Hello,
This patch simplifies the nodatacow checker. If all references
were created after the latest snapshot, then we can avoid COW
safely. This patch also updates run_delalloc_nocow to do more
fine-grained checking.
Regards
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
---
diff -urp 3/fs/btrfs/ctree.h 4/fs/btrfs/ctree.h
--- 3/fs/btrfs/ctree.h 2008-10-30 13:06:26.000000000 +0800
+++ 4/fs/btrfs/ctree.h 2008-10-30 13:45:33.000000000 +0800
@@ -454,6 +454,7 @@ struct btrfs_root_item {
__le64 bytenr;
__le64 byte_limit;
__le64 bytes_used;
+ __le64 last_snapshot;
__le32 flags;
__le32 refs;
struct btrfs_disk_key drop_progress;
@@ -1413,6 +1414,8 @@ BTRFS_SETGET_STACK_FUNCS(root_refs, stru
BTRFS_SETGET_STACK_FUNCS(root_flags, struct btrfs_root_item, flags, 32);
BTRFS_SETGET_STACK_FUNCS(root_used, struct btrfs_root_item, bytes_used, 64);
BTRFS_SETGET_STACK_FUNCS(root_limit, struct btrfs_root_item, byte_limit, 64);
+BTRFS_SETGET_STACK_FUNCS(root_last_snapshot, struct btrfs_root_item,
+ last_snapshot, 64);
/* struct btrfs_super_block */
BTRFS_SETGET_STACK_FUNCS(super_bytenr, struct btrfs_super_block, bytenr, 64);
@@ -1564,9 +1567,8 @@ int btrfs_update_pinned_extents(struct b
u64 bytenr, u64 num, int pin);
int btrfs_drop_leaf_ref(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *leaf);
-int btrfs_cross_ref_exists(struct btrfs_trans_handle *trans,
- struct btrfs_root *root,
- struct btrfs_key *key, u64 bytenr);
+int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, u64 bytenr);
int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy);
diff -urp 3/fs/btrfs/extent-tree.c 4/fs/btrfs/extent-tree.c
--- 3/fs/btrfs/extent-tree.c 2008-10-30 15:22:16.000000000 +0800
+++ 4/fs/btrfs/extent-tree.c 2008-10-30 15:21:55.000000000 +0800
@@ -848,9 +848,8 @@ out:
return 0;
}
-static int get_reference_status(struct btrfs_root *root, u64 bytenr,
- u64 parent_gen, u64 ref_objectid,
- u64 *min_generation, u32 *ref_count)
+int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, u64 bytenr)
{
struct btrfs_root *extent_root = root->fs_info->extent_root;
struct btrfs_path *path;
@@ -858,8 +857,8 @@ static int get_reference_status(struct b
struct btrfs_extent_ref *ref_item;
struct btrfs_key key;
struct btrfs_key found_key;
- u64 root_objectid = root->root_key.objectid;
- u64 ref_generation;
+ u64 ref_root;
+ u64 last_snapshot;
u32 nritems;
int ret;
@@ -872,7 +871,9 @@ static int get_reference_status(struct b
if (ret < 0)
goto out;
BUG_ON(ret == 0);
- if (ret < 0 || path->slots[0] == 0)
+
+ ret = -ENOENT;
+ if (path->slots[0] == 0)
goto out;
path->slots[0]--;
@@ -880,14 +881,10 @@ static int get_reference_status(struct b
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
if (found_key.objectid != bytenr ||
- found_key.type != BTRFS_EXTENT_ITEM_KEY) {
- ret = 1;
+ found_key.type != BTRFS_EXTENT_ITEM_KEY)
goto out;
- }
-
- *ref_count = 0;
- *min_generation = (u64)-1;
+ last_snapshot = btrfs_root_last_snapshot(&root->root_item);
while (1) {
leaf = path->nodes[0];
nritems = btrfs_header_nritems(leaf);
@@ -910,114 +907,22 @@ static int get_reference_status(struct b
ref_item = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_extent_ref);
- ref_generation = btrfs_ref_generation(leaf, ref_item);
- /*
- * For (parent_gen > 0 && parent_gen > ref_generation):
- *
- * we reach here through the oldest root, therefore
- * all other reference from same snapshot should have
- * a larger generation.
