diff options
Diffstat (limited to 'target/linux/generic/hack-5.4/551-loop-Better-discard-support-for-block-devices.patch')
| -rw-r--r-- | target/linux/generic/hack-5.4/551-loop-Better-discard-support-for-block-devices.patch | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/target/linux/generic/hack-5.4/551-loop-Better-discard-support-for-block-devices.patch b/target/linux/generic/hack-5.4/551-loop-Better-discard-support-for-block-devices.patch new file mode 100644 index 0000000000..ac393e5f13 --- /dev/null +++ b/target/linux/generic/hack-5.4/551-loop-Better-discard-support-for-block-devices.patch @@ -0,0 +1,101 @@ +From 3117c3f45edbcc269baaebd3d13f39b7bf884aa6 Mon Sep 17 00:00:00 2001 +From: Evan Green <evgreen@chromium.org> +Date: Thu, 14 Nov 2019 15:50:08 -0800 +Subject: loop: Better discard support for block devices + +If the backing device for a loop device is itself a block device, +then mirror the "write zeroes" capabilities of the underlying +block device into the loop device. Copy this capability into both +max_write_zeroes_sectors and max_discard_sectors of the loop device. + +The reason for this is that REQ_OP_DISCARD on a loop device translates +into blkdev_issue_zeroout(), rather than blkdev_issue_discard(). This +presents a consistent interface for loop devices (that discarded data +is zeroed), regardless of the backing device type of the loop device. +There should be no behavior change for loop devices backed by regular +files. + +This change fixes blktest block/003, and removes an extraneous +error print in block/013 when testing on a loop device backed +by a block device that does not support discard. + +Signed-off-by: Evan Green <evgreen@chromium.org> +Reviewed-by: Gwendal Grignou <gwendal@chromium.org> +Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> +--- + drivers/block/loop.c | 40 +++++++++++++++++++++++++++++----------- + 1 file changed, 29 insertions(+), 11 deletions(-) + +--- a/drivers/block/loop.c ++++ b/drivers/block/loop.c +@@ -426,11 +426,12 @@ static int lo_fallocate(struct loop_devi + * information. + */ + struct file *file = lo->lo_backing_file; ++ struct request_queue *q = lo->lo_queue; + int ret; + + mode |= FALLOC_FL_KEEP_SIZE; + +- if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) { ++ if (!blk_queue_discard(q)) { + ret = -EOPNOTSUPP; + goto out; + } +@@ -863,6 +864,21 @@ static void loop_config_discard(struct l + struct file *file = lo->lo_backing_file; + struct inode *inode = file->f_mapping->host; + struct request_queue *q = lo->lo_queue; ++ struct request_queue *backingq; ++ ++ /* ++ * If the backing device is a block device, mirror its zeroing ++ * capability. REQ_OP_DISCARD translates to a zero-out even when backed ++ * by block devices to keep consistent behavior with file-backed loop ++ * devices. ++ */ ++ if (S_ISBLK(inode->i_mode) && !lo->lo_encrypt_key_size) { ++ 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); + + /* + * We use punch hole to reclaim the free space used by the +@@ -870,22 +886,24 @@ static void loop_config_discard(struct l + * encryption is enabled, because it may give an attacker + * useful information. + */ +- if ((!file->f_op->fallocate) || +- lo->lo_encrypt_key_size) { ++ } 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); +- blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q); +- return; +- } + +- q->limits.discard_granularity = inode->i_sb->s_blocksize; +- q->limits.discard_alignment = 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); +- blk_queue_flag_set(QUEUE_FLAG_DISCARD, q); ++ blk_queue_max_discard_sectors(q, UINT_MAX >> 9); ++ blk_queue_max_write_zeroes_sectors(q, UINT_MAX >> 9); ++ } ++ ++ if (q->limits.max_write_zeroes_sectors) ++ blk_queue_flag_set(QUEUE_FLAG_DISCARD, q); ++ else ++ blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q); + } + + static void loop_unprepare_queue(struct loop_device *lo) |