Re: [PATCH RESEND] Btrfs: make should_defrag_range() understood compressed extents

[Timofey Titovets]

вт, 18 сент. 2018 г. в 13:09, Timofey Titovets <timofey.titov...@synesis.ru>:
>
> From: Timofey Titovets <nefelim...@gmail.com>
>
>  Both, defrag ioctl and autodefrag - call btrfs_defrag_file()
>  for file defragmentation.
>
>  Kernel default target extent size - 256KiB.
>  Btrfs progs default - 32MiB.
>
>  Both bigger then maximum size of compressed extent - 128KiB.
>  That lead to rewrite all compressed data on disk.
>
>  Fix that by check compression extents with different logic.
>
>  As addition, make should_defrag_range() understood compressed extent type,
>  if requested target compression are same as current extent compression type.
>  Just don't recompress/rewrite extents.
>  To avoid useless recompression of compressed extents.
>
> Signed-off-by: Timofey Titovets <nefelim...@gmail.com>
> ---
>  fs/btrfs/ioctl.c | 28 +++++++++++++++++++++++++---
>  1 file changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index a990a9045139..0a5ea1ccc89d 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -1142,7 +1142,7 @@ static bool defrag_check_next_extent(struct inode 
> *inode, struct extent_map *em)
>
>  static int should_defrag_range(struct inode *inode, u64 start, u32 thresh,
>                                u64 *last_len, u64 *skip, u64 *defrag_end,
> -                              int compress)
> +                              int compress, int compress_type)
>  {
>         struct extent_map *em;
>         int ret = 1;
> @@ -1177,8 +1177,29 @@ static int should_defrag_range(struct inode *inode, 
> u64 start, u32 thresh,
>          * real extent, don't bother defragging it
>          */
>         if (!compress && (*last_len == 0 || *last_len >= thresh) &&
> -           (em->len >= thresh || (!next_mergeable && !prev_mergeable)))
> +           (em->len >= thresh || (!next_mergeable && !prev_mergeable))) {
>                 ret = 0;
> +               goto out;
> +       }
> +
> +
> +       /*
> +        * Try not recompress compressed extents
> +        * thresh >= BTRFS_MAX_UNCOMPRESSED will lead to
> +        * recompress all compressed extents
> +        */
> +       if (em->compress_type != 0 && thresh >= BTRFS_MAX_UNCOMPRESSED) {
> +               if (!compress) {
> +                       if (em->len == BTRFS_MAX_UNCOMPRESSED)
> +                               ret = 0;
> +               } else {
> +                       if (em->compress_type != compress_type)
> +                               goto out;
> +                       if (em->len == BTRFS_MAX_UNCOMPRESSED)
> +                               ret = 0;
> +               }
> +       }
> +
>  out:
>         /*
>          * last_len ends up being a counter of how many bytes we've defragged.
> @@ -1477,7 +1498,8 @@ int btrfs_defrag_file(struct inode *inode, struct file 
> *file,
>
>                 if (!should_defrag_range(inode, (u64)i << PAGE_SHIFT,
>                                          extent_thresh, &last_len, &skip,
> -                                        &defrag_end, do_compress)){
> +                                        &defrag_end, do_compress,
> +                                        compress_type)){
>                         unsigned long next;
>                         /*
>                          * the should_defrag function tells us how much to 
> skip
> --
> 2.19.0

Ok, If no one like that patch,
may be at least fix autodefarag on compressed files?
By change default extent target size 256K -> 128K?

-- 
Have a nice day,
Timofey.