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(struct inode *inode, struct page *page) 30 { 31 int error; 32 33 error = NFS_PROTO(inode)->readlink(inode, page, 0, PAGE_SIZE); 34 if (error < 0) 35 goto error; 36 SetPageUptodate(page); 37 unlock_page(page); 38 return 0; 39 40 error: 41 SetPageError(page); 42 unlock_page(page); 43 return -EIO; 44 } 45 46 static const char *nfs_get_link(struct dentry *dentry, 47 struct inode *inode, 48 struct delayed_call *done) 49 { 50 struct page *page; 51 void *err; 52 53 if (!dentry) { 54 err = ERR_PTR(nfs_revalidate_mapping_rcu(inode)); 55 if (err) 56 return err; 57 page = find_get_page(inode->i_mapping, 0); 58 if (!page) 59 return ERR_PTR(-ECHILD); 60 if (!PageUptodate(page)) { 61 put_page(page); 62 return ERR_PTR(-ECHILD); 63 } 64 } else { 65 err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping)); 66 if (err) 67 return err; 68 page = read_cache_page(&inode->i_data, 0, 69 (filler_t *)nfs_symlink_filler, inode); 70 if (IS_ERR(page)) 71 return ERR_CAST(page); 72 } 73 set_delayed_call(done, page_put_link, page); 74 return page_address(page); 75 } 76 77 /* 78 * symlinks can't do much... 79 */ 80 const struct inode_operations nfs_symlink_inode_operations = { 81 .get_link = nfs_get_link, 82 .getattr = nfs_getattr, 83 .setattr = nfs_setattr, 84 }; 85