Messages in this thread | | | From | Miklos Szeredi <> | Date | Mon, 24 Feb 2020 16:28:40 +0100 | Subject | Re: [PATCH 00/17] VFS: Filesystem information and notifications [ver #17] |
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On Mon, Feb 24, 2020 at 3:55 PM James Bottomley <James.Bottomley@hansenpartnership.com> wrote:
> Once it's table driven, certainly a sysfs directory becomes possible. > The problem with ST_DEV is filesystems like btrfs and xfs that may have > multiple devices.
For XFS there's always a single sb->s_dev though, that's what st_dev will be set to on all files.
Btrfs subvolume is sort of a lightweight superblock, so basically all such st_dev's are aliases of the same master superblock. So lookup of all subvolume st_dev's could result in referencing the same underlying struct super_block (just like /proc/$PID will reference the same underlying task group regardless of which of the task group member's PID is used).
Having this info in sysfs would spare us a number of issues that a set of new syscalls would bring. The question is, would that be enough, or is there a reason that sysfs can't be used to present the various filesystem related information that fsinfo is supposed to present?
Thanks, Miklos
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