From be20aa9dbadc8c06283784ee12bbc0d97dea3418 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Mon, 17 Dec 2007 20:14:01 -0500 Subject: [PATCH] Btrfs: Add mount option to turn off data cow A number of workloads do not require copy on write data or checksumming. mount -o nodatasum to disable checksums and -o nodatacow to disable both copy on write and checksumming. In nodatacow mode, copy on write is still performed when a given extent is under snapshot. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 53 +++++++++++++++++- fs/btrfs/ctree.h | 8 +++ fs/btrfs/extent-tree.c | 101 +++++++++++++++++++++++++++++++++- fs/btrfs/inode.c | 122 ++++++++++++++++++++++++++++++++++++----- fs/btrfs/super.c | 34 +++++++++--- 5 files changed, 293 insertions(+), 25 deletions(-) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index fd8233e05cf4..585f279d1112 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -70,7 +70,58 @@ void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p) memset(p, 0, sizeof(*p)); } -static int __btrfs_cow_block(struct btrfs_trans_handle *trans, +int btrfs_copy_root(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct extent_buffer *buf, + struct extent_buffer **cow_ret, u64 new_root_objectid) +{ + struct extent_buffer *cow; + u32 nritems; + int ret = 0; + int level; + struct btrfs_key first_key; + struct btrfs_root new_root; + + memcpy(&new_root, root, sizeof(new_root)); + new_root.root_key.objectid = new_root_objectid; + + WARN_ON(root->ref_cows && trans->transid != + root->fs_info->running_transaction->transid); + WARN_ON(root->ref_cows && trans->transid != root->last_trans); + + level = btrfs_header_level(buf); + nritems = btrfs_header_nritems(buf); + if (nritems) { + if (level == 0) + btrfs_item_key_to_cpu(buf, &first_key, 0); + else + btrfs_node_key_to_cpu(buf, &first_key, 0); + } else { + first_key.objectid = 0; + } + cow = __btrfs_alloc_free_block(trans, &new_root, buf->len, + new_root_objectid, + trans->transid, first_key.objectid, + level, buf->start, 0); + if (IS_ERR(cow)) + return PTR_ERR(cow); + + copy_extent_buffer(cow, buf, 0, 0, cow->len); + btrfs_set_header_bytenr(cow, cow->start); + btrfs_set_header_generation(cow, trans->transid); + btrfs_set_header_owner(cow, new_root_objectid); + + WARN_ON(btrfs_header_generation(buf) > trans->transid); + ret = btrfs_inc_ref(trans, &new_root, buf); + if (ret) + return ret; + + btrfs_mark_buffer_dirty(cow); + *cow_ret = cow; + return 0; +} + +int __btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer *parent, int parent_slot, diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 5e255cabfd10..b51b021fff85 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -431,6 +431,7 @@ struct btrfs_root { #define BTRFS_STRING_ITEM_KEY 253 #define BTRFS_MOUNT_NODATASUM 0x1 +#define BTRFS_MOUNT_NODATACOW 0x2 #define btrfs_clear_opt(o, opt) ((o) &= ~BTRFS_MOUNT_##opt) #define btrfs_set_opt(o, opt) ((o) |= BTRFS_MOUNT_##opt) @@ -915,6 +916,9 @@ static inline u32 btrfs_level_size(struct btrfs_root *root, int level) { btrfs_item_offset_nr(leaf, slot))) /* extent-tree.c */ +u32 btrfs_count_snapshots_in_path(struct btrfs_root *root, + struct btrfs_path *count_path, + u64 first_extent); int btrfs_extent_post_op(struct btrfs_trans_handle *trans, struct btrfs_root *root); int btrfs_copy_pinned(struct btrfs_root *root, struct extent_map_tree *copy); @@ -974,6 +978,10 @@ int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer *parent, int parent_slot, struct extent_buffer **cow_ret); +int btrfs_copy_root(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + struct extent_buffer *buf, + struct extent_buffer **cow_ret, u64 new_root_objectid); int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, u32 data_size); int btrfs_truncate_item(struct btrfs_trans_handle *trans, diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 00414836e963..1412d556313f 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -679,6 +679,104 @@ out: return 0; } +u32 btrfs_count_snapshots_in_path(struct btrfs_root *root, + struct btrfs_path *count_path, + u64 first_extent) +{ + struct btrfs_root *extent_root = root->fs_info->extent_root; + struct btrfs_path *path; + u64 bytenr; + u64 found_objectid; + u64 root_objectid = 0; + u32 total_count = 