git: c5fcd06736f9 - stable/13 - zfs: add support for lockless symlink lookup
Mateusz Guzik
mjg at FreeBSD.org
Mon Feb 1 12:40:34 UTC 2021
The branch stable/13 has been updated by mjg:
URL: https://cgit.FreeBSD.org/src/commit/?id=c5fcd06736f93ab6dd7b93d54dbeae68ae06ed7b
commit c5fcd06736f93ab6dd7b93d54dbeae68ae06ed7b
Author: Mateusz Guzik <mjg at FreeBSD.org>
AuthorDate: 2021-01-23 13:46:32 +0000
Commit: Mateusz Guzik <mjg at FreeBSD.org>
CommitDate: 2021-02-01 12:39:15 +0000
zfs: add support for lockless symlink lookup
Reviewed by: kib (previous version)
Tested by: pho (previous version)
Differential Revision: https://reviews.freebsd.org/D27488
(cherry picked from commit 3110d4ebd6c0848cf5e25890d01791bb407e2a9b)
---
.../include/os/freebsd/zfs/sys/zfs_znode_impl.h | 1 +
.../openzfs/module/os/freebsd/zfs/zfs_vnops_os.c | 73 +++++++++++++++++++++-
.../openzfs/module/os/freebsd/zfs/zfs_znode.c | 7 +++
3 files changed, 78 insertions(+), 3 deletions(-)
diff --git a/sys/contrib/openzfs/include/os/freebsd/zfs/sys/zfs_znode_impl.h b/sys/contrib/openzfs/include/os/freebsd/zfs/sys/zfs_znode_impl.h
index ac2625d9a8ab..091186f23174 100644
--- a/sys/contrib/openzfs/include/os/freebsd/zfs/sys/zfs_znode_impl.h
+++ b/sys/contrib/openzfs/include/os/freebsd/zfs/sys/zfs_znode_impl.h
@@ -53,6 +53,7 @@ extern "C" {
#define ZNODE_OS_FIELDS \
struct zfsvfs *z_zfsvfs; \
vnode_t *z_vnode; \
+ char *z_cached_symlink; \
uint64_t z_uid; \
uint64_t z_gid; \
uint64_t z_gen; \
diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
index 2e8eadb5e16e..1ee0895625a6 100644
--- a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
+++ b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
@@ -4463,6 +4463,29 @@ zfs_freebsd_fplookup_vexec(struct vop_fplookup_vexec_args *v)
}
#endif
+static int
+zfs_freebsd_fplookup_symlink(struct vop_fplookup_symlink_args *v)
+{
+ vnode_t *vp;
+ znode_t *zp;
+ char *target;
+
+ vp = v->a_vp;
+ zp = VTOZ_SMR(vp);
+ if (__predict_false(zp == NULL)) {
+ return (EAGAIN);
+ }
+
+ /*
+ * FIXME: Load consume would be sufficient but there is no primitive to do it.
+ */
+ target = (char *)atomic_load_acq_ptr((uintptr_t *)&zp->z_cached_symlink);
+ if (target == NULL) {
+ return (EAGAIN);
+ }
+ return (cache_symlink_resolve(v->a_fpl, target, strlen(target)));
+}
+
#ifndef _SYS_SYSPROTO_H_
struct vop_access_args {
struct vnode *a_vp;
@@ -4949,6 +4972,8 @@ zfs_freebsd_symlink(struct vop_symlink_args *ap)
struct componentname *cnp = ap->a_cnp;
vattr_t *vap = ap->a_vap;
znode_t *zp = NULL;
+ char *symlink;
+ size_t symlink_len;
int rc;
ASSERT(cnp->cn_flags & SAVENAME);
@@ -4959,8 +4984,19 @@ zfs_freebsd_symlink(struct vop_symlink_args *ap)
rc = zfs_symlink(VTOZ(ap->a_dvp), cnp->cn_nameptr, vap,
ap->a_target, &zp, cnp->cn_cred, 0 /* flags */);
- if (rc == 0)
+ if (rc == 0) {
*ap->a_vpp = ZTOV(zp);
+ ASSERT_VOP_ELOCKED(ZTOV(zp), __func__);
+ MPASS(zp->z_cached_symlink == NULL);
+ symlink_len = strlen(ap->a_target);
+ symlink = cache_symlink_alloc(symlink_len + 1, M_WAITOK);
+ if (symlink != NULL) {
+ memcpy(symlink, ap->a_target, symlink_len);
+ symlink[symlink_len] = '\0';
+ atomic_store_rel_ptr((uintptr_t *)&zp->z_cached_symlink,
