From: Wang Xiaoguang <wangxg.f...@cn.fujitsu.com> Introduce static function inmem_del() to remove hash from in-memory dedupe tree. And implement btrfs_dedupe_del() and btrfs_dedup_disable() interfaces.
Also for btrfs_dedupe_disable(), add new functions to wait existing writer and block incoming writers to eliminate all possible race. Cc: Mark Fasheh <mfas...@suse.de> Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com> Signed-off-by: Wang Xiaoguang <wangxg.f...@cn.fujitsu.com> --- fs/btrfs/dedupe.c | 132 +++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 126 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/dedupe.c b/fs/btrfs/dedupe.c index a0911dcdf502..3232fe5ae530 100644 --- a/fs/btrfs/dedupe.c +++ b/fs/btrfs/dedupe.c @@ -175,12 +175,6 @@ int btrfs_dedupe_enable(struct btrfs_fs_info *fs_info, return ret; } -int btrfs_dedupe_disable(struct btrfs_fs_info *fs_info) -{ - /* Place holder for bisect, will be implemented in later patches */ - return 0; -} - static int inmem_insert_hash(struct rb_root *root, struct inmem_hash *hash, int hash_len) { @@ -323,3 +317,129 @@ int btrfs_dedupe_add(struct btrfs_trans_handle *trans, return inmem_add(dedupe_info, hash); return -EINVAL; } + +static struct inmem_hash * +inmem_search_bytenr(struct btrfs_dedupe_info *dedupe_info, u64 bytenr) +{ + struct rb_node **p = &dedupe_info->bytenr_root.rb_node; + struct rb_node *parent = NULL; + struct inmem_hash *entry = NULL; + + while (*p) { + parent = *p; + entry = rb_entry(parent, struct inmem_hash, bytenr_node); + + if (bytenr < entry->bytenr) + p = &(*p)->rb_left; + else if (bytenr > entry->bytenr) + p = &(*p)->rb_right; + else + return entry; + } + + return NULL; +} + +/* Delete a hash from in-memory dedupe tree */ +static int inmem_del(struct btrfs_dedupe_info *dedupe_info, u64 bytenr) +{ + struct inmem_hash *hash; + + mutex_lock(&dedupe_info->lock); + hash = inmem_search_bytenr(dedupe_info, bytenr); + if (!hash) { + mutex_unlock(&dedupe_info->lock); + return 0; + } + + __inmem_del(dedupe_info, hash); + mutex_unlock(&dedupe_info->lock); + return 0; +} + +/* Remove a dedupe hash from dedupe tree */ +int btrfs_dedupe_del(struct btrfs_trans_handle *trans, + struct btrfs_fs_info *fs_info, u64 bytenr) +{ + struct btrfs_dedupe_info *dedupe_info = fs_info->dedupe_info; + + if (!fs_info->dedupe_enabled) + return 0; + + if (WARN_ON(dedupe_info == NULL)) + return -EINVAL; + + if (dedupe_info->backend == BTRFS_DEDUPE_BACKEND_INMEMORY) + return inmem_del(dedupe_info, bytenr); + return -EINVAL; +} + +static void inmem_destroy(struct btrfs_dedupe_info *dedupe_info) +{ + struct inmem_hash *entry, *tmp; + + mutex_lock(&dedupe_info->lock); + list_for_each_entry_safe(entry, tmp, &dedupe_info->lru_list, lru_list) + __inmem_del(dedupe_info, entry); + mutex_unlock(&dedupe_info->lock); +} + +/* + * Helper function to wait and block all incoming writers + * + * Use rw_sem introduced for freeze to wait/block writers. + * So during the block time, no new write will happen, so we can + * do something quite safe, espcially helpful for dedupe disable, + * as it affect buffered write. + */ +static void block_all_writers(struct btrfs_fs_info *fs_info) +{ + struct super_block *sb = fs_info->sb; + + percpu_down_write(sb->s_writers.rw_sem + SB_FREEZE_WRITE - 1); + down_write(&sb->s_umount); +} + +static void unblock_all_writers(struct btrfs_fs_info *fs_info) +{ + struct super_block *sb = fs_info->sb; + + up_write(&sb->s_umount); + percpu_up_write(sb->s_writers.rw_sem + SB_FREEZE_WRITE - 1); +} + +int btrfs_dedupe_disable(struct btrfs_fs_info *fs_info) +{ + struct btrfs_dedupe_info *dedupe_info; + int ret; + + dedupe_info = fs_info->dedupe_info; + + if (!dedupe_info) + return 0; + + /* Don't allow disable status change in RO mount */ + if (fs_info->sb->s_flags & MS_RDONLY) + return -EROFS; + + /* + * Wait for all unfinished writers and block further writers. + * Then sync the whole fs so all current write will go through + * dedupe, and all later write won't go through dedupe. + */ + block_all_writers(fs_info); + ret = sync_filesystem(fs_info->sb); + fs_info->dedupe_enabled = 0; + fs_info->dedupe_info = NULL; + unblock_all_writers(fs_info); + if (ret < 0) + return ret; + + /* now we are OK to clean up everything */ + if (dedupe_info->backend == BTRFS_DEDUPE_BACKEND_INMEMORY) + inmem_destroy(dedupe_info); + + crypto_free_shash(dedupe_info->dedupe_driver); + kfree(dedupe_info); + return 0; +} -- 2.18.0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html