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dm thin metadata: speed up discard of partially mapped volumes
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Use dm_btree_lookup_next() to more quickly discard partially mapped
volumes.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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Joe Thornber authored and Mike Snitzer committed Dec 10, 2015
1 parent ed8b45a commit 3d5f673
Showing 1 changed file with 41 additions and 25 deletions.
66 changes: 41 additions & 25 deletions drivers/md/dm-thin-metadata.c
Original file line number Diff line number Diff line change
Expand Up @@ -1395,6 +1395,19 @@ static bool __snapshotted_since(struct dm_thin_device *td, uint32_t time)
return td->snapshotted_time > time;
}

static void unpack_lookup_result(struct dm_thin_device *td, __le64 value,
struct dm_thin_lookup_result *result)
{
uint64_t block_time = 0;
dm_block_t exception_block;
uint32_t exception_time;

block_time = le64_to_cpu(value);
unpack_block_time(block_time, &exception_block, &exception_time);
result->block = exception_block;
result->shared = __snapshotted_since(td, exception_time);
}

int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
int can_issue_io, struct dm_thin_lookup_result *result)
{
Expand All @@ -1416,23 +1429,36 @@ int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
info = &pmd->nb_info;

r = dm_btree_lookup(info, pmd->root, keys, &value);
if (!r) {
uint64_t block_time = 0;
dm_block_t exception_block;
uint32_t exception_time;

block_time = le64_to_cpu(value);
unpack_block_time(block_time, &exception_block,
&exception_time);
result->block = exception_block;
result->shared = __snapshotted_since(td, exception_time);
if (!r)
unpack_lookup_result(td, value, result);

up_read(&pmd->root_lock);
return r;
}

static int dm_thin_find_next_mapped_block(struct dm_thin_device *td, dm_block_t block,
dm_block_t *vblock,
struct dm_thin_lookup_result *result)
{
int r;
__le64 value;
struct dm_pool_metadata *pmd = td->pmd;
dm_block_t keys[2] = { td->id, block };

down_read(&pmd->root_lock);
if (pmd->fail_io) {
up_read(&pmd->root_lock);
return -EINVAL;
}

r = dm_btree_lookup_next(&pmd->info, pmd->root, keys, vblock, &value);
if (!r)
unpack_lookup_result(td, value, result);

up_read(&pmd->root_lock);
return r;
}

/* FIXME: write a more efficient one in btree */
int dm_thin_find_mapped_range(struct dm_thin_device *td,
dm_block_t begin, dm_block_t end,
dm_block_t *thin_begin, dm_block_t *thin_end,
Expand All @@ -1445,21 +1471,11 @@ int dm_thin_find_mapped_range(struct dm_thin_device *td,
if (end < begin)
return -ENODATA;

/*
* Find first mapped block.
*/
while (begin < end) {
r = dm_thin_find_block(td, begin, true, &lookup);
if (r) {
if (r != -ENODATA)
return r;
} else
break;

begin++;
}
r = dm_thin_find_next_mapped_block(td, begin, &begin, &lookup);
if (r)
return r;

if (begin == end)
if (begin >= end)
return -ENODATA;

*thin_begin = begin;
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