- 根目录:
- fs
- coda
- dir.c
/*
* Directory operations for Coda filesystem
* Original version: (C) 1996 P. Braam and M. Callahan
* Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University
*
* Carnegie Mellon encourages users to contribute improvements to
* the Coda project. Contact Peter Braam (coda@cs.cmu.edu).
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/namei.h>
#include <linux/uaccess.h>
#include <linux/coda.h>
#include <linux/coda_psdev.h>
#include "coda_linux.h"
#include "coda_cache.h"
#include "coda_int.h"
/* same as fs/bad_inode.c */
static int coda_return_EIO(void)
{
return -EIO;
}
#define CODA_EIO_ERROR ((void *) (coda_return_EIO))
/* inode operations for directories */
/* access routines: lookup, readlink, permission */
static struct dentry *coda_lookup(struct inode *dir, struct dentry *entry, unsigned int flags)
{
struct super_block *sb = dir->i_sb;
const char *name = entry->d_name.name;
size_t length = entry->d_name.len;
struct inode *inode;
int type = 0;
if (length > CODA_MAXNAMLEN) {
pr_err("name too long: lookup, %s (%*s)\n",
coda_i2s(dir), (int)length, name);
return ERR_PTR(-ENAMETOOLONG);
}
/* control object, create inode on the fly */
if (is_root_inode(dir) && coda_iscontrol(name, length)) {
inode = coda_cnode_makectl(sb);
type = CODA_NOCACHE;
} else {
struct CodaFid fid = { { 0, } };
int error = venus_lookup(sb, coda_i2f(dir), name, length,
&type, &fid);
inode = !error ? coda_cnode_make(&fid, sb) : ERR_PTR(error);
}
if (!IS_ERR(inode) && (type & CODA_NOCACHE))
coda_flag_inode(inode, C_VATTR | C_PURGE);
if (inode == ERR_PTR(-ENOENT))
inode = NULL;
return d_splice_alias(inode, entry);
}
int coda_permission(struct inode *inode, int mask)
{
int error;
if (mask & MAY_NOT_BLOCK)
return -ECHILD;
mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
if (!mask)
return 0;
if ((mask & MAY_EXEC) && !execute_ok(inode))
return -EACCES;
if (coda_cache_check(inode, mask))
return 0;
error = venus_access(inode->i_sb, coda_i2f(inode), mask);
if (!error)
coda_cache_enter(inode, mask);
return error;
}
static inline void coda_dir_update_mtime(struct inode *dir)
{
#ifdef REQUERY_VENUS_FOR_MTIME
/* invalidate the directory cnode's attributes so we refetch the
* attributes from venus next time the inode is referenced */
coda_flag_inode(dir, C_VATTR);
#else
/* optimistically we can also act as if our nose bleeds. The
* granularity of the mtime is coarse anyways so we might actually be
* right most of the time. Note: we only do this for directories. */
dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
#endif
}
/* we have to wrap inc_nlink/drop_nlink because sometimes userspace uses a
* trick to fool GNU find's optimizations. If we can't be sure of the link
* (because of volume mount points) we set i_nlink to 1 which forces find
* to consider every child as a possible directory. We should also never
* see an increment or decrement for deleted directories where i_nlink == 0 */
static inline void coda_dir_inc_nlink(struct inode *dir)
{
if (dir->i_nlink >= 2)
inc_nlink(dir);
}
static inline void coda_dir_drop_nlink(struct inode *dir)
{
if (dir->i_nlink > 2)
drop_nlink(dir);
}
/* creation routines: create, mknod, mkdir, link, symlink */
static int coda_create(struct inode *dir, struct dentry *de, umode_t mode, bool excl)
{
int error;
const char *name=de->d_name.name;
int length=de->d_name.len;
struct inode *inode;
struct CodaFid newfid;
struct coda_vattr attrs;
if (is_root_inode(dir) && coda_iscontrol(name, length))
return -EPERM;
error = venus_create(dir->i_sb, coda_i2f(dir), name, length,
0, mode, &newfid, &attrs);
if (error)
goto err_out;
inode = coda_iget(dir->i_sb, &newfid, &attrs);
