linux/fs/reiserfs/xattr_acl.c
Jeff Mahoney 0ab2621ebd reiserfs: journaled xattrs
Deadlocks are possible in the xattr code between the journal lock and the
xattr sems.

This patch implements journalling for xattr operations. The benefit is
twofold:
 * It gets rid of the deadlock possibility by always ensuring that xattr
   write operations are initiated inside a transaction.
 * It corrects the problem where xattr backing files aren't considered any
   differently than normal files, despite the fact they are metadata.

I discussed the added journal load with Chris Mason, and we decided that
since xattrs (versus other journal activity) is fairly rare, the introduction
of larger transactions to support journaled xattrs wouldn't be too big a deal.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-03-30 12:16:38 -07:00

594 lines
14 KiB
C

#include <linux/capability.h>
#include <linux/fs.h>
#include <linux/posix_acl.h>
#include <linux/reiserfs_fs.h>
#include <linux/errno.h>
#include <linux/pagemap.h>
#include <linux/xattr.h>
#include <linux/posix_acl_xattr.h>
#include <linux/reiserfs_xattr.h>
#include <linux/reiserfs_acl.h>
#include <asm/uaccess.h>
static int reiserfs_set_acl(struct reiserfs_transaction_handle *th,
struct inode *inode, int type,
struct posix_acl *acl);
static int
xattr_set_acl(struct inode *inode, int type, const void *value, size_t size)
{
struct posix_acl *acl;
int error, error2;
struct reiserfs_transaction_handle th;
size_t jcreate_blocks;
if (!reiserfs_posixacl(inode->i_sb))
return -EOPNOTSUPP;
if (!is_owner_or_cap(inode))
return -EPERM;
if (value) {
acl = posix_acl_from_xattr(value, size);
if (IS_ERR(acl)) {
return PTR_ERR(acl);
} else if (acl) {
error = posix_acl_valid(acl);
if (error)
goto release_and_out;
}
} else
acl = NULL;
/* Pessimism: We can't assume that anything from the xattr root up
* has been created. */
jcreate_blocks = reiserfs_xattr_jcreate_nblocks(inode) +
reiserfs_xattr_nblocks(inode, size) * 2;
reiserfs_write_lock(inode->i_sb);
error = journal_begin(&th, inode->i_sb, jcreate_blocks);
if (error == 0) {
error = reiserfs_set_acl(&th, inode, type, acl);
error2 = journal_end(&th, inode->i_sb, jcreate_blocks);
if (error2)
error = error2;
}
reiserfs_write_unlock(inode->i_sb);
release_and_out:
posix_acl_release(acl);
return error;
}
static int
xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
{
struct posix_acl *acl;
int error;
if (!reiserfs_posixacl(inode->i_sb))
return -EOPNOTSUPP;
acl = reiserfs_get_acl(inode, type);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (acl == NULL)
return -ENODATA;
error = posix_acl_to_xattr(acl, buffer, size);
posix_acl_release(acl);
return error;
}
/*
* Convert from filesystem to in-memory representation.
*/
static struct posix_acl *posix_acl_from_disk(const void *value, size_t size)
{
const char *end = (char *)value + size;
int n, count;
struct posix_acl *acl;
if (!value)
return NULL;
if (size < sizeof(reiserfs_acl_header))
return ERR_PTR(-EINVAL);
if (((reiserfs_acl_header *) value)->a_version !=
cpu_to_le32(REISERFS_ACL_VERSION))
return ERR_PTR(-EINVAL);
value = (char *)value + sizeof(reiserfs_acl_header);
count = reiserfs_acl_count(size);
if (count < 0)
return ERR_PTR(-EINVAL);
if (count == 0)
return NULL;
acl = posix_acl_alloc(count, GFP_NOFS);
if (!acl)
return ERR_PTR(-ENOMEM);
for (n = 0; n < count; n++) {
reiserfs_acl_entry *entry = (reiserfs_acl_entry *) value;
if ((char *)value + sizeof(reiserfs_acl_entry_short) > end)
goto fail;
acl->a_entries[n].e_tag = le16_to_cpu(entry->e_tag);
acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
switch (acl->a_entries[n].e_tag) {
case ACL_USER_OBJ:
case ACL_GROUP_OBJ:
case ACL_MASK:
case ACL_OTHER:
value = (char *)value +
sizeof(reiserfs_acl_entry_short);
acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
break;
case ACL_USER:
case ACL_GROUP:
value = (char *)value + sizeof(reiserfs_acl_entry);
if ((char *)value > end)
goto fail;
acl->a_entries[n].e_id = le32_to_cpu(entry->e_id);
break;
default:
goto fail;
}
}
if (value != end)
goto fail;
return acl;
fail:
posix_acl_release(acl);
return ERR_PTR(-EINVAL);
}
/*
* Convert from in-memory to filesystem representation.
