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Commit be6d4305 authored by Mike Snitzer's avatar Mike Snitzer Committed by Alasdair G Kergon
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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: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 02acc3a4

drivers/md/dm-table.c

+69 −0
Original line number Diff line number Diff line
@@ -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);