git: b4889992d787 - stable/13 - Add vfs_remount_ro()
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Date: Sat, 15 Jan 2022 00:51:43 UTC
The branch stable/13 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=b4889992d787275e9b67bdff6d08d585e6659cab commit b4889992d787275e9b67bdff6d08d585e6659cab Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2021-12-25 19:44:59 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2022-01-14 18:11:02 +0000 Add vfs_remount_ro() (cherry picked from commit 4a4b059a97950740f04b091d7050460a984e7555) --- sys/kern/vfs_mount.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++ sys/sys/mount.h | 2 ++ 2 files changed, 91 insertions(+) diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c index c10c24f4501b..1ecb2b5939d5 100644 --- a/sys/kern/vfs_mount.c +++ b/sys/kern/vfs_mount.c @@ -2557,6 +2557,95 @@ mount_devctl_event(const char *type, struct mount *mp, bool donew) free(buf, M_MOUNT); } +/* + * Force remount specified mount point to read-only. The argument + * must be busied to avoid parallel unmount attempts. + * + * Intended use is to prevent further writes if some metadata + * inconsistency is detected. Note that the function still flushes + * all cached metadata and data for the mount point, which might be + * not always suitable. + */ +int +vfs_remount_ro(struct mount *mp) +{ + struct vfsoptlist *opts; + struct vfsopt *opt; + struct vnode *vp_covered, *rootvp; + int error; + + KASSERT(mp->mnt_lockref > 0, + ("vfs_remount_ro: mp %p is not busied", mp)); + KASSERT((mp->mnt_kern_flag & MNTK_UNMOUNT) == 0, + ("vfs_remount_ro: mp %p is being unmounted (and busy?)", mp)); + + rootvp = NULL; + vp_covered = mp->mnt_vnodecovered; + error = vget(vp_covered, LK_EXCLUSIVE | LK_NOWAIT); + if (error != 0) + return (error); + VI_LOCK(vp_covered); + if ((vp_covered->v_iflag & VI_MOUNT) != 0) { + VI_UNLOCK(vp_covered); + vput(vp_covered); + return (EBUSY); + } + vp_covered->v_iflag |= VI_MOUNT; + VI_UNLOCK(vp_covered); + vfs_op_enter(mp); + vn_seqc_write_begin(vp_covered); + + MNT_ILOCK(mp); + if ((mp->mnt_flag & MNT_RDONLY) != 0) { + MNT_IUNLOCK(mp); + error = EBUSY; + goto out; + } + mp->mnt_flag |= MNT_UPDATE | MNT_FORCE | MNT_RDONLY; + rootvp = vfs_cache_root_clear(mp); + MNT_IUNLOCK(mp); + + opts = malloc(sizeof(struct vfsoptlist), M_MOUNT, M_WAITOK | M_ZERO); + TAILQ_INIT(opts); + opt = malloc(sizeof(struct vfsopt), M_MOUNT, M_WAITOK | M_ZERO); + opt->name = strdup("ro", M_MOUNT); + opt->value = NULL; + TAILQ_INSERT_TAIL(opts, opt, link); + vfs_mergeopts(opts, mp->mnt_opt); + mp->mnt_optnew = opts; + + error = VFS_MOUNT(mp); + + if (error == 0) { + MNT_ILOCK(mp); + mp->mnt_flag &= ~(MNT_UPDATE | MNT_FORCE); + MNT_IUNLOCK(mp); + vfs_deallocate_syncvnode(mp); + if (mp->mnt_opt != NULL) + vfs_freeopts(mp->mnt_opt); + mp->mnt_opt = mp->mnt_optnew; + } else { + MNT_ILOCK(mp); + mp->mnt_flag &= ~(MNT_UPDATE | MNT_FORCE | MNT_RDONLY); + MNT_IUNLOCK(mp); + vfs_freeopts(mp->mnt_optnew); + } + mp->mnt_optnew = NULL; + +out: + vfs_op_exit(mp); + VI_LOCK(vp_covered); + vp_covered->v_iflag &= ~VI_MOUNT; + VI_UNLOCK(vp_covered); + vput(vp_covered); + vn_seqc_write_end(vp_covered); + if (rootvp != NULL) { + vn_seqc_write_end(rootvp); + vrele(rootvp); + } + return (error); +} + /* * Suspend write operations on all local writeable filesystems. Does * full sync of them in the process. diff --git a/sys/sys/mount.h b/sys/sys/mount.h index aa876cdb00e9..93193eb3e28c 100644 --- a/sys/sys/mount.h +++ b/sys/sys/mount.h @@ -1004,6 +1004,8 @@ struct mount *vfs_mount_alloc(struct vnode *, struct vfsconf *, const char *, int vfs_suser(struct mount *, struct thread *); void vfs_unbusy(struct mount *); void vfs_unmountall(void); +int vfs_remount_ro(struct mount *mp); + extern TAILQ_HEAD(mntlist, mount) mountlist; /* mounted filesystem list */ extern struct mtx_padalign mountlist_mtx; extern struct nfs_public nfs_pub;