diff options
Diffstat (limited to 'module')
-rw-r--r-- | module/os/linux/zfs/zfs_uio.c | 55 |
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); |