- */
- if ((root_objectid != btrfs_ref_root(leaf, ref_item)) ||
- (parent_gen > 0 && parent_gen > ref_generation) ||
- (ref_objectid >= BTRFS_FIRST_FREE_OBJECTID &&
- ref_objectid != btrfs_ref_objectid(leaf, ref_item))) {
- *ref_count = 2;
- break;
- }
-
- *ref_count = 1;
- if (*min_generation > ref_generation)
- *min_generation = ref_generation;
-
- path->slots[0]++;
- }
- ret = 0;
-out:
- btrfs_free_path(path);
- return ret;
-}
-
-int btrfs_cross_ref_exists(struct btrfs_trans_handle *trans,
- struct btrfs_root *root,
- struct btrfs_key *key, u64 bytenr)
-{
- struct btrfs_root *old_root;
- struct btrfs_path *path = NULL;
- struct extent_buffer *eb;
- struct btrfs_file_extent_item *item;
- u64 ref_generation;
- u64 min_generation;
- u64 extent_start;
- u32 ref_count;
- int level;
- int ret;
-
- BUG_ON(trans == NULL);
- BUG_ON(key->type != BTRFS_EXTENT_DATA_KEY);
- ret = get_reference_status(root, bytenr, 0, key->objectid,
- &min_generation, &ref_count);
- if (ret)
- return ret;
-
- if (ref_count != 1)
- return 1;
-
- old_root = root->dirty_root->root;
- ref_generation = old_root->root_key.offset;
-
- /* all references are created in running transaction */
- if (min_generation > ref_generation) {
- ret = 0;
- goto out;
- }
-
- path = btrfs_alloc_path();
- if (!path) {
- ret = -ENOMEM;
- goto out;
- }
-
- path->skip_locking = 1;
- /* if no item found, the extent is referenced by other snapshot */
- ret = btrfs_search_slot(NULL, old_root, key, path, 0, 0);
- if (ret)
- goto out;
-
- eb = path->nodes[0];
- item = btrfs_item_ptr(eb, path->slots[0],
- struct btrfs_file_extent_item);
- if (btrfs_file_extent_type(eb, item) != BTRFS_FILE_EXTENT_REG ||
- btrfs_file_extent_disk_bytenr(eb, item) != bytenr) {
- ret = 1;
- goto out;
- }
-
- for (level = BTRFS_MAX_LEVEL - 1; level >= -1; level--) {
- if (level >= 0) {
- eb = path->nodes[level];
- if (!eb)
- continue;
- extent_start = eb->start;
- } else
- extent_start = bytenr;
-
- ret = get_reference_status(root, extent_start, ref_generation,
- 0, &min_generation, &ref_count);
- if (ret)
+ ref_root = btrfs_ref_root(leaf, ref_item);
+ if (ref_root != root->root_key.objectid &&
+ ref_root != BTRFS_TREE_LOG_OBJECTID) {
+ ret = 1;
goto out;
-
- if (ref_count != 1) {
+ }
+ if (btrfs_ref_generation(leaf, ref_item) <= last_snapshot) {
ret = 1;
goto out;
}
- if (level >= 0)
- ref_generation = btrfs_header_generation(eb);
+
+ path->slots[0]++;
}
ret = 0;
out:
- if (path)
- btrfs_free_path(path);
+ btrfs_free_path(path);
return ret;
}
diff -urp 3/fs/btrfs/inode.c 4/fs/btrfs/inode.c
--- 3/fs/btrfs/inode.c 2008-10-30 15:48:35.000000000 +0800
+++ 4/fs/btrfs/inode.c 2008-10-30 15:48:49.000000000 +0800
@@ -298,6 +298,7 @@ static int cow_file_range(struct inode *
unsigned long max_compressed = 128 * 1024;
unsigned long max_uncompressed = 256 * 1024;
int i;
+ int ordered_type;
int will_compress;
trans = btrfs_join_transaction(root, 1);
@@ -491,9 +492,10 @@ again:
}
cur_alloc_size = ins.offset;
+ ordered_type = will_compress ? BTRFS_ORDERED_COMPRESSED : 0;
ret = btrfs_add_ordered_extent(inode, start, ins.objectid,
- ram_size, cur_alloc_size, 0,
- will_compress);
+ ram_size, cur_alloc_size,
+ ordered_type);
BUG_ON(ret);
if (disk_num_bytes < cur_alloc_size) {
@@ -587,115 +589,148 @@ free_pages_out:
static int run_delalloc_nocow(struct inode *inode, struct page *locked_page,
u64 start, u64 end, int *page_started)
{
- u64 extent_start;
- u64 extent_end;
- u64 bytenr;
- u64 loops = 0;
- u64 total_fs_bytes;
struct btrfs_root *root = BTRFS_I(inode)->root;
- struct btrfs_block_group_cache *block_group;
struct btrfs_trans_handle *trans;
struct extent_buffer *leaf;
- int found_type;
struct btrfs_path *path;
- struct btrfs_file_extent_item *item;
- int ret;
- int err = 0;
