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![Christian Brauner](/assets/img/avatar_default.png)
Extend some inode methods with an additional user namespace argument. A filesystem that is aware of idmapped mounts will receive the user namespace the mount has been marked with. This can be used for additional permission checking and also to enable filesystems to translate between uids and gids if they need to. We have implemented all relevant helpers in earlier patches. As requested we simply extend the exisiting inode method instead of introducing new ones. This is a little more code churn but it's mostly mechanical and doesnt't leave us with additional inode methods. Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
593 lines
14 KiB
C
593 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Directory operations for Coda filesystem
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* Original version: (C) 1996 P. Braam and M. Callahan
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* Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University
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*
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* Carnegie Mellon encourages users to contribute improvements to
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* the Coda project. Contact Peter Braam (coda@cs.cmu.edu).
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/time.h>
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#include <linux/fs.h>
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#include <linux/slab.h>
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#include <linux/file.h>
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#include <linux/stat.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/spinlock.h>
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#include <linux/namei.h>
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#include <linux/uaccess.h>
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#include <linux/coda.h>
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#include "coda_psdev.h"
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#include "coda_linux.h"
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#include "coda_cache.h"
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#include "coda_int.h"
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/* same as fs/bad_inode.c */
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static int coda_return_EIO(void)
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{
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return -EIO;
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}
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#define CODA_EIO_ERROR ((void *) (coda_return_EIO))
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/* inode operations for directories */
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/* access routines: lookup, readlink, permission */
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static struct dentry *coda_lookup(struct inode *dir, struct dentry *entry, unsigned int flags)
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{
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struct super_block *sb = dir->i_sb;
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const char *name = entry->d_name.name;
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size_t length = entry->d_name.len;
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struct inode *inode;
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int type = 0;
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if (length > CODA_MAXNAMLEN) {
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pr_err("name too long: lookup, %s %zu\n",
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coda_i2s(dir), length);
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return ERR_PTR(-ENAMETOOLONG);
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}
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/* control object, create inode on the fly */
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if (is_root_inode(dir) && coda_iscontrol(name, length)) {
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inode = coda_cnode_makectl(sb);
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type = CODA_NOCACHE;
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} else {
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struct CodaFid fid = { { 0, } };
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int error = venus_lookup(sb, coda_i2f(dir), name, length,
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&type, &fid);
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inode = !error ? coda_cnode_make(&fid, sb) : ERR_PTR(error);
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}
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if (!IS_ERR(inode) && (type & CODA_NOCACHE))
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coda_flag_inode(inode, C_VATTR | C_PURGE);
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if (inode == ERR_PTR(-ENOENT))
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inode = NULL;
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return d_splice_alias(inode, entry);
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}
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int coda_permission(struct user_namespace *mnt_userns, struct inode *inode,
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int mask)
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{
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int error;
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if (mask & MAY_NOT_BLOCK)
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return -ECHILD;
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mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
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if (!mask)
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return 0;
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if ((mask & MAY_EXEC) && !execute_ok(inode))
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return -EACCES;
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if (coda_cache_check(inode, mask))
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return 0;
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error = venus_access(inode->i_sb, coda_i2f(inode), mask);
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if (!error)
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coda_cache_enter(inode, mask);
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return error;
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}
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static inline void coda_dir_update_mtime(struct inode *dir)
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{
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#ifdef REQUERY_VENUS_FOR_MTIME
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/* invalidate the directory cnode's attributes so we refetch the
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* attributes from venus next time the inode is referenced */
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coda_flag_inode(dir, C_VATTR);
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#else
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/* optimistically we can also act as if our nose bleeds. The
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* granularity of the mtime is coarse anyways so we might actually be
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* right most of the time. Note: we only do this for directories. */
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dir->i_mtime = dir->i_ctime = current_time(dir);
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#endif
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}
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/* we have to wrap inc_nlink/drop_nlink because sometimes userspace uses a
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* trick to fool GNU find's optimizations. If we can't be sure of the link
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* (because of volume mount points) we set i_nlink to 1 which forces find
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* to consider every child as a possible directory. We should also never
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* see an increment or decrement for deleted directories where i_nlink == 0 */
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static inline void coda_dir_inc_nlink(struct inode *dir)
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{
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if (dir->i_nlink >= 2)
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inc_nlink(dir);
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}
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static inline void coda_dir_drop_nlink(struct inode *dir)
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{
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if (dir->i_nlink > 2)
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drop_nlink(dir);
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}
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/* creation routines: create, mknod, mkdir, link, symlink */
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static int coda_create(struct user_namespace *mnt_userns, struct inode *dir,
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struct dentry *de, umode_t mode, bool excl)
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{
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int error;
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const char *name=de->d_name.name;
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int length=de->d_name.len;
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struct inode *inode;
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struct CodaFid newfid;
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struct coda_vattr attrs;
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if (is_root_inode(dir) && coda_iscontrol(name, length))
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return -EPERM;
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error = venus_create(dir->i_sb, coda_i2f(dir), name, length,
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0, mode, &newfid, &attrs);
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if (error)
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goto err_out;
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inode = coda_iget(dir->i_sb, &newfid, &attrs);
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if (IS_ERR(inode)) {
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error = PTR_ERR(inode);
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goto err_out;
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}
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/* invalidate the directory cnode's attributes */
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coda_dir_update_mtime(dir);