*/
static void *posix_acl_to_disk(const struct posix_acl *acl, size_t * size)
{
reiserfs_acl_header *ext_acl;
char *e;
int n;
*size = reiserfs_acl_size(acl->a_count);
ext_acl = kmalloc(sizeof(reiserfs_acl_header) +
acl->a_count *
sizeof(reiserfs_acl_entry),
GFP_NOFS);
if (!ext_acl)
return ERR_PTR(-ENOMEM);
ext_acl->a_version = cpu_to_le32(REISERFS_ACL_VERSION);
e = (char *)ext_acl + sizeof(reiserfs_acl_header);
for (n = 0; n < acl->a_count; n++) {
reiserfs_acl_entry *entry = (reiserfs_acl_entry *) e;
entry->e_tag = cpu_to_le16(acl->a_entries[n].e_tag);
entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
switch (acl->a_entries[n].e_tag) {
case ACL_USER:
case ACL_GROUP:
entry->e_id = cpu_to_le32(acl->a_entries[n].e_id);
e += sizeof(reiserfs_acl_entry);
break;
case ACL_USER_OBJ:
case ACL_GROUP_OBJ:
case ACL_MASK:
case ACL_OTHER:
e += sizeof(reiserfs_acl_entry_short);
break;
default:
goto fail;
}
}
return (char *)ext_acl;
fail:
kfree(ext_acl);
return ERR_PTR(-EINVAL);
}
static inline void iset_acl(struct inode *inode, struct posix_acl **i_acl,
struct posix_acl *acl)
{
spin_lock(&inode->i_lock);
if (*i_acl != ERR_PTR(-ENODATA))
posix_acl_release(*i_acl);
*i_acl = posix_acl_dup(acl);
spin_unlock(&inode->i_lock);
}
static inline struct posix_acl *iget_acl(struct inode *inode,
struct posix_acl **i_acl)
{
struct posix_acl *acl = ERR_PTR(-ENODATA);
spin_lock(&inode->i_lock);
if (*i_acl != ERR_PTR(-ENODATA))
acl = posix_acl_dup(*i_acl);
spin_unlock(&inode->i_lock);
return acl;
}
/*
* Inode operation get_posix_acl().
*
* inode->i_mutex: down
* BKL held [before 2.5.x]
*/
struct posix_acl *reiserfs_get_acl(struct inode *inode, int type)
{
char *name, *value;
struct posix_acl *acl, **p_acl;
int size;
int retval;
struct reiserfs_inode_info *reiserfs_i = REISERFS_I(inode);
switch (type) {
case ACL_TYPE_ACCESS:
name = POSIX_ACL_XATTR_ACCESS;
p_acl = &reiserfs_i->i_acl_access;
break;
case ACL_TYPE_DEFAULT:
name = POSIX_ACL_XATTR_DEFAULT;
p_acl = &reiserfs_i->i_acl_default;
break;
default:
return ERR_PTR(-EINVAL);
}
acl = iget_acl(inode, p_acl);
if (acl && !IS_ERR(acl))
return acl;
else if (PTR_ERR(acl) == -ENODATA)
return NULL;
size = reiserfs_xattr_get(inode, name, NULL, 0);
if (size < 0) {
if (size == -ENODATA || size == -ENOSYS) {
*p_acl = ERR_PTR(-ENODATA);
return NULL;
}
return ERR_PTR(size);
}
value = kmalloc(size, GFP_NOFS);
if (!value)
return ERR_PTR(-ENOMEM);
retval = reiserfs_xattr_get(inode, name, value, size);
if (retval == -ENODATA || retval == -ENOSYS) {
/* This shouldn't actually happen as it should have
been caught above.. but just in case */
acl = NULL;
*p_acl = ERR_PTR(-ENODATA);
} else if (retval < 0) {
acl = ERR_PTR(retval);
} else {
acl = posix_acl_from_disk(value, retval);
if (!IS_ERR(acl))
iset_acl(inode, p_acl, acl);
}
kfree(value);
return acl;
}
/*
* Inode operation set_posix_acl().
*
* inode->i_mutex: down
* BKL held [before 2.5.x]
*/
static int
reiserfs_set_acl(struct reiserfs_transaction_handle *th, struct inode *inode,
int type, struct posix_acl *acl)
{
char *name;
void *value = NULL;
struct posix_acl **p_acl;
size_t size = 0;
int error;
struct reiserfs_inode_info *reiserfs_i = REISERFS_I(inode);
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
switch (type) {
case ACL_TYPE_ACCESS:
name = POSIX_ACL_XATTR_ACCESS;
p_acl = &reiserfs_i->i_acl_access;
if (acl) {
mode_t mode = inode->i_mode;
error = posix_acl_equiv_mode(acl, &mode);
if (error < 0)
return error;
else {
inode->i_mode = mode;
if (error == 0)
acl = NULL;
}
}
break;
case ACL_TYPE_DEFAULT:
name = POSIX_ACL_XATTR_DEFAULT;
p_acl = &reiserfs_i->i_acl_default;
if (!S_ISDIR(inode->i_mode))
return acl ? -EACCES : 0;
break;
default:
return -EINVAL;
}
if (acl) {
value = posix_acl_to_disk(acl, &size);
if (IS_ERR(value))
return (int)PTR_ERR(value);
}
error = reiserfs_xattr_set_handle(th, inode, name, value, size, 0);
/*
* Ensure that the inode gets dirtied if we're only using
* the mode bits and an old ACL didn't exist. We don't need
* to check if the inode is hashed here since we won't get
* called by reiserfs_inherit_default_acl().
*/
if (error == -ENODATA) {
error = 0;
if (type == ACL_TYPE_ACCESS) {
inode->i_ctime = CURRENT_TIME_SEC;
mark_inode_dirty(inode);
}
}
kfree(value);
if (!error)
iset_acl(inode, p_acl, acl);
return error;
}
/* dir->i_mutex: locked,
* inode is new and not released into the wild yet */
int
reiserfs_inherit_default_acl(struct reiserfs_transaction_handle *th,
struct inode *dir, struct dentry *dentry,
struct inode *inode)
{
struct posix_acl *acl;
int err = 0;
/* ACLs only get applied to files and directories */
if (S_ISLNK(inode->i_mode))
return 0;
/* ACLs can only be used on "new" objects, so if it's an old object
* there is nothing to inherit from */
if (get_inode_sd_version(dir) == STAT_DATA_V1)
goto apply_umask;
/* Don't apply ACLs to objects in the .reiserfs_priv tree.. This
* would be useless since permissions are ignored, and a pain because
* it introduces locking cycles */
if (IS_PRIVATE(dir)) {
inode->i_flags |= S_PRIVATE;
goto apply_umask;
}
acl = reiserfs_get_acl(dir, ACL_TYPE_DEFAULT);
if (IS_ERR(acl)) {
if (PTR_ERR(acl) == -ENODATA)
goto apply_umask;
return PTR_ERR(acl);
}
if (acl) {
struct posix_acl *acl_copy;
mode_t mode = inode->i_mode;
int need_acl;
/* Copy the default ACL to the default ACL of a new directory */
if (S_ISDIR(inode->i_mode)) {
err = reiserfs_set_acl(th, inode, ACL_TYPE_DEFAULT,
acl);
if (err)
goto cleanup;
}
/* Now we reconcile the new ACL and the mode,
potentially modifying both */
acl_copy = posix_acl_clone(acl, GFP_NOFS);
if (!acl_copy) {
err = -ENOMEM;
goto cleanup;
}
need_acl = posix_acl_create_masq(acl_copy, &mode);
if (need_acl >= 0) {
if (mode != inode->i_mode) {
inode->i_mode = mode;
}
/* If we need an ACL.. */
if (need_acl > 0) {
err = reiserfs_set_acl(th, inode,
ACL_TYPE_ACCESS,
acl_copy);
if (err)
goto cleanup_copy;
}
}
cleanup_copy:
posix_acl_release(acl_copy);
cleanup:
posix_acl_release(acl);
} else {
apply_umask:
/* no ACL, apply umask */
inode->i_mode &= ~current->fs->umask;
}
return err;
}
/* This is used to cache the default acl before a new object is created.
* The biggest reason for this is to get an idea of how many blocks will
* actually be required for the create operation if we must inherit an ACL.
