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NFS: Fix spurious readdir cookie loop messages
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If the directory contents change, then we have to accept that the
file->f_pos value may shrink if we do a 'search-by-cookie'. In that
case, we should turn off the loop detection and let the NFS client
try to recover.

The patch also fixes a second loop detection bug by ensuring
that after turning on the ctx->duped flag, we read at least one new
cookie into ctx->dir_cookie before attempting to match with
ctx->dup_cookie.

Reported-by: Petr Vandrovec <petr@vandrovec.name>
Cc: stable@kernel.org [2.6.39+]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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Trond Myklebust authored and Trond Myklebust committed Jul 30, 2011
1 parent ed1e621 commit 0c03080
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Showing 2 changed files with 35 additions and 24 deletions.
56 changes: 33 additions & 23 deletions fs/nfs/dir.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -134,18 +134,19 @@ const struct inode_operations nfs4_dir_inode_operations = {

#endif /* CONFIG_NFS_V4 */

static struct nfs_open_dir_context *alloc_nfs_open_dir_context(struct rpc_cred *cred)
static struct nfs_open_dir_context *alloc_nfs_open_dir_context(struct inode *dir, struct rpc_cred *cred)
{
struct nfs_open_dir_context *ctx;
ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
if (ctx != NULL) {
ctx->duped = 0;
ctx->attr_gencount = NFS_I(dir)->attr_gencount;
ctx->dir_cookie = 0;
ctx->dup_cookie = 0;
ctx->cred = get_rpccred(cred);
} else
ctx = ERR_PTR(-ENOMEM);
return ctx;
return ctx;
}
return ERR_PTR(-ENOMEM);
}

static void put_nfs_open_dir_context(struct nfs_open_dir_context *ctx)
Expand Down Expand Up @@ -173,7 +174,7 @@ nfs_opendir(struct inode *inode, struct file *filp)
cred = rpc_lookup_cred();
if (IS_ERR(cred))
return PTR_ERR(cred);
ctx = alloc_nfs_open_dir_context(cred);
ctx = alloc_nfs_open_dir_context(inode, cred);
if (IS_ERR(ctx)) {
res = PTR_ERR(ctx);
goto out;
Expand Down Expand Up @@ -323,7 +324,6 @@ int nfs_readdir_search_for_pos(struct nfs_cache_array *array, nfs_readdir_descri
{
loff_t diff = desc->file->f_pos - desc->current_index;
unsigned int index;
struct nfs_open_dir_context *ctx = desc->file->private_data;

if (diff < 0)
goto out_eof;
Expand All @@ -336,7 +336,6 @@ 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;
ctx->duped = 0;
return 0;
out_eof:
desc->eof = 1;
Expand All @@ -349,14 +348,33 @@ int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_des
int i;
loff_t new_pos;
int status = -EAGAIN;
struct nfs_open_dir_context *ctx = desc->file->private_data;

for (i = 0; i < array->size; i++) {
if (array->array[i].cookie == *desc->dir_cookie) {
struct nfs_inode *nfsi = NFS_I(desc->file->f_path.dentry->d_inode);
struct nfs_open_dir_context *ctx = desc->file->private_data;

new_pos = desc->current_index + i;
if (new_pos < desc->file->f_pos) {
if (ctx->attr_gencount != nfsi->attr_gencount
|| (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))) {
ctx->duped = 0;
ctx->attr_gencount = nfsi->attr_gencount;
} else if (new_pos < desc->file->f_pos) {
if (ctx->duped > 0
&& ctx->dup_cookie == *desc->dir_cookie) {
if (printk_ratelimit()) {
pr_notice("NFS: directory %s/%s contains a readdir loop."
"Please contact your server vendor. "
"Offending cookie: %llu\n",
desc->file->f_dentry->d_parent->d_name.name,
desc->file->f_dentry->d_name.name,
*desc->dir_cookie);
}
status = -ELOOP;
goto out;
}
ctx->dup_cookie = *desc->dir_cookie;
ctx->duped = 1;
ctx->duped = -1;
}
desc->file->f_pos = new_pos;
desc->cache_entry_index = i;
Expand All @@ -368,6 +386,7 @@ int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_des
if (*desc->dir_cookie == array->last_cookie)
desc->eof = 1;
}
out:
return status;
}

Expand Down Expand Up @@ -740,19 +759,6 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent,
struct nfs_cache_array *array = NULL;
struct nfs_open_dir_context *ctx = file->private_data;

if (ctx->duped != 0 && ctx->dup_cookie == *desc->dir_cookie) {
if (printk_ratelimit()) {
pr_notice("NFS: directory %s/%s contains a readdir loop. "
"Please contact your server vendor. "
"Offending cookie: %llu\n",
file->f_dentry->d_parent->d_name.name,
file->f_dentry->d_name.name,
*desc->dir_cookie);
}
res = -ELOOP;
goto out;
}

array = nfs_readdir_get_array(desc->page);
if (IS_ERR(array)) {
res = PTR_ERR(array);
Expand All @@ -774,6 +780,8 @@ 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 (ctx->duped != 0)
ctx->duped = 1;
}
if (array->eof_index >= 0)
desc->eof = 1;
Expand Down Expand Up @@ -805,6 +813,7 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent,
struct page *page = NULL;
int status;
struct inode *inode = desc->file->f_path.dentry->d_inode;
struct nfs_open_dir_context *ctx = desc->file->private_data;

dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %Lu\n",
(unsigned long long)*desc->dir_cookie);
Expand All @@ -818,6 +827,7 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent,
desc->page_index = 0;
desc->last_cookie = *desc->dir_cookie;
desc->page = page;
ctx->duped = 0;

status = nfs_readdir_xdr_to_array(desc, page, inode);
if (status < 0)
Expand Down
3 changes: 2 additions & 1 deletion include/linux/nfs_fs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -99,9 +99,10 @@ struct nfs_open_context {

struct nfs_open_dir_context {
struct rpc_cred *cred;
unsigned long attr_gencount;
__u64 dir_cookie;
__u64 dup_cookie;
int duped;
signed char duped;
};

/*
Expand Down

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