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d_instantiate(de, inode);
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return 0;
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err_out:
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d_drop(de);
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return error;
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}
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static int coda_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
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struct dentry *de, umode_t mode)
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{
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struct inode *inode;
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struct coda_vattr attrs;
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const char *name = de->d_name.name;
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int len = de->d_name.len;
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int error;
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struct CodaFid newfid;
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if (is_root_inode(dir) && coda_iscontrol(name, len))
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return -EPERM;
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attrs.va_mode = mode;
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error = venus_mkdir(dir->i_sb, coda_i2f(dir),
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name, len, &newfid, &attrs);
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if (error)
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goto err_out;
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inode = coda_iget(dir->i_sb, &newfid, &attrs);
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if (IS_ERR(inode)) {
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error = PTR_ERR(inode);
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goto err_out;
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}
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/* invalidate the directory cnode's attributes */
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coda_dir_inc_nlink(dir);
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coda_dir_update_mtime(dir);
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d_instantiate(de, inode);
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return 0;
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err_out:
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d_drop(de);
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return error;
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}
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/* try to make de an entry in dir_inodde linked to source_de */
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static int coda_link(struct dentry *source_de, struct inode *dir_inode,
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struct dentry *de)
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{
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struct inode *inode = d_inode(source_de);
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const char * name = de->d_name.name;
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int len = de->d_name.len;
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int error;
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if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
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return -EPERM;
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error = venus_link(dir_inode->i_sb, coda_i2f(inode),
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coda_i2f(dir_inode), (const char *)name, len);
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if (error) {
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d_drop(de);
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return error;
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}
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coda_dir_update_mtime(dir_inode);
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ihold(inode);
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d_instantiate(de, inode);
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inc_nlink(inode);
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return 0;
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}
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static int coda_symlink(struct user_namespace *mnt_userns,
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struct inode *dir_inode, struct dentry *de,
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const char *symname)
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{
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const char *name = de->d_name.name;
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int len = de->d_name.len;
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int symlen;
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int error;
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if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
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return -EPERM;
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symlen = strlen(symname);
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if (symlen > CODA_MAXPATHLEN)
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return -ENAMETOOLONG;
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/*
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* This entry is now negative. Since we do not create
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* an inode for the entry we have to drop it.
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*/
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d_drop(de);
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error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len,
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symname, symlen);
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/* mtime is no good anymore */
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if (!error)
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coda_dir_update_mtime(dir_inode);
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return error;
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}
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/* destruction routines: unlink, rmdir */
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static int coda_unlink(struct inode *dir, struct dentry *de)
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{
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int error;
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const char *name = de->d_name.name;
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int len = de->d_name.len;
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error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);
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if (error)
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return error;
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coda_dir_update_mtime(dir);
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drop_nlink(d_inode(de));
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return 0;
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}
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static int coda_rmdir(struct inode *dir, struct dentry *de)
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{
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const char *name = de->d_name.name;
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int len = de->d_name.len;
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int error;
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error = venus_rmdir(dir->i_sb, coda_i2f(dir), name, len);
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if (!error) {
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/* VFS may delete the child */
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if (d_really_is_positive(de))
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clear_nlink(d_inode(de));
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/* fix the link count of the parent */
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coda_dir_drop_nlink(dir);
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coda_dir_update_mtime(dir);
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}
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return error;
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}
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/* rename */
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static int coda_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
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struct dentry *old_dentry, struct inode *new_dir,
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struct dentry *new_dentry, unsigned int flags)
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{
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const char *old_name = old_dentry->d_name.name;
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const char *new_name = new_dentry->d_name.name;
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int old_length = old_dentry->d_name.len;
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int new_length = new_dentry->d_name.len;
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int error;
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if (flags)
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return -EINVAL;
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error = venus_rename(old_dir->i_sb, coda_i2f(old_dir),
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coda_i2f(new_dir), old_length, new_length,
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(const char *) old_name, (const char *)new_name);
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if (!error) {
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if (d_really_is_positive(new_dentry)) {
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if (d_is_dir(new_dentry)) {
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coda_dir_drop_nlink(old_dir);
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coda_dir_inc_nlink(new_dir);
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}
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coda_dir_update_mtime(old_dir);
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coda_dir_update_mtime(new_dir);
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coda_flag_inode(d_inode(new_dentry), C_VATTR);
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} else {
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coda_flag_inode(old_dir, C_VATTR);
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coda_flag_inode(new_dir, C_VATTR);
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}
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}
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return error;
