]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
btrfs: call btrfs_check_rw_degradable only if there is a missing device
authorAnand Jain <anand.jain@oracle.com>
Tue, 19 Oct 2021 10:43:38 +0000 (18:43 +0800)
committerDavid Sterba <dsterba@suse.com>
Fri, 29 Oct 2021 10:39:13 +0000 (12:39 +0200)
commit5c78a5e7aa835c4f08a7c90fe02d19f95a776f29
tree5d65c12b04f3bf07e146a10433f369893c3e7a0f
parente77fbf990316d47968a793d8aa920fd62385aec9
btrfs: call btrfs_check_rw_degradable only if there is a missing device

In open_ctree() in btrfs_check_rw_degradable() [1], we check each block
group individually if at least the minimum number of devices is available
for that profile. If all the devices are available, then we don't have to
check degradable.

[1]
open_ctree()
::
3559 if (!sb_rdonly(sb) && !btrfs_check_rw_degradable(fs_info, NULL)) {

Also before calling btrfs_check_rw_degradable() in open_ctee() at the
line number shown below [2] we call btrfs_read_chunk_tree() and down to
add_missing_dev() to record number of missing devices.

[2]
open_ctree()
::
3454         ret = btrfs_read_chunk_tree(fs_info);

btrfs_read_chunk_tree()
  read_one_chunk() / read_one_dev()
    add_missing_dev()

So, check if there is any missing device before btrfs_check_rw_degradable()
in open_ctree().

Also, with this the mount command could save ~16ms.[3] in the most
common case, that is no device is missing.

[3]
 1) * 16934.96 us | btrfs_check_rw_degradable [btrfs]();

CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
fs/btrfs/disk-io.c