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btrfs: add optimized version of eb to eb copy 

Using copy_extent_buffer is suitable for copying betwenn buffers from an
arbitrary offset and deals with page boundaries. This is not necessary
when doing a full extent_buffer-to-extent_buffer copy. We can utilize
the copy_page helper as well.

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2016-11-08 18:30:31 +01:00
parent b159fa2808
commit 58e8012cc1
3 changed files with 18 additions and 2 deletions
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4
fs/btrfs/ctree.c
View File

@ -260,7 +260,7 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
if (IS_ERR(cow))
return PTR_ERR(cow);
copy_extent_buffer(cow, buf, 0, 0, cow->len);
copy_extent_buffer_full(cow, buf);
btrfs_set_header_bytenr(cow, cow->start);
btrfs_set_header_generation(cow, trans->transid);
btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
@ -1129,7 +1129,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
/* cow is set to blocking by btrfs_init_new_buffer */
copy_extent_buffer(cow, buf, 0, 0, cow->len);
copy_extent_buffer_full(cow, buf);
btrfs_set_header_bytenr(cow, cow->start);
btrfs_set_header_generation(cow, trans->transid);
btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);

14
fs/btrfs/extent_io.c
View File

@ -5546,6 +5546,20 @@ void memzero_extent_buffer(struct extent_buffer *eb, unsigned long start,
}
}
void copy_extent_buffer_full(struct extent_buffer *dst,
struct extent_buffer *src)
{
int i;
unsigned num_pages;
ASSERT(dst->len == src->len);
num_pages = num_extent_pages(dst->start, dst->len);
for (i = 0; i < num_pages; i++)
copy_page(page_address(dst->pages[i]),
page_address(src->pages[i]));
}
void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
unsigned long dst_offset, unsigned long src_offset,
unsigned long len)

2
fs/btrfs/extent_io.h
View File

@ -410,6 +410,8 @@ void write_extent_buffer_chunk_tree_uuid(struct extent_buffer *eb,
const void *src);
void write_extent_buffer(struct extent_buffer *eb, const void *src,
unsigned long start, unsigned long len);
void copy_extent_buffer_full(struct extent_buffer *dst,
struct extent_buffer *src);
void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
unsigned long dst_offset, unsigned long src_offset,
unsigned long len);