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Btrfs: add helper for em merge logic

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This is a prepare work for the following extent map selftest, which
runs tests against em merge logic.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Liu Bo 2018-01-05 12:51:10 -07:00 committed by David Sterba
parent 18e83ac75b
commit 7b4df058b0
2 changed files with 48 additions and 34 deletions
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2
fs/btrfs/ctree.h
View File

@ -3143,6 +3143,8 @@ struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode,
int delay_iput);
void btrfs_wait_and_free_delalloc_work(struct btrfs_delalloc_work *work);
int btrfs_add_extent_mapping(struct extent_map_tree *em_tree,
struct extent_map **em_in, u64 start, u64 len);
struct extent_map *btrfs_get_extent_fiemap(struct btrfs_inode *inode,
struct page *page, size_t pg_offset, u64 start,
u64 len, int create);

80
fs/btrfs/inode.c
View File

@ -6925,6 +6925,51 @@ static noinline int uncompress_inline(struct btrfs_path *path,
return ret;
}
int btrfs_add_extent_mapping(struct extent_map_tree *em_tree,
struct extent_map **em_in, u64 start, u64 len)
{
int ret;
struct extent_map *em = *em_in;
ret = add_extent_mapping(em_tree, em, 0);
/* it is possible that someone inserted the extent into the tree
* while we had the lock dropped. It is also possible that
* an overlapping map exists in the tree
*/
if (ret == -EEXIST) {
struct extent_map *existing;
ret = 0;
existing = search_extent_mapping(em_tree, start, len);
/*
* existing will always be non-NULL, since there must be
* extent causing the -EEXIST.
*/
if (start >= existing->start &&
start < extent_map_end(existing)) {
free_extent_map(em);
*em_in = existing;
ret = 0;
} else {
/*
* The existing extent map is the one nearest to
* the [start, start + len) range which overlaps
*/
ret = merge_extent_mapping(em_tree, existing,
em, start);
free_extent_map(existing);
if (ret) {
free_extent_map(em);
*em_in = NULL;
}
}
}
ASSERT(ret == 0 || ret == -EEXIST);
return ret;
}
/*
* a bit scary, this does extent mapping from logical file offset to the disk.
* the ugly parts come from merging extents from the disk with the in-ram
@ -7138,40 +7183,7 @@ insert:
err = 0;
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em, 0);
/* it is possible that someone inserted the extent into the tree
* while we had the lock dropped. It is also possible that
* an overlapping map exists in the tree
*/
if (ret == -EEXIST) {
struct extent_map *existing;
ret = 0;
existing = search_extent_mapping(em_tree, start, len);
/*
* existing will always be non-NULL, since there must be
* extent causing the -EEXIST.
*/
if (start >= existing->start &&
start < extent_map_end(existing)) {
free_extent_map(em);
em = existing;
err = 0;
} else {
/*
* The existing extent map is the one nearest to
* the [start, start + len) range which overlaps
*/
err = merge_extent_mapping(em_tree, existing,
em, start);
free_extent_map(existing);
if (err) {
free_extent_map(em);
em = NULL;
}
}
}
err = btrfs_add_extent_mapping(em_tree, &em, start, len);
write_unlock(&em_tree->lock);
out: