linux/fs/coda/dir.c
Linus Torvalds 615e95831e v6.6-vfs.ctime
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Merge tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs timestamp updates from Christian Brauner:
 "This adds VFS support for multi-grain timestamps and converts tmpfs,
  xfs, ext4, and btrfs to use them. This carries acks from all relevant
  filesystems.

  The VFS always uses coarse-grained timestamps when updating the ctime
  and mtime after a change. This has the benefit of allowing filesystems
  to optimize away a lot of metadata updates, down to around 1 per
  jiffy, even when a file is under heavy writes.

  Unfortunately, this has always been an issue when we're exporting via
  NFSv3, which relies on timestamps to validate caches. A lot of changes
  can happen in a jiffy, so timestamps aren't sufficient to help the
  client decide to invalidate the cache.

  Even with NFSv4, a lot of exported filesystems don't properly support
  a change attribute and are subject to the same problems with timestamp
  granularity. Other applications have similar issues with timestamps
  (e.g., backup applications).

  If we were to always use fine-grained timestamps, that would improve
  the situation, but that becomes rather expensive, as the underlying
  filesystem would have to log a lot more metadata updates.

  This introduces fine-grained timestamps that are used when they are
  actively queried.

  This uses the 31st bit of the ctime tv_nsec field to indicate that
  something has queried the inode for the mtime or ctime. When this flag
  is set, on the next mtime or ctime update, the kernel will fetch a
  fine-grained timestamp instead of the usual coarse-grained one.

  As POSIX generally mandates that when the mtime changes, the ctime
  must also change the kernel always stores normalized ctime values, so
  only the first 30 bits of the tv_nsec field are ever used.

  Filesytems can opt into this behavior by setting the FS_MGTIME flag in
  the fstype. Filesystems that don't set this flag will continue to use
  coarse-grained timestamps.

  Various preparatory changes, fixes and cleanups are included:

   - Fixup all relevant places where POSIX requires updating ctime
     together with mtime. This is a wide-range of places and all
     maintainers provided necessary Acks.

   - Add new accessors for inode->i_ctime directly and change all
     callers to rely on them. Plain accesses to inode->i_ctime are now
     gone and it is accordingly rename to inode->__i_ctime and commented
     as requiring accessors.

   - Extend generic_fillattr() to pass in a request mask mirroring in a
     sense the statx() uapi. This allows callers to pass in a request
     mask to only get a subset of attributes filled in.

   - Rework timestamp updates so it's possible to drop the @now
     parameter the update_time() inode operation and associated helpers.

   - Add inode_update_timestamps() and convert all filesystems to it
     removing a bunch of open-coding"

* tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (107 commits)
  btrfs: convert to multigrain timestamps
  ext4: switch to multigrain timestamps
  xfs: switch to multigrain timestamps
  tmpfs: add support for multigrain timestamps
  fs: add infrastructure for multigrain timestamps
  fs: drop the timespec64 argument from update_time
  xfs: have xfs_vn_update_time gets its own timestamp
  fat: make fat_update_time get its own timestamp
  fat: remove i_version handling from fat_update_time
  ubifs: have ubifs_update_time use inode_update_timestamps
  btrfs: have it use inode_update_timestamps
  fs: drop the timespec64 arg from generic_update_time
  fs: pass the request_mask to generic_fillattr
  fs: remove silly warning from current_time
  gfs2: fix timestamp handling on quota inodes
  fs: rename i_ctime field to __i_ctime
  selinux: convert to ctime accessor functions
  security: convert to ctime accessor functions
  apparmor: convert to ctime accessor functions
  sunrpc: convert to ctime accessor functions
  ...
2023-08-28 09:31:32 -07:00

590 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* 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 "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 %zu\n",
coda_i2s(dir), length);
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 mnt_idmap *idmap, 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 = inode_set_ctime_current(dir);
#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 mnt_idmap *idmap, 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 mnt_idmap *idmap, 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 mnt_idmap *idmap,
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 mnt_idmap *idmap, struct inode *old_dir,
struct dentry *old_dentry, struct inode *new_dir,
struct dentry *new_dentry, unsigned int flags)
{
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;
if (flags)
return -EINVAL;
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_flag_inode(d_inode(new_dentry), C_VATTR);
}
coda_dir_update_mtime(old_dir);
coda_dir_update_mtime(new_dir);
}
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);
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) {
loff_t pos = ctx->pos - 2;
/* read entries from the directory file */
ret = kernel_read(host_file, vdir, sizeof(*vdir), &pos);
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);
host_file = cfi->cfi_container;
if (host_file->f_op->iterate_shared) {
struct inode *host_inode = file_inode(host_file);
ret = -ENOENT;
if (!IS_DEADDIR(host_inode)) {
inode_lock_shared(host_inode);
ret = host_file->f_op->iterate_shared(host_file, ctx);
file_accessed(host_file);
inode_unlock_shared(host_inode);
}
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)
{
struct inode *inode;
struct coda_inode_info *cii;
if (d_really_is_negative(dentry))
return 0;
inode = d_inode(dentry);
if (!inode || is_bad_inode(inode))
return 1;
cii = ITOC(inode);
if (cii->c_flags & C_PURGE)
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,
};
WRAP_DIR_ITER(coda_readdir) // FIXME!
const struct file_operations coda_dir_operations = {
.llseek = generic_file_llseek,
.read = generic_read_dir,
.iterate_shared = shared_coda_readdir,
.open = coda_open,
.release = coda_release,
.fsync = coda_fsync,
};