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FreeBSD: add support for lockless symlink lookup
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Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Closes #11883
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@mjguzik
mjguzik authored Apr 12, 2021
1 parent 53e9540 commit d8c09f3
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Showing 3 changed files with 100 additions and 2 deletions.
1 change: 1 addition & 0 deletions include/os/freebsd/zfs/sys/zfs_znode_impl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,7 @@ 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; \
Expand Down
86 changes: 84 additions & 2 deletions module/os/freebsd/zfs/zfs_vnops_os.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4466,6 +4466,28 @@ zfs_freebsd_fplookup_vexec(struct vop_fplookup_vexec_args *v)
}
#endif

#if __FreeBSD_version >= 1300139
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);
}

target = atomic_load_consume_ptr(&zp->z_cached_symlink);
if (target == NULL) {
return (EAGAIN);
}
return (cache_symlink_resolve(v->a_fpl, target, strlen(target)));
}
#endif

#ifndef _SYS_SYSPROTO_H_
struct vop_access_args {
struct vnode *a_vp;
Expand Down Expand Up @@ -4953,6 +4975,10 @@ zfs_freebsd_symlink(struct vop_symlink_args *ap)
struct componentname *cnp = ap->a_cnp;
vattr_t *vap = ap->a_vap;
znode_t *zp = NULL;
#if __FreeBSD_version >= 1300139
char *symlink;
size_t symlink_len;
#endif
int rc;

ASSERT(cnp->cn_flags & SAVENAME);
Expand All @@ -4963,8 +4989,21 @@ 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__);
#if __FreeBSD_version >= 1300139
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);
}
#endif
}
return (rc);
}

Expand All @@ -4980,8 +5019,42 @@ static int
zfs_freebsd_readlink(struct vop_readlink_args *ap)
{
zfs_uio_t uio;
int error;
#if __FreeBSD_version >= 1300139
znode_t *zp = VTOZ(ap->a_vp);
char *symlink, *base;
size_t symlink_len;
bool trycache;
#endif

zfs_uio_init(&uio, ap->a_uio);
return (zfs_readlink(ap->a_vp, &uio, ap->a_cred, NULL));
#if __FreeBSD_version >= 1300139
trycache = false;
if (zfs_uio_segflg(&uio) == UIO_SYSSPACE &&
zfs_uio_iovcnt(&uio) == 1) {
base = zfs_uio_iovbase(&uio, 0);
symlink_len = zfs_uio_iovlen(&uio, 0);
trycache = true;
}
#endif
error = zfs_readlink(ap->a_vp, &uio, ap->a_cred, NULL);
#if __FreeBSD_version >= 1300139
if (atomic_load_ptr(&zp->z_cached_symlink) != NULL ||
error != 0 || !trycache) {
return (error);
}
symlink_len -= zfs_uio_resid(&uio);
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);
}
}
#endif
return (error);
}

#ifndef _SYS_SYSPROTO_H_
Expand Down Expand Up @@ -5743,6 +5816,9 @@ struct vop_vector zfs_vnodeops = {
.vop_reclaim = zfs_freebsd_reclaim,
#if __FreeBSD_version >= 1300102
.vop_fplookup_vexec = zfs_freebsd_fplookup_vexec,
#endif
#if __FreeBSD_version >= 1300139
.vop_fplookup_symlink = zfs_freebsd_fplookup_symlink,
#endif
.vop_access = zfs_freebsd_access,
.vop_allocate = VOP_EINVAL,
Expand Down Expand Up @@ -5792,6 +5868,9 @@ struct vop_vector zfs_fifoops = {
.vop_fsync = zfs_freebsd_fsync,
#if __FreeBSD_version >= 1300102
.vop_fplookup_vexec = zfs_freebsd_fplookup_vexec,
#endif
#if __FreeBSD_version >= 1300139
.vop_fplookup_symlink = zfs_freebsd_fplookup_symlink,
#endif
.vop_access = zfs_freebsd_access,
.vop_getattr = zfs_freebsd_getattr,
Expand All @@ -5815,6 +5894,9 @@ struct vop_vector zfs_shareops = {
.vop_default = &default_vnodeops,
#if __FreeBSD_version >= 1300121
.vop_fplookup_vexec = VOP_EAGAIN,
#endif
#if __FreeBSD_version >= 1300139
.vop_fplookup_symlink = VOP_EAGAIN,
#endif
.vop_access = zfs_freebsd_access,
.vop_inactive = zfs_freebsd_inactive,
Expand Down
15 changes: 15 additions & 0 deletions module/os/freebsd/zfs/zfs_znode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -444,6 +444,9 @@ 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;
#if __FreeBSD_version >= 1300139
atomic_store_ptr(&zp->z_cached_symlink, NULL);
#endif

vp = ZTOV(zp);

Expand Down Expand Up @@ -1237,6 +1240,9 @@ void
zfs_znode_free(znode_t *zp)
{
zfsvfs_t *zfsvfs = zp->z_zfsvfs;
#if __FreeBSD_version >= 1300139
char *symlink;
#endif

ASSERT(zp->z_sa_hdl == NULL);
zp->z_vnode = NULL;
Expand All @@ -1246,6 +1252,15 @@ zfs_znode_free(znode_t *zp)
zfsvfs->z_nr_znodes--;
mutex_exit(&zfsvfs->z_znodes_lock);

#if __FreeBSD_version >= 1300139
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);
}
#endif

if (zp->z_acl_cached) {
zfs_acl_free(zp->z_acl_cached);
zp->z_acl_cached = NULL;
Expand Down

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