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pnfs: defer release of pages in layoutget

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we have encountered a bug whereby reading a lot of files (copying
fedora's /bin) from a pNFS mount and hitting Ctrl+C in the middle caused
a general protection fault in xdr_shrink_bufhead. this function is
called when decoding the response from LAYOUTGET. the decoding is done
by a worker thread, and the caller of LAYOUTGET waits for the worker
thread to complete.

hitting Ctrl+C caused the synchronous wait to end and the next thing the
caller does is to free the pages, so when the worker thread calls
xdr_shrink_bufhead, the pages are gone. therefore, the cleanup of these
pages has been moved to nfs4_layoutget_release.

Signed-off-by: Idan Kedar <idank@tonian.com>
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Idan Kedar 2012-08-02 11:47:10 +03:00 committed by Trond Myklebust
parent 3dd4765fce
commit 8554116e17
3 changed files with 58 additions and 40 deletions
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57
fs/nfs/nfs4proc.c
View File

@ -6223,11 +6223,58 @@ static void nfs4_layoutget_done(struct rpc_task *task, void *calldata)
dprintk("<-- %s\n", __func__);
}
static size_t max_response_pages(struct nfs_server *server)
{
u32 max_resp_sz = server->nfs_client->cl_session->fc_attrs.max_resp_sz;
return nfs_page_array_len(0, max_resp_sz);
}
static void nfs4_free_pages(struct page **pages, size_t size)
{
int i;
if (!pages)
return;
for (i = 0; i < size; i++) {
if (!pages[i])
break;
__free_page(pages[i]);
}
kfree(pages);
}
static struct page **nfs4_alloc_pages(size_t size, gfp_t gfp_flags)
{
struct page **pages;
int i;
pages = kcalloc(size, sizeof(struct page *), gfp_flags);
if (!pages) {
dprintk("%s: can't alloc array of %zu pages\n", __func__, size);
return NULL;
}
for (i = 0; i < size; i++) {
pages[i] = alloc_page(gfp_flags);
if (!pages[i]) {
dprintk("%s: failed to allocate page\n", __func__);
nfs4_free_pages(pages, size);
return NULL;
}
}
return pages;
}
static void nfs4_layoutget_release(void *calldata)
{
struct nfs4_layoutget *lgp = calldata;
struct nfs_server *server = NFS_SERVER(lgp->args.inode);
size_t max_pages = max_response_pages(server);
dprintk("--> %s\n", __func__);
nfs4_free_pages(lgp->args.layout.pages, max_pages);
put_nfs_open_context(lgp->args.ctx);
kfree(calldata);
dprintk("<-- %s\n", __func__);
@ -6239,9 +6286,10 @@ static const struct rpc_call_ops nfs4_layoutget_call_ops = {
.rpc_release = nfs4_layoutget_release,
};
int nfs4_proc_layoutget(struct nfs4_layoutget *lgp)
int nfs4_proc_layoutget(struct nfs4_layoutget *lgp, gfp_t gfp_flags)
{
struct nfs_server *server = NFS_SERVER(lgp->args.inode);
size_t max_pages = max_response_pages(server);
struct rpc_task *task;
struct rpc_message msg = {
.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_LAYOUTGET],
@ -6259,6 +6307,13 @@ int nfs4_proc_layoutget(struct nfs4_layoutget *lgp)
dprintk("--> %s\n", __func__);
lgp->args.layout.pages = nfs4_alloc_pages(max_pages, gfp_flags);
if (!lgp->args.layout.pages) {
nfs4_layoutget_release(lgp);
return -ENOMEM;
}
lgp->args.layout.pglen = max_pages * PAGE_SIZE;
lgp->res.layoutp = &lgp->args.layout;
lgp->res.seq_res.sr_slot = NULL;
nfs41_init_sequence(&lgp->args.seq_args, &lgp->res.seq_res, 0);

39
fs/nfs/pnfs.c
View File

@ -583,9 +583,6 @@ send_layoutget(struct pnfs_layout_hdr *lo,
struct nfs_server *server = NFS_SERVER(ino);
struct nfs4_layoutget *lgp;
struct pnfs_layout_segment *lseg = NULL;
struct page **pages = NULL;
int i;
u32 max_resp_sz, max_pages;
dprintk("--> %s\n", __func__);
@ -594,20 +591,6 @@ send_layoutget(struct pnfs_layout_hdr *lo,
if (lgp == NULL)
return NULL;
/* allocate pages for xdr post processing */
max_resp_sz = server->nfs_client->cl_session->fc_attrs.max_resp_sz;
max_pages = nfs_page_array_len(0, max_resp_sz);
pages = kcalloc(max_pages, sizeof(struct page *), gfp_flags);
if (!pages)
goto out_err_free;
for (i = 0; i < max_pages; i++) {
pages[i] = alloc_page(gfp_flags);
if (!pages[i])
goto out_err_free;
}
lgp->args.minlength = PAGE_CACHE_SIZE;
if (lgp->args.minlength > range->length)
lgp->args.minlength = range->length;
@ -616,39 +599,19 @@ send_layoutget(struct pnfs_layout_hdr *lo,
lgp->args.type = server->pnfs_curr_ld->id;
lgp->args.inode = ino;
lgp->args.ctx = get_nfs_open_context(ctx);
lgp->args.layout.pages = pages;
lgp->args.layout.pglen = max_pages * PAGE_SIZE;
lgp->lsegpp = &lseg;
lgp->gfp_flags = gfp_flags;
/* Synchronously retrieve layout information from server and
* store in lseg.
*/
nfs4_proc_layoutget(lgp);
nfs4_proc_layoutget(lgp, gfp_flags);
if (!lseg) {
/* remember that LAYOUTGET failed and suspend trying */
set_bit(lo_fail_bit(range->iomode), &lo->plh_flags);
}
/* free xdr pages */
for (i = 0; i < max_pages; i++)
__free_page(pages[i]);
kfree(pages);
return lseg;
out_err_free:
/* free any allocated xdr pages, lgp as it's not used */
if (pages) {
for (i = 0; i < max_pages; i++) {
if (!pages[i])
break;
__free_page(pages[i]);
}
kfree(pages);
}
kfree(lgp);
return NULL;
}
/*

2
fs/nfs/pnfs.h
View File

@ -172,7 +172,7 @@ extern int nfs4_proc_getdevicelist(struct nfs_server *server,
struct pnfs_devicelist *devlist);
extern int nfs4_proc_getdeviceinfo(struct nfs_server *server,
struct pnfs_device *dev);
extern int nfs4_proc_layoutget(struct nfs4_layoutget *lgp);
extern int nfs4_proc_layoutget(struct nfs4_layoutget *lgp, gfp_t gfp_flags);
extern int nfs4_proc_layoutreturn(struct nfs4_layoutreturn *lrp);
/* pnfs.c */