From db4542b6617b60810315fe72f40a623e73ee1b66 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Mon, 17 Aug 2020 18:01:30 +0800 Subject: [PATCH] block: loop: set discard granularity and alignment for block device backed loop commit bcb21c8cc9947286211327d663ace69f07d37a76 upstream. In case of block device backend, if the backend supports write zeros, the loop device will set queue flag of QUEUE_FLAG_DISCARD. However, limits.discard_granularity isn't setup, and this way is wrong, see the following description in Documentation/ABI/testing/sysfs-block: A discard_granularity of 0 means that the device does not support discard functionality. Especially 9b15d109a6b2 ("block: improve discard bio alignment in __blkdev_issue_discard()") starts to take q->limits.discard_granularity for computing max discard sectors. And zero discard granularity may cause kernel oops, or fail discard request even though the loop queue claims discard support via QUEUE_FLAG_DISCARD. Fix the issue by setup discard granularity and alignment. Fixes: c52abf563049 ("loop: Better discard support for block devices") Signed-off-by: Ming Lei Reviewed-by: Christoph Hellwig Acked-by: Coly Li Cc: Hannes Reinecke Cc: Xiao Ni Cc: Martin K. Petersen Cc: Evan Green Cc: Gwendal Grignou Cc: Chaitanya Kulkarni Cc: Andrzej Pietrasiewicz Cc: Christoph Hellwig Cc: Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/block/loop.c | 33 ++++++++++++++++++--------------- 1 file changed, 18 insertions(+), 15 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index bddbbf5b3dda2..ffbe792410d1c 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -863,6 +863,7 @@ static void loop_config_discard(struct loop_device *lo) struct file *file = lo->lo_backing_file; struct inode *inode = file->f_mapping->host; struct request_queue *q = lo->lo_queue; + u32 granularity, max_discard_sectors; /* * If the backing device is a block device, mirror its zeroing @@ -875,11 +876,10 @@ static void loop_config_discard(struct loop_device *lo) struct request_queue *backingq; backingq = bdev_get_queue(inode->i_bdev); - blk_queue_max_discard_sectors(q, - backingq->limits.max_write_zeroes_sectors); - blk_queue_max_write_zeroes_sectors(q, - backingq->limits.max_write_zeroes_sectors); + max_discard_sectors = backingq->limits.max_write_zeroes_sectors; + granularity = backingq->limits.discard_granularity ?: + queue_physical_block_size(backingq); /* * We use punch hole to reclaim the free space used by the @@ -888,23 +888,26 @@ static void loop_config_discard(struct loop_device *lo) * useful information. */ } else if (!file->f_op->fallocate || lo->lo_encrypt_key_size) { - q->limits.discard_granularity = 0; - q->limits.discard_alignment = 0; - blk_queue_max_discard_sectors(q, 0); - blk_queue_max_write_zeroes_sectors(q, 0); + max_discard_sectors = 0; + granularity = 0; } else { - q->limits.discard_granularity = inode->i_sb->s_blocksize; - q->limits.discard_alignment = 0; - - blk_queue_max_discard_sectors(q, UINT_MAX >> 9); - blk_queue_max_write_zeroes_sectors(q, UINT_MAX >> 9); + max_discard_sectors = UINT_MAX >> 9; + granularity = inode->i_sb->s_blocksize; } - if (q->limits.max_write_zeroes_sectors) + if (max_discard_sectors) { + q->limits.discard_granularity = granularity; + blk_queue_max_discard_sectors(q, max_discard_sectors); + blk_queue_max_write_zeroes_sectors(q, max_discard_sectors); blk_queue_flag_set(QUEUE_FLAG_DISCARD, q); - else + } else { + q->limits.discard_granularity = 0; + blk_queue_max_discard_sectors(q, 0); + blk_queue_max_write_zeroes_sectors(q, 0); blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q); + } + q->limits.discard_alignment = 0; } static void loop_unprepare_queue(struct loop_device *lo)