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}
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static inline unsigned int CDT2DT(unsigned char cdt)
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{
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unsigned int dt;
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switch(cdt) {
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case CDT_UNKNOWN: dt = DT_UNKNOWN; break;
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case CDT_FIFO: dt = DT_FIFO; break;
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case CDT_CHR: dt = DT_CHR; break;
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case CDT_DIR: dt = DT_DIR; break;
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case CDT_BLK: dt = DT_BLK; break;
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case CDT_REG: dt = DT_REG; break;
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case CDT_LNK: dt = DT_LNK; break;
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case CDT_SOCK: dt = DT_SOCK; break;
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case CDT_WHT: dt = DT_WHT; break;
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default: dt = DT_UNKNOWN; break;
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}
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return dt;
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}
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/* support routines */
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static int coda_venus_readdir(struct file *coda_file, struct dir_context *ctx)
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{
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struct coda_file_info *cfi;
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struct coda_inode_info *cii;
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struct file *host_file;
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struct venus_dirent *vdir;
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unsigned long vdir_size = offsetof(struct venus_dirent, d_name);
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unsigned int type;
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struct qstr name;
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ino_t ino;
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int ret;
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cfi = coda_ftoc(coda_file);
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host_file = cfi->cfi_container;
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cii = ITOC(file_inode(coda_file));
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vdir = kmalloc(sizeof(*vdir), GFP_KERNEL);
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if (!vdir) return -ENOMEM;
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if (!dir_emit_dots(coda_file, ctx))
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goto out;
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while (1) {
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loff_t pos = ctx->pos - 2;
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/* read entries from the directory file */
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ret = kernel_read(host_file, vdir, sizeof(*vdir), &pos);
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if (ret < 0) {
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pr_err("%s: read dir %s failed %d\n",
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__func__, coda_f2s(&cii->c_fid), ret);
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break;
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}
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if (ret == 0) break; /* end of directory file reached */
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/* catch truncated reads */
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if (ret < vdir_size || ret < vdir_size + vdir->d_namlen) {
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pr_err("%s: short read on %s\n",
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__func__, coda_f2s(&cii->c_fid));
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ret = -EBADF;
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break;
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}
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/* validate whether the directory file actually makes sense */
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if (vdir->d_reclen < vdir_size + vdir->d_namlen) {
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pr_err("%s: invalid dir %s\n",
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__func__, coda_f2s(&cii->c_fid));
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ret = -EBADF;
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break;
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}
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name.len = vdir->d_namlen;
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name.name = vdir->d_name;
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/* Make sure we skip '.' and '..', we already got those */
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if (name.name[0] == '.' && (name.len == 1 ||
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(name.name[1] == '.' && name.len == 2)))
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vdir->d_fileno = name.len = 0;
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/* skip null entries */
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if (vdir->d_fileno && name.len) {
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ino = vdir->d_fileno;
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type = CDT2DT(vdir->d_type);
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if (!dir_emit(ctx, name.name, name.len, ino, type))
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break;
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}
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/* we'll always have progress because d_reclen is unsigned and
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* we've already established it is non-zero. */
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ctx->pos += vdir->d_reclen;
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}
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out:
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kfree(vdir);
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return 0;
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}
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/* file operations for directories */
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static int coda_readdir(struct file *coda_file, struct dir_context *ctx)
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{
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struct coda_file_info *cfi;
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struct file *host_file;
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int ret;
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cfi = coda_ftoc(coda_file);
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host_file = cfi->cfi_container;
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if (host_file->f_op->iterate || host_file->f_op->iterate_shared) {
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struct inode *host_inode = file_inode(host_file);
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ret = -ENOENT;
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if (!IS_DEADDIR(host_inode)) {
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if (host_file->f_op->iterate_shared) {
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inode_lock_shared(host_inode);
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ret = host_file->f_op->iterate_shared(host_file, ctx);
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file_accessed(host_file);
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inode_unlock_shared(host_inode);
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} else {
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inode_lock(host_inode);
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ret = host_file->f_op->iterate(host_file, ctx);
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file_accessed(host_file);
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inode_unlock(host_inode);
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}
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}
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return ret;
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}
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/* Venus: we must read Venus dirents from a file */
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return coda_venus_readdir(coda_file, ctx);
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}
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/* called when a cache lookup succeeds */
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static int coda_dentry_revalidate(struct dentry *de, unsigned int flags)
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{
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struct inode *inode;
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struct coda_inode_info *cii;
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if (flags & LOOKUP_RCU)
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return -ECHILD;
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inode = d_inode(de);
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if (!inode || is_root_inode(inode))
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goto out;
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if (is_bad_inode(inode))
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goto bad;
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cii = ITOC(d_inode(de));
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if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
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goto out;
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shrink_dcache_parent(de);
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/* propagate for a flush */
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if (cii->c_flags & C_FLUSH)
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coda_flag_inode_children(inode, C_FLUSH);
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if (d_count(de) > 1)
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/* pretend it's valid, but don't change the flags */
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goto out;
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/* clear the flags. */
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spin_lock(&cii->c_lock);
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cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
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spin_unlock(&cii->c_lock);
|
|
bad:
|
|
return 0;
|
|
out:
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* This is the callback from dput() when d_count is going to 0.
