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Date: Wed, 03 Nov 2010 09:31:15 +0200
From: Benny Halevy <bhalevy@...asas.com>
To: Trond Myklebust <Trond.Myklebust@...app.com>
CC: Andi Kleen <andi@...stfloor.org>, bjschuma@...app.com,
torvalds@...ux-foundation.org, linux-nfs@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [regression] NFS readdir change break fully cached nfs root
On 2010-11-02 23:05, Trond Myklebust wrote:
> On Tue, 2010-11-02 at 19:00 +0100, Andi Kleen wrote:
>> My NFS root test systems stopped booting with 2.6.37-rc1. It just
>> hangs after entering user space.
>>
>> The NFS root setup uses a slightly fancy parameter setup to minimize
>> network traffic:
>>
>> nfsroot=10.23.204.1:/home/nfsroot/edwin,nocto,acregmin=86400,acregmax=86400,acdirmin=86400,acdirmax=86400 root=/dev/nfs
>>
>> I bisected it down to this commit from Bryan.
>>
>> Unfortunately it's not trivially revertable because that conflicts
>> with later patches.
>
> Does the following patch help?
This patch helps me too with an infinite readdir loop I've seen
with 2.6.37-rc1.
I'll queue it up in the linux-pnfs tree until it hits upstream.
Benny
>
> Cheers
> Trond
> ------------------------------------------------------------------------
> NFS: Fix a couple of regressions in readdir.
>
> From: Trond Myklebust <Trond.Myklebust@...app.com>
>
> Fix up the issue that array->eof_index needs to be able to be set
> even if array->size == 0.
>
> Ensure that we catch all important memory allocation error conditions
> and/or kmap() failures.
>
> Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
> ---
>
> fs/nfs/dir.c | 73 ++++++++++++++++++++++++++++++++++++++--------------------
> 1 files changed, 48 insertions(+), 25 deletions(-)
>
>
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index 07ac384..8c22d60 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -194,9 +194,13 @@ typedef struct {
> static
> struct nfs_cache_array *nfs_readdir_get_array(struct page *page)
> {
> + void *ptr;
> if (page == NULL)
> return ERR_PTR(-EIO);
> - return (struct nfs_cache_array *)kmap(page);
> + ptr = kmap(page);
> + if (ptr == NULL)
> + return ERR_PTR(-ENOMEM);
> + return ptr;
> }
>
> static
> @@ -213,6 +217,9 @@ int nfs_readdir_clear_array(struct page *page, gfp_t mask)
> {
> struct nfs_cache_array *array = nfs_readdir_get_array(page);
> int i;
> +
> + if (IS_ERR(array))
> + return PTR_ERR(array);
> for (i = 0; i < array->size; i++)
> kfree(array->array[i].string.name);
> nfs_readdir_release_array(page);
> @@ -244,7 +251,7 @@ int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
>
> if (IS_ERR(array))
> return PTR_ERR(array);
> - ret = -EIO;
> + ret = -ENOSPC;
> if (array->size >= MAX_READDIR_ARRAY)
> goto out;
>
> @@ -255,9 +262,9 @@ int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
> if (ret)
> goto out;
> array->last_cookie = entry->cookie;
> + array->size++;
> if (entry->eof == 1)
> array->eof_index = array->size;
> - array->size++;
> out:
> nfs_readdir_release_array(page);
> return ret;
> @@ -272,7 +279,7 @@ int nfs_readdir_search_for_pos(struct nfs_cache_array *array, nfs_readdir_descri
> if (diff < 0)
> goto out_eof;
> if (diff >= array->size) {
> - if (array->eof_index > 0)
> + if (array->eof_index >= 0)
> goto out_eof;
> desc->current_index += array->size;
> return -EAGAIN;
> @@ -281,8 +288,6 @@ int nfs_readdir_search_for_pos(struct nfs_cache_array *array, nfs_readdir_descri
> index = (unsigned int)diff;