+ struct btrfs_file_extent_item *fi;
struct btrfs_key found_key;
+ u64 cow_start;
+ u64 cur_offset;
+ u64 extent_end;
+ u64 disk_bytenr;
+ u64 num_bytes;
+ int extent_type;
+ int ret;
+ int nocow;
+ int check_prev = 1;
- total_fs_bytes =
btrfs_super_total_bytes(&root->fs_info->super_copy);
path = btrfs_alloc_path();
BUG_ON(!path);
trans = btrfs_join_transaction(root, 1);
BUG_ON(!trans);
-again:
- ret = btrfs_lookup_file_extent(NULL, root, path,
- inode->i_ino, start, 0);
- if (ret < 0) {
- err = ret;
- goto out;
- }
- 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) {
- u64 extent_num_bytes;
-
- extent_num_bytes = btrfs_file_extent_num_bytes(leaf, item);
- extent_end = extent_start + extent_num_bytes;
- err = 0;
-
- if (btrfs_file_extent_compression(leaf, item) ||
- btrfs_file_extent_encryption(leaf,item) ||
- btrfs_file_extent_other_encoding(leaf, item))
- goto not_found;
-
- if (loops && start != extent_start)
- goto not_found;
+ cow_start = (u64)-1;
+ cur_offset = start;
+ while (1) {
+ ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
+ cur_offset, 0);
+ BUG_ON(ret < 0);
+ if (ret > 0 && path->slots[0] > 0 && check_prev) {
+ leaf = path->nodes[0];
+ btrfs_item_key_to_cpu(leaf, &found_key,
+ path->slots[0] - 1);
+ if (found_key.objectid == inode->i_ino &&
+ found_key.type == BTRFS_EXTENT_DATA_KEY)
+ path->slots[0]--;
+ }
+ check_prev = 0;
+next_slot:
+ leaf = path->nodes[0];
+ if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+ ret = btrfs_next_leaf(root, path);
+ if (ret < 0)
+ BUG_ON(1);
+ if (ret > 0)
+ break;
+ leaf = path->nodes[0];
+ }
- if (start < extent_start || start >= extent_end)
- goto not_found;
+ nocow = 0;
+ disk_bytenr = 0;
+ btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
- bytenr = btrfs_file_extent_disk_bytenr(leaf, item);
- if (bytenr == 0)
- goto not_found;
+ if (found_key.objectid > inode->i_ino ||
+ found_key.type > BTRFS_EXTENT_DATA_KEY ||
+ found_key.offset > end)
+ break;
- if (btrfs_cross_ref_exists(trans, root, &found_key, bytenr))
- goto not_found;
- /*
- * we may be called by the resizer, make sure we''re inside
- * the limits of the FS
- */
- block_group = btrfs_lookup_block_group(root->fs_info,
- bytenr);
- if (!block_group || block_group->ro)
- goto not_found;
+ if (found_key.offset > cur_offset) {
+ extent_end = found_key.offset;
+ goto out_check;
+ }
- bytenr += btrfs_file_extent_offset(leaf, item);
- extent_num_bytes = min(end + 1, extent_end) - start;
- ret = btrfs_add_ordered_extent(inode, start, bytenr,
- extent_num_bytes,
- extent_num_bytes, 1, 0);
- if (ret) {
- err = ret;
- goto out;
+ fi = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_file_extent_item);
+ extent_type = btrfs_file_extent_type(leaf, fi);
+
+ if (extent_type == BTRFS_FILE_EXTENT_REG) {
+ struct btrfs_block_group_cache *block_group;
+ disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
+ extent_end = found_key.offset +
+ btrfs_file_extent_num_bytes(leaf, fi);
+ if (extent_end <= start) {
+ path->slots[0]++;
+ goto next_slot;
+ }
+ if (btrfs_file_extent_compression(leaf, fi) ||
+ btrfs_file_extent_encryption(leaf, fi) ||
+ btrfs_file_extent_other_encoding(leaf, fi))
+ goto out_check;
+ if (disk_bytenr == 0)
+ goto out_check;
+ if (btrfs_cross_ref_exist(trans, root, disk_bytenr))
+ goto out_check;
+ block_group = btrfs_lookup_block_group(root->fs_info,
+ disk_bytenr);
+ if (!block_group || block_group->ro)
+ goto out_check;
+ disk_bytenr += btrfs_file_extent_offset(leaf, fi);
+ nocow = 1;
+ } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+ extent_end = found_key.offset +
+ btrfs_file_extent_inline_len(leaf, fi);
+ extent_end = ALIGN(extent_end, root->sectorsize);
+ } else {
+ BUG_ON(1);
+ }
+out_check:
+ if (extent_end <= start) {
+ path->slots[0]++;
+ goto next_slot;
