Re: [PATCH 09/18] f2fs: use generic posix ACL infrastructure

Christoph Hellwig
2013-12-08T09:15:20Z

On Fri, Dec 06, 2013 at 10:37:34AM +0900, Jaegeuk Kim wrote:
> f2fs caches a new mode bit for a while to make the consistency between
> xattr's acl mode and the inode mode.

Can you explain what exactly you're trying to do there? I've been
trying to unwrap what's going on and can't really see the point:

- i_acl_mode and FI_ACL_MODE get set in __setattr_copy, but right
after that call, still under i_mutex and before marking the inode
dirty f2fs_acl_chmod makes use of it, and it gets cleared right
after. Is there any race that could happen with a locked inode
not marked dirty yet on f2fs? We could pass a mode argument
to posix_acl_create, but I'd prefer to avoid that if we can.
- on the set_acl side it gets set in __f2fs_set_acl, and then
i_mode is update in __f2fs_setxattr which could easily done with
a stack variable.

RFC patch below:

diff --git a/fs/f2fs/acl.c b/fs/f2fs/acl.c
index 4f52fe0f..6647545 100644
--- a/fs/f2fs/acl.c
+++ b/fs/f2fs/acl.c
@@ -17,9 +17,6 @@
#include "xattr.h"
#include "acl.h"

-#define get_inode_mode(i) ((is_inode_flag_set(F2FS_I(i), FI_ACL_MODE)) ? \
- (F2FS_I(i)->i_acl_mode) : ((i)->i_mode))
-
static inline size_t f2fs_acl_size(int count)
{
if (count <= 4) {
@@ -209,11 +206,11 @@ static int __f2fs_set_acl(struct inode *inode, int type,
struct posix_acl *acl, struct page *ipage)
{
struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
- struct f2fs_inode_info *fi = F2FS_I(inode);
int name_index;
void *value = NULL;
size_t size = 0;
int error;
+ umode_t mode = 0;

if (!test_opt(sbi, POSIX_ACL))
return 0;
@@ -224,10 +221,10 @@ static int __f2fs_set_acl(struct inode *inode, int type,
case ACL_TYPE_ACCESS:
name_index = F2FS_XATTR_INDEX_POSIX_ACL_ACCESS;
if (acl) {
- error = posix_acl_equiv_mode(acl, &inode->i_mode);
+ mode = inode->i_mode;
+ error = posix_acl_equiv_mode(acl, &mode);
if (error < 0)
return error;
- set_acl_inode(fi, inode->i_mode);
if (error == 0)
acl = NULL;
}
@@ -245,19 +242,15 @@ static int __f2fs_set_acl(struct inode *inode, int type,

if (acl) {
value = f2fs_acl_to_disk(acl, &size);
- if (IS_ERR(value)) {
- cond_clear_inode_flag(fi, FI_ACL_MODE);
+ if (IS_ERR(value))
return (int)PTR_ERR(value);
- }
}

- error = f2fs_setxattr(inode, name_index, "", value, size, ipage);
+ error = f2fs_setxattr(inode, name_index, "", value, size, ipage, mode);

kfree(value);
if (!error)
set_cached_acl(inode, type, acl);
-
- cond_clear_inode_flag(fi, FI_ACL_MODE);
return error;
}

@@ -289,28 +282,3 @@ int f2fs_init_acl(struct inode *inode, struct inode *dir, struct page *ipage)

return error;
}
-
-int f2fs_acl_chmod(struct inode *inode)
-{
- struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
- struct posix_acl *acl;
- int error;
- umode_t mode = get_inode_mode(inode);
-
- if (!test_opt(sbi, POSIX_ACL))
- return 0;
- if (S_ISLNK(mode))
- return -EOPNOTSUPP;
-
- acl = f2fs_get_acl(inode, ACL_TYPE_ACCESS);
- if (IS_ERR(acl) || !acl)
- return PTR_ERR(acl);
-
- error = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
- if (error)
- return error;
-
- error = __f2fs_set_acl(inode, ACL_TYPE_ACCESS, acl, NULL);
- posix_acl_release(acl);
- return error;
-}
diff --git a/fs/f2fs/acl.h b/fs/f2fs/acl.h
index 2af31fe..e086465 100644
--- a/fs/f2fs/acl.h
+++ b/fs/f2fs/acl.h
@@ -38,18 +38,12 @@ struct f2fs_acl_header {

extern struct posix_acl *f2fs_get_acl(struct inode *, int);
extern int f2fs_set_acl(struct inode *inode, struct posix_acl *acl, int type);
-extern int f2fs_acl_chmod(struct inode *);
extern int f2fs_init_acl(struct inode *, struct inode *, struct page *);
#else
#define f2fs_check_acl NULL
#define f2fs_get_acl NULL
#define f2fs_set_acl NULL

-static inline int f2fs_acl_chmod(struct inode *inode)
-{
- return 0;
-}
-
static inline int f2fs_init_acl(struct inode *inode, struct inode *dir,
struct page *page)
{
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 89dc750..1e774e6 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -181,7 +181,6 @@ struct f2fs_inode_info {
unsigned char i_advise; /* use to give file attribute hints */
unsigned int i_current_depth; /* use only in directory structure */
unsigned int i_pino; /* parent inode number */
- umode_t i_acl_mode; /* keep file acl mode temporarily */

/* Use below internally in f2fs*/
unsigned long flags; /* use to pass per-file flags */
@@ -872,7 +871,6 @@ enum {
FI_NEW_INODE, /* indicate newly allocated inode */
FI_DIRTY_INODE, /* indicate inode is dirty or not */
FI_INC_LINK, /* need to increment i_nlink */
- FI_ACL_MODE, /* indicate acl mode */
FI_NO_ALLOC, /* should not allocate any blocks */
FI_UPDATE_DIR, /* should update inode block for consistency */
FI_DELAY_IPUT, /* used for the recovery */
@@ -894,21 +892,6 @@ static inline void clear_inode_flag(struct f2fs_inode_info *fi, int flag)
clear_bit(flag, &fi->flags);
}

