118 lines
2.6 KiB
C
118 lines
2.6 KiB
C
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/*
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* linux/fs/nfs/symlink.c
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*
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* Copyright (C) 1992 Rick Sladkey
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*
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* Optimization changes Copyright (C) 1994 Florian La Roche
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*
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* Jun 7 1999, cache symlink lookups in the page cache. -DaveM
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*
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* nfs symlink handling code
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*/
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#define NFS_NEED_XDR_TYPES
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#include <linux/time.h>
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#include <linux/errno.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/nfs.h>
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#include <linux/nfs2.h>
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#include <linux/nfs_fs.h>
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#include <linux/pagemap.h>
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#include <linux/stat.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/smp_lock.h>
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#include <linux/namei.h>
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/* Symlink caching in the page cache is even more simplistic
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* and straight-forward than readdir caching.
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*
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* At the beginning of the page we store pointer to struct page in question,
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* simplifying nfs_put_link() (if inode got invalidated we can't find the page
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* to be freed via pagecache lookup).
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* The NUL-terminated string follows immediately thereafter.
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*/
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struct nfs_symlink {
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struct page *page;
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char body[0];
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};
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static int nfs_symlink_filler(struct inode *inode, struct page *page)
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{
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const unsigned int pgbase = offsetof(struct nfs_symlink, body);
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const unsigned int pglen = PAGE_SIZE - pgbase;
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int error;
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lock_kernel();
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error = NFS_PROTO(inode)->readlink(inode, page, pgbase, pglen);
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unlock_kernel();
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if (error < 0)
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goto error;
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SetPageUptodate(page);
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unlock_page(page);
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return 0;
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error:
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SetPageError(page);
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unlock_page(page);
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return -EIO;
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}
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static int nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
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{
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struct inode *inode = dentry->d_inode;
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struct page *page;
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struct nfs_symlink *p;
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void *err = ERR_PTR(nfs_revalidate_inode(NFS_SERVER(inode), inode));
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if (err)
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goto read_failed;
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page = read_cache_page(&inode->i_data, 0,
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(filler_t *)nfs_symlink_filler, inode);
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if (IS_ERR(page)) {
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err = page;
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goto read_failed;
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}
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if (!PageUptodate(page)) {
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err = ERR_PTR(-EIO);
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goto getlink_read_error;
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}
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p = kmap(page);
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p->page = page;
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nd_set_link(nd, p->body);
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return 0;
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getlink_read_error:
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page_cache_release(page);
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read_failed:
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nd_set_link(nd, err);
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return 0;
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}
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static void nfs_put_link(struct dentry *dentry, struct nameidata *nd)
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{
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char *s = nd_get_link(nd);
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if (!IS_ERR(s)) {
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struct nfs_symlink *p;
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struct page *page;
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p = container_of(s, struct nfs_symlink, body[0]);
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page = p->page;
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kunmap(page);
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page_cache_release(page);
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}
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}
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/*
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* symlinks can't do much...
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*/
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struct inode_operations nfs_symlink_inode_operations = {
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.readlink = generic_readlink,
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.follow_link = nfs_follow_link,
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.put_link = nfs_put_link,
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.getattr = nfs_getattr,
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.setattr = nfs_setattr,
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};
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