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Commit 0c030806 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Fix spurious readdir cookie loop messages 



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: default avatarPetr Vandrovec <petr@vandrovec.name>
Cc: stable@kernel.org [2.6.39+]
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent ed1e6211

fs/nfs/dir.c

+33 −23
Original line number Diff line number Diff line
@@ -134,19 +134,20 @@ 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  ERR_PTR(-ENOMEM);

}



static void put_nfs_open_dir_context(struct nfs_open_dir_context *ctx)

{
@@ -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;
@@ -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;
@@ -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;
@@ -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;
@@ -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;

}
@@ -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);
@@ -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;
@@ -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);
@@ -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)

include/linux/nfs_fs.h

+2 −1
Original line number Diff line number Diff line
@@ -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;

};



/*