0; + u32 cur_count; + u32 refs; + u32 nritems; + int ret; + struct btrfs_key key; + struct btrfs_key found_key; + struct extent_buffer *l; + struct btrfs_extent_item *item; + struct btrfs_extent_ref *ref_item; + int level = -1; + + path = btrfs_alloc_path(); +again: + if (level == -1) + bytenr = first_extent; + else + bytenr = count_path->nodes[level]->start; + + cur_count = 0; + key.objectid = bytenr; + key.offset = 0; + + btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY); + ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0); + if (ret < 0) + goto out; + BUG_ON(ret == 0); + + l = path->nodes[0]; + btrfs_item_key_to_cpu(l, &found_key, path->slots[0]); + + if (found_key.objectid != bytenr || + found_key.type != BTRFS_EXTENT_ITEM_KEY) { + goto out; + } + + item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item); + refs = btrfs_extent_refs(l, item); + while (1) { + nritems = btrfs_header_nritems(l); + if (path->slots[0] >= nritems) { + ret = btrfs_next_leaf(extent_root, path); + if (ret == 0) + continue; + break; + } + btrfs_item_key_to_cpu(l, &found_key, path->slots[0]); + if (found_key.objectid != bytenr) + break; + if (found_key.type != BTRFS_EXTENT_REF_KEY) { + path->slots[0]++; + continue; + } + + cur_count++; + ref_item = btrfs_item_ptr(l, path->slots[0], + struct btrfs_extent_ref); + found_objectid = btrfs_ref_root(l, ref_item); + + if (found_objectid != root_objectid) + total_count++; + + if (total_count > 1) + goto out; + + if (root_objectid == 0) + root_objectid = found_objectid; + + path->slots[0]++; + } + if (cur_count == 0) { + total_count = 0; + goto out; + } + if (total_count > 1) + goto out; + if (level >= 0 && root->node == count_path->nodes[level]) + goto out; + level++; + btrfs_release_path(root, path); + goto again; + +out: + btrfs_free_path(path); + return total_count; + +} + int btrfs_inc_root_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root, u64 owner_objectid) { @@ -1127,9 +1225,6 @@ static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root if (!path) return -ENOMEM; - if (ref_generation && owner_objectid == 0 && root_objectid == 3) { -//printk("drop backref root %Lu gen %Lu byte %Lu\n", root_objectid, ref_generation, bytenr ); - } ret = lookup_extent_backref(trans, extent_root, path, bytenr, root_objectid, ref_generation, diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 11885cb114e2..91f3fc43e2a9 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -72,21 +72,22 @@ static unsigned char btrfs_type_by_mode[S_IFMT >> S_SHIFT] = { [S_IFLNK >> S_SHIFT] = BTRFS_FT_SYMLINK, }; -static int run_delalloc_range(struct inode *inode, u64 start, u64 end) +static int cow_file_range(struct inode *inode, u64 start, u64 end) { struct btrfs_root *root = BTRFS_I(inode)->root; struct btrfs_trans_handle *trans; - struct btrfs_key ins; u64 alloc_hint = 0; u64 num_bytes; - int ret; u64 blocksize = root->sectorsize; + struct btrfs_key ins; + int ret; - mutex_lock(&root->fs_info->fs_mutex); trans = btrfs_start_transaction(root, 1); - btrfs_set_trans_block_group(trans, inode); BUG_ON(!trans); + btrfs_set_trans_block_group(trans, inode); + num_bytes = (end - start + blocksize) & ~(blocksize - 1); + num_bytes = max(blocksize, num_bytes); ret = btrfs_drop_extents(trans, root, inode, start, start + num_bytes, start, &alloc_hint); @@ -106,6 +107,101 @@ static int run_delalloc_range(struct inode *inode, u64 start, u64 end) ins.offset); out: btrfs_end_transaction(trans, root); + return ret; +} + +static int run_delalloc_nocow(struct inode *inode, u64 start, u64 end) +{ + u64 extent_start; + u64 extent_end; + u64 bytenr; + u64 cow_end; + struct btrfs_root *root = BTRFS_I(inode)->root; + struct extent_buffer *leaf; + int found_type; + struct btrfs_path *path; + struct btrfs_file_extent_item *item; + int ret; + int err; + struct btrfs_key found_key; + + path = btrfs_alloc_path(); + BUG_ON(!path); +again: + ret = btrfs_lookup_file_extent(NULL, root, path, + inode->i_ino, start, 0); + if (ret < 0) { + btrfs_free_path(path); + return ret; + } + + cow_end = end; + if (ret != 0) { + if (path->slots[0] == 0) + goto not_found; + path->slots[0]--; + } + + leaf = path->nodes[0]; + item = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + + /* are we inside the extent