1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/nfs/symlink.c 4 * 5 * Copyright (C) 1992 Rick Sladkey 6 * 7 * Optimization changes Copyright (C) 1994 Florian La Roche 8 * 9 * Jun 7 1999, cache symlink lookups in the page cache. -DaveM 10 * 11 * nfs symlink handling code 12 */ 13 14 #include <linux/time.h> 15 #include <linux/errno.h> 16 #include <linux/sunrpc/clnt.h> 17 #include <linux/nfs.h> 18 #include <linux/nfs2.h> 19 #include <linux/nfs_fs.h> 20 #include <linux/pagemap.h> 21 #include <linux/stat.h> 22 #include <linux/mm.h> 23 #include <linux/string.h> 24 25 /* Symlink caching in the page cache is even more simplistic 26 * and straight-forward than readdir caching. 27 */ 28 29 static int nfs_symlink_filler(void *data, struct page *page) 30 { 31 struct inode *inode = data; 32 int error; 33 34 error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE); 35 if (error < 0) 36 goto error; 37 SetPageUptodate(page); 38 unlock_page(page); 39 return 0; 40 41 error: 42 SetPageError(page); 43 unlock_page(page); 44 return -EIO; 45 } 46 47 static const char *nfs_get_link(struct dentry *dentry, 48 struct inode *inode, 49 struct delayed_call *done) 50 { 51 struct page *page; 52 void *err; 53 54 if (!dentry) { 55 err = ERR_PTR(nfs_revalidate_mapping_rcu(inode)); 56 if (err) 57 return err; 58 page = find_get_page(inode->i_mapping, 0); 59 if (!page) 60 return ERR_PTR(-ECHILD); 61 if (!PageUptodate(page)) { 62 put_page(page); 63 return ERR_PTR(-ECHILD); 64 } 65 } else { 66 err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping)); 67 if (err) 68 return err; 69 page = read_cache_page(&inode->i_data, 0, nfs_symlink_filler, 70 inode); 71 if (IS_ERR(page)) 72 return ERR_CAST(page); 73 } 74 set_delayed_call(done, page_put_link, page); 75 return page_address(page); 76 } 77 78 /* 79 * symlinks can't do much... 80 */ 81 const struct inode_operations nfs_symlink_inode_operations = { 82 .get_link = nfs_get_link, 83 .getattr = nfs_getattr, 84 .setattr = nfs_setattr, 85 }; 86