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Btrfs: Add mount option to turn off data cow

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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 <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
2007-12-17 20:14:01 -05:00
parent b6cda9bcb4
commit be20aa9dba
5 changed files with 293 additions and 25 deletions
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8
fs/btrfs/ctree.h
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@@ -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,