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authorMateusz Guzik <mjg@FreeBSD.org>2020-10-10 03:48:17 +0000
committerMateusz Guzik <mjg@FreeBSD.org>2020-10-10 03:48:17 +0000
commitdd28b379cb8d5b02442782a2586d729e3e197818 (patch)
tree79b478af8961197d978256e98ccfd10974f191d7 /sys/kern/kern_descrip.c
parent49d48f45c8f728956cc2d982bf33ae79cd6fd8e9 (diff)
downloadsrc-dd28b379cb8d5b02442782a2586d729e3e197818.tar.gz
src-dd28b379cb8d5b02442782a2586d729e3e197818.zip
vfs: support lockless dirfd lookups
Notes
Notes: svn path=/head/; revision=366597
Diffstat (limited to 'sys/kern/kern_descrip.c')
-rw-r--r--sys/kern/kern_descrip.c105
1 files changed, 105 insertions, 0 deletions
diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index c533e714ce52..af7d51057893 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -2708,6 +2708,111 @@ get_locked:
return (error);
}
+#ifdef CAPABILITIES
+int
+fgetvp_lookup_smr(int fd, struct nameidata *ndp, struct vnode **vpp, bool *fsearch)
+{
+ const struct filedescent *fde;
+ const struct fdescenttbl *fdt;
+ struct filedesc *fdp;
+ struct file *fp;
+ struct vnode *vp;
+ const cap_rights_t *haverights;
+ cap_rights_t rights;
+ seqc_t seq;
+
+ VFS_SMR_ASSERT_ENTERED();
+
+ rights = *ndp->ni_rightsneeded;
+ cap_rights_set_one(&rights, CAP_LOOKUP);
+
+ fdp = curproc->p_fd;
+ fdt = fdp->fd_files;
+ if (__predict_false((u_int)fd >= fdt->fdt_nfiles))
+ return (EBADF);
+ seq = seqc_read_any(fd_seqc(fdt, fd));
+ if (__predict_false(seqc_in_modify(seq)))
+ return (EAGAIN);
+ fde = &fdt->fdt_ofiles[fd];
+ haverights = cap_rights_fde_inline(fde);
+ fp = fde->fde_file;
+ if (__predict_false(fp == NULL))
+ return (EAGAIN);
+ if (__predict_false(cap_check_inline_transient(haverights, &rights)))
+ return (EAGAIN);
+ *fsearch = ((fp->f_flag & FSEARCH) != 0);
+ vp = fp->f_vnode;
+ if (__predict_false(vp == NULL || vp->v_type != VDIR)) {
+ return (EAGAIN);
+ }
+ if (!filecaps_copy(&fde->fde_caps, &ndp->ni_filecaps, false)) {
+ return (EAGAIN);
+ }
+ /*
+ * Use an acquire barrier to force re-reading of fdt so it is
+ * refreshed for verification.
+ */
+ atomic_thread_fence_acq();
+ fdt = fdp->fd_files;
+ if (__predict_false(!seqc_consistent_nomb(fd_seqc(fdt, fd), seq)))
+ return (EAGAIN);
+ /*
+ * If file descriptor doesn't have all rights,
+ * all lookups relative to it must also be
+ * strictly relative.
+ *
+ * Not yet supported by fast path.
+ */
+ CAP_ALL(&rights);
+ if (!cap_rights_contains(&ndp->ni_filecaps.fc_rights, &rights) ||
+ ndp->ni_filecaps.fc_fcntls != CAP_FCNTL_ALL ||
+ ndp->ni_filecaps.fc_nioctls != -1) {
+#ifdef notyet
+ ndp->ni_lcf |= NI_LCF_STRICTRELATIVE;
+#else
+ return (EAGAIN);
+#endif
+ }
+ *vpp = vp;
+ return (0);
+}
+#else
+int
+fgetvp_lookup_smr(int fd, struct nameidata *ndp, struct vnode **vpp, bool *fsearch)
+{
+ const struct fdescenttbl *fdt;
+ struct filedesc *fdp;
+ struct file *fp;
+ struct vnode *vp;
+
+ VFS_SMR_ASSERT_ENTERED();
+
+ fdp = curproc->p_fd;
+ fdt = fdp->fd_files;
+ if (__predict_false((u_int)fd >= fdt->fdt_nfiles))
+ return (EBADF);
+ fp = fdt->fdt_ofiles[fd].fde_file;
+ if (__predict_false(fp == NULL))
+ return (EAGAIN);
+ *fsearch = ((fp->f_flag & FSEARCH) != 0);
+ vp = fp->f_vnode;
+ if (__predict_false(vp == NULL || vp->v_type != VDIR)) {
+ return (EAGAIN);
+ }
+ /*
+ * Use an acquire barrier to force re-reading of fdt so it is
+ * refreshed for verification.
+ */
+ atomic_thread_fence_acq();
+ fdt = fdp->fd_files;
+ if (__predict_false(fp != fdt->fdt_ofiles[fd].fde_file))
+ return (EAGAIN);
+ filecaps_fill(&ndp->ni_filecaps);
+ *vpp = vp;
+ return (0);
+}
+#endif
+
int
fget_unlocked_seq(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
struct file **fpp, seqc_t *seqp)