On Thu, Jan 14, 2016 at 8:54 AM, Qu Wenruo <quwenruo@xxxxxxxxxxxxxx> wrote:
> Now on-disk backend should be able to search hash now.
>
> Signed-off-by: Wang Xiaoguang <wangxg.fnst@xxxxxxxxxxxxxx>
> Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
> ---
> v4.1:
> Fix a stupid typo where info->hash_type should be info->backend.
> This makes on-disk backend almost unable to dedup.
Having test cases (xfstests) would avoid such simple errors... wouldn't it?
As in the reply I just sent for another patch:
"Take a look at the good example of xfs development. For example when
all the recent patches for their reflink implementation was posted
(and before getting merged), a comprehensive set of test cases for
xfstests was also posted..."
Test cases are a good thing :)
>
> ---
> fs/btrfs/dedup.c | 145 +++++++++++++++++++++++++++++++++++++++++++++++--------
> fs/btrfs/dedup.h | 3 ++
> 2 files changed, 127 insertions(+), 21 deletions(-)
>
> diff --git a/fs/btrfs/dedup.c b/fs/btrfs/dedup.c
> index c97823f..bee9589 100644
> --- a/fs/btrfs/dedup.c
> +++ b/fs/btrfs/dedup.c
> @@ -482,6 +482,79 @@ int btrfs_dedup_disable(struct btrfs_fs_info *fs_info)
> }
>
> /*
> + * Return 0 for not found
> + * Return >0 for found and set bytenr_ret
> + * Return <0 for error
> + */
> +static int ondisk_search_hash(struct btrfs_dedup_info *dedup_info, u8 *hash,
> + u64 *bytenr_ret, u32 *num_bytes_ret)
> +{
> + struct btrfs_path *path;
> + struct btrfs_key key;
> + struct btrfs_root *dedup_root = dedup_info->dedup_root;
> + u8 *buf = NULL;
> + u64 hash_key;
> + int hash_len = btrfs_dedup_sizes[dedup_info->hash_type];
> + int ret;
> +
> + path = btrfs_alloc_path();
> + if (!path)
> + return -ENOMEM;
> +
> + buf = kmalloc(hash_len, GFP_NOFS);
> + if (!buf) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + memcpy(&hash_key, hash + hash_len - 8, 8);
> + key.objectid = hash_key;
> + key.type = BTRFS_DEDUP_HASH_ITEM_KEY;
> + key.offset = (u64)-1;
> +
> + ret = btrfs_search_slot(NULL, dedup_root, &key, path, 0, 0);
> + if (ret < 0)
> + goto out;
> + WARN_ON(ret == 0);
> + while (1) {
> + struct extent_buffer *node;
> + struct btrfs_dedup_hash_item *hash_item;
> + int slot;
> +
> + ret = btrfs_previous_item(dedup_root, path, hash_key,
> + BTRFS_DEDUP_HASH_ITEM_KEY);
> + if (ret < 0)
> + goto out;
> + if (ret > 0) {
> + ret = 0;
> + goto out;
> + }
> +
> + node = path->nodes[0];
> + slot = path->slots[0];
> + btrfs_item_key_to_cpu(node, &key, slot);
> +
> + if (key.type != BTRFS_DEDUP_HASH_ITEM_KEY ||
> + memcmp(&key.objectid, hash + hash_len - 8, 8))
> + break;
> + hash_item = btrfs_item_ptr(node, slot,
> + struct btrfs_dedup_hash_item);
> + read_extent_buffer(node, buf, (unsigned long)(hash_item + 1),
> + hash_len);
> + if (!memcmp(buf, hash, hash_len)) {
> + ret = 1;
> + *bytenr_ret = key.offset;
> + *num_bytes_ret = btrfs_dedup_hash_len(node, hash_item);
> + break;
> + }
> + }
> +out:
> + kfree(buf);
> + btrfs_free_path(path);
> + return ret;
> +}
> +
> +/*
> * Caller must ensure the corresponding ref head is not being run.
