diff options
| author | Josef Bacik <josef@redhat.com> | 2009-11-10 21:23:47 -0500 |
|---|---|---|
| committer | Chris Mason <chris.mason@oracle.com> | 2009-11-11 14:20:16 -0500 |
| commit | 6346c93988caa3048bf4d81f9ba3608a7a195aa2 (patch) | |
| tree | 78e5fbc5fa6ed8c692db24dfff475e2b95413570 /fs | |
| parent | 444528b3e614f7f2391488d9bca8e0b872db909b (diff) | |
Btrfs: fix data allocation hint start
Sometimes our start allocation hint when we cow a file can be either
EXTENT_HOLE or some other such place holder, which is not optimal. So if we
find that our em->block_start is one of these special values, check to see
where the first block of the inode is stored, and use that as a hint. If that
block is also a special value, just fallback on a hint of 0 and let the
allocator figure out a good place to put the data.
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/inode.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 78139efe41fc..d8393ddc72a3 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -743,8 +743,22 @@ static noinline int cow_file_range(struct inode *inode, em = search_extent_mapping(&BTRFS_I(inode)->extent_tree, start, num_bytes); if (em) { - alloc_hint = em->block_start; - free_extent_map(em); + /* + * if block start isn't an actual block number then find the + * first block in this inode and use that as a hint. If that + * block is also bogus then just don't worry about it. + */ + if (em->block_start >= EXTENT_MAP_LAST_BYTE) { + free_extent_map(em); + em = search_extent_mapping(em_tree, 0, 0); + if (em && em->block_start < EXTENT_MAP_LAST_BYTE) + alloc_hint = em->block_start; + if (em) + free_extent_map(em); + } else { + alloc_hint = em->block_start; + free_extent_map(em); + } } read_unlock(&BTRFS_I(inode)->extent_tree.lock); btrfs_drop_extent_cache(inode, start, start + num_bytes - 1, 0); |