Commit 99eb1908 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer

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: default avatarJay Wang <jwang@nimblestorage.com>
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent b0246530
...@@ -137,13 +137,23 @@ static void switch_get_position(struct switch_ctx *sctx, unsigned long region_nr ...@@ -137,13 +137,23 @@ static void switch_get_position(struct switch_ctx *sctx, unsigned long region_nr
*bit *= sctx->region_table_entry_bits; *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. * Find which path to use at given offset.
*/ */
static unsigned switch_get_path_nr(struct switch_ctx *sctx, sector_t offset) static unsigned switch_get_path_nr(struct switch_ctx *sctx, sector_t offset)
{ {
unsigned long region_index; unsigned path_nr;
unsigned bit, path_nr;
sector_t p; sector_t p;
p = offset; p = offset;
...@@ -152,9 +162,7 @@ static unsigned switch_get_path_nr(struct switch_ctx *sctx, sector_t offset) ...@@ -152,9 +162,7 @@ static unsigned switch_get_path_nr(struct switch_ctx *sctx, sector_t offset)
else else
sector_div(p, sctx->region_size); sector_div(p, sctx->region_size);
switch_get_position(sctx, p, &region_index, &bit); path_nr = switch_region_table_read(sctx, p);
path_nr = (ACCESS_ONCE(sctx->region_table[region_index]) >> bit) &
((1 << sctx->region_table_entry_bits) - 1);
/* This can only happen if the processor uses non-atomic stores. */ /* This can only happen if the processor uses non-atomic stores. */
if (unlikely(path_nr >= sctx->nr_paths)) if (unlikely(path_nr >= sctx->nr_paths))
......
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