> */
> static struct inmem_hash *
> @@ -511,7 +584,34 @@ inmem_search_hash(struct btrfs_dedup_info *dedup_info, u8 *hash)
> return NULL;
> }
>
> -static int inmem_search(struct inode *inode, u64 file_pos,
> +/* Wrapper for different backends, caller needs to hold dedup_info->lock */
> +static inline int generic_search_hash(struct btrfs_dedup_info *dedup_info,
> + u8 *hash, u64 *bytenr_ret,
> + u32 *num_bytes_ret)
> +{
> + if (dedup_info->backend == BTRFS_DEDUP_BACKEND_INMEMORY) {
> + struct inmem_hash *found_hash;
> + int ret;
> +
> + found_hash = inmem_search_hash(dedup_info, hash);
> + if (found_hash) {
> + ret = 1;
> + *bytenr_ret = found_hash->bytenr;
> + *num_bytes_ret = found_hash->num_bytes;
> + } else {
> + ret = 0;
> + *bytenr_ret = 0;
> + *num_bytes_ret = 0;
> + }
> + return ret;
> + } else if (dedup_info->backend == BTRFS_DEDUP_BACKEND_ONDISK) {
> + return ondisk_search_hash(dedup_info, hash, bytenr_ret,
> + num_bytes_ret);
> + }
> + return -EINVAL;
> +}
> +
> +static int generic_search(struct inode *inode, u64 file_pos,
> struct btrfs_dedup_hash *hash)
> {
> int ret;
> @@ -520,9 +620,9 @@ static int inmem_search(struct inode *inode, u64 file_pos,
> struct btrfs_trans_handle *trans;
> struct btrfs_delayed_ref_root *delayed_refs;
> struct btrfs_delayed_ref_head *head;
> - struct inmem_hash *found_hash;
> struct btrfs_dedup_info *dedup_info = fs_info->dedup_info;
> u64 bytenr;
> + u64 tmp_bytenr;
> u32 num_bytes;
>
> trans = btrfs_join_transaction(root);
> @@ -531,14 +631,9 @@ static int inmem_search(struct inode *inode, u64 file_pos,
>
> again:
> mutex_lock(&dedup_info->lock);
> - found_hash = inmem_search_hash(dedup_info, hash->hash);
> - /* If we don't find a duplicated extent, just return. */
> - if (!found_hash) {
> - ret = 0;
> + ret = generic_search_hash(dedup_info, hash->hash, &bytenr, &num_bytes);
> + if (ret <= 0)
> goto out;
> - }
> - bytenr = found_hash->bytenr;
> - num_bytes = found_hash->num_bytes;
>
> delayed_refs = &trans->transaction->delayed_refs;
>
> @@ -574,13 +669,21 @@ again:
> goto again;
>
> mutex_lock(&dedup_info->lock);
> - /* Search again to ensure the hash is still here */
> - found_hash = inmem_search_hash(dedup_info, hash->hash);
> - if (!found_hash) {
> - ret = 0;
> + /*
> + * Search again to ensure the hash is still here and bytenr didn't
> + * change
> + */
> + ret = generic_search_hash(dedup_info, hash->hash, &tmp_bytenr,
> + &num_bytes);
> + if (ret <= 0) {
> mutex_unlock(&head->mutex);
> goto out;
> }
> + if (tmp_bytenr != bytenr) {
> + mutex_unlock(&head->mutex);
> + mutex_unlock(&dedup_info->lock);
> + goto again;
> + }
> hash->bytenr = bytenr;
> hash->num_bytes = num_bytes;
>
> @@ -609,15 +712,15 @@ int btrfs_dedup_search(struct inode *inode, u64 file_pos,
> if (WARN_ON(!dedup_info || !hash))
> return 0;
>
> - if (dedup_info->backend == BTRFS_DEDUP_BACKEND_INMEMORY)
> - ret = inmem_search(inode, file_pos, hash);
> -
> - /* It's possible hash->bytenr/num_bytenr already changed */
> - if (ret == 0) {
> - hash->num_bytes = 0;
> - hash->bytenr = 0;
> + if (dedup_info->backend < BTRFS_DEDUP_BACKEND_LAST) {
> + ret = generic_search(inode, file_pos, hash);
> + if (ret == 0) {
> + hash->num_bytes = 0;
> + hash->bytenr = 0;
> + }
> + return ret;
> }
> - return ret;
> + return -EINVAL;
> }
>
> static int hash_data(struct btrfs_dedup_info *dedup_info, const char *data,
> diff --git a/fs/btrfs/dedup.h b/fs/btrfs/dedup.h
> index f23053c..3c08b86 100644
> --- a/fs/btrfs/dedup.h
> +++ b/fs/btrfs/dedup.h
> @@ -137,6 +137,9 @@ int btrfs_dedup_calc_hash(struct btrfs_root *root, struct inode *inode,
> * *INCREASED*, and hash->bytenr/num_bytes will record the existing
> * extent data.
> * Return 0 for a hash miss. Nothing is done
> + * Return <0 for error.
> + *
> + * Only on-disk backedn may return error though.
> */
> int btrfs_dedup_search(struct inode *inode, u64 file_pos,
> struct btrfs_dedup_hash *hash);
> --
> 2.7.0
>
>
>
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--
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"Reasonable men adapt themselves to the world.
Unreasonable men adapt the world to themselves.
That's why all progress depends on unreasonable men."
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