вт, 18 сент. 2018 г. в 13:09, Timofey Titovets <timofey.titovets@xxxxxxxxxx>:
>
> From: Timofey Titovets <nefelim4ag@xxxxxxxxx>
>
> 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 <nefelim4ag@xxxxxxxxx>
> ---
> 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.
