d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

vfs: add vfs_ref_from_vp

Browse Source 
This generalizes what vop_stdgetwritemount used to be doing.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D28695
This commit is contained in:
Mateusz Guzik 2021-02-15 23:08:40 +01:00
parent 5fa12fe0cd
commit a15f787adb
3 changed files with 40 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
sys/kern/vfs_default.c
View File

@ -680,7 +680,6 @@ vop_stdgetwritemount(ap)
} */ *ap;
{
struct mount *mp;
struct mount_pcpu *mpcpu;
struct vnode *vp;
/*
@ -693,29 +692,7 @@ vop_stdgetwritemount(ap)
* with releasing it.
*/
vp = ap->a_vp;
mp = vp->v_mount;
if (mp == NULL) {
*(ap->a_mpp) = NULL;
return (0);
}
if (vfs_op_thread_enter(mp, mpcpu)) {
if (mp == vp->v_mount) {
vfs_mp_count_add_pcpu(mpcpu, ref, 1);
vfs_op_thread_exit(mp, mpcpu);
} else {
vfs_op_thread_exit(mp, mpcpu);
mp = NULL;
}
} else {
MNT_ILOCK(mp);
if (mp == vp->v_mount) {
MNT_REF(mp);
MNT_IUNLOCK(mp);
} else {
MNT_IUNLOCK(mp);
mp = NULL;
}
}
mp = vfs_ref_from_vp(vp);
*(ap->a_mpp) = mp;
return (0);
}

38
sys/kern/vfs_mount.c
View File

@ -449,6 +449,44 @@ sys_nmount(struct thread *td, struct nmount_args *uap)
* Various utility functions
*/
/*
* Get a reference on a mount point from a vnode.
*
* The vnode is allowed to be passed unlocked and race against dooming. Note in
* such case there are no guarantees the referenced mount point will still be
* associated with it after the function returns.
*/
struct mount *
vfs_ref_from_vp(struct vnode *vp)
{
struct mount *mp;
struct mount_pcpu *mpcpu;
mp = atomic_load_ptr(&vp->v_mount);
if (__predict_false(mp == NULL)) {
return (mp);
}
if (vfs_op_thread_enter(mp, mpcpu)) {
if (__predict_true(mp == vp->v_mount)) {
vfs_mp_count_add_pcpu(mpcpu, ref, 1);
vfs_op_thread_exit(mp, mpcpu);
} else {
vfs_op_thread_exit(mp, mpcpu);
mp = NULL;
}
} else {
MNT_ILOCK(mp);
if (mp == vp->v_mount) {
MNT_REF(mp);
MNT_IUNLOCK(mp);
} else {
MNT_IUNLOCK(mp);
mp = NULL;
}
}
return (mp);
}
void
vfs_ref(struct mount *mp)
{

1
sys/sys/mount.h
View File

@ -997,6 +997,7 @@ void vfs_mount_error(struct mount *, const char *, ...);
void vfs_mountroot(void); /* mount our root filesystem */
void vfs_mountedfrom(struct mount *, const char *from);
void vfs_notify_upper(struct vnode *, int);
struct mount *vfs_ref_from_vp(struct vnode *);
void vfs_ref(struct mount *);
void vfs_rel(struct mount *);
struct mount *vfs_mount_alloc(struct vnode *, struct vfsconf *, const char *,