if (IS_ERR(inode)) {
error = PTR_ERR(inode);
goto err_out;
}
/* invalidate the directory cnode's attributes */
coda_dir_update_mtime(dir);
d_instantiate(de, inode);
return 0;
err_out:
d_drop(de);
return error;
}
static int coda_mkdir(struct inode *dir, struct dentry *de, umode_t mode)
{
struct inode *inode;
struct coda_vattr attrs;
const char *name = de->d_name.name;
int len = de->d_name.len;
int error;
struct CodaFid newfid;
if (is_root_inode(dir) && coda_iscontrol(name, len))
return -EPERM;
attrs.va_mode = mode;
error = venus_mkdir(dir->i_sb, coda_i2f(dir),
name, len, &newfid, &attrs);
if (error)
goto err_out;
inode = coda_iget(dir->i_sb, &newfid, &attrs);
if (IS_ERR(inode)) {
error = PTR_ERR(inode);
goto err_out;
}
/* invalidate the directory cnode's attributes */
coda_dir_inc_nlink(dir);
coda_dir_update_mtime(dir);
d_instantiate(de, inode);
return 0;
err_out:
d_drop(de);
return error;
}
/* try to make de an entry in dir_inodde linked to source_de */
static int coda_link(struct dentry *source_de, struct inode *dir_inode,
struct dentry *de)
{
struct inode *inode = d_inode(source_de);
const char * name = de->d_name.name;
int len = de->d_name.len;
int error;
if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
return -EPERM;
error = venus_link(dir_inode->i_sb, coda_i2f(inode),
coda_i2f(dir_inode), (const char *)name, len);
if (error) {
d_drop(de);
return error;
}
coda_dir_update_mtime(dir_inode);
ihold(inode);
d_instantiate(de, inode);
inc_nlink(inode);
return 0;
}
static int coda_symlink(struct inode *dir_inode, struct dentry *de,
const char *symname)
{
const char *name = de->d_name.name;
int len = de->d_name.len;
int symlen;
int error;
if (is_root_inode(dir_inode) && coda_iscontrol(name, len))
return -EPERM;
symlen = strlen(symname);
if (symlen > CODA_MAXPATHLEN)
return -ENAMETOOLONG;
/*
* This entry is now negative. Since we do not create
* an inode for the entry we have to drop it.
*/
d_drop(de);
error = venus_symlink(dir_inode->i_sb, coda_i2f(dir_inode), name, len,
symname, symlen);
/* mtime is no good anymore */
if (!error)
coda_dir_update_mtime(dir_inode);
return error;
}
/* destruction routines: unlink, rmdir */
static int coda_unlink(struct inode *dir, struct dentry *de)
{
int error;
const char *name = de->d_name.name;
int len = de->d_name.len;
error = venus_remove(dir->i_sb, coda_i2f(dir), name, len);
if (error)
return error;
coda_dir_update_mtime(dir);
drop_nlink(d_inode(de));
return 0;
}
static int coda_rmdir(struct inode *dir, struct dentry *de)
{
const char *name = de->d_name.name;
int len = de->d_name.len;
int error;
error = venus_rmdir(dir->i_sb, coda_i2f(dir), name, len);
if (!error) {
/* VFS may delete the child */
if (d_really_is_positive(de))
clear_nlink(d_inode(de));
/* fix the link count of the parent */
coda_dir_drop_nlink(dir);
coda_dir_update_mtime(dir);
}
return error;
}
/* rename */
static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
const char *old_name = old_dentry->d_name.name;
const char *new_name = new_dentry->d_name.name;
int old_length = old_dentry->d_name.len;
int new_length = new_dentry->d_name.len;
int error;
error = venus_rename(old_dir->i_sb, coda_i2f(old_dir),
coda_i2f(new_dir), old_length, new_length,
(const char *) old_name, (const char *)new_name);
if (!error) {
if (d_really_is_positive(new_dentry)) {
if (d_is_dir(new_dentry)) {
coda_dir_drop_nlink(old_dir);
coda_dir_inc_nlink(new_dir);
}
coda_dir_update_mtime(old_dir);
coda_dir_update_mtime(new_dir);
coda_flag_inode(d_inode(new_dentry), C_VATTR);
} else {
coda_flag_inode(old_dir, C_VATTR);
coda_flag_inode(new_dir, C_VATTR);
}
}
return error;
}
static inline unsigned int CDT2DT(unsigned char cdt)
