Author: kib
Date: Fri Nov 29 14:02:32 2019
New Revision: 355211
URL: https://svnweb.freebsd.org/changeset/base/355211
Log:
Add a VN_OPEN_INVFS flag.
vn_open_cred() assumes that it is called from the top-level of a VFS
syscall. Writers must call bwillwrite() before locking any VFS
resource to wait for cleanup of dirty buffers.
ZFS getextattr() and setextattr() VOPs do call vn_open_cred(), which
results in wait for unrelated buffers while owning ZFS vnode lock (and
ZFS does not use buffer cache). VN_OPEN_INVFS allows caller to skip
bwillwrite.
Note that ZFS is still incorrect there, because it starts write on an
mp and locks a vnode while holding another vnode lock.
Reported by: Willem Jan Withagen <w...@digiware.nl>
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Modified:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
head/sys/kern/vfs_vnops.c
head/sys/sys/vnode.h
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c Fri Nov
29 13:55:56 2019 (r355210)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c Fri Nov
29 14:02:32 2019 (r355211)
@@ -5490,7 +5490,7 @@ vop_getextattr {
flags = FREAD;
NDINIT_ATVP(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, attrname,
xvp, td);
- error = vn_open_cred(&nd, &flags, 0, 0, ap->a_cred, NULL);
+ error = vn_open_cred(&nd, &flags, VN_OPEN_INVFS, 0, ap->a_cred, NULL);
vp = nd.ni_vp;
NDFREE(&nd, NDF_ONLY_PNBUF);
if (error != 0) {
@@ -5627,7 +5627,8 @@ vop_setextattr {
flags = FFLAGS(O_WRONLY | O_CREAT);
NDINIT_ATVP(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, attrname,
xvp, td);
- error = vn_open_cred(&nd, &flags, 0600, 0, ap->a_cred, NULL);
+ error = vn_open_cred(&nd, &flags, 0600, VN_OPEN_INVFS, ap->a_cred,
+ NULL);
vp = nd.ni_vp;
NDFREE(&nd, NDF_ONLY_PNBUF);
if (error != 0) {
Modified: head/sys/kern/vfs_vnops.c
==============================================================================
--- head/sys/kern/vfs_vnops.c Fri Nov 29 13:55:56 2019 (r355210)
+++ head/sys/kern/vfs_vnops.c Fri Nov 29 14:02:32 2019 (r355211)
@@ -219,7 +219,8 @@ restart:
ndp->ni_cnd.cn_flags |= AUDITVNODE1;
if (vn_open_flags & VN_OPEN_NOCAPCHECK)
ndp->ni_cnd.cn_flags |= NOCAPCHECK;
- bwillwrite();
+ if ((vn_open_flags & VN_OPEN_INVFS) == 0)
+ bwillwrite();
if ((error = namei(ndp)) != 0)
return (error);
if (ndp->ni_vp == NULL) {
Modified: head/sys/sys/vnode.h
==============================================================================
--- head/sys/sys/vnode.h Fri Nov 29 13:55:56 2019 (r355210)
+++ head/sys/sys/vnode.h Fri Nov 29 14:02:32 2019 (r355211)
@@ -579,6 +579,7 @@ typedef void vop_getpages_iodone_t(void *, vm_page_t *
#define VN_OPEN_NOAUDIT 0x00000001
#define VN_OPEN_NOCAPCHECK 0x00000002
#define VN_OPEN_NAMECACHE 0x00000004
+#define VN_OPEN_INVFS 0x00000008
/*
* Public vnode manipulation functions.
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