-static inline void set_acl_inode(struct f2fs_inode_info *fi, umode_t mode)
-{
- fi->i_acl_mode = mode;
- set_inode_flag(fi, FI_ACL_MODE);
-}
-
-static inline int cond_clear_inode_flag(struct f2fs_inode_info *fi, int flag)
-{
- if (is_inode_flag_set(fi, FI_ACL_MODE)) {
- clear_inode_flag(fi, FI_ACL_MODE);
- return 1;
- }
- return 0;
-}
-
static inline void get_inline_info(struct f2fs_inode_info *fi,
struct f2fs_inode *ri)
{
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 13eff60..80ef669 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -339,41 +339,9 @@ int f2fs_getattr(struct vfsmount *mnt,
return 0;
}

-#ifdef CONFIG_F2FS_FS_POSIX_ACL
-static void __setattr_copy(struct inode *inode, const struct iattr *attr)
-{
- struct f2fs_inode_info *fi = F2FS_I(inode);
- unsigned int ia_valid = attr->ia_valid;
-
- if (ia_valid & ATTR_UID)
- inode->i_uid = attr->ia_uid;
- if (ia_valid & ATTR_GID)
- inode->i_gid = attr->ia_gid;
- if (ia_valid & ATTR_ATIME)
- inode->i_atime = timespec_trunc(attr->ia_atime,
- inode->i_sb->s_time_gran);
- if (ia_valid & ATTR_MTIME)
- inode->i_mtime = timespec_trunc(attr->ia_mtime,
- inode->i_sb->s_time_gran);
- if (ia_valid & ATTR_CTIME)
- inode->i_ctime = timespec_trunc(attr->ia_ctime,
- inode->i_sb->s_time_gran);
- if (ia_valid & ATTR_MODE) {
- umode_t mode = attr->ia_mode;
-
- if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
- mode &= ~S_ISGID;
- set_acl_inode(fi, mode);
- }
-}
-#else
-#define __setattr_copy setattr_copy
-#endif
-
int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = dentry->d_inode;
- struct f2fs_inode_info *fi = F2FS_I(inode);
int err;

err = inode_change_ok(inode, attr);
@@ -387,15 +355,9 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
f2fs_balance_fs(F2FS_SB(inode->i_sb));
}

- __setattr_copy(inode, attr);
-
- if (attr->ia_valid & ATTR_MODE) {
- err = f2fs_acl_chmod(inode);
- if (err || is_inode_flag_set(fi, FI_ACL_MODE)) {
- inode->i_mode = fi->i_acl_mode;
- clear_inode_flag(fi, FI_ACL_MODE);
- }
- }
+ setattr_copy(inode, attr);
+ if (attr->ia_valid & ATTR_MODE)
+ err = posix_acl_chmod(inode);

mark_inode_dirty(inode);
return err;
diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
index e2b9299..8820857 100644
--- a/fs/f2fs/xattr.c
+++ b/fs/f2fs/xattr.c
@@ -108,7 +108,7 @@ static int f2fs_xattr_generic_set(struct dentry *dentry, const char *name,
if (strcmp(name, "") == 0)
return -EINVAL;

- return f2fs_setxattr(dentry->d_inode, type, name, value, size, NULL);
+ return f2fs_setxattr(dentry->d_inode, type, name, value, size, NULL, 0);
}

static size_t f2fs_xattr_advise_list(struct dentry *dentry, char *list,
@@ -157,7 +157,7 @@ static int f2fs_xattr_advise_set(struct dentry *dentry, const char *name,
#ifdef CONFIG_F2FS_FS_SECURITY
static int __f2fs_setxattr(struct inode *inode, int name_index,
const char *name, const void *value, size_t value_len,
- struct page *ipage);
+ struct page *ipage, umode_t mode);
static int f2fs_initxattrs(struct inode *inode, const struct xattr *xattr_array,
void *page)
{
@@ -167,7 +167,7 @@ static int f2fs_initxattrs(struct inode *inode, const struct xattr *xattr_array,
for (xattr = xattr_array; xattr->name != NULL; xattr++) {
err = __f2fs_setxattr(inode, F2FS_XATTR_INDEX_SECURITY,
xattr->name, xattr->value,
- xattr->value_len, (struct page *)page);
+ xattr->value_len, (struct page *)page, 0);
if (err < 0)
break;
}
@@ -475,9 +475,8 @@ cleanup:

static int __f2fs_setxattr(struct inode *inode, int name_index,
const char *name, const void *value, size_t value_len,
- struct page *ipage)
+ struct page *ipage, umode_t mode)
{
- struct f2fs_inode_info *fi = F2FS_I(inode);
struct f2fs_xattr_entry *here, *last;
void *base_addr;
int found, newsize;
@@ -566,10 +565,9 @@ static int __f2fs_setxattr(struct inode *inode, int name_index,
if (error)
goto exit;

- if (is_inode_flag_set(fi, FI_ACL_MODE)) {
- inode->i_mode = fi->i_acl_mode;
+ if (mode) {
+ inode->i_mode = mode;
inode->i_ctime = CURRENT_TIME;
- clear_inode_flag(fi, FI_ACL_MODE);
}

if (ipage)
@@ -582,7 +580,8 @@ exit:
}

int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
- const void *value, size_t value_len, struct page *ipage)
+ const void *value, size_t value_len, struct page *ipage,
+ umode_t mode)
{
struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
int err;
