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NFS: Fix asynchronous read error handling 

We must always call ->read_done() before we truncate the page data, or
decide to flag an error. The reasons are that
	in NFSv2, ->read_done() is where the eof flag gets set.
	in NFSv3/v4 ->read_done() handles EJUKEBOX-type errors, and
		  v4 state recovery.

However, we need to mark the pages as uptodate before we deal with short
read errors, since we may need to modify the nfs_read_data arguments.

We therefore split the current nfs_readpage_result() into two parts:
nfs_readpage_result(), which calls ->read_done() etc, and
nfs_readpage_retry(), which subsequently handles short reads.

Note: Removing the code that retries in case of a short read also fixes a
bug in nfs_direct_read_result(), which used to return a corrupted number of
bytes.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2006-11-14 16:12:23 -05:00
parent 46b9f8e148
commit 0b67130149
1 changed files with 69 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

140
fs/nfs/read.c
View File

@ -460,6 +460,55 @@ nfs_pagein_list(struct list_head *head, int rpages)
return error;
}
/*
* This is the callback from RPC telling us whether a reply was
* received or some error occurred (timeout or socket shutdown).
*/
int nfs_readpage_result(struct rpc_task *task, struct nfs_read_data *data)
{
int status;
dprintk("%s: %4d, (status %d)\n", __FUNCTION__, task->tk_pid,
task->tk_status);
status = NFS_PROTO(data->inode)->read_done(task, data);
if (status != 0)
return status;
nfs_add_stats(data->inode, NFSIOS_SERVERREADBYTES, data->res.count);
if (task->tk_status == -ESTALE) {
set_bit(NFS_INO_STALE, &NFS_FLAGS(data->inode));
nfs_mark_for_revalidate(data->inode);
}
spin_lock(&data->inode->i_lock);
NFS_I(data->inode)->cache_validity |= NFS_INO_INVALID_ATIME;
spin_unlock(&data->inode->i_lock);
return 0;
}
static int nfs_readpage_retry(struct rpc_task *task, struct nfs_read_data *data)
{
struct nfs_readargs *argp = &data->args;
struct nfs_readres *resp = &data->res;
if (resp->eof || resp->count == argp->count)
return 0;
/* This is a short read! */
nfs_inc_stats(data->inode, NFSIOS_SHORTREAD);
/* Has the server at least made some progress? */
if (resp->count == 0)
return 0;
/* Yes, so retry the read at the end of the data */
argp->offset += resp->count;
argp->pgbase += resp->count;
argp->count -= resp->count;
rpc_restart_call(task);
return -EAGAIN;
}
/*
* Handle a read reply that fills part of a page.
*/
@ -469,12 +518,16 @@ 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 (likely(task->tk_status >= 0)) {
nfs_readpage_truncate_uninitialised_page(data);
if (nfs_readpage_retry(task, data) != 0)
return;
}
if (unlikely(task->tk_status < 0))
SetPageError(page);
if (atomic_dec_and_test(&req->wb_complete)) {
if (!PageError(page))
SetPageUptodate(page);
@ -502,25 +555,13 @@ static void nfs_readpage_set_pages_uptodate(struct nfs_read_data *data)
count += base;
for (;count >= PAGE_CACHE_SIZE; count -= PAGE_CACHE_SIZE, pages++)
SetPageUptodate(*pages);
if (count != 0)
if (count == 0)
return;
/* Was this a short read? */
if (data->res.eof || data->res.count == data->args.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);
if (count != 0)
SetPageError(*pages);
}
/*
* This is the callback from RPC telling us whether a reply was
* received or some error occurred (timeout or socket shutdown).
@ -529,19 +570,20 @@ static void nfs_readpage_result_full(struct rpc_task *task, void *calldata)
{
struct nfs_read_data *data = calldata;
if (nfs_readpage_result(task, data) != 0)
return;
/*
* Note: nfs_readpage_result may change the values of
* Note: nfs_readpage_retry 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.
* to ensure that we call nfs_readpage_set_pages_uptodate()
* first.
*/
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;
if (nfs_readpage_retry(task, data) != 0)
return;
}
while (!list_empty(&data->pages)) {
struct nfs_page *req = nfs_list_entry(data->pages.next);
@ -555,50 +597,6 @@ static const struct rpc_call_ops nfs_read_full_ops = {
.rpc_release = nfs_readdata_release,
};
/*
* This is the callback from RPC telling us whether a reply was
* received or some error occurred (timeout or socket shutdown).
*/
int nfs_readpage_result(struct rpc_task *task, struct nfs_read_data *data)
{
struct nfs_readargs *argp = &data->args;
struct nfs_readres *resp = &data->res;
int status;
dprintk("NFS: %4d nfs_readpage_result, (status %d)\n",
task->tk_pid, task->tk_status);
status = NFS_PROTO(data->inode)->read_done(task, data);
if (status != 0)
return status;
nfs_add_stats(data->inode, NFSIOS_SERVERREADBYTES, resp->count);
if (task->tk_status < 0) {
if (task->tk_status == -ESTALE) {
set_bit(NFS_INO_STALE, &NFS_FLAGS(data->inode));
nfs_mark_for_revalidate(data->inode);
}
} else if (resp->count < argp->count && !resp->eof) {
/* This is a short read! */
nfs_inc_stats(data->inode, NFSIOS_SHORTREAD);
/* Has the server at least made some progress? */
if (resp->count != 0) {
/* Yes, so retry the read at the end of the data */
argp->offset += resp->count;
argp->pgbase += resp->count;
argp->count -= resp->count;
rpc_restart_call(task);
return -EAGAIN;
}
task->tk_status = -EIO;
}
spin_lock(&data->inode->i_lock);
NFS_I(data->inode)->cache_validity |= NFS_INO_INVALID_ATIME;
spin_unlock(&data->inode->i_lock);
return 0;
}
/*
* Read a page over NFS.
* We read the page synchronously in the following case: