1 /* 2 * linux/fs/nfs/symlink.c 3 * 4 * Copyright (C) 1992 Rick Sladkey 5 * 6 * Optimization changes Copyright (C) 1994 Florian La Roche 7 * 8 * Jun 7 1999, cache symlink lookups in the page cache. -DaveM 9 * 10 * nfs symlink handling code 11 */ 12 13 #include <linux/time.h> 14 #include <linux/errno.h> 15 #include <linux/sunrpc/clnt.h> 16 #include <linux/nfs.h> 17 #include <linux/nfs2.h> 18 #include <linux/nfs_fs.h> 19 #include <linux/pagemap.h> 20 #include <linux/stat.h> 21 #include <linux/mm.h> 22 #include <linux/slab.h> 23 #include <linux/string.h> 24 #include <linux/namei.h> 25 26 /* Symlink caching in the page cache is even more simplistic 27 * and straight-forward than readdir caching. 28 */ 29 30 static int nfs_symlink_filler(struct inode *inode, struct page *page) 31 { 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 void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd) 48 { 49 struct inode *inode = dentry->d_inode; 50 struct page *page; 51 void *err; 52 53 err = ERR_PTR(nfs_revalidate_mapping_nolock(inode, inode->i_mapping)); 54 if (err) 55 goto read_failed; 56 page = read_cache_page(&inode->i_data, 0, 57 (filler_t *)nfs_symlink_filler, inode); 58 if (IS_ERR(page)) { 59 err = page; 60 goto read_failed; 61 } 62 nd_set_link(nd, kmap(page)); 63 return page; 64 65 read_failed: 66 nd_set_link(nd, err); 67 return NULL; 68 } 69 70 /* 71 * symlinks can't do much... 72 */ 73 const struct inode_operations nfs_symlink_inode_operations = { 74 .readlink = generic_readlink, 75 .follow_link = nfs_follow_link, 76 .put_link = page_put_link, 77 .getattr = nfs_getattr, 78 .setattr = nfs_setattr, 79 }; 80