kernel: bump 4.19 to 4.19.93

[openwrt/staging/dedeckeh.git] / target / linux / generic / hack-4.19 / 551-loop-Better-discard-support-for-block-devices.patch

diff --git a/target/linux/generic/hack-4.19/551-loop-Better-discard-support-for-block-devices.patch b/target/linux/generic/hack-4.19/551-loop-Better-discard-support-for-block-devices.patch
new file mode 100644 (file)
index 0000000..ac393e5
--- /dev/null
+++ b/target/linux/generic/hack-4.19/551-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)