On 6/13/22, Doug Ambrisko <[email protected]> wrote:
> The branch main has been updated by ambrisko:
>
> URL:
> https://cgit.FreeBSD.org/src/commit/?id=6468cd8e0ef9d1d3331e9de26cd2be59bc778494
>
> commit 6468cd8e0ef9d1d3331e9de26cd2be59bc778494
> Author: Doug Ambrisko <[email protected]>
> AuthorDate: 2022-06-13 14:56:38 +0000
> Commit: Doug Ambrisko <[email protected]>
> CommitDate: 2022-06-13 14:56:38 +0000
>
> mount: add vnode usage per file system with mount -v
>
> This avoids the need to drop into the ddb to figure out vnode
> usage per file system. It helps to see if they are or are not
> being freed. Suggestion to report active vnode count was from
> kib@
>
> Reviewed by: kib
> Differential Revision: https://reviews.freebsd.org/D35436
> ---
> sbin/mount/mount.c | 7 +++++++
> sys/kern/vfs_mount.c | 12 ++++++++++++
> sys/sys/mount.h | 4 +++-
> 3 files changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/sbin/mount/mount.c b/sbin/mount/mount.c
> index 79d9d6cb0caf..bd3d0073c474 100644
> --- a/sbin/mount/mount.c
> +++ b/sbin/mount/mount.c
> @@ -692,6 +692,13 @@ prmount(struct statfs *sfp)
> xo_emit("{D:, }{Lw:fsid}{:fsid}", fsidbuf);
> free(fsidbuf);
> }
> + if (sfp->f_nvnodelistsize != 0 || sfp->f_avnodecount != 0) {
> + xo_open_container("vnodes");
> + xo_emit("{D:,
> }{Lwc:vnodes}{Lw:count}{w:count/%ju}{Lw:active}{:active/%ju}",
> + (uintmax_t)sfp->f_nvnodelistsize,
> + (uintmax_t)sfp->f_avnodecount);
> + xo_close_container("vnodes");
> + }
> }
> xo_emit("{D:)}\n");
> }
> diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
> index 71a40fd97a9c..e3818b67e841 100644
> --- a/sys/kern/vfs_mount.c
> +++ b/sys/kern/vfs_mount.c
> @@ -2610,6 +2610,8 @@ vfs_copyopt(struct vfsoptlist *opts, const char *name,
> void *dest, int len)
> int
> __vfs_statfs(struct mount *mp, struct statfs *sbp)
> {
> + struct vnode *vp;
> + uint32_t count;
>
> /*
> * Filesystems only fill in part of the structure for updates, we
> @@ -2624,6 +2626,16 @@ __vfs_statfs(struct mount *mp, struct statfs *sbp)
> sbp->f_version = STATFS_VERSION;
> sbp->f_namemax = NAME_MAX;
> sbp->f_flags = mp->mnt_flag & MNT_VISFLAGMASK;
> + sbp->f_nvnodelistsize = mp->mnt_nvnodelistsize;
> +
> + count = 0;
> + MNT_ILOCK(mp);
> + TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
> + if (vrefcnt(vp) > 0) /* racy but does not matter */
> + count++;
> + }
> + MNT_IUNLOCK(mp);
> + sbp->f_avnodecount = count;
>
libc uses statfs for dir walk (see gen/fts.c), most notably find
immediately runs into it. As such the linear scan by default is a
non-starter.
I don't know if mount is the right place to dump this kind of info to
begin with, but even so, it should only happen with a dedicated flag.
As statfs does not take any flags on its own, there is no way to
prevent it from doing the above walk. Perhaps a dedicated sysctl which
takes mount point id could do the walk instead, when asked.
Short of making the walk optional I'm afraid this will have to be reverted.
> return (mp->mnt_op->vfs_statfs(mp, sbp));
> }
> diff --git a/sys/sys/mount.h b/sys/sys/mount.h
> index 3383bfe8f431..edac64171f9a 100644
> --- a/sys/sys/mount.h
> +++ b/sys/sys/mount.h
> @@ -91,7 +91,9 @@ struct statfs {
> uint64_t f_asyncwrites; /* count of async writes since mount */
> uint64_t f_syncreads; /* count of sync reads since mount */
> uint64_t f_asyncreads; /* count of async reads since mount */
> - uint64_t f_spare[10]; /* unused spare */
> + uint32_t f_nvnodelistsize; /* # of vnodes */
> + uint32_t f_avnodecount; /* # of active vnodes */
> + uint64_t f_spare[9]; /* unused spare */
> uint32_t f_namemax; /* maximum filename length */
> uid_t f_owner; /* user that mounted the filesystem */
> fsid_t f_fsid; /* filesystem id */
>
--
Mateusz Guzik <mjguzik gmail.com>
