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[PATCH 5/5] rumpdisk: Fault-in the memory pages
From: |
Damien Zammit |
Subject: |
[PATCH 5/5] rumpdisk: Fault-in the memory pages |
Date: |
Sun, 26 Dec 2021 22:38:57 +1100 |
This ensures memory pages are allocated before written to.
---
rumpdisk/block-rump.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/rumpdisk/block-rump.c b/rumpdisk/block-rump.c
index 7a4a167e..fe97bf85 100644
--- a/rumpdisk/block-rump.c
+++ b/rumpdisk/block-rump.c
@@ -284,10 +284,18 @@ rumpdisk_device_write (void *d, mach_port_t reply_port,
{
struct block_data *bd = d;
ssize_t written;
+ volatile uint8_t dummy_read;
+ int pagesize = sysconf (_SC_PAGE_SIZE);
+ int npages = (count + pagesize - 1) / pagesize;
+ int i;
if ((bd->mode & D_WRITE) == 0)
return D_INVALID_OPERATION;
+ /* Fault-in the memory pages by reading a single byte of each */
+ for (i = 0; i < npages; i++)
+ dummy_read = ((volatile uint8_t *)data)[i * pagesize];
+
written = rump_sys_pwrite (bd->rump_fd, (const void *)data, (size_t)count,
(off_t)bn * bd->block_size);
vm_deallocate (mach_task_self (), (vm_address_t) data, count);
@@ -313,6 +321,7 @@ rumpdisk_device_read (void *d, mach_port_t reply_port,
vm_address_t buf;
int pagesize = sysconf (_SC_PAGE_SIZE);
int npages = (count + pagesize - 1) / pagesize;
+ int i;
ssize_t err;
kern_return_t ret;
@@ -327,8 +336,9 @@ rumpdisk_device_read (void *d, mach_port_t reply_port,
if (ret != KERN_SUCCESS)
return ENOMEM;
- /* Ensure physical allocation. */
- memset (buf, 0, npages * pagesize);
+ /* Ensure physical allocation by writing a single byte of each */
+ for (i = 0; i < npages; i++)
+ ((uint8_t *)buf)[i * pagesize] = 0;
err = rump_sys_pread (bd->rump_fd, (void *)buf, (size_t)count, (off_t)bn *
bd->block_size);
if (err < 0)
--
2.33.1
- [PATCH 0/5] hurd: Patches for new librump, Damien Zammit, 2021/12/26
- [PATCH 1/5] rumpdisk: define _STANDALONE to avoid register_t, Damien Zammit, 2021/12/26
- [PATCH 2/5] rumpdisk: Link with rumpvfs_nofifofs if present, Damien Zammit, 2021/12/26
- [PATCH 4/5] pci-arbiter,rumpdisk: Lock all memory for swapping, Damien Zammit, 2021/12/26
- [PATCH 5/5] rumpdisk: Fault-in the memory pages,
Damien Zammit <=
- [PATCH 3/5] rumpdisk: Use raw uncached character device rwdXd, Damien Zammit, 2021/12/26