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author | Josef Bacik <josef@redhat.com> | 2011-04-06 18:53:07 (GMT) |
---|---|---|
committer | Josef Bacik <josef@redhat.com> | 2011-04-08 17:00:41 (GMT) |
commit | 16d299ac7446b5a75c5683a9ae11d7907d444c86 (patch) | |
tree | 95358c2fdd7af672ec68c18fb43e2e90a7cd4551 /fs | |
parent | 1ae399382512b3e4d6c923e53da9e45935577040 (diff) | |
download | linux-16d299ac7446b5a75c5683a9ae11d7907d444c86.tar.xz |
Btrfs: reuse the extent_map we found when calling btrfs_get_extent
In btrfs_get_block_direct we call btrfs_get_extent to lookup the extent for the
range that we are looking for. If we don't find an extent, btrfs_get_extent
will insert a extent_map for that area and mark it as a hole. So it does the
job of allocating a new extent map and inserting it into the io tree. But if
we're creating a new extent we free it up and redo all of that work. So instead
pass the em to btrfs_new_extent_direct(), and if it will work just allocate the
disk space and set it up properly and bypass the freeing/allocating of a new
extent map and the expensive operation of inserting the thing into the io_tree.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/btrfs/inode.c | 36 |
1 files changed, 28 insertions, 8 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 2bb76c6..24310c9 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5445,17 +5445,30 @@ out: } static struct extent_map *btrfs_new_extent_direct(struct inode *inode, + struct extent_map *em, u64 start, u64 len) { struct btrfs_root *root = BTRFS_I(inode)->root; struct btrfs_trans_handle *trans; - struct extent_map *em; struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree; struct btrfs_key ins; u64 alloc_hint; int ret; + bool insert = false; - btrfs_drop_extent_cache(inode, start, start + len - 1, 0); + /* + * Ok if the extent map we looked up is a hole and is for the exact + * range we want, there is no reason to allocate a new one, however if + * it is not right then we need to free this one and drop the cache for + * our range. + */ + if (em->block_start != EXTENT_MAP_HOLE || em->start != start || + em->len != len) { + free_extent_map(em); + em = NULL; + insert = true; + btrfs_drop_extent_cache(inode, start, start + len - 1, 0); + } trans = btrfs_join_transaction(root, 0); if (IS_ERR(trans)) @@ -5471,10 +5484,12 @@ static struct extent_map *btrfs_new_extent_direct(struct inode *inode, goto out; } - em = alloc_extent_map(GFP_NOFS); if (!em) { - em = ERR_PTR(-ENOMEM); - goto out; + em = alloc_extent_map(GFP_NOFS); + if (!em) { + em = ERR_PTR(-ENOMEM); + goto out; + } } em->start = start; @@ -5484,9 +5499,15 @@ static struct extent_map *btrfs_new_extent_direct(struct inode *inode, em->block_start = ins.objectid; em->block_len = ins.offset; em->bdev = root->fs_info->fs_devices->latest_bdev; + + /* + * We need to do this because if we're using the original em we searched + * for, we could have EXTENT_FLAG_VACANCY set, and we don't want that. + */ + em->flags = 0; set_bit(EXTENT_FLAG_PINNED, &em->flags); - while (1) { + while (insert) { write_lock(&em_tree->lock); ret = add_extent_mapping(em_tree, em); write_unlock(&em_tree->lock); @@ -5704,8 +5725,7 @@ must_cow: * it above */ len = bh_result->b_size; - free_extent_map(em); - em = btrfs_new_extent_direct(inode, start, len); + em = btrfs_new_extent_direct(inode, em, start, len); if (IS_ERR(em)) return PTR_ERR(em); len = min(len, em->len - (start - em->start)); |