> *desc->dir_cookie = array->array[index].cookie;
> desc->cache_entry_index = index;
> - if (index == array->eof_index)
> - desc->eof = 1;
> return 0;
> out_eof:
> desc->eof = 1;
> @@ -296,17 +301,17 @@ int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_des
> int status = -EAGAIN;
>
> for (i = 0; i < array->size; i++) {
> - if (i == array->eof_index) {
> - desc->eof = 1;
> - status = -EBADCOOKIE;
> - }
> if (array->array[i].cookie == *desc->dir_cookie) {
> desc->cache_entry_index = i;
> status = 0;
> - break;
> + goto out;
> }
> }
> -
> + if (i == array->eof_index) {
> + desc->eof = 1;
> + status = -EBADCOOKIE;
> + }
> +out:
> return status;
> }
>
> @@ -449,7 +454,7 @@ out:
>
> /* Perform conversion from xdr to cache array */
> static
> -void nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *entry,
> +int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *entry,
> void *xdr_page, struct page *page, unsigned int buflen)
> {
> struct xdr_stream stream;
> @@ -471,21 +476,29 @@ void nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *e
>
> do {
> status = xdr_decode(desc, entry, &stream);
> - if (status != 0)
> + if (status != 0) {
> + if (status == -EAGAIN)
> + status = 0;
> break;
> + }
>
> - if (nfs_readdir_add_to_array(entry, page) == -1)
> - break;
> if (desc->plus == 1)
> nfs_prime_dcache(desc->file->f_path.dentry, entry);
> +
> + status = nfs_readdir_add_to_array(entry, page);
> + if (status != 0)
> + break;
> } while (!entry->eof);
>
> if (status == -EBADCOOKIE && entry->eof) {
> array = nfs_readdir_get_array(page);
> - array->eof_index = array->size - 1;
> - status = 0;
> - nfs_readdir_release_array(page);
> + if (!IS_ERR(array)) {
> + array->eof_index = array->size;
> + status = 0;
> + nfs_readdir_release_array(page);
> + }
> }
> + return status;
> }
>
> static
> @@ -549,9 +562,14 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,
> goto out;
>
> array = nfs_readdir_get_array(page);
> + if (IS_ERR(array)) {
> + status = PTR_ERR(array);
> + goto out;
> + }
> memset(array, 0, sizeof(struct nfs_cache_array));
> array->eof_index = -1;
>
> + status = -ENOMEM;
> pages_ptr = nfs_readdir_large_page(pages, array_size);
> if (!pages_ptr)
> goto out_release_array;
> @@ -560,8 +578,13 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,
>
> if (status < 0)
> break;
> - nfs_readdir_page_filler(desc, &entry, pages_ptr, page, array_size * PAGE_SIZE);
> - } while (array->eof_index < 0 && array->size < MAX_READDIR_ARRAY);
> + status = nfs_readdir_page_filler(desc, &entry, pages_ptr, page, array_size * PAGE_SIZE);
> + if (status < 0) {
> + if (status == -ENOSPC)
> + status = 0;
> + break;
> + }
> + } while (array->eof_index < 0);
>
> nfs_readdir_free_large_page(pages_ptr, pages, array_size);
> out_release_array:
> @@ -670,6 +693,8 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent,
> struct dentry *dentry = NULL;
>
> array = nfs_readdir_get_array(desc->page);
> + if (IS_ERR(array))
> + return PTR_ERR(array);
>
> for (i = desc->cache_entry_index; i < array->size; i++) {
> d_type = DT_UNKNOWN;
> @@ -685,11 +710,9 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent,
> *desc->dir_cookie = array->array[i+1].cookie;
> else
> *desc->dir_cookie = array->last_cookie;
> - if (i == array->eof_index) {
> - desc->eof = 1;
> - break;
> - }
> }
> + if (i == array->eof_index)
> + desc->eof = 1;
>
> nfs_readdir_release_array(desc->page);
> cache_page_release(desc);
>
> --
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