| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | #define NFS_NEED_XDR_TYPES |
| 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/slab.h> |
| 24 | #include <linux/string.h> |
| 25 | #include <linux/smp_lock.h> |
| 26 | #include <linux/namei.h> |
| 27 | |
| 28 | /* Symlink caching in the page cache is even more simplistic |
| 29 | * and straight-forward than readdir caching. |
| 30 | * |
| 31 | * At the beginning of the page we store pointer to struct page in question, |
| 32 | * simplifying nfs_put_link() (if inode got invalidated we can't find the page |
| 33 | * to be freed via pagecache lookup). |
| 34 | * The NUL-terminated string follows immediately thereafter. |
| 35 | */ |
| 36 | |
| 37 | struct nfs_symlink { |
| 38 | struct page *page; |
| 39 | char body[0]; |
| 40 | }; |
| 41 | |
| 42 | static int nfs_symlink_filler(struct inode *inode, struct page *page) |
| 43 | { |
| 44 | const unsigned int pgbase = offsetof(struct nfs_symlink, body); |
| 45 | const unsigned int pglen = PAGE_SIZE - pgbase; |
| 46 | int error; |
| 47 | |
| 48 | lock_kernel(); |
| 49 | error = NFS_PROTO(inode)->readlink(inode, page, pgbase, pglen); |
| 50 | unlock_kernel(); |
| 51 | if (error < 0) |
| 52 | goto error; |
| 53 | SetPageUptodate(page); |
| 54 | unlock_page(page); |
| 55 | return 0; |
| 56 | |
| 57 | error: |
| 58 | SetPageError(page); |
| 59 | unlock_page(page); |
| 60 | return -EIO; |
| 61 | } |
| 62 | |
| 63 | static int nfs_follow_link(struct dentry *dentry, struct nameidata *nd) |
| 64 | { |
| 65 | struct inode *inode = dentry->d_inode; |
| 66 | struct page *page; |
| 67 | struct nfs_symlink *p; |
| 68 | void *err = ERR_PTR(nfs_revalidate_inode(NFS_SERVER(inode), inode)); |
| 69 | if (err) |
| 70 | goto read_failed; |
| 71 | page = read_cache_page(&inode->i_data, 0, |
| 72 | (filler_t *)nfs_symlink_filler, inode); |
| 73 | if (IS_ERR(page)) { |
| 74 | err = page; |
| 75 | goto read_failed; |
| 76 | } |
| 77 | if (!PageUptodate(page)) { |
| 78 | err = ERR_PTR(-EIO); |
| 79 | goto getlink_read_error; |
| 80 | } |
| 81 | p = kmap(page); |
| 82 | p->page = page; |
| 83 | nd_set_link(nd, p->body); |
| 84 | return 0; |
| 85 | |
| 86 | getlink_read_error: |
| 87 | page_cache_release(page); |
| 88 | read_failed: |
| 89 | nd_set_link(nd, err); |
| 90 | return 0; |
| 91 | } |
| 92 | |
| 93 | static void nfs_put_link(struct dentry *dentry, struct nameidata *nd) |
| 94 | { |
| 95 | char *s = nd_get_link(nd); |
| 96 | if (!IS_ERR(s)) { |
| 97 | struct nfs_symlink *p; |
| 98 | struct page *page; |
| 99 | |
| 100 | p = container_of(s, struct nfs_symlink, body[0]); |
| 101 | page = p->page; |
| 102 | |
| 103 | kunmap(page); |
| 104 | page_cache_release(page); |
| 105 | } |
| 106 | } |
| 107 | |
| 108 | /* |
| 109 | * symlinks can't do much... |
| 110 | */ |
| 111 | struct inode_operations nfs_symlink_inode_operations = { |
| 112 | .readlink = generic_readlink, |
| 113 | .follow_link = nfs_follow_link, |
| 114 | .put_link = nfs_put_link, |
| 115 | .getattr = nfs_getattr, |
| 116 | .setattr = nfs_setattr, |
| 117 | }; |