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Allow some VOPs to return ERELOOKUP to indicate VFS operation restart at top level.

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Restart syscalls and some sync operations when filesystem indicated
ERELOOKUP condition, mostly for VOPs operating on metdata.  In
particular, lookup results cached in the inode/v_data is no longer
valid and needs recalculating.  Right now this should be nop.

Assert that ERELOOKUP is catched everywhere and not returned to
userspace, by asserting that td_errno != ERELOOKUP on syscall return
path.

In collaboration with:	pho
Reviewed by:	mckusick (previous version), markj
Tested by:	markj (syzkaller), pho
Sponsored by:	The FreeBSD Foundation
Differential revision:	https://reviews.freebsd.org/D26136
This commit is contained in:
Konstantin Belousov 2020-11-13 09:42:32 +00:00
parent 7cde2ec4fd
commit 441eb16a95
4 changed files with 39 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
sys/kern/subr_syscall.c
View File

@ -217,6 +217,8 @@ syscallret(struct thread *td)
KASSERT((td->td_pflags & TDP_FORKING) == 0,
("fork() did not clear TDP_FORKING upon completion"));
KASSERT(td->td_errno != ERELOOKUP,
("ERELOOKUP not consumed syscall %d", td->td_sa.code));
p = td->td_proc;
sa = &td->td_sa;

2
sys/kern/uipc_usrreq.c
View File

@ -671,6 +671,8 @@ restart:
vput(nd.ni_dvp);
if (error) {
vn_finished_write(mp);
if (error == ERELOOKUP)
goto restart;
goto error;
}
vp = nd.ni_vp;

9
sys/kern/vfs_subr.c
View File

@ -1937,7 +1937,10 @@ bufobj_invalbuf(struct bufobj *bo, int flags, int slpflag, int slptimeo)
}
if (bo->bo_dirty.bv_cnt > 0) {
BO_UNLOCK(bo);
if ((error = BO_SYNC(bo, MNT_WAIT)) != 0)
do {
error = BO_SYNC(bo, MNT_WAIT);
} while (error == ERELOOKUP);
if (error != 0)
return (error);
/*
* XXX We could save a lock/unlock if this was only
@ -3678,7 +3681,9 @@ loop:
vm_object_page_clean(vp->v_object, 0, 0, 0);
VM_OBJECT_WUNLOCK(vp->v_object);
}
error = VOP_FSYNC(vp, MNT_WAIT, td);
do {
error = VOP_FSYNC(vp, MNT_WAIT, td);
} while (error == ERELOOKUP);
if (error != 0) {
VOP_UNLOCK(vp);
vdrop(vp);

33
sys/kern/vfs_syscalls.c
View File

@ -1384,6 +1384,8 @@ restart:
NDFREE(&nd, NDF_ONLY_PNBUF);
vput(nd.ni_dvp);
vn_finished_write(mp);
if (error == ERELOOKUP)
goto restart;
return (error);
}
@ -1470,6 +1472,8 @@ out:
vput(nd.ni_dvp);
vn_finished_write(mp);
NDFREE(&nd, NDF_ONLY_PNBUF);
if (error == ERELOOKUP)
goto restart;
return (error);
}
@ -1568,7 +1572,7 @@ kern_linkat(struct thread *td, int fd1, int fd2, const char *path1,
return (error);
NDFREE(&nd, NDF_ONLY_PNBUF);
error = kern_linkat_vp(td, nd.ni_vp, fd2, path2, segflag);
} while (error == EAGAIN);
} while (error == EAGAIN || error == ERELOOKUP);
return (error);
}
@ -1741,6 +1745,8 @@ out2:
NDFREE(&nd, NDF_ONLY_PNBUF);
vput(nd.ni_dvp);
vn_finished_write(mp);
if (error == ERELOOKUP)
goto restart;
out:
if (segflg != UIO_SYSSPACE)
uma_zfree(namei_zone, tmppath);
@ -1791,6 +1797,8 @@ restart:
NDFREE(&nd, NDF_ONLY_PNBUF);
vput(nd.ni_dvp);
vn_finished_write(mp);
if (error == ERELOOKUP)
goto restart;
return (error);
}
@ -1937,6 +1945,8 @@ out:
vrele(vp);
else
vput(vp);
if (error == ERELOOKUP)
goto restart;
fdout:
if (fp != NULL)
fdrop(fp, td);
@ -3395,7 +3405,8 @@ kern_truncate(struct thread *td, const char *path, enum uio_seg pathseg,
int error;
if (length < 0)
return(EINVAL);
return (EINVAL);
retry:
NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, pathseg, path, td);
if ((error = namei(&nd)) != 0)
return (error);
@ -3424,6 +3435,8 @@ kern_truncate(struct thread *td, const char *path, enum uio_seg pathseg,
vn_finished_write(mp);
vn_rangelock_unlock(vp, rl_cookie);
vrele(vp);
if (error == ERELOOKUP)
goto retry;
return (error);
}
@ -3479,6 +3492,7 @@ kern_fsync(struct thread *td, int fd, bool fullsync)
if (!fullsync)
/* XXXKIB: compete outstanding aio writes */;
#endif
retry:
error = vn_start_write(vp, &mp, V_WAIT | PCATCH);
if (error != 0)
goto drop;
@ -3498,6 +3512,8 @@ kern_fsync(struct thread *td, int fd, bool fullsync)
error = fullsync ? VOP_FSYNC(vp, MNT_WAIT, td) : VOP_FDATASYNC(vp, td);
VOP_UNLOCK(vp);
vn_finished_write(mp);
if (error == ERELOOKUP)
goto retry;
drop:
fdrop(fp, td);
return (error);
@ -3679,7 +3695,7 @@ again:
* are links to the same vnode), then there is nothing to do.
*/
if (fvp == tvp)
error = -1;
error = ERESTART;
#ifdef MAC
else
error = mac_vnode_check_rename_to(td->td_ucred, tdvp,
@ -3708,8 +3724,10 @@ out:
out1:
if (fromnd.ni_startdir)
vrele(fromnd.ni_startdir);
if (error == -1)
if (error == ERESTART)
return (0);
if (error == ERELOOKUP)
goto again;
return (error);
}
@ -3803,6 +3821,8 @@ out:
if (error == 0)
vput(nd.ni_vp);
vn_finished_write(mp);
if (error == ERELOOKUP)
goto restart;
return (error);
}
@ -3903,6 +3923,8 @@ out:
vrele(nd.ni_dvp);
else
vput(nd.ni_dvp);
if (error == ERELOOKUP)
goto restart;
fdout:
if (fp != NULL)
fdrop(fp, td);
@ -4416,7 +4438,8 @@ kern_fhlinkat(struct thread *td, int fd, const char *path,
if (error != 0)
return (error);
VOP_UNLOCK(vp);
} while ((error = kern_linkat_vp(td, vp, fd, path, pathseg)) == EAGAIN);
error = kern_linkat_vp(td, vp, fd, path, pathseg);
} while (error == EAGAIN || error == ERELOOKUP);
return (error);
}