Hi Jan:
Was there ever a resolution for this patch and the series? I looked
for but found no ack/nack for V4 of your "Cleanup and improve sync"
patch series.
We've been carrying a crappy hack/patch to sync all block device
inodes in order to allow lilo to not break, and it'd be nice to have a
real fix for it upstream.
Thanks,
Curt
On Thu, Jan 5, 2012 at 3:46 PM, Jan Kara <jack@xxxxxxx> wrote:
> In case block device does not have filesystem mounted on it, sys_sync will just
> ignore it and doesn't writeout its dirty pages. This is because writeback code
> avoids writing inodes from superblock without backing device and
> blockdev_superblock is such a superblock. Since it's unexpected that sync
> doesn't writeout dirty data for block devices be nice to users and change the
> behavior to do so. So now we iterate over all block devices on blockdev_super
> instead of iterating over all superblocks when syncing block devices.
>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> fs/sync.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++-------
> 1 files changed, 51 insertions(+), 7 deletions(-)
>
> diff --git a/fs/sync.c b/fs/sync.c
> index e62a57b..ccaaa1b 100644
> --- a/fs/sync.c
> +++ b/fs/sync.c
> @@ -86,10 +86,54 @@ static void sync_fs_one_sb(struct super_block *sb, void *arg)
> sb->s_op->sync_fs(sb, *(int *)arg);
> }
>
> -static void sync_blkdev_one_sb(struct super_block *sb, void *arg)
> +/*
> + * We go through all existing block devices so that even devices without
> + * filesystem mounted are synced.
> + */
> +static void sync_all_bdevs(int wait)
> {
> - if (!(sb->s_flags & MS_RDONLY))
> - __sync_blockdev(sb->s_bdev, *(int *)arg);
> + struct inode *inode, *old_inode = NULL;
> +
> + spin_lock(&inode_sb_list_lock);
> + list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
> + struct address_space *mapping = inode->i_mapping;
> +
> + spin_lock(&inode->i_lock);
> + if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
> + mapping->nrpages == 0) {
> + spin_unlock(&inode->i_lock);
> + continue;
> + }
> + __iget(inode);
> + spin_unlock(&inode->i_lock);
> + spin_unlock(&inode_sb_list_lock);
> + /*
> + * We hold a reference to 'inode' so it couldn't have been
> + * removed from s_inodes list while we dropped the
> + * inode_sb_list_lock. We cannot iput the inode now as we can
> + * be holding the last reference and we cannot iput it under
> + * inode_sb_list_lock. So we keep the reference and iput it
> + * later.
> + */
> + iput(old_inode);
> + old_inode = inode;
> +
> + __sync_blockdev(I_BDEV(inode), wait);
> +
> + spin_lock(&inode_sb_list_lock);
> + }
> + spin_unlock(&inode_sb_list_lock);
> + iput(old_inode);
> +}
> +
> +static void flush_one_bdev(struct block_device *bdev, void *arg)
> +{
> + __sync_blockdev(bdev, 0);
> +}
> +
> +static void sync_one_bdev(struct block_device *bdev, void *arg)
> +{
> + sync_blockdev(bdev);
> }
>
> /*
> @@ -103,10 +147,10 @@ SYSCALL_DEFINE0(sync)
> wakeup_flusher_threads(0, WB_REASON_SYNC);
> iterate_supers(writeback_inodes_one_sb, NULL);
> iterate_supers(sync_fs_one_sb, &nowait);
> - iterate_supers(sync_blkdev_one_sb, &nowait);
> + iterate_bdevs(flush_one_bdev, NULL);
> iterate_supers(sync_inodes_one_sb, NULL);
> iterate_supers(sync_fs_one_sb, &wait);
> - iterate_supers(sync_blkdev_one_sb, &wait);
> + iterate_bdevs(sync_one_bdev, NULL);
> if (unlikely(laptop_mode))
> laptop_sync_completion();
> return 0;
> @@ -122,10 +166,10 @@ static void do_sync_work(struct work_struct *work)
> */
> iterate_supers(sync_inodes_one_sb, &nowait);
> iterate_supers(sync_fs_one_sb, &nowait);
> - iterate_supers(sync_blkdev_one_sb, &nowait);
> + sync_all_bdevs(nowait);
> iterate_supers(sync_inodes_one_sb, &nowait);
> iterate_supers(sync_fs_one_sb, &nowait);
> - iterate_supers(sync_blkdev_one_sb, &nowait);
> + sync_all_bdevs(nowait);
> printk("Emergency Sync complete\n");
> kfree(work);
> }
> --
> 1.7.1
>
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