[PATCH] NFSv4: client-side caching NFSv4 ACLs

 Add nfs4_acl field to the nfs_inode, and use it to cache acls.  Only cache
 acls of size up to a page.  Also prepare for up to a page of acl data even
 when the user doesn't pass in a buffer, as when they want to get the acl
 length to decide what size buffer to allocate.

 Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index c45bd52..350c48c 100644 (file)
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -142,10 +142,6 @@ nfs_delete_inode(struct inode * inode)
        clear_inode(inode);
 }
 
-/*
- * For the moment, the only task for the NFS clear_inode method is to
- * release the mmap credential
- */
 static void
 nfs_clear_inode(struct inode *inode)
 {
@@ -1923,6 +1919,9 @@ static struct inode *nfs_alloc_inode(struct super_block *sb)
        if (!nfsi)
                return NULL;
        nfsi->flags = 0;
+#ifdef CONFIG_NFS_V4
+       nfsi->nfs4_acl = NULL;
+#endif /* CONFIG_NFS_V4 */
        return &nfsi->vfs_inode;
 }
 

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index d969dd1..128d01c 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2188,9 +2188,75 @@ static void buf_to_pages(const void *buf, size_t buflen,
        }
 }
 
-static ssize_t nfs4_proc_get_acl(struct inode *inode, void *buf, size_t buflen)
+struct nfs4_cached_acl {
+       int cached;
+       size_t len;
+       char data[];
+};
+
+static void nfs4_set_cached_acl(struct inode *inode, struct nfs4_cached_acl *acl)
+{
+       struct nfs_inode *nfsi = NFS_I(inode);
+
+       spin_lock(&inode->i_lock);
+       kfree(nfsi->nfs4_acl);
+       nfsi->nfs4_acl = acl;
+       spin_unlock(&inode->i_lock);
+}
+
+static void nfs4_zap_acl_attr(struct inode *inode)
+{
+       nfs4_set_cached_acl(inode, NULL);
+}
+
+static inline ssize_t nfs4_read_cached_acl(struct inode *inode, char *buf, size_t buflen)
+{
+       struct nfs_inode *nfsi = NFS_I(inode);
+       struct nfs4_cached_acl *acl;
+       int ret = -ENOENT;
+
+       spin_lock(&inode->i_lock);
+       acl = nfsi->nfs4_acl;
+       if (acl == NULL)
+               goto out;
+       if (buf == NULL) /* user is just asking for length */
+               goto out_len;
+       if (acl->cached == 0)
+               goto out;
+       ret = -ERANGE; /* see getxattr(2) man page */
+       if (acl->len > buflen)
+               goto out;
+       memcpy(buf, acl->data, acl->len);
+out_len:
+       ret = acl->len;
+out:
+       spin_unlock(&inode->i_lock);
+       return ret;
+}
+
+static void nfs4_write_cached_acl(struct inode *inode, const char *buf, size_t acl_len)
+{
+       struct nfs4_cached_acl *acl;
+
+       if (buf && acl_len <= PAGE_SIZE) {
+               acl = kmalloc(sizeof(*acl) + acl_len, GFP_KERNEL);
+               if (acl == NULL)
+                       goto out;
+               acl->cached = 1;
+               memcpy(acl->data, buf, acl_len);
+       } else {
+               acl = kmalloc(sizeof(*acl), GFP_KERNEL);
+               if (acl == NULL)
+                       goto out;
+               acl->cached = 0;
+       }
+       acl->len = acl_len;
+out:
+       nfs4_set_cached_acl(inode, acl);
+}
+
+static inline ssize_t nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t buflen)
 {
-       struct nfs_server *server = NFS_SERVER(inode);
        struct page *pages[NFS4ACL_MAXPAGES];
        struct nfs_getaclargs args = {
                .fh = NFS_FH(inode),
@@ -2198,24 +2264,66 @@ static ssize_t nfs4_proc_get_acl(struct inode *inode, void *buf, size_t buflen)
                .acl_len = buflen,
        };
        size_t resp_len = buflen;
+       void *resp_buf;
        struct rpc_message msg = {
                .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_GETACL],
                .rpc_argp = &args,
                .rpc_resp = &resp_len,
        };
+       struct page *localpage = NULL;
        int ret;
 
-       if (!nfs4_server_supports_acls(server))
-               return -EOPNOTSUPP;
-       buf_to_pages(buf, buflen, args.acl_pages, &args.acl_pgbase);
+       if (buflen < PAGE_SIZE) {
+               /* As long as we're doing a round trip to the server anyway,
+                * let's be prepared for a page of acl data. */
+               localpage = alloc_page(GFP_KERNEL);
+               resp_buf = page_address(localpage);
+               if (localpage == NULL)
+                       return -ENOMEM;
+               args.acl_pages[0] = localpage;
+               args.acl_pgbase = 0;
+               args.acl_len = PAGE_SIZE;
+       } else {
+               resp_buf = buf;
+               buf_to_pages(buf, buflen, args.acl_pages, &args.acl_pgbase);
+       }
        ret = rpc_call_sync(NFS_CLIENT(inode), &msg, 0);
-       if (buflen && resp_len > buflen)
-               return -ERANGE;
-       if (ret == 0)
-               ret = resp_len;
+       if (ret)
+               goto out_free;
+       if (resp_len > args.acl_len)
+               nfs4_write_cached_acl(inode, NULL, resp_len);
+       else
+               nfs4_write_cached_acl(inode, resp_buf, resp_len);
+       if (buf) {
+               ret = -ERANGE;
+               if (resp_len > buflen)
+                       goto out_free;
+               if (localpage)
+                       memcpy(buf, resp_buf, resp_len);
+       }
+       ret = resp_len;
+out_free:
+       if (localpage)
+               __free_page(localpage);
        return ret;
 }
 
+static ssize_t nfs4_proc_get_acl(struct inode *inode, void *buf, size_t buflen)
+{
+       struct nfs_server *server = NFS_SERVER(inode);
+       int ret;
+
+       if (!nfs4_server_supports_acls(server))
+               return -EOPNOTSUPP;
+       ret = nfs_revalidate_inode(server, inode);
+       if (ret < 0)
+               return ret;
+       ret = nfs4_read_cached_acl(inode, buf, buflen);
+       if (ret != -ENOENT)
+               return ret;
+       return nfs4_get_acl_uncached(inode, buf, buflen);
+}
+
 static int nfs4_proc_set_acl(struct inode *inode, const void *buf, size_t buflen)
 {
        struct nfs_server *server = NFS_SERVER(inode);
@@ -2236,6 +2344,8 @@ static int nfs4_proc_set_acl(struct inode *inode, const void *buf, size_t buflen
                return -EOPNOTSUPP;
        buf_to_pages(buf, buflen, arg.acl_pages, &arg.acl_pgbase);
        ret = rpc_call_sync(NFS_SERVER(inode)->client, &msg, 0);
+       if (ret == 0)
+               nfs4_write_cached_acl(inode, buf, buflen);
        return ret;
 }
 
@@ -2907,6 +3017,7 @@ struct nfs_rpc_ops        nfs_v4_clientops = {
        .file_open      = nfs4_proc_file_open,
        .file_release   = nfs4_proc_file_release,
        .lock           = nfs4_proc_lock,
+       .clear_acl_cache = nfs4_zap_acl_attr,
 };
 
 /*

diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 140bdf4..d2b5d7e 100644 (file)
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -169,13 +169,13 @@ struct nfs_inode {
        wait_queue_head_t       nfs_i_wait;
 
 #ifdef CONFIG_NFS_V4
+       struct nfs4_cached_acl  *nfs4_acl;
         /* NFSv4 state */
        struct list_head        open_states;
        struct nfs_delegation   *delegation;
        int                      delegation_state;
        struct rw_semaphore     rwsem;
 #endif /* CONFIG_NFS_V4*/
-
        struct inode            vfs_inode;
 };