+ (uintptr_t)symlink);
+ }
+ }
return (rc);
}
@@ -4975,8 +5011,36 @@ struct vop_readlink_args {
static int
zfs_freebsd_readlink(struct vop_readlink_args *ap)
{
-
- return (zfs_readlink(ap->a_vp, ap->a_uio, ap->a_cred, NULL));
+ znode_t *zp = VTOZ(ap->a_vp);
+ struct uio *auio;
+ char *symlink, *base;
+ size_t symlink_len;
+ int error;
+ bool trycache;
+
+ auio = ap->a_uio;
+ trycache = false;
+ if (auio->uio_segflg == UIO_SYSSPACE && auio->uio_iovcnt == 1) {
+ base = auio->uio_iov->iov_base;
+ symlink_len = auio->uio_iov->iov_len;
+ trycache = true;
+ }
+ error = zfs_readlink(ap->a_vp, auio, ap->a_cred, NULL);
+ if (atomic_load_ptr(&zp->z_cached_symlink) != NULL ||
+ error != 0 || !trycache) {
+ return (error);
+ }
+ symlink_len -= auio->uio_resid;
+ symlink = cache_symlink_alloc(symlink_len + 1, M_WAITOK);
+ if (symlink != NULL) {
+ memcpy(symlink, base, symlink_len);
+ symlink[symlink_len] = '\0';
+ if (!atomic_cmpset_rel_ptr((uintptr_t *)&zp->z_cached_symlink,
+ (uintptr_t)NULL, (uintptr_t)symlink)) {
+ cache_symlink_free(symlink, symlink_len + 1);
+ }
+ }
+ return (error);
}
#ifndef _SYS_SYSPROTO_H_
@@ -5734,6 +5798,7 @@ struct vop_vector zfs_vnodeops = {
#if __FreeBSD_version >= 1300102
.vop_fplookup_vexec = zfs_freebsd_fplookup_vexec,
#endif
+ .vop_fplookup_symlink = zfs_freebsd_fplookup_symlink,
.vop_access = zfs_freebsd_access,
.vop_allocate = VOP_EINVAL,
.vop_lookup = zfs_cache_lookup,
@@ -5783,6 +5848,7 @@ struct vop_vector zfs_fifoops = {
#if __FreeBSD_version >= 1300102
.vop_fplookup_vexec = zfs_freebsd_fplookup_vexec,
#endif
+ .vop_fplookup_symlink = zfs_freebsd_fplookup_symlink,
.vop_access = zfs_freebsd_access,
.vop_getattr = zfs_freebsd_getattr,
.vop_inactive = zfs_freebsd_inactive,
@@ -5806,6 +5872,7 @@ struct vop_vector zfs_shareops = {
#if __FreeBSD_version >= 1300121
.vop_fplookup_vexec = VOP_EAGAIN,
#endif
+ .vop_fplookup_symlink = VOP_EAGAIN,
.vop_access = zfs_freebsd_access,
.vop_inactive = zfs_freebsd_inactive,
.vop_reclaim = zfs_freebsd_reclaim,
diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_znode.c b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_znode.c
index 6a21623c5f67..f9a0820eda2d 100644
--- a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_znode.c
+++ b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_znode.c
@@ -444,6 +444,7 @@ zfs_znode_alloc(zfsvfs_t *zfsvfs, dmu_buf_t *db, int blksz,
zp->z_blksz = blksz;
zp->z_seq = 0x7A4653;
zp->z_sync_cnt = 0;
+ atomic_store_ptr((uintptr_t *)&zp->z_cached_symlink, (uintptr_t)NULL);
vp = ZTOV(zp);
@@ -1237,6 +1238,7 @@ void
zfs_znode_free(znode_t *zp)
{
zfsvfs_t *zfsvfs = zp->z_zfsvfs;
+ char *symlink;
ASSERT(zp->z_sa_hdl == NULL);
zp->z_vnode = NULL;
@@ -1245,6 +1247,11 @@ zfs_znode_free(znode_t *zp)
list_remove(&zfsvfs->z_all_znodes, zp);
zfsvfs->z_nr_znodes--;
mutex_exit(&zfsvfs->z_znodes_lock);
+ symlink = atomic_load_ptr(&zp->z_cached_symlink);
+ if (symlink != NULL) {
+ atomic_store_rel_ptr((uintptr_t *)&zp->z_cached_symlink, (uintptr_t)NULL);
+ cache_symlink_free(symlink, strlen(symlink) + 1);
+ }
if (zp->z_acl_cached) {
zfs_acl_free(zp->z_acl_cached);
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