{
unsigned int dt;
switch(cdt) {
case CDT_UNKNOWN: dt = DT_UNKNOWN; break;
case CDT_FIFO: dt = DT_FIFO; break;
case CDT_CHR: dt = DT_CHR; break;
case CDT_DIR: dt = DT_DIR; break;
case CDT_BLK: dt = DT_BLK; break;
case CDT_REG: dt = DT_REG; break;
case CDT_LNK: dt = DT_LNK; break;
case CDT_SOCK: dt = DT_SOCK; break;
case CDT_WHT: dt = DT_WHT; break;
default: dt = DT_UNKNOWN; break;
}
return dt;
}
/* support routines */
static int coda_venus_readdir(struct file *coda_file, struct dir_context *ctx)
{
struct coda_file_info *cfi;
struct coda_inode_info *cii;
struct file *host_file;
struct venus_dirent *vdir;
unsigned long vdir_size = offsetof(struct venus_dirent, d_name);
unsigned int type;
struct qstr name;
ino_t ino;
int ret;
cfi = CODA_FTOC(coda_file);
BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
host_file = cfi->cfi_container;
cii = ITOC(file_inode(coda_file));
vdir = kmalloc(sizeof(*vdir), GFP_KERNEL);
if (!vdir) return -ENOMEM;
if (!dir_emit_dots(coda_file, ctx))
goto out;
while (1) {
/* read entries from the directory file */
ret = kernel_read(host_file, ctx->pos - 2, (char *)vdir,
sizeof(*vdir));
if (ret < 0) {
pr_err("%s: read dir %s failed %d\n",
__func__, coda_f2s(&cii->c_fid), ret);
break;
}
if (ret == 0) break; /* end of directory file reached */
/* catch truncated reads */
if (ret < vdir_size || ret < vdir_size + vdir->d_namlen) {
pr_err("%s: short read on %s\n",
__func__, coda_f2s(&cii->c_fid));
ret = -EBADF;
break;
}
/* validate whether the directory file actually makes sense */
if (vdir->d_reclen < vdir_size + vdir->d_namlen) {
pr_err("%s: invalid dir %s\n",
__func__, coda_f2s(&cii->c_fid));
ret = -EBADF;
break;
}
name.len = vdir->d_namlen;
name.name = vdir->d_name;
/* Make sure we skip '.' and '..', we already got those */
if (name.name[0] == '.' && (name.len == 1 ||
(name.name[1] == '.' && name.len == 2)))
vdir->d_fileno = name.len = 0;
/* skip null entries */
if (vdir->d_fileno && name.len) {
ino = vdir->d_fileno;
type = CDT2DT(vdir->d_type);
if (!dir_emit(ctx, name.name, name.len, ino, type))
break;
}
/* we'll always have progress because d_reclen is unsigned and
* we've already established it is non-zero. */
ctx->pos += vdir->d_reclen;
}
out:
kfree(vdir);
return 0;
}
/* file operations for directories */
static int coda_readdir(struct file *coda_file, struct dir_context *ctx)
{
struct coda_file_info *cfi;
struct file *host_file;
int ret;
cfi = CODA_FTOC(coda_file);
BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
host_file = cfi->cfi_container;
if (host_file->f_op->iterate) {
struct inode *host_inode = file_inode(host_file);
mutex_lock(&host_inode->i_mutex);
ret = -ENOENT;
if (!IS_DEADDIR(host_inode)) {
ret = host_file->f_op->iterate(host_file, ctx);
file_accessed(host_file);
}
mutex_unlock(&host_inode->i_mutex);
return ret;
}
/* Venus: we must read Venus dirents from a file */
return coda_venus_readdir(coda_file, ctx);
}
/* called when a cache lookup succeeds */
static int coda_dentry_revalidate(struct dentry *de, unsigned int flags)
{
struct inode *inode;
struct coda_inode_info *cii;
if (flags & LOOKUP_RCU)
return -ECHILD;
inode = d_inode(de);
if (!inode || is_root_inode(inode))
goto out;
if (is_bad_inode(inode))
goto bad;
cii = ITOC(d_inode(de));
if (!(cii->c_flags & (C_PURGE | C_FLUSH)))
goto out;
shrink_dcache_parent(de);
/* propagate for a flush */
if (cii->c_flags & C_FLUSH)
coda_flag_inode_children(inode, C_FLUSH);
if (d_count(de) > 1)
/* pretend it's valid, but don't change the flags */
goto out;
/* clear the flags. */
spin_lock(&cii->c_lock);
cii->c_flags &= ~(C_VATTR | C_PURGE | C_FLUSH);
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,
};