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NFS: Clean up and fix page zeroing when we have short reads 

The code that is supposed to zero the uninitialised partial pages when the
server returns a short read is currently broken: it looks at the nfs_page
wb_pgbase and wb_bytes fields instead of the equivalent nfs_read_data
values when deciding where to start truncating the page.

Also ensure that we are more careful about setting PG_uptodate
before retrying a short read: the retry will change the nfs_read_data
args.pgbase and args.count.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2006-05-25 01:40:44 -04:00
parent 128e6ced24
commit 1de3fc12ea
1 changed files with 75 additions and 32 deletions
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107
fs/nfs/read.c
View File

@ -104,6 +104,28 @@ int nfs_return_empty_page(struct page *page)
return 0;
}
static void nfs_readpage_truncate_uninitialised_page(struct nfs_read_data *data)
{
unsigned int remainder = data->args.count - data->res.count;
unsigned int base = data->args.pgbase + data->res.count;
unsigned int pglen;
struct page **pages;
if (data->res.eof == 0 || remainder == 0)
return;
/*
* Note: "remainder" can never be negative, since we check for
* this in the XDR code.
*/
pages = &data->args.pages[base >> PAGE_CACHE_SHIFT];
base &= ~PAGE_CACHE_MASK;
pglen = PAGE_CACHE_SIZE - base;
if (pglen < remainder)
memclear_highpage_flush(*pages, base, pglen);
else
memclear_highpage_flush(*pages, base, remainder);
}
/*
* Read a page synchronously.
*/
@ -177,11 +199,9 @@ static int nfs_readpage_sync(struct nfs_open_context *ctx, struct inode *inode,
NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ATIME;
spin_unlock(&inode->i_lock);
if (count)
memclear_highpage_flush(page, rdata->args.pgbase, count);
SetPageUptodate(page);
if (PageError(page))
ClearPageError(page);
nfs_readpage_truncate_uninitialised_page(rdata);
if (rdata->res.eof || rdata->res.count == rdata->args.count)
SetPageUptodate(page);
result = 0;
io_error:
@ -436,20 +456,12 @@ static void nfs_readpage_result_partial(struct rpc_task *task, void *calldata)
struct nfs_page *req = data->req;
struct page *page = req->wb_page;
if (likely(task->tk_status >= 0))
nfs_readpage_truncate_uninitialised_page(data);
else
SetPageError(page);
if (nfs_readpage_result(task, data) != 0)
return;
if (task->tk_status >= 0) {
unsigned int request = data->args.count;
unsigned int result = data->res.count;
if (result < request) {
memclear_highpage_flush(page,
data->args.pgbase + result,
request - result);
}
} else
SetPageError(page);
if (atomic_dec_and_test(&req->wb_complete)) {
if (!PageError(page))
SetPageUptodate(page);
@ -462,6 +474,40 @@ static const struct rpc_call_ops nfs_read_partial_ops = {
.rpc_release = nfs_readdata_release,
};
static void nfs_readpage_set_pages_uptodate(struct nfs_read_data *data)
{
unsigned int count = data->res.count;
unsigned int base = data->args.pgbase;
struct page **pages;
if (unlikely(count == 0))
return;
pages = &data->args.pages[base >> PAGE_CACHE_SHIFT];
base &= ~PAGE_CACHE_MASK;
count += base;
for (;count >= PAGE_CACHE_SIZE; count -= PAGE_CACHE_SIZE, pages++)
SetPageUptodate(*pages);
/*
* Was this an eof or a short read? If the latter, don't mark the page
* as uptodate yet.
*/
if (count > 0 && (data->res.eof || data->args.count == data->res.count))
SetPageUptodate(*pages);
}
static void nfs_readpage_set_pages_error(struct nfs_read_data *data)
{
unsigned int count = data->args.count;
unsigned int base = data->args.pgbase;
struct page **pages;
pages = &data->args.pages[base >> PAGE_CACHE_SHIFT];
base &= ~PAGE_CACHE_MASK;
count += base;
for (;count >= PAGE_CACHE_SIZE; count -= PAGE_CACHE_SIZE, pages++)
SetPageError(*pages);
}
/*
* This is the callback from RPC telling us whether a reply was
* received or some error occurred (timeout or socket shutdown).
@ -469,27 +515,24 @@ static const struct rpc_call_ops nfs_read_partial_ops = {
static void nfs_readpage_result_full(struct rpc_task *task, void *calldata)
{
struct nfs_read_data *data = calldata;
unsigned int count = data->res.count;
/*
* Note: nfs_readpage_result may change the values of
* data->args. In the multi-page case, we therefore need
* to ensure that we call the next nfs_readpage_set_page_uptodate()
* first in the multi-page case.
*/
if (likely(task->tk_status >= 0)) {
nfs_readpage_truncate_uninitialised_page(data);
nfs_readpage_set_pages_uptodate(data);
} else
nfs_readpage_set_pages_error(data);
if (nfs_readpage_result(task, data) != 0)
return;
while (!list_empty(&data->pages)) {
struct nfs_page *req = nfs_list_entry(data->pages.next);
struct page *page = req->wb_page;
nfs_list_remove_request(req);
if (task->tk_status >= 0) {
if (count < PAGE_CACHE_SIZE) {
if (count < req->wb_bytes)
memclear_highpage_flush(page,
req->wb_pgbase + count,
req->wb_bytes - count);
count = 0;
} else
count -= PAGE_CACHE_SIZE;
SetPageUptodate(page);
} else
SetPageError(page);
nfs_list_remove_request(req);
nfs_readpage_release(req);
}
}