diff options
Diffstat (limited to 'block/blk-settings.c')
-rw-r--r-- | block/blk-settings.c | 133 |
1 files changed, 103 insertions, 30 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index dd1f1e0e196..5eeb9e0d256 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -505,21 +505,30 @@ static unsigned int lcm(unsigned int a, unsigned int b) /** * blk_stack_limits - adjust queue_limits for stacked devices - * @t: the stacking driver limits (top) - * @b: the underlying queue limits (bottom) + * @t: the stacking driver limits (top device) + * @b: the underlying queue limits (bottom, component device) * @offset: offset to beginning of data within component device * * Description: - * Merges two queue_limit structs. Returns 0 if alignment didn't - * change. Returns -1 if adding the bottom device caused - * misalignment. + * This function is used by stacking drivers like MD and DM to ensure + * that all component devices have compatible block sizes and + * alignments. The stacking driver must provide a queue_limits + * struct (top) and then iteratively call the stacking function for + * all component (bottom) devices. The stacking function will + * attempt to combine the values and ensure proper alignment. + * + * Returns 0 if the top and bottom queue_limits are compatible. The + * top device's block sizes and alignment offsets may be adjusted to + * ensure alignment with the bottom device. If no compatible sizes + * and alignments exist, -1 is returned and the resulting top + * queue_limits will have the misaligned flag set to indicate that + * the alignment_offset is undefined. */ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, sector_t offset) { - int ret; - - ret = 0; + sector_t alignment; + unsigned int top, bottom, ret = 0; t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); @@ -537,6 +546,26 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, t->max_segment_size = min_not_zero(t->max_segment_size, b->max_segment_size); + t->misaligned |= b->misaligned; + + alignment = queue_limit_alignment_offset(b, offset); + + /* Bottom device has different alignment. Check that it is + * compatible with the current top alignment. + */ + if (t->alignment_offset != alignment) { + + top = max(t->physical_block_size, t->io_min) + + t->alignment_offset; + bottom = max(b->physical_block_size, b->io_min) + alignment; + + /* Verify that top and bottom intervals line up */ + if (max(top, bottom) & (min(top, bottom) - 1)) { + t->misaligned = 1; + ret = -1; + } + } + t->logical_block_size = max(t->logical_block_size, b->logical_block_size); @@ -544,51 +573,95 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, b->physical_block_size); t->io_min = max(t->io_min, b->io_min); + t->io_opt = lcm(t->io_opt, b->io_opt); + t->no_cluster |= b->no_cluster; t->discard_zeroes_data &= b->discard_zeroes_data; - /* Bottom device offset aligned? */ - if (offset && - (offset & (b->physical_block_size - 1)) != b->alignment_offset) { + /* Physical block size a multiple of the logical block size? */ + if (t->physical_block_size & (t->logical_block_size - 1)) { + t->physical_block_size = t->logical_block_size; t->misaligned = 1; ret = -1; } - if (offset && - (offset & (b->discard_granularity - 1)) != b->discard_alignment) { - t->discard_misaligned = 1; + /* Minimum I/O a multiple of the physical block size? */ + if (t->io_min & (t->physical_block_size - 1)) { + t->io_min = t->physical_block_size; + t->misaligned = 1; ret = -1; } - /* If top has no alignment offset, inherit from bottom */ - if (!t->alignment_offset) - t->alignment_offset = - b->alignment_offset & (b->physical_block_size - 1); + /* Optimal I/O a multiple of the physical block size? */ + if (t->io_opt & (t->physical_block_size - 1)) { + t->io_opt = 0; + t->misaligned = 1; + ret = -1; + } - if (!t->discard_alignment) - t->discard_alignment = - b->discard_alignment & (b->discard_granularity - 1); + /* Find lowest common alignment_offset */ + t->alignment_offset = lcm(t->alignment_offset, alignment) + & (max(t->physical_block_size, t->io_min) - 1); - /* Top device aligned on logical block boundary? */ + /* Verify that new alignment_offset is on a logical block boundary */ if (t->alignment_offset & (t->logical_block_size - 1)) { t->misaligned = 1; ret = -1; } - /* Find lcm() of optimal I/O size and granularity */ - t->io_opt = lcm(t->io_opt, b->io_opt); - t->discard_granularity = lcm(t->discard_granularity, - b->discard_granularity); - - /* Verify that optimal I/O size is a multiple of io_min */ - if (t->io_min && t->io_opt % t->io_min) - ret = -1; + /* Discard alignment and granularity */ + if (b->discard_granularity) { + unsigned int granularity = b->discard_granularity; + offset &= granularity - 1; + + alignment = (granularity + b->discard_alignment - offset) + & (granularity - 1); + + if (t->discard_granularity != 0 && + t->discard_alignment != alignment) { + top = t->discard_granularity + t->discard_alignment; + bottom = b->discard_granularity + alignment; + + /* Verify that top and bottom intervals line up */ + if (max(top, bottom) & (min(top, bottom) - 1)) + t->discard_misaligned = 1; + } + + t->max_discard_sectors = min_not_zero(t->max_discard_sectors, + b->max_discard_sectors); + t->discard_granularity = max(t->discard_granularity, + b->discard_granularity); + t->discard_alignment = lcm(t->discard_alignment, alignment) & + (t->discard_granularity - 1); + } return ret; } EXPORT_SYMBOL(blk_stack_limits); /** + * bdev_stack_limits - adjust queue limits for stacked drivers + * @t: the stacking driver limits (top device) + * @bdev: the component block_device (bottom) + * @start: first data sector within component device + * + * Description: + * Merges queue limits for a top device and a block_device. Returns + * 0 if alignment didn't change. Returns -1 if adding the bottom + * device caused misalignment. + */ +int bdev_stack_limits(struct queue_limits *t, struct block_device *bdev, + sector_t start) +{ + struct request_queue *bq = bdev_get_queue(bdev); + + start += get_start_sect(bdev); + + return blk_stack_limits(t, &bq->limits, start << 9); +} +EXPORT_SYMBOL(bdev_stack_limits); + +/** * disk_stack_limits - adjust queue limits for stacked drivers * @disk: MD/DM gendisk (top) * @bdev: the underlying block device (bottom) |