From 512875bd9661368da6f993205a61213b79ba1df0 Mon Sep 17 00:00:00 2001 From: Jun'ichi Nomura Date: Thu, 13 Dec 2007 14:15:25 +0000 Subject: dm: table detect io beyond device This patch fixes a panic on shrinking a DM device if there is outstanding I/O to the part of the device that is being removed. (Normally this doesn't happen - a filesystem would be resized first, for example.) The bug is that __clone_and_map() assumes dm_table_find_target() always returns a valid pointer. It may fail if a bio arrives from the block layer but its target sector is no longer included in the DM btree. This patch appends an empty entry to table->targets[] which will be returned by a lookup beyond the end of the device. After calling dm_table_find_target(), __clone_and_map() and target_message() check for this condition using dm_target_is_valid(). Sample test script to trigger oops: --- drivers/md/dm-table.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index e298d8d11f24..f3f952e347ed 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -189,8 +189,10 @@ static int alloc_targets(struct dm_table *t, unsigned int num) /* * Allocate both the target array and offset array at once. + * Append an empty entry to catch sectors beyond the end of + * the device. */ - n_highs = (sector_t *) dm_vcalloc(num, sizeof(struct dm_target) + + n_highs = (sector_t *) dm_vcalloc(num + 1, sizeof(struct dm_target) + sizeof(sector_t)); if (!n_highs) return -ENOMEM; @@ -867,6 +869,9 @@ struct dm_target *dm_table_get_target(struct dm_table *t, unsigned int index) /* * Search the btree for the correct target. + * + * Caller should check returned pointer with dm_target_is_valid() + * to trap I/O beyond end of device. */ struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector) { -- cgit v1.2.3 From 91212507f93778c09d4c1335207b6f4b995f5ad1 Mon Sep 17 00:00:00 2001 From: Neil Brown Date: Thu, 13 Dec 2007 14:16:04 +0000 Subject: dm: merge max_hw_sector Make sure dm honours max_hw_sectors of underlying devices We still have no firm testing evidence in support of this patch but believe it may help to resolve some bug reports. - agk Signed-off-by: Neil Brown Signed-off-by: Alasdair G Kergon --- drivers/md/dm-table.c | 9 +++++++++ include/linux/device-mapper.h | 1 + 2 files changed, 10 insertions(+) (limited to 'drivers/md/dm-table.c') diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index f3f952e347ed..47818d8249cb 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -99,6 +99,9 @@ static void combine_restrictions_low(struct io_restrictions *lhs, lhs->max_segment_size = min_not_zero(lhs->max_segment_size, rhs->max_segment_size); + lhs->max_hw_sectors = + min_not_zero(lhs->max_hw_sectors, rhs->max_hw_sectors); + lhs->seg_boundary_mask = min_not_zero(lhs->seg_boundary_mask, rhs->seg_boundary_mask); @@ -566,6 +569,9 @@ void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev) rs->max_segment_size = min_not_zero(rs->max_segment_size, q->max_segment_size); + rs->max_hw_sectors = + min_not_zero(rs->max_hw_sectors, q->max_hw_sectors); + rs->seg_boundary_mask = min_not_zero(rs->seg_boundary_mask, q->seg_boundary_mask); @@ -703,6 +709,8 @@ static void check_for_valid_limits(struct io_restrictions *rs) { if (!rs->max_sectors) rs->max_sectors = SAFE_MAX_SECTORS; + if (!rs->max_hw_sectors) + rs->max_hw_sectors = SAFE_MAX_SECTORS; if (!rs->max_phys_segments) rs->max_phys_segments = MAX_PHYS_SEGMENTS; if (!rs->max_hw_segments) @@ -901,6 +909,7 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q) q->max_hw_segments = t->limits.max_hw_segments; q->hardsect_size = t->limits.hardsect_size; q->max_segment_size = t->limits.max_segment_size; + q->max_hw_sectors = t->limits.max_hw_sectors; q->seg_boundary_mask = t->limits.seg_boundary_mask; q->bounce_pfn = t->limits.bounce_pfn; if (t->limits.no_cluster) diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index b8b7c51389fe..e765e191663d 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -115,6 +115,7 @@ struct io_restrictions { unsigned short max_hw_segments; unsigned short hardsect_size; unsigned int max_segment_size; + unsigned int max_hw_sectors; unsigned long seg_boundary_mask; unsigned long bounce_pfn; unsigned char no_cluster; /* inverted so that 0 is default */ -- cgit v1.2.3