kernel.git/fs/btrfs/sysfs.c, branch linux-6.10.y

btrfs: use btrfs_is_testing() everywhere

2024-05-07T19:31:07Z

There are open coded tests of BTRFS_FS_STATE_DUMMY_FS_INFO and we have a wrapper for that that's a compile-time constant when self-tests are not built in. As this is only for development we can save some bytes and conditions on release configs by using the helper in the remaining cases. Reviewed-by: Josef Bacik Signed-off-by: David Sterba

btrfs: introduce offload_csum_mode to tweak checksum offloading behavior

2024-03-04T15:24:52Z

We disable offloading checksum to workqueues and do it synchronously when the checksum algorithm is fast. However, as reported in the link below, RAID0 with multiple devices may suffer from the sync checksum, because "fast checksum" is still not fast enough to catch up with RAID0 writing. We don't have an effective way to determine whether to offload or not, for now add a sysfs knob so this can be debugged. This is intentionally under CONFIG_BTRFS_DEBUG so ti's not exposed to users as it may be removed in the future agin. Introduce fs_devices->offload_csum_mode, so that a btrfs developer can change the behavior by writing to /sys/fs/btrfs//offload_csum. The default is "auto" which is the same as the previous behavior. Or, you can set "on" or "off" (or "y" or "n" whatever kstrtobool() accepts) to always/never offload checksum. More benchmark need to be collected with this knob to implement a proper criteria to enable/disable checksum offloading. Link: https://lore.kernel.org/linux-btrfs/20230731152223.4EFB.409509F4@e16-tech.com/ Link: https://lore.kernel.org/linux-btrfs/p3vo3g7pqn664mhmdhlotu5dzcna6vjtcoc2hb2lsgo2fwct7k@xzaxclba5tae/ Reviewed-by: Johannes Thumshirn Signed-off-by: Naohiro Aota Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: sysfs: drop unnecessary double logical negation in acl_show()

2024-03-04T15:24:52Z

The IS_ENABLED() macro already guarantees the result will be a suitable boolean return value ("1" for enabled, and "0" for disabled). Thus, it seems that the "!!" used right before is unnecessary to force the 0/1 values. Reviewed-by: Anand Jain Signed-off-by: Neal Gompa Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: use READ/WRITE_ONCE for fs_devices->read_policy

2024-03-04T15:24:47Z

Since we can read/modify the value from the sysfs interface concurrently, it would be better to protect it from compiler optimizations. Currently, there is only one read policy BTRFS_READ_POLICY_PID available, so no actual problem can happen now. This is a preparation for the future expansion. Reviewed-by: Anand Jain Signed-off-by: Naohiro Aota Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: sysfs: validate scrub_speed_max value

2023-12-15T22:01:04Z

The value set as scrub_speed_max accepts size with suffixes (k/m/g/t/p/e) but we should still validate it for trailing characters, similar to what we do with chunk_size_store. CC: stable@vger.kernel.org # 5.15+ Signed-off-by: David Disseldorp Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: sysfs: show temp_fsid feature

2023-10-12T14:44:18Z

This adds sysfs objects to indicate temp_fsid feature support and its status. /sys/fs/btrfs/features/temp_fsid /sys/fs/btrfs//temp_fsid For example: Consider two cloned and mounted devices. $ blkid /dev/sdc[1-2] /dev/sdc1: UUID="509ad44b-ad2a-4a8a-bc8d-fe69db7220d5" .. /dev/sdc2: UUID="509ad44b-ad2a-4a8a-bc8d-fe69db7220d5" .. One gets actual fsid, and the other gets the temp_fsid when mounted. $ btrfs filesystem show -m Label: none uuid: 509ad44b-ad2a-4a8a-bc8d-fe69db7220d5 Total devices 1 FS bytes used 54.14MiB devid 1 size 300.00MiB used 144.00MiB path /dev/sdc1 Label: none uuid: 33bad74e-c91b-43a5-aef8-b3cab97ae63a Total devices 1 FS bytes used 54.14MiB devid 1 size 300.00MiB used 144.00MiB path /dev/sdc2 Their sysfs as below. $ cat /sys/fs/btrfs/features/temp_fsid 0 $ cat /sys/fs/btrfs/509ad44b-ad2a-4a8a-bc8d-fe69db7220d5/temp_fsid 0 $ cat /sys/fs/btrfs/33bad74e-c91b-43a5-aef8-b3cab97ae63a/temp_fsid 1 Signed-off-by: Anand Jain Signed-off-by: David Sterba

btrfs: add and use helpers for reading and writing fs_info->generation

2023-10-12T14:44:17Z

Currently the generation field of struct btrfs_fs_info is always modified while holding fs_info->trans_lock locked. Most readers will access this field without taking that lock but while holding a transaction handle, which is safe to do due to the transaction life cycle. However there are other readers that are neither holding the lock nor holding a transaction handle open: 1) When reading an inode from disk, at btrfs_read_locked_inode(); 2) When reading the generation to expose it to sysfs, at btrfs_generation_show(); 3) Early in the fsync path, at skip_inode_logging(); 4) When creating a hole at btrfs_cont_expand(), during write paths, truncate and reflinking; 5) In the fs_info ioctl (btrfs_ioctl_fs_info()); 6) While mounting the filesystem, in the open_ctree() path. In these cases it's safe to directly read fs_info->generation as no one can concurrently start a transaction and update fs_info->generation. In case of the fsync path, races here should be harmless, and in the worst case they may cause a fsync to log an inode when it's not really needed, so nothing bad from a functional perspective. In the other cases it's not so clear if functional problems may arise, though in case 1 rare things like a load/store tearing [1] may cause the BTRFS_INODE_NEEDS_FULL_SYNC flag not being set on an inode and therefore result in incorrect logging later on in case a fsync call is made. To avoid data race warnings from tools like KCSAN and other issues such as load and store tearing (amongst others, see [1]), create helpers to access the generation field of struct btrfs_fs_info using READ_ONCE() and WRITE_ONCE(), and use these helpers where needed. [1] https://lwn.net/Articles/793253/ Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: sysfs: add simple_quota incompat feature entry

2023-10-12T14:44:10Z

Add an entry in the features directory for the new incompat flag Signed-off-by: Boris Burkov Signed-off-by: David Sterba

btrfs: sysfs: expose quota mode via sysfs

2023-10-12T14:44:10Z

Add a new sysfs file /sys/fs/btrfs//qgroups/mode which prints out the mode qgroups is running in. The possible modes are qgroup, and squota. If quotas are not enabled, then the qgroups directory will not exist, so don't handle that mode. Signed-off-by: Boris Burkov Signed-off-by: David Sterba

btrfs: sysfs: announce presence of raid-stripe-tree

2023-10-12T14:44:09Z

If a filesystem with a raid-stripe-tree is mounted, show the RST feature in sysfs, currently still under the CONFIG_BTRFS_DEBUG option. Reviewed-by: Josef Bacik Signed-off-by: Johannes Thumshirn Reviewed-by: David Sterba Signed-off-by: David Sterba