+ }
+ if (!nocow) {
+ if (cow_start == (u64)-1)
+ cow_start = cur_offset;
+ cur_offset = extent_end;
+ if (cur_offset > end)
+ break;
+ path->slots[0]++;
+ goto next_slot;
}
btrfs_release_path(root, path);
- start = extent_end;
- if (start <= end) {
- loops++;
- goto again;
+ if (cow_start != (u64)-1) {
+ ret = cow_file_range(inode, locked_page, cow_start,
+ found_key.offset - 1, page_started);
+ BUG_ON(ret);
+ cow_start = (u64)-1;
}
- } else {
-not_found:
- btrfs_end_transaction(trans, root);
- btrfs_free_path(path);
- return cow_file_range(inode, locked_page, start, end,
- page_started);
+
+ disk_bytenr += cur_offset - found_key.offset;
+ num_bytes = min(end + 1, extent_end) - cur_offset;
+
+ ret = btrfs_add_ordered_extent(inode, cur_offset, disk_bytenr,
+ num_bytes, num_bytes,
+ BTRFS_ORDERED_NOCOW);
+ cur_offset = extent_end;
+ if (cur_offset > end)
+ break;
}
-out:
- WARN_ON(err);
- btrfs_end_transaction(trans, root);
+ btrfs_release_path(root, path);
+
+ if (cur_offset <= end && cow_start == (u64)-1)
+ cow_start = cur_offset;
+ if (cow_start != (u64)-1) {
+ ret = cow_file_range(inode, locked_page, cow_start, end,
+ page_started);
+ BUG_ON(ret);
+ }
+
+ ret = btrfs_end_transaction(trans, root);
+ BUG_ON(ret);
btrfs_free_path(path);
- return err;
+ return 0;
}
/*
diff -urp 3/fs/btrfs/ioctl.c 4/fs/btrfs/ioctl.c
--- 3/fs/btrfs/ioctl.c 2008-10-30 07:22:02.000000000 +0800
+++ 4/fs/btrfs/ioctl.c 2008-10-30 15:58:12.000000000 +0800
@@ -112,6 +112,7 @@ static noinline int create_subvol(struct
btrfs_set_root_level(&root_item, 0);
btrfs_set_root_refs(&root_item, 1);
btrfs_set_root_used(&root_item, 0);
+ btrfs_set_root_last_snapshot(&root_item, 0);
memset(&root_item.drop_progress, 0, sizeof(root_item.drop_progress));
root_item.drop_level = 0;
diff -urp 3/fs/btrfs/ordered-data.c 4/fs/btrfs/ordered-data.c
--- 3/fs/btrfs/ordered-data.c 2008-10-30 07:22:02.000000000 +0800
+++ 4/fs/btrfs/ordered-data.c 2008-10-30 14:11:17.000000000 +0800
@@ -165,8 +165,7 @@ static inline struct rb_node *tree_searc
* inserted.
*/
int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
- u64 start, u64 len, u64 disk_len, int nocow,
- int compressed)
+ u64 start, u64 len, u64 disk_len, int type)
{
struct btrfs_ordered_inode_tree *tree;
struct rb_node *node;
@@ -183,10 +182,8 @@ int btrfs_add_ordered_extent(struct inod
entry->len = len;
entry->disk_len = disk_len;
entry->inode = inode;
- if (nocow)
- set_bit(BTRFS_ORDERED_NOCOW, &entry->flags);
- if (compressed)
- set_bit(BTRFS_ORDERED_COMPRESSED, &entry->flags);
+ if (type == BTRFS_ORDERED_NOCOW || type == BTRFS_ORDERED_COMPRESSED)
+ set_bit(type, &entry->flags);
/* one ref for the tree */
atomic_set(&entry->refs, 1);
diff -urp 3/fs/btrfs/ordered-data.h 4/fs/btrfs/ordered-data.h
--- 3/fs/btrfs/ordered-data.h 2008-10-30 07:22:02.000000000 +0800
+++ 4/fs/btrfs/ordered-data.h 2008-10-30 15:56:37.000000000 +0800
@@ -132,8 +132,7 @@ int btrfs_remove_ordered_extent(struct i
int btrfs_dec_test_ordered_pending(struct inode *inode,
u64 file_offset, u64 io_size);
int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
- u64 start, u64 len, u64 disk_len, int nocow,
- int compressed);
+ u64 start, u64 len, u64 disk_len, int type);
int btrfs_add_ordered_sum(struct inode *inode,
struct btrfs_ordered_extent *entry,
struct btrfs_ordered_sum *sum);
diff -urp 3/fs/btrfs/transaction.c 4/fs/btrfs/transaction.c
--- 3/fs/btrfs/transaction.c 2008-10-30 07:22:02.000000000 +0800
+++ 4/fs/btrfs/transaction.c 2008-10-30 15:57:16.000000000 +0800
@@ -751,6 +751,8 @@ static noinline int create_pending_snaps
if (ret)
goto fail;
+ btrfs_record_root_in_trans(root);
+ btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
key.objectid = objectid;
--
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