that was found? */ + btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); + found_type = btrfs_key_type(&found_key); + if (found_key.objectid != inode->i_ino || + found_type != BTRFS_EXTENT_DATA_KEY) { + goto not_found; + } + + found_type = btrfs_file_extent_type(leaf, item); + extent_start = found_key.offset; + if (found_type == BTRFS_FILE_EXTENT_REG) { + extent_end = extent_start + + btrfs_file_extent_num_bytes(leaf, item); + err = 0; + + if (start < extent_start || start >= extent_end) + goto not_found; + + cow_end = min(end, extent_end - 1); + bytenr = btrfs_file_extent_disk_bytenr(leaf, item); + if (bytenr == 0) + goto not_found; + + bytenr += btrfs_file_extent_offset(leaf, item); + if (btrfs_count_snapshots_in_path(root, path, bytenr) != 1) { + goto not_found; + } + + start = extent_end; + } else if (found_type == BTRFS_FILE_EXTENT_INLINE) { + goto not_found; + } +loop: + if (start > end) { + btrfs_free_path(path); + return 0; + } + btrfs_release_path(root, path); + goto again; + +not_found: + cow_file_range(inode, start, cow_end); + start = cow_end + 1; + goto loop; +} + +static int run_delalloc_range(struct inode *inode, u64 start, u64 end) +{ + struct btrfs_root *root = BTRFS_I(inode)->root; + int ret; + + mutex_lock(&root->fs_info->fs_mutex); + if (btrfs_test_opt(root, NODATACOW)) + ret = run_delalloc_nocow(inode, start, end); + else + ret = cow_file_range(inode, start, end); mutex_unlock(&root->fs_info->fs_mutex); return ret; } @@ -1907,9 +2003,6 @@ int btrfs_commit_write(struct file *file, struct page *page, btrfs_cow_one_page(inode, page, PAGE_CACHE_SIZE); - set_page_extent_mapped(page); - set_page_dirty(page); - if (pos > inode->i_size) { i_size_write(inode, pos); mark_inode_dirty(inode); @@ -2078,13 +2171,18 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen) key.objectid = objectid; key.offset = 1; btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY); + extent_buffer_get(root->node); btrfs_cow_block(trans, root, root->node, NULL, 0, &tmp); free_extent_buffer(tmp); - btrfs_set_root_bytenr(&new_root_item, root->node->start); - btrfs_set_root_level(&new_root_item, btrfs_header_level(root->node)); + + btrfs_copy_root(trans, root, root->node, &tmp, objectid); + + btrfs_set_root_bytenr(&new_root_item, tmp->start); + btrfs_set_root_level(&new_root_item, btrfs_header_level(tmp)); ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key, &new_root_item); + free_extent_buffer(tmp); if (ret) goto fail; @@ -2106,10 +2204,6 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen) if (ret) goto fail; - - ret = btrfs_inc_root_ref(trans, root, objectid); - if (ret) - goto fail; fail: nr = trans->blocks_used; err = btrfs_commit_transaction(trans, root); diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index ad4f280ec777..2116728d1f98 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -61,12 +61,13 @@ static void btrfs_put_super (struct super_block * sb) } enum { - Opt_subvol, Opt_nodatasum, Opt_err, + Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_err, }; static match_table_t tokens = { {Opt_subvol, "subvol=%s"}, {Opt_nodatasum, "nodatasum"}, + {Opt_nodatacow, "nodatacow"}, {Opt_err, NULL} }; @@ -78,12 +79,20 @@ static int parse_options (char * options, struct btrfs_fs_info *info = NULL; substring_t args[MAX_OPT_ARGS]; - if (root) - info = root->fs_info; - if (!options) return 1; + /* + * strsep changes the string, duplicate it because parse_options + * gets called twice + */ + options = kstrdup(options, GFP_NOFS); + if (!options) + return -ENOMEM; + + if (root) + info = root->fs_info; + while ((p = strsep (&options, ",")) != NULL) { int token; if (!*p) @@ -92,17 +101,28 @@ static int parse_options (char * options, token = match_token(p, tokens, args); switch (token) { case Opt_subvol: - if (subvol_name) + if (subvol_name) { *subvol_name = match_strdup(&args[0]); + } break; case Opt_nodatasum: - if (root) + if (info) { + printk("btrfs: setting nodatacsum\n"); btrfs_set_opt(info->mount_opt, NODATASUM); + } + break; + case Opt_nodatacow: + if (info) { + printk("btrfs: setting nodatacow\n"); + btrfs_set_opt(info->mount_opt, NODATACOW); + btrfs_set_opt(info->mount_opt, NODATASUM); + } break; default: - return 0; + break; } } + kfree(options); return 1; } -- 2.34.1