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