* An ACL write can add up to 3 object creations and an additional file write
* so we'd prefer not to reserve that many blocks in the journal if we can.
* It also has the advantage of not loading the ACL with a transaction open,
* this may seem silly, but if the owner of the directory is doing the
* creation, the ACL may not be loaded since the permissions wouldn't require
* it.
* We return the number of blocks required for the transaction.
*/
int reiserfs_cache_default_acl(struct inode *inode)
{
struct posix_acl *acl;
int nblocks = 0;
if (IS_PRIVATE(inode))
return 0;
acl = reiserfs_get_acl(inode, ACL_TYPE_DEFAULT);
if (acl && !IS_ERR(acl)) {
int size = reiserfs_acl_size(acl->a_count);
/* Other xattrs can be created during inode creation. We don't
* want to claim too many blocks, so we check to see if we
* we need to create the tree to the xattrs, and then we
* just want two files. */
nblocks = reiserfs_xattr_jcreate_nblocks(inode);
nblocks += JOURNAL_BLOCKS_PER_OBJECT(inode->i_sb);
REISERFS_I(inode)->i_flags |= i_has_xattr_dir;
/* We need to account for writes + bitmaps for two files */
nblocks += reiserfs_xattr_nblocks(inode, size) * 4;
posix_acl_release(acl);
}
return nblocks;
}
int reiserfs_acl_chmod(struct inode *inode)
{
struct posix_acl *acl, *clone;
int error;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
if (get_inode_sd_version(inode) == STAT_DATA_V1 ||
!reiserfs_posixacl(inode->i_sb)) {
return 0;
}
acl = reiserfs_get_acl(inode, ACL_TYPE_ACCESS);
if (!acl)
return 0;
if (IS_ERR(acl))
return PTR_ERR(acl);
clone = posix_acl_clone(acl, GFP_NOFS);
posix_acl_release(acl);
if (!clone)
return -ENOMEM;
error = posix_acl_chmod_masq(clone, inode->i_mode);
if (!error) {
struct reiserfs_transaction_handle th;
size_t size = reiserfs_xattr_nblocks(inode,
reiserfs_acl_size(clone->a_count));
reiserfs_write_lock(inode->i_sb);
error = journal_begin(&th, inode->i_sb, size * 2);
if (!error) {
int error2;
error = reiserfs_set_acl(&th, inode, ACL_TYPE_ACCESS,
clone);
error2 = journal_end(&th, inode->i_sb, size * 2);
if (error2)
error = error2;
}
reiserfs_write_unlock(inode->i_sb);
}
posix_acl_release(clone);
return error;
}
static int
posix_acl_access_get(struct inode *inode, const char *name,
void *buffer, size_t size)
{
if (strlen(name) != sizeof(POSIX_ACL_XATTR_ACCESS) - 1)
return -EINVAL;
return xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
}
static int
posix_acl_access_set(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
if (strlen(name) != sizeof(POSIX_ACL_XATTR_ACCESS) - 1)
return -EINVAL;
return xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
}
static size_t posix_acl_access_list(struct inode *inode, char *list,
size_t list_size, const char *name,
size_t name_len)
{
const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
if (!reiserfs_posixacl(inode->i_sb))
return 0;
if (list && size <= list_size)
memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
return size;
}
struct xattr_handler reiserfs_posix_acl_access_handler = {
.prefix = POSIX_ACL_XATTR_ACCESS,
.get = posix_acl_access_get,
.set = posix_acl_access_set,
.list = posix_acl_access_list,
};
static int
posix_acl_default_get(struct inode *inode, const char *name,
void *buffer, size_t size)
{
if (strlen(name) != sizeof(POSIX_ACL_XATTR_DEFAULT) - 1)
return -EINVAL;
return xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
}
static int
posix_acl_default_set(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
if (strlen(name) != sizeof(POSIX_ACL_XATTR_DEFAULT) - 1)
return -EINVAL;
return xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
}
static size_t posix_acl_default_list(struct inode *inode, char *list,
size_t list_size, const char *name,
size_t name_len)
{
const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
if (!reiserfs_posixacl(inode->i_sb))
return 0;
if (list && size <= list_size)
memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
return size;
}
struct xattr_handler reiserfs_posix_acl_default_handler = {
.prefix = POSIX_ACL_XATTR_DEFAULT,
.get = posix_acl_default_get,
.set = posix_acl_default_set,
.list = posix_acl_default_list,
};