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dm table: validate device logical_block_size 

Impose necessary and sufficient conditions on a devices's table such
that any incoming bio which respects its logical_block_size can be
processed successfully.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Mike Snitzer 2009-06-22 10:12:31 +01:00 committed by Alasdair G Kergon
parent 02acc3a4fa
commit be6d4305db
1 changed files with 69 additions and 0 deletions
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69
drivers/md/dm-table.c
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@ -724,6 +724,71 @@ static void check_for_valid_limits(struct io_restrictions *rs)
rs->bounce_pfn = -1;
}
/*
* Impose necessary and sufficient conditions on a devices's table such
* that any incoming bio which respects its logical_block_size can be
* processed successfully. If it falls across the boundary between
* two or more targets, the size of each piece it gets split into must
* be compatible with the logical_block_size of the target processing it.
*/
static int validate_hardware_logical_block_alignment(struct dm_table *table)
{
/*
* This function uses arithmetic modulo the logical_block_size
* (in units of 512-byte sectors).
*/
unsigned short device_logical_block_size_sects =
table->limits.logical_block_size >> SECTOR_SHIFT;
/*
* Offset of the start of the next table entry, mod logical_block_size.
*/
unsigned short next_target_start = 0;
/*
* Given an aligned bio that extends beyond the end of a
* target, how many sectors must the next target handle?
*/
unsigned short remaining = 0;
struct dm_target *uninitialized_var(ti);
unsigned i = 0;
/*
* Check each entry in the table in turn.
*/
while (i < dm_table_get_num_targets(table)) {
ti = dm_table_get_target(table, i++);
/*
* If the remaining sectors fall entirely within this
* table entry are they compatible with its logical_block_size?
*/
if (remaining < ti->len &&
remaining & ((ti->limits.logical_block_size >>
SECTOR_SHIFT) - 1))
break; /* Error */
next_target_start =
(unsigned short) ((next_target_start + ti->len) &
(device_logical_block_size_sects - 1));
remaining = next_target_start ?
device_logical_block_size_sects - next_target_start : 0;
}
if (remaining) {
DMWARN("%s: table line %u (start sect %llu len %llu) "
"not aligned to hardware logical block size %hu",
dm_device_name(table->md), i,
(unsigned long long) ti->begin,
(unsigned long long) ti->len,
table->limits.logical_block_size);
return -EINVAL;
}
return 0;
}
int dm_table_add_target(struct dm_table *t, const char *type,
sector_t start, sector_t len, char *params)
{
@ -823,6 +888,10 @@ int dm_table_complete(struct dm_table *t)
check_for_valid_limits(&t->limits);
r = validate_hardware_logical_block_alignment(t);
if (r)
return r;
/* how many indexes will the btree have ? */
leaf_nodes = dm_div_up(t->num_targets, KEYS_PER_NODE);
t->depth = 1 + int_log(leaf_nodes, CHILDREN_PER_NODE);