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dm switch: factor out switch_region_table_read 

Move code that reads the table to a switch_region_table_read.
It will be needed for the next commit.  No functional change.

Tested-by: Jay Wang <jwang@nimblestorage.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka 2014-07-28 17:49:41 -04:00 committed by Mike Snitzer
parent b02465308f
commit 99eb1908e6
1 changed files with 13 additions and 5 deletions
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18
drivers/md/dm-switch.c
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@ -137,13 +137,23 @@ static void switch_get_position(struct switch_ctx *sctx, unsigned long region_nr
*bit *= sctx->region_table_entry_bits;
}
static unsigned switch_region_table_read(struct switch_ctx *sctx, unsigned long region_nr)
{
unsigned long region_index;
unsigned bit;
switch_get_position(sctx, region_nr, &region_index, &bit);
return (ACCESS_ONCE(sctx->region_table[region_index]) >> bit) &
((1 << sctx->region_table_entry_bits) - 1);
}
/*
* Find which path to use at given offset.
*/
static unsigned switch_get_path_nr(struct switch_ctx *sctx, sector_t offset)
{
unsigned long region_index;
unsigned bit, path_nr;
unsigned path_nr;
sector_t p;
p = offset;
@ -152,9 +162,7 @@ static unsigned switch_get_path_nr(struct switch_ctx *sctx, sector_t offset)
else
sector_div(p, sctx->region_size);
switch_get_position(sctx, p, &region_index, &bit);
path_nr = (ACCESS_ONCE(sctx->region_table[region_index]) >> bit) &
((1 << sctx->region_table_entry_bits) - 1);
path_nr = switch_region_table_read(sctx, p);
/* This can only happen if the processor uses non-atomic stores. */
if (unlikely(path_nr >= sctx->nr_paths))