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@@ -1,101 +0,0 @@
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-From 3117c3f45edbcc269baaebd3d13f39b7bf884aa6 Mon Sep 17 00:00:00 2001
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-From: Evan Green <[email protected]>
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-Date: Thu, 14 Nov 2019 15:50:08 -0800
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-Subject: loop: Better discard support for block devices
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-
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-If the backing device for a loop device is itself a block device,
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-then mirror the "write zeroes" capabilities of the underlying
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-block device into the loop device. Copy this capability into both
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-max_write_zeroes_sectors and max_discard_sectors of the loop device.
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-
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-The reason for this is that REQ_OP_DISCARD on a loop device translates
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-into blkdev_issue_zeroout(), rather than blkdev_issue_discard(). This
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-presents a consistent interface for loop devices (that discarded data
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-is zeroed), regardless of the backing device type of the loop device.
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-There should be no behavior change for loop devices backed by regular
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-files.
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-
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-This change fixes blktest block/003, and removes an extraneous
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-error print in block/013 when testing on a loop device backed
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-by a block device that does not support discard.
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-
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-Signed-off-by: Evan Green <[email protected]>
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-Reviewed-by: Gwendal Grignou <[email protected]>
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-Reviewed-by: Chaitanya Kulkarni <[email protected]>
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----
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- drivers/block/loop.c | 40 +++++++++++++++++++++++++++++-----------
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- 1 file changed, 29 insertions(+), 11 deletions(-)
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-
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---- a/drivers/block/loop.c
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-+++ b/drivers/block/loop.c
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-@@ -427,11 +427,12 @@ static int lo_fallocate(struct loop_devi
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- * information.
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- */
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- struct file *file = lo->lo_backing_file;
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-+ struct request_queue *q = lo->lo_queue;
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- int ret;
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-
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- mode |= FALLOC_FL_KEEP_SIZE;
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-
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-- if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) {
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-+ if (!blk_queue_discard(q)) {
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- ret = -EOPNOTSUPP;
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- goto out;
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- }
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-@@ -862,6 +863,21 @@ static void loop_config_discard(struct l
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- struct file *file = lo->lo_backing_file;
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- struct inode *inode = file->f_mapping->host;
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- struct request_queue *q = lo->lo_queue;
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-+ struct request_queue *backingq;
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-+
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-+ /*
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-+ * If the backing device is a block device, mirror its zeroing
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-+ * capability. REQ_OP_DISCARD translates to a zero-out even when backed
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-+ * by block devices to keep consistent behavior with file-backed loop
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-+ * devices.
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-+ */
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-+ if (S_ISBLK(inode->i_mode) && !lo->lo_encrypt_key_size) {
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-+ backingq = bdev_get_queue(inode->i_bdev);
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-+ blk_queue_max_discard_sectors(q,
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-+ backingq->limits.max_write_zeroes_sectors);
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-+
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-+ blk_queue_max_write_zeroes_sectors(q,
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-+ backingq->limits.max_write_zeroes_sectors);
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-
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- /*
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- * We use punch hole to reclaim the free space used by the
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-@@ -869,22 +885,24 @@ static void loop_config_discard(struct l
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- * encryption is enabled, because it may give an attacker
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- * useful information.
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- */
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-- if ((!file->f_op->fallocate) ||
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-- lo->lo_encrypt_key_size) {
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-+ } else if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) {
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- q->limits.discard_granularity = 0;
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- q->limits.discard_alignment = 0;
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- blk_queue_max_discard_sectors(q, 0);
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- blk_queue_max_write_zeroes_sectors(q, 0);
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-- blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
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-- return;
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-- }
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-
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-- q->limits.discard_granularity = inode->i_sb->s_blocksize;
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-- q->limits.discard_alignment = 0;
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-+ } else {
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-+ q->limits.discard_granularity = inode->i_sb->s_blocksize;
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-+ q->limits.discard_alignment = 0;
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-
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-- blk_queue_max_discard_sectors(q, UINT_MAX >> 9);
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-- blk_queue_max_write_zeroes_sectors(q, UINT_MAX >> 9);
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-- blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
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-+ blk_queue_max_discard_sectors(q, UINT_MAX >> 9);
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-+ blk_queue_max_write_zeroes_sectors(q, UINT_MAX >> 9);
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-+ }
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-+
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-+ if (q->limits.max_write_zeroes_sectors)
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-+ blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
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-+ else
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-+ blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
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- }
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-
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- static void loop_unprepare_queue(struct loop_device *lo)
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