Update of the Documentation/filesystes/btrfs.txt file. --- 0 files changed diff --git a/Documentation/filesystems/btrfs.txt b/Documentation/filesystems/btrfs.txt index 7671352..35840ab 100644 --- a/Documentation/filesystems/btrfs.txt +++ b/Documentation/filesystems/btrfs.txt @@ -89,3 +89,78 @@ btrfsck: do a limited check of the FS extent trees. btrfs-debug-tree: print all of the FS metadata in text form. Example: btrfs-debug-tree /dev/sda2 >& big_output_file + + + + SYSFS SUPPORT + ============= + +If the option CONFIG_BTRFS_FS_SYSFS is enabled, BTRFS exports some +information via the sysfs filesystem. +Todate these information are read-only. + +The information exported are related to both the devices and the filesystems. +When a devices is registred (for example via the btrfs filesystem scan +command), BTRFS creates the following entries under /sys/fs/btrfs: + +/sys/fs/btrfs: + + - devices -> information per device basis + - filesystem -> information per filesystem basis + +/sys/fs/btrfs/devices/<device-UUID>: + + - bytes_used + - devid + - disk_total_bytes + - fsid -> fielsystem UUID + - generation + - major [*] + - minor [*] + - missing + - name -> device name (eg: /dev/sda) + - total_bytes + - write_errors -> error info + - corruption_errors -> error info + - read_errors -> error info + - generation_errors -> error info + - flush_errors -> error info + - writeable + +[*] These information are available only after the mounting of the +filesystem. + +/sys/fs/btrfs/filesystem/<filesystem-UUID>/fs_info: + + - balance_cancel_req -> balance status information + - balance_pause_req -> balance status information + - balance_running -> balance status information + - fs_state + - generation + - label -> label of the filesystem + - last_trans_committed + - scrub_cancel_req -> scrub status information + - scrub_pause_req -> scrub status information + - scrubs_paused -> scrub status information + - scrubs_running -> scrub status information + +/sys/fs/btrfs/filesystem/<filesystem-UUID>/fs_devices: + + - latest_devid + - latest_trans + - missing_devices + - num_can_discard + - open_devices + - opened + - rw_devices + - seeding + - total_rw_bytes + +The filesystems information are split in two section (fs_info and fs_devices) +because the fs_devices entries are available after the scan of the device(s), +but the fs_info entries are available only after the mount of the +filesystem. + +The link between the filesystem and the device(s) is the fsid == +filesystem-UUID. + -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
