aboutsummaryrefslogtreecommitdiffstats
path: root/module
diff options
context:
space:
mode:
Diffstat (limited to 'module')
-rw-r--r--module/os/linux/zfs/zfs_uio.c55
1 files changed, 44 insertions, 11 deletions
diff --git a/module/os/linux/zfs/zfs_uio.c b/module/os/linux/zfs/zfs_uio.c
index e435e1a9f..7d2267f0a 100644
--- a/module/os/linux/zfs/zfs_uio.c
+++ b/module/os/linux/zfs/zfs_uio.c
@@ -209,25 +209,58 @@ uiomove(void *p, size_t n, enum uio_rw rw, struct uio *uio)
}
EXPORT_SYMBOL(uiomove);
+/*
+ * Fault in the pages of the first n bytes specified by the uio structure.
+ * 1 byte in each page is touched and the uio struct is unmodified. Any
+ * error will terminate the process as this is only a best attempt to get
+ * the pages resident.
+ */
int
uio_prefaultpages(ssize_t n, struct uio *uio)
{
- struct iov_iter iter, *iterp = NULL;
-
-#if defined(HAVE_IOV_ITER_FAULT_IN_READABLE)
- if (uio->uio_segflg == UIO_USERSPACE) {
- iterp = &iter;
- iov_iter_init_compat(iterp, READ, uio->uio_iov,
- uio->uio_iovcnt, uio->uio_resid);
+ if (uio->uio_segflg == UIO_SYSSPACE || uio->uio_segflg == UIO_BVEC) {
+ /* There's never a need to fault in kernel pages */
+ return (0);
#if defined(HAVE_VFS_IOV_ITER)
} else if (uio->uio_segflg == UIO_ITER) {
- iterp = uio->uio_iter;
+ /*
+ * At least a Linux 4.9 kernel, iov_iter_fault_in_readable()
+ * can be relied on to fault in user pages when referenced.
+ */
+ if (iov_iter_fault_in_readable(uio->uio_iter, n))
+ return (EFAULT);
#endif
+ } else {
+ /* Fault in all user pages */
+ ASSERT3S(uio->uio_segflg, ==, UIO_USERSPACE);
+ const struct iovec *iov = uio->uio_iov;
+ int iovcnt = uio->uio_iovcnt;
+ size_t skip = uio->uio_skip;
+ uint8_t tmp;
+ caddr_t p;
+
+ for (; n > 0 && iovcnt > 0; iov++, iovcnt--, skip = 0) {
+ ulong_t cnt = MIN(iov->iov_len - skip, n);
+ /* empty iov */
+ if (cnt == 0)
+ continue;
+ n -= cnt;
+ /* touch each page in this segment. */
+ p = iov->iov_base + skip;
+ while (cnt) {
+ if (get_user(tmp, (uint8_t *)p))
+ return (EFAULT);
+ ulong_t incr = MIN(cnt, PAGESIZE);
+ p += incr;
+ cnt -= incr;
+ }
+ /* touch the last byte in case it straddles a page. */
+ p--;
+ if (get_user(tmp, (uint8_t *)p))
+ return (EFAULT);
+ }
}
- if (iterp && iov_iter_fault_in_readable(iterp, n))
- return (EFAULT);
-#endif
return (0);
}
EXPORT_SYMBOL(uio_prefaultpages);