On Tue, Dec 04, 2012 at 05:18:05PM -0600, Mark Tinguely wrote:
> Per Dave Chinner suggestion, this patch:
> 1) Corrects the detection of whether a multi-segment buffer is
> still tracking data.
> 2) Clears all the buffer log formats for a multi-segment buffer.
>
> Signed-off-by: Mark Tinguely <tinguely@xxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/xfs/xfs_buf_item.c | 13 ++++++++++---
> fs/xfs/xfs_buf_item.c | 13 ++++++++++---
> fs/xfs/xfs_trans_buf.c | 7 +++++--
> 2 files changed, 15 insertions(+), 5 deletions(-)
>
> Index: b/fs/xfs/xfs_buf_item.c
> ===================================================================
> --- a/fs/xfs/xfs_buf_item.c
> +++ b/fs/xfs/xfs_buf_item.c
> @@ -611,7 +611,7 @@ xfs_buf_item_unlock(
> {
> struct xfs_buf_log_item *bip = BUF_ITEM(lip);
> struct xfs_buf *bp = bip->bli_buf;
> - int aborted;
> + int aborted, clean, i;
> uint hold;
>
> /* Clear the buffer's association with this transaction. */
> @@ -654,8 +654,15 @@ xfs_buf_item_unlock(
> * If the buf item isn't tracking any data, free it, otherwise drop the
> * reference we hold to it.
> */
> - if (xfs_bitmap_empty(bip->__bli_format.blf_data_map,
> - bip->__bli_format.blf_map_size))
> + clean = 1;
> + for (i = 0; i < bip->bli_format_count; i++) {
> + if (!xfs_bitmap_empty(bip->bli_formats[i].blf_data_map,
> + bip->bli_formats[i].blf_map_size)) {
> + clean = 0;
> + break;
> + }
> + }
> + if (clean)
> xfs_buf_item_relse(bp);
> else
> atomic_dec(&bip->bli_refcount);
Looks ok, although avoiding the clean variable would be even better:
for (i = 0; i < bip->bli_format_count; i++) {
if (!xfs_bitmap_empty(bip->bli_formats[i].blf_data_map,
bip->bli_formats[i].blf_map_size)) {
atomic_dec(&bip->bli_refcount);
goto out;
}
}
xfs_buf_item_relse(bp);
out:
bu that might be getting a bit too much into bikeshedding.
What I'm worried more about is how we semi-duplicate this bli_refcount
decrement vs xfs_buf_item_relse in xfs_trans_brelse, but use the
xfs_buf_item_dirty (aka XFS_BLI_DIRTY) check there instead.
It seems like the proper fix might be to:
- only set XFS_BLI_DIRTY in xfs_buf_item_log if we actually set
any bits in a bitmap
- use the XFS_BLI_DIRTY check in xfs_buf_item_unlock as well
- kill the useless xfs_buf_item_dirty wrapper
Probably both of these aren't worth doing it for now as we'll need to
get fixes into Linus tree quickly, so:
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
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