(inode, wb);
    + redirty_tail_locked(inode, wb);
    return;
    }

    @@ -1333,7 +1345,7 @@ static void requeue_inode(struct inode *
    * retrying writeback of the dirty page/inode
    * that cannot be performed immediately.
    */
    - redirty_tail(inode, wb);
    + redirty_tail_locked(inode, wb);
    }
    } else if (inode->i_state & I_DIRTY) {
    /*
    @@ -1341,7 +1353,7 @@ static void requeue_inode(struct inode *
    * such as delayed allocation during submission or metadata
    * updates after data IO completion.
    */
    - redirty_tail(inode, wb);
    + redirty_tail_locked(inode, wb);
    } else if (inode->i_state & I_DIRTY_TIME) {
    inode->dirtied_when = jiffies;
    inode_io_list_move_locked(inode, wb, &wb->b_dirty_time);
    @@ -1588,8 +1600,8 @@ static long writeback_sb_inodes(struct s
    */
    spin_lock(&inode->i_lock);
    if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
    + redirty_tail_locked(inode, wb);
    spin_unlock(&inode->i_lock);
    - redirty_tail(inode, wb);
    continue;
    }
    if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) {

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