On 21.01.21 г. 8:13 ч., Qu Wenruo wrote:
> [BUG]
> There is a long existing bug in the last parameter of
> btrfs_add_ordered_extent(), in commit 771ed689d2cd ("Btrfs: Optimize
> compressed writeback and reads") back to 2008.
>
> In that ancient commit btrfs_add_ordered_extent() expects the @type
> parameter to be one of the following:
> - BTRFS_ORDERED_REGULAR
> - BTRFS_ORDERED_NOCOW
> - BTRFS_ORDERED_PREALLOC
> - BTRFS_ORDERED_COMPRESSED
>
> But we pass 0 in cow_file_range(), which means BTRFS_ORDERED_IO_DONE.
>
> Ironically extra check in __btrfs_add_ordered_extent() won't set the bit
> if we're seeing (type == IO_DONE || type == IO_COMPLETE), and avoid any
> obvious bug.
>
> But this still leads to regular COW ordered extent having no bit to
> indicate its type in various trace events, rendering REGULAR bit
> useless.
>
> [FIX]
> This patch will change the following aspects to avoid such problem:
> - Reorder btrfs_ordered_extent::flags
> Now the type bits go first (REGULAR/NOCOW/PREALLCO/COMPRESSED), then
> DIRECT bit, finally extra status bits like IO_DONE/COMPLETE/IOERR.
>
> - Add extra ASSERT() for btrfs_add_ordered_extent_*()
>
> - Remove @type parameter for btrfs_add_ordered_extent_compress()
> As the only valid @type here is BTRFS_ORDERED_COMPRESSED.
>
> - Remove the unnecessary special check for IO_DONE/COMPLETE in
> __btrfs_add_ordered_extent()
> This is just to make the code work, with extra ASSERT(), there are
> limited values can be passed in.
>
> Signed-off-by: Qu Wenruo <w...@suse.com>
Reviewed-by: Nikolay Borisov <nbori...@suse.com>