|
|
* We use this to unhash dentries with bad inodes.
|
|
*/
|
|
static int coda_dentry_delete(const struct dentry * dentry)
|
|
{
|
|
int flags;
|
|
|
|
if (d_really_is_negative(dentry))
|
|
return 0;
|
|
|
|
flags = (ITOC(d_inode(dentry))->c_flags) & C_PURGE;
|
|
if (is_bad_inode(d_inode(dentry)) || flags) {
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
* This is called when we want to check if the inode has
|
|
* changed on the server. Coda makes this easy since the
|
|
* cache manager Venus issues a downcall to the kernel when this
|
|
* happens
|
|
*/
|
|
int coda_revalidate_inode(struct inode *inode)
|
|
{
|
|
struct coda_vattr attr;
|
|
int error;
|
|
int old_mode;
|
|
ino_t old_ino;
|
|
struct coda_inode_info *cii = ITOC(inode);
|
|
|
|
if (!cii->c_flags)
|
|
return 0;
|
|
|
|
if (cii->c_flags & (C_VATTR | C_PURGE | C_FLUSH)) {
|
|
error = venus_getattr(inode->i_sb, &(cii->c_fid), &attr);
|
|
if (error)
|
|
return -EIO;
|
|
|
|
/* this inode may be lost if:
|
|
- it's ino changed
|
|
- type changes must be permitted for repair and
|
|
missing mount points.
|
|
*/
|
|
old_mode = inode->i_mode;
|
|
old_ino = inode->i_ino;
|
|
coda_vattr_to_iattr(inode, &attr);
|
|
|
|
if ((old_mode & S_IFMT) != (inode->i_mode & S_IFMT)) {
|
|
pr_warn("inode %ld, fid %s changed type!\n",
|
|
inode->i_ino, coda_f2s(&(cii->c_fid)));
|
|
}
|
|
|
|
/* the following can happen when a local fid is replaced
|
|
with a global one, here we lose and declare the inode bad */
|
|
if (inode->i_ino != old_ino)
|
|
return -EIO;
|
|
|
|
coda_flag_inode_children(inode, C_FLUSH);
|
|
|
|
spin_lock(&cii->c_lock);
|
|
cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
|
|
spin_unlock(&cii->c_lock);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
const struct dentry_operations coda_dentry_operations = {
|
|
.d_revalidate = coda_dentry_revalidate,
|
|
.d_delete = coda_dentry_delete,
|
|
};
|
|
|
|
const struct inode_operations coda_dir_inode_operations = {
|
|
.create = coda_create,
|
|
.lookup = coda_lookup,
|
|
.link = coda_link,
|
|
.unlink = coda_unlink,
|
|
.symlink = coda_symlink,
|
|
.mkdir = coda_mkdir,
|
|
.rmdir = coda_rmdir,
|
|
.mknod = CODA_EIO_ERROR,
|
|
.rename = coda_rename,
|
|
.permission = coda_permission,
|
|
.getattr = coda_getattr,
|
|
.setattr = coda_setattr,
|
|
};
|
|
|
|
const struct file_operations coda_dir_operations = {
|
|
.llseek = generic_file_llseek,
|
|
.read = generic_read_dir,
|
|
.iterate = coda_readdir,
|
|
.open = coda_open,
|
|
.release = coda_release,
|
|
.fsync = coda_fsync,
|
|
};
|