This patch have LOT of errors, sorry, please ignore it.
2015-10-21 4:11 GMT+03:00 Timofey Titovets <nefelim...@gmail.com>:
> It's just a proof of concept, and i hope to see feedback/ideas/review about
> it.
> ---
> While deduplication,
> Btrfs produce extent and file fragmentation
> But it's can be optimized by compute - which inode data placed a closest to
> beginning of hdd
> It's allow to:
> 1. Performance boost on hdd (beginning of disk faster then end)
> 2. Make sparse only on tail of fs, what can give boost later for
> balancing and resizing operations
>
> New function:
> static u64 btrfs_avg_disko(struct inode *inode,
> const u64 off, const u64 olen_aligned);
>
> It normalize offsets with data lengths, by represent it like offsets of
> blocks
> It return average data offset of all "pagesized" blocks in given range for
> inode
> Function cloned from btrfs_clone()
>
> Changes from V1:
> Added new function which compute "normal" offset
>
> Signed-off-by: Timofey Titovets <nefelim...@gmail.com>
> ---
> fs/btrfs/ioctl.c | 147
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 145 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 3e3e613..17e5313 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -86,6 +86,9 @@ struct btrfs_ioctl_received_subvol_args_32 {
> #endif
>
>
> +static u64 btrfs_avg_disko(struct inode *inode,
> + const u64 off, const u64 olen_aligned);
> +
> static int btrfs_clone(struct inode *src, struct inode *inode,
> u64 off, u64 olen, u64 olen_aligned, u64 destoff,
> int no_time_update);
> @@ -3074,8 +3077,20 @@ static int btrfs_extent_same(struct inode *src, u64
> loff, u64 olen,
>
> /* pass original length for comparison so we stay within i_size */
> ret = btrfs_cmp_data(src, loff, dst, dst_loff, olen, &cmp);
> - if (ret == 0)
> - ret = btrfs_clone(src, dst, loff, olen, len, dst_loff, 1);
> + if (ret == 0) {
> + /* prefer inode with lowest offset as source for clone*/
> + u64 src_weight;
> + u64 dst_weight;
> + src_weight = btrfs_avg_disko(src, off, olen);
> + dst_weight = btrfs_avg_disko(dest, dst_loff, olen);
> + /* if one of weight == 0 -> fallback */
> + if (dest_weight == 0)
> + src_weight = 0;
> + if (src_weight > dest_weight)
> + ret = btrfs_clone(dst, src, dst_loff, olen, len, loff, 1);
> + else
> + ret = btrfs_clone(src, dst, loff, olen, len, dst_loff, 1);
> + }
>
> if (same_inode)
> unlock_extent(&BTRFS_I(src)->io_tree, same_lock_start,
> @@ -3329,6 +3344,134 @@ static void clone_update_extent_map(struct inode
> *inode,
> }
>
> /**
> + * btrfs_avg_disko() - return avg data offset weight for inode
> + *
> + * @inode: Inode
> + * @off: Offset for computing
> + * @olen_aligned: Block-aligned len of data
> + *
> + * Computing avg address place of data, allow to heuristically
> + * determine where on the disk placed most fragment of data
> + */
> +static u64 btrfs_avg_disko(struct inode *inode,
> + const u64 off, const u64 olen_aligned)
> +{
> + struct btrfs_root *root = BTRFS_I(inode)->root;
> + struct btrfs_path *path = NULL;
> + struct extent_buffer *leaf;
> + char *buf = NULL;
> + struct btrfs_key key;
> + u32 nritems;
> + int slot;
> + int no_quota;
> + double sum = 0;
> + u64 ret = 0;
> + u64 counter = 0;
> +
> + buf = vmalloc(root->nodesize);
> + if (!buf)
> + return ret;
> +
> + path = btrfs_alloc_path();
> + if (!path) {
> + vfree(buf);
> + return ret;
> + }
> +
> + path->reada = 2;
> + /* clone data */
> + key.objectid = btrfs_ino(inode);
> + key.type = BTRFS_EXTENT_DATA_KEY;
> + key.offset = off;
> +
> + while (1) {
> + u64 next_key_min_offset = key.offset + 1;
> +
> + /*
> + * note the key will change type as we walk through the
> + * tree.
> + */
> + path->leave_spinning = 1;
> + ret = btrfs_search_slot(NULL, BTRFS_I(inode)->root, &key, path,
> 0, 0);
> + if (ret < 0)
> + goto out;
> + /*
> + * First search, if no extent item that starts at offset off was
> + * found but the previous item is an extent item, it's possible
> + * it might overlap our target range, therefore process it.
> + */
> + if (key.offset == off && ret > 0 && path->slots[0] > 0) {
> + btrfs_item_key_to_cpu(path->nodes[0], &key,
> + path->slots[0] - 1);
> + if (key.type == BTRFS_EXTENT_DATA_KEY)
> + path->slots[0]--;
> + }
> +
> + nritems = btrfs_header_nritems(path->nodes[0]);
> +process_slot:
> + no_quota = 1;
> + if (path->slots[0] >= nritems) {
> + ret = btrfs_next_leaf(BTRFS_I(inode)->root, path);
> + if (ret < 0)
> + goto out;
> + if (ret > 0)
> + break;
> + nritems = btrfs_header_nritems(path->nodes[0]);
> + }
> + leaf = path->nodes[0];
> + slot = path->slots[0];
> +
> + btrfs_item_key_to_cpu(leaf, &key, slot);
> + if (key.type > BTRFS_EXTENT_DATA_KEY ||
> + key.objectid != btrfs_ino(inode))
> + break;
> +
> + if (key.type == BTRFS_EXTENT_DATA_KEY) {
> + struct btrfs_file_extent_item *extent;
> + int type;
> + u64 disko = 0;
> + u64 diskl = 0;
> + u64 datal = 0;
> +
> + extent = btrfs_item_ptr(leaf, slot, struct
> btrfs_file_extent_item);
> + type = btrfs_file_extent_type(leaf, extent);
> + if (type == BTRFS_FILE_EXTENT_REG ||
> + type == BTRFS_FILE_EXTENT_PREALLOC) {
> + disko = btrfs_file_extent_disk_bytenr(leaf, extent);
> + diskl = btrfs_file_extent_disk_num_bytes(leaf, extent);
> + datal = btrfs_file_extent_num_bytes(leaf, extent);
> + }
> +
> + /*
> + * The first search might have left us at an extent
> + * item that ends before our target range's start, can
> + * happen if we have holes and NO_HOLES feature enabled.
> + */
> + if (key.offset + datal <= off) {
> + path->slots[0]++;
> + goto process_slot;
> + } else if (key.offset >= off + olen_aligned) {
> + break;
> + }
> + next_key_min_offset = key.offset + datal;
> +
> + for (;diskl >= 0; diskl -= pagesize) {
> + sum += disko+diskl;
> + counter++;
> + }
> +
> + btrfs_release_path(path);
> + path->leave_spinning = 0;
> + }
> +
> +out:
> + ret = sum/counter;
> + btrfs_free_path(path);
> + vfree(buf);
> + return ret;
> +}
> +
> +/**
> * btrfs_clone() - clone a range from inode file to another
> *
> * @src: Inode to clone from
> --
> 2.6.1
>
>
--
Have a nice day,
Timofey.
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