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In the VOP_PUTPAGES() implementations, change the default error from

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VM_PAGER_AGAIN to VM_PAGER_ERROR for the uwritten pages. Return
VM_PAGER_AGAIN for the partially written page. Always forward at least
one page in the loop of vm_object_page_clean().

VM_PAGER_ERROR causes the page reactivation and does not clear the
page dirty state, so the write is not lost.

The change fixes an infinite loop in vm_object_page_clean() when the
filesystem returns permanent errors for some page writes.

Reported and tested by:	gavin
Reviewed by:	alc, rmacklem
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2011-06-01 21:00:28 +00:00
parent 48237774e4
commit 031ec8c10a
7 changed files with 48 additions and 34 deletions
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15
sys/fs/nfsclient/nfs_clbio.c
View File

@ -302,7 +302,7 @@ ncl_putpages(struct vop_putpages_args *ap)
}
for (i = 0; i < npages; i++)
rtvals[i] = VM_PAGER_AGAIN;
rtvals[i] = VM_PAGER_ERROR;
/*
* When putting pages, do not extend file past EOF.
@ -345,16 +345,9 @@ ncl_putpages(struct vop_putpages_args *ap)
pmap_qremove(kva, npages);
relpbuf(bp, &ncl_pbuf_freecnt);
if (!error) {
int nwritten = round_page(count - uio.uio_resid) / PAGE_SIZE;
for (i = 0; i < nwritten; i++) {
rtvals[i] = VM_PAGER_OK;
vm_page_undirty(pages[i]);
}
if (must_commit) {
ncl_clearcommit(vp->v_mount);
}
}
vnode_pager_undirty_pages(pages, rtvals, count - uio.uio_resid);
if (must_commit)
ncl_clearcommit(vp->v_mount);
return rtvals[0];
}

11
sys/fs/nwfs/nwfs_io.c
View File

@ -544,7 +544,7 @@ nwfs_putpages(ap)
npages = btoc(count);
for (i = 0; i < npages; i++) {
rtvals[i] = VM_PAGER_AGAIN;
rtvals[i] = VM_PAGER_ERROR;
}
bp = getpbuf(&nwfs_pbuf_freecnt);
@ -569,13 +569,8 @@ nwfs_putpages(ap)
pmap_qremove(kva, npages);
relpbuf(bp, &nwfs_pbuf_freecnt);
if (!error) {
int nwritten = round_page(count - uio.uio_resid) / PAGE_SIZE;
for (i = 0; i < nwritten; i++) {
rtvals[i] = VM_PAGER_OK;
vm_page_undirty(pages[i]);
}
}
if (!error)
vnode_pager_undirty_pages(pages, rtvals, count - uio.uio_resid);
return rtvals[0];
#endif /* NWFS_RWCACHE */
}

11
sys/fs/smbfs/smbfs_io.c
View File

@ -609,7 +609,7 @@ smbfs_putpages(ap)
npages = btoc(count);
for (i = 0; i < npages; i++) {
rtvals[i] = VM_PAGER_AGAIN;
rtvals[i] = VM_PAGER_ERROR;
}
bp = getpbuf(&smbfs_pbuf_freecnt);
@ -639,13 +639,8 @@ smbfs_putpages(ap)
relpbuf(bp, &smbfs_pbuf_freecnt);
if (!error) {
int nwritten = round_page(count - uio.uio_resid) / PAGE_SIZE;
for (i = 0; i < nwritten; i++) {
rtvals[i] = VM_PAGER_OK;
vm_page_undirty(pages[i]);
}
}
if (!error)
vnode_pager_undirty_pages(pages, rtvals, count - uio.uio_resid);
return rtvals[0];
#endif /* SMBFS_RWGENERIC */
}

8
sys/nfsclient/nfs_bio.c
View File

@ -300,7 +300,7 @@ nfs_putpages(struct vop_putpages_args *ap)
}
for (i = 0; i < npages; i++)
rtvals[i] = VM_PAGER_AGAIN;
rtvals[i] = VM_PAGER_ERROR;
/*
* When putting pages, do not extend file past EOF.
@ -344,11 +344,7 @@ nfs_putpages(struct vop_putpages_args *ap)
relpbuf(bp, &nfs_pbuf_freecnt);
if (!error) {
int nwritten = round_page(count - uio.uio_resid) / PAGE_SIZE;
for (i = 0; i < nwritten; i++) {
rtvals[i] = VM_PAGER_OK;
vm_page_undirty(pages[i]);
}
vnode_pager_undirty_pages(pages, rtvals, count - uio.uio_resid);
if (must_commit) {
nfs_clearcommit(vp->v_mount);
}

15
sys/vm/vm_object.c
View File

@ -852,6 +852,21 @@ vm_object_page_clean(vm_object_t object, vm_ooffset_t start, vm_ooffset_t end,
flags, &clearobjflags);
if (object->generation != curgeneration)
goto rescan;
/*
* If the VOP_PUTPAGES() did a truncated write, so
* that even the first page of the run is not fully
* written, vm_pageout_flush() returns 0 as the run
* length. Since the condition that caused truncated
* write may be permanent, e.g. exhausted free space,
* accepting n == 0 would cause an infinite loop.
*
* Forwarding the iterator leaves the unwritten page
* behind, but there is not much we can do there if
* filesystem refuses to write it.
*/
if (n == 0)
n = 1;
np = vm_page_find_least(object, pi + n);
}
#if 0

19
sys/vm/vnode_pager.c
View File

@ -1089,7 +1089,7 @@ vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
count = bytecount / PAGE_SIZE;
for (i = 0; i < count; i++)
rtvals[i] = VM_PAGER_AGAIN;
rtvals[i] = VM_PAGER_ERROR;
if ((int64_t)ma[0]->pindex < 0) {
printf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%lx)\n",
@ -1191,3 +1191,20 @@ vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
}
return rtvals[0];
}
void
vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written)
{
int i, pos;
for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) {
if (pos < trunc_page(written)) {
rtvals[i] = VM_PAGER_OK;
vm_page_undirty(ma[i]);
} else {
/* Partially written page. */
rtvals[i] = VM_PAGER_AGAIN;
vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK);
}
}
}

3
sys/vm/vnode_pager.h
View File

@ -49,5 +49,8 @@ int vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m,
int vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *m,
int count, boolean_t sync,
int *rtvals);
void vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written);
#endif /* _KERNEL */
#endif /* _VNODE_PAGER_ */