Btrfs: update nodatacow code v2
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>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e8511d1..3e6f056 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -298,6 +298,7 @@
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 @@
}
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 @@
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;
}
/*
