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
Родитель
46b9f8e148
Коммит
0b67130149
140
fs/nfs/read.c
140
fs/nfs/read.c
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@ -460,6 +460,55 @@ nfs_pagein_list(struct list_head *head, int rpages)
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return error;
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}
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/*
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* This is the callback from RPC telling us whether a reply was
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* received or some error occurred (timeout or socket shutdown).
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*/
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int nfs_readpage_result(struct rpc_task *task, struct nfs_read_data *data)
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{
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int status;
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dprintk("%s: %4d, (status %d)\n", __FUNCTION__, task->tk_pid,
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task->tk_status);
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status = NFS_PROTO(data->inode)->read_done(task, data);
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if (status != 0)
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return status;
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nfs_add_stats(data->inode, NFSIOS_SERVERREADBYTES, data->res.count);
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if (task->tk_status == -ESTALE) {
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set_bit(NFS_INO_STALE, &NFS_FLAGS(data->inode));
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nfs_mark_for_revalidate(data->inode);
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}
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spin_lock(&data->inode->i_lock);
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NFS_I(data->inode)->cache_validity |= NFS_INO_INVALID_ATIME;
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spin_unlock(&data->inode->i_lock);
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return 0;
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}
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static int nfs_readpage_retry(struct rpc_task *task, struct nfs_read_data *data)
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{
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struct nfs_readargs *argp = &data->args;
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struct nfs_readres *resp = &data->res;
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if (resp->eof || resp->count == argp->count)
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return 0;
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/* This is a short read! */
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nfs_inc_stats(data->inode, NFSIOS_SHORTREAD);
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/* Has the server at least made some progress? */
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if (resp->count == 0)
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return 0;
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/* Yes, so retry the read at the end of the data */
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argp->offset += resp->count;
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argp->pgbase += resp->count;
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argp->count -= resp->count;
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rpc_restart_call(task);
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return -EAGAIN;
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}
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/*
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* Handle a read reply that fills part of a page.
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*/
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@ -469,12 +518,16 @@ static void nfs_readpage_result_partial(struct rpc_task *task, void *calldata)
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struct nfs_page *req = data->req;
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struct page *page = req->wb_page;
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if (likely(task->tk_status >= 0))
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nfs_readpage_truncate_uninitialised_page(data);
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else
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SetPageError(page);
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if (nfs_readpage_result(task, data) != 0)
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return;
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if (likely(task->tk_status >= 0)) {
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nfs_readpage_truncate_uninitialised_page(data);
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if (nfs_readpage_retry(task, data) != 0)
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return;
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}
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if (unlikely(task->tk_status < 0))
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SetPageError(page);
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if (atomic_dec_and_test(&req->wb_complete)) {
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if (!PageError(page))
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SetPageUptodate(page);
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@ -502,25 +555,13 @@ static void nfs_readpage_set_pages_uptodate(struct nfs_read_data *data)
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count += base;
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for (;count >= PAGE_CACHE_SIZE; count -= PAGE_CACHE_SIZE, pages++)
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SetPageUptodate(*pages);
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if (count != 0)
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if (count == 0)
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return;
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/* Was this a short read? */
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if (data->res.eof || data->res.count == data->args.count)
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SetPageUptodate(*pages);
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}
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static void nfs_readpage_set_pages_error(struct nfs_read_data *data)
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{
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unsigned int count = data->args.count;
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unsigned int base = data->args.pgbase;
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struct page **pages;
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pages = &data->args.pages[base >> PAGE_CACHE_SHIFT];
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base &= ~PAGE_CACHE_MASK;
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count += base;
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for (;count >= PAGE_CACHE_SIZE; count -= PAGE_CACHE_SIZE, pages++)
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SetPageError(*pages);
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if (count != 0)
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SetPageError(*pages);
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}
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/*
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* This is the callback from RPC telling us whether a reply was
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* received or some error occurred (timeout or socket shutdown).
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@ -529,19 +570,20 @@ static void nfs_readpage_result_full(struct rpc_task *task, void *calldata)
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{
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struct nfs_read_data *data = calldata;
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if (nfs_readpage_result(task, data) != 0)
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return;
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/*
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* Note: nfs_readpage_result may change the values of
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* Note: nfs_readpage_retry may change the values of
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* data->args. In the multi-page case, we therefore need
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* to ensure that we call the next nfs_readpage_set_page_uptodate()
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* first in the multi-page case.
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* to ensure that we call nfs_readpage_set_pages_uptodate()
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* first.
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*/
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if (likely(task->tk_status >= 0)) {
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nfs_readpage_truncate_uninitialised_page(data);
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nfs_readpage_set_pages_uptodate(data);
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} else
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nfs_readpage_set_pages_error(data);
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if (nfs_readpage_result(task, data) != 0)
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return;
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if (nfs_readpage_retry(task, data) != 0)
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return;
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}
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while (!list_empty(&data->pages)) {
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struct nfs_page *req = nfs_list_entry(data->pages.next);
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@ -555,50 +597,6 @@ static const struct rpc_call_ops nfs_read_full_ops = {
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.rpc_release = nfs_readdata_release,
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};
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/*
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* This is the callback from RPC telling us whether a reply was
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* received or some error occurred (timeout or socket shutdown).
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*/
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int nfs_readpage_result(struct rpc_task *task, struct nfs_read_data *data)
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{
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struct nfs_readargs *argp = &data->args;
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struct nfs_readres *resp = &data->res;
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int status;
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dprintk("NFS: %4d nfs_readpage_result, (status %d)\n",
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task->tk_pid, task->tk_status);
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status = NFS_PROTO(data->inode)->read_done(task, data);
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if (status != 0)
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return status;
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nfs_add_stats(data->inode, NFSIOS_SERVERREADBYTES, resp->count);
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if (task->tk_status < 0) {
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if (task->tk_status == -ESTALE) {
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set_bit(NFS_INO_STALE, &NFS_FLAGS(data->inode));
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nfs_mark_for_revalidate(data->inode);
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}
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} else if (resp->count < argp->count && !resp->eof) {
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/* This is a short read! */
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nfs_inc_stats(data->inode, NFSIOS_SHORTREAD);
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/* Has the server at least made some progress? */
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if (resp->count != 0) {
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/* Yes, so retry the read at the end of the data */
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argp->offset += resp->count;
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argp->pgbase += resp->count;
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argp->count -= resp->count;
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rpc_restart_call(task);
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return -EAGAIN;
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}
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task->tk_status = -EIO;
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}
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spin_lock(&data->inode->i_lock);
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NFS_I(data->inode)->cache_validity |= NFS_INO_INVALID_ATIME;
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spin_unlock(&data->inode->i_lock);
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return 0;
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}
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/*
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* Read a page over NFS.
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* We read the page synchronously in the following case:
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