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dm thin metadata: add dm_thin_find_mapped_range()

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Retrieve the next run of contiguously mapped blocks.  Useful for working
out where to break up IO.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2015-04-16 12:47:21 +01:00 committed by Mike Snitzer
parent 4ec331c3ea
commit a5d895a90b
2 changed files with 66 additions and 0 deletions
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57
drivers/md/dm-thin-metadata.c
View File

@ -1417,6 +1417,63 @@ int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
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,
dm_block_t *pool_begin, bool *maybe_shared)
{
int r;
dm_block_t pool_end;
struct dm_thin_lookup_result lookup;
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++;
}
if (begin == end)
return -ENODATA;
*thin_begin = begin;
*pool_begin = lookup.block;
*maybe_shared = lookup.shared;
begin++;
pool_end = *pool_begin + 1;
while (begin != end) {
r = dm_thin_find_block(td, begin, true, &lookup);
if (r) {
if (r == -ENODATA)
break;
else
return r;
}
if ((lookup.block != pool_end) ||
(lookup.shared != *maybe_shared))
break;
pool_end++;
begin++;
}
*thin_end = begin;
return 0;
}
static int __insert(struct dm_thin_device *td, dm_block_t block,
dm_block_t data_block)
{

9
drivers/md/dm-thin-metadata.h
View File

@ -146,6 +146,15 @@ struct dm_thin_lookup_result {
int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
int can_issue_io, struct dm_thin_lookup_result *result);
/*
* Retrieve the next run of contiguously mapped blocks. Useful for working
* out where to break up IO. Returns 0 on success, < 0 on error.
*/
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,
dm_block_t *pool_begin, bool *maybe_shared);
/*
* Obtain an unused block.
*/