| Message ID | f417a0730df69830b07db681eb0992a3ceb99d81.1630639255.git.anand.jain@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [resend] btrfs: mount: call btrfs_check_rw_degradable only if there is a missing device | expand |
On Tue, Oct 19, 2021 at 06:43:38PM +0800, Anand Jain wrote: > 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(). > > With this, in an example, 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](); > > Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Thanks, Josef
On Tue, Oct 19, 2021 at 06:43:38PM +0800, Anand Jain wrote: > 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(). > > With this, in an example, 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](); > > Signed-off-by: Anand Jain <anand.jain@oracle.com> Added to misc-next, thanks.
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 7d80e5b22d32..b86049a16a27 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3564,7 +3564,8 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device 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;
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(). With this, in an example, 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](); Signed-off-by: Anand Jain <anand.jain@oracle.com> --- fs/btrfs/disk-io.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)