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Btrfs: update nodatacow code v2

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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.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This commit is contained in:
Yan Zheng 2008-10-30 14:20:02 -04:00 committed by Chris Mason
parent 6643558db2
commit 80ff385665
7 changed files with 154 additions and 213 deletions
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8
fs/btrfs/ctree.h
View File

@ -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, struct btrfs_root_item, refs, 32);
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 btrfs_root *root,
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);

131
fs/btrfs/extent-tree.c
View File

@ -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 btrfs_root *root, u64 bytenr,
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 btrfs_root *root, u64 bytenr,
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 btrfs_root *root, u64 bytenr,
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);
@ -910,25 +907,16 @@ static int get_reference_status(struct btrfs_root *root, u64 bytenr,
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_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 (btrfs_ref_generation(leaf, ref_item) <= last_snapshot) {
ret = 1;
goto out;
}
*ref_count = 1;
if (*min_generation > ref_generation)
*min_generation = ref_generation;
path->slots[0]++;
}
@ -938,89 +926,6 @@ out:
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)
goto out;
if (ref_count != 1) {
ret = 1;
goto out;
}
if (level >= 0)
ref_generation = btrfs_header_generation(eb);
}
ret = 0;
out:
if (path)
btrfs_free_path(path);
return ret;
}
int btrfs_cache_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
struct extent_buffer *buf, u32 nr_extents)
{

213
fs/btrfs/inode.c
View File

@ -298,6 +298,7 @@ static int cow_file_range(struct inode *inode, struct page *locked_page,
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]--;
}
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];
}
leaf = path->nodes[0];
item = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
nocow = 0;
disk_bytenr = 0;
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
/* 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;
if (found_key.objectid > inode->i_ino ||
found_key.type > BTRFS_EXTENT_DATA_KEY ||
found_key.offset > end)
break;
found_type = btrfs_file_extent_type(leaf, item);
extent_start = found_key.offset;
if (found_type == BTRFS_FILE_EXTENT_REG) {
u64 extent_num_bytes;
if (found_key.offset > cur_offset) {
extent_end = found_key.offset;
goto out_check;
}
extent_num_bytes = btrfs_file_extent_num_bytes(leaf, item);
extent_end = extent_start + extent_num_bytes;
err = 0;
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
extent_type = btrfs_file_extent_type(leaf, fi);
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;
if (start < extent_start || start >= extent_end)
goto not_found;
bytenr = btrfs_file_extent_disk_bytenr(leaf, item);
if (bytenr == 0)
goto not_found;
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;
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;
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;
}
/*

1
fs/btrfs/ioctl.c
View File

@ -112,6 +112,7 @@ static noinline int create_subvol(struct btrfs_root *root,
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;

9
fs/btrfs/ordered-data.c
View File

@ -165,8 +165,7 @@ static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
* 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 inode *inode, u64 file_offset,
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);

3
fs/btrfs/ordered-data.h
View File

@ -132,8 +132,7 @@ int btrfs_remove_ordered_extent(struct inode *inode,
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);

2
fs/btrfs/transaction.c
View File

@ -763,6 +763,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
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;