From: Anand Jain anand.jain@oracle.com
commit 5c78a5e7aa835c4f08a7c90fe02d19f95a776f29 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/disk-io.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3145,7 +3145,8 @@ retry_root_backup: goto fail_sysfs; }
- if (!sb_rdonly(sb) && !btrfs_check_rw_degradable(fs_info, NULL)) { + if (!sb_rdonly(sb) && fs_info->fs_devices->missing_devices && + !btrfs_check_rw_degradable(fs_info, NULL)) { btrfs_warn(fs_info, "writable mount is not allowed due to too many missing devices"); goto fail_sysfs;