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

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 57f578e2560a0be44a6e29978627f315f57db01d..d23108b1e33834be2323b1e07d859be7ce4074c7 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -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)
@@ -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)

diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 8b579beb63586c9561c9da1c2c87790587ebf84c..b96fb99072ffdb4fbdb687438d19d5a629106a02 100644 (file)
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -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;
 };
 
 /*