svn commit: r197850 - head/sys/fs/tmpfs
Yoshihiro Ota
ota at j.email.ne.jp
Fri Oct 9 20:10:25 UTC 2009
Could someone explain what was the cause and why this fixes the issue?
When I read it, it looked like that a vm object could be in 2 locations
and one of them looked the cause of the problem.
But I couldn't figure out thereafter.
Thanks,
Hiro
On Wed, 7 Oct 2009 23:17:15 +0000 (UTC)
Xin LI <delphij at FreeBSD.org> wrote:
> Author: delphij
> Date: Wed Oct 7 23:17:15 2009
> New Revision: 197850
> URL: http://svn.freebsd.org/changeset/base/197850
>
> Log:
> Add a special workaround to handle UIO_NOCOPY case. This fixes data
> corruption observed when sendfile() is being used.
>
> PR: kern/127213
> Submitted by: gk
> MFC after: 2 weeks
>
> Modified:
> head/sys/fs/tmpfs/tmpfs_vnops.c
>
> Modified: head/sys/fs/tmpfs/tmpfs_vnops.c
> ==============================================================================
> --- head/sys/fs/tmpfs/tmpfs_vnops.c Wed Oct 7 23:01:31 2009 (r197849)
> +++ head/sys/fs/tmpfs/tmpfs_vnops.c Wed Oct 7 23:17:15 2009 (r197850)
> @@ -43,6 +43,8 @@ __FBSDID("$FreeBSD$");
> #include <sys/priv.h>
> #include <sys/proc.h>
> #include <sys/resourcevar.h>
> +#include <sys/sched.h>
> +#include <sys/sf_buf.h>
> #include <sys/stat.h>
> #include <sys/systm.h>
> #include <sys/unistd.h>
> @@ -428,15 +430,72 @@ tmpfs_setattr(struct vop_setattr_args *v
> }
>
> /* --------------------------------------------------------------------- */
> +static int
> +tmpfs_nocacheread(vm_object_t tobj, vm_pindex_t idx,
> + vm_offset_t offset, size_t tlen, struct uio *uio)
> +{
> + vm_page_t m;
> + int error;
> +
> + VM_OBJECT_LOCK(tobj);
> + vm_object_pip_add(tobj, 1);
> + m = vm_page_grab(tobj, idx, VM_ALLOC_WIRED |
> + VM_ALLOC_ZERO | VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
> + if (m->valid != VM_PAGE_BITS_ALL) {
> + if (vm_pager_has_page(tobj, idx, NULL, NULL)) {
> + error = vm_pager_get_pages(tobj, &m, 1, 0);
> + if (error != 0) {
> + printf("tmpfs get pages from pager error [read]\n");
> + goto out;
> + }
> + } else
> + vm_page_zero_invalid(m, TRUE);
> + }
> + VM_OBJECT_UNLOCK(tobj);
> + error = uiomove_fromphys(&m, offset, tlen, uio);
> + VM_OBJECT_LOCK(tobj);
> +out:
> + vm_page_lock_queues();
> + vm_page_unwire(m, TRUE);
> + vm_page_unlock_queues();
> + vm_page_wakeup(m);
> + vm_object_pip_subtract(tobj, 1);
> + VM_OBJECT_UNLOCK(tobj);
> +
> + return (error);
> +}
> +
> +static __inline int
> +tmpfs_nocacheread_buf(vm_object_t tobj, vm_pindex_t idx,
> + vm_offset_t offset, size_t tlen, void *buf)
> +{
> + struct uio uio;
> + struct iovec iov;
> +
> + uio.uio_iovcnt = 1;
> + uio.uio_iov = &iov;
> + iov.iov_base = buf;
> + iov.iov_len = tlen;
> +
> + uio.uio_offset = 0;
> + uio.uio_resid = tlen;
> + uio.uio_rw = UIO_READ;
> + uio.uio_segflg = UIO_SYSSPACE;
> + uio.uio_td = curthread;
> +
> + return (tmpfs_nocacheread(tobj, idx, offset, tlen, &uio));
> +}
>
> static int
> tmpfs_mappedread(vm_object_t vobj, vm_object_t tobj, size_t len, struct uio *uio)
> {
> + struct sf_buf *sf;
> vm_pindex_t idx;
> vm_page_t m;
> vm_offset_t offset;
> off_t addr;
> size_t tlen;
> + char *ma;
> int error;
>
> addr = uio->uio_offset;
> @@ -461,33 +520,30 @@ lookupvpg:
> vm_page_wakeup(m);
> VM_OBJECT_UNLOCK(vobj);
> return (error);
> + } else if (m != NULL && uio->uio_segflg == UIO_NOCOPY) {
> + if (vm_page_sleep_if_busy(m, FALSE, "tmfsmr"))
> + goto lookupvpg;
> + vm_page_busy(m);
> + VM_OBJECT_UNLOCK(vobj);
> + sched_pin();
> + sf = sf_buf_alloc(m, SFB_CPUPRIVATE);
> + ma = (char *)sf_buf_kva(sf);
> + error = tmpfs_nocacheread_buf(tobj, idx, offset, tlen,
> + ma + offset);
> + if (error == 0) {
> + uio->uio_offset += tlen;
> + uio->uio_resid -= tlen;
> + }
> + sf_buf_free(sf);
> + sched_unpin();
> + VM_OBJECT_LOCK(vobj);
> + vm_page_wakeup(m);
> + VM_OBJECT_UNLOCK(vobj);
> + return (error);
> }
> VM_OBJECT_UNLOCK(vobj);
> nocache:
> - VM_OBJECT_LOCK(tobj);
> - vm_object_pip_add(tobj, 1);
> - m = vm_page_grab(tobj, idx, VM_ALLOC_WIRED |
> - VM_ALLOC_ZERO | VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
> - if (m->valid != VM_PAGE_BITS_ALL) {
> - if (vm_pager_has_page(tobj, idx, NULL, NULL)) {
> - error = vm_pager_get_pages(tobj, &m, 1, 0);
> - if (error != 0) {
> - printf("tmpfs get pages from pager error [read]\n");
> - goto out;
> - }
> - } else
> - vm_page_zero_invalid(m, TRUE);
> - }
> - VM_OBJECT_UNLOCK(tobj);
> - error = uiomove_fromphys(&m, offset, tlen, uio);
> - VM_OBJECT_LOCK(tobj);
> -out:
> - vm_page_lock_queues();
> - vm_page_unwire(m, TRUE);
> - vm_page_unlock_queues();
> - vm_page_wakeup(m);
> - vm_object_pip_subtract(tobj, 1);
> - VM_OBJECT_UNLOCK(tobj);
> + error = tmpfs_nocacheread(tobj, idx, offset, tlen, uio);
>
> return (error);
> }
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