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dm thin metadata: change dm_thin_find_block to allow blocking, but not issuing, IO

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This change is a prerequisite for allowing metadata to be prefetched.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2014-10-06 15:24:55 +01:00 committed by Mike Snitzer
parent a195db2d29
commit e5cfc69a51
2 changed files with 16 additions and 20 deletions
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32
drivers/md/dm-thin-metadata.c
View File

@ -1384,42 +1384,38 @@ static bool __snapshotted_since(struct dm_thin_device *td, uint32_t time)
}
int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
int can_block, struct dm_thin_lookup_result *result)
int can_issue_io, struct dm_thin_lookup_result *result)
{
int r = -EINVAL;
uint64_t block_time = 0;
int r;
__le64 value;
struct dm_pool_metadata *pmd = td->pmd;
dm_block_t keys[2] = { td->id, block };
struct dm_btree_info *info;
if (can_block) {
down_read(&pmd->root_lock);
info = &pmd->info;
} else if (down_read_trylock(&pmd->root_lock))
info = &pmd->nb_info;
else
return -EWOULDBLOCK;
if (pmd->fail_io)
goto out;
return -EINVAL;
down_read(&pmd->root_lock);
if (can_issue_io) {
info = &pmd->info;
} else
info = &pmd->nb_info;
r = dm_btree_lookup(info, pmd->root, keys, &value);
if (!r)
block_time = le64_to_cpu(value);
out:
up_read(&pmd->root_lock);
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);
}
up_read(&pmd->root_lock);
return r;
}

4
drivers/md/dm-thin-metadata.h
View File

@ -139,12 +139,12 @@ struct dm_thin_lookup_result {
/*
* Returns:
* -EWOULDBLOCK iff @can_block is set and would block.
* -EWOULDBLOCK iff @can_issue_io is set and would issue IO
* -ENODATA iff that mapping is not present.
* 0 success
*/
int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
int can_block, struct dm_thin_lookup_result *result);
int can_issue_io, struct dm_thin_lookup_result *result);
/*
* Obtain an unused block.