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SubjectRe: [regression] NFS readdir change break fully cached nfs root
From
Date
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?

Cheers
Trond
------------------------------------------------------------------------
NFS: Fix a couple of regressions in readdir.
From: Trond Myklebust <Trond.Myklebust@netapp.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@netapp.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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