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btrfs: clear oneshot options on mount and remount

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Some options only apply during mount time and are cleared at the end
of mount. For now, the example is USEBACKUPROOT, but CLEAR_CACHE also
fits the bill, and this is a preparation patch for also clearing that
option.

One subtlety is that the current code only resets USEBACKUPROOT on rw
mounts, but the option is meaningfully "consumed" by a ro mount, so it
feels appropriate to clear in that case as well. A subsequent read-write
remount would not go through open_ctree, which is the only place that
checks the option, so the change should be benign.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Boris Burkov 2020-11-18 15:06:20 -08:00 committed by David Sterba
parent 5011139a47
commit 8cd2908846
3 changed files with 15 additions and 1 deletions
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14
fs/btrfs/disk-io.c
View File

@ -2870,6 +2870,16 @@ static int btrfs_check_uuid_tree(struct btrfs_fs_info *fs_info)
return 0;
}
/*
* Some options only have meaning at mount time and shouldn't persist across
* remounts, or be displayed. Clear these at the end of mount and remount
* code paths.
*/
void btrfs_clear_oneshot_options(struct btrfs_fs_info *fs_info)
{
btrfs_clear_opt(fs_info->mount_opt, USEBACKUPROOT);
}
/*
* Mounting logic specific to read-write file systems. Shared by open_ctree
* and btrfs_remount when remounting from read-only to read-write.
@ -3359,7 +3369,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
}
if (sb_rdonly(sb))
return 0;
goto clear_oneshot;
if (btrfs_test_opt(fs_info, CLEAR_CACHE) &&
btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
@ -3402,6 +3412,8 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
}
set_bit(BTRFS_FS_OPEN, &fs_info->flags);
clear_oneshot:
btrfs_clear_oneshot_options(fs_info);
return 0;
fail_qgroup:

1
fs/btrfs/disk-io.h
View File

@ -50,6 +50,7 @@ struct extent_buffer *btrfs_find_create_tree_block(
u64 bytenr, u64 owner_root,
int level);
void btrfs_clean_tree_block(struct extent_buffer *buf);
void btrfs_clear_oneshot_options(struct btrfs_fs_info *fs_info);
int btrfs_start_pre_rw_mount(struct btrfs_fs_info *fs_info);
int __cold open_ctree(struct super_block *sb,
struct btrfs_fs_devices *fs_devices,

1
fs/btrfs/super.c
View File

@ -1999,6 +1999,7 @@ out:
wake_up_process(fs_info->transaction_kthread);
btrfs_remount_cleanup(fs_info, old_opts);
btrfs_clear_oneshot_options(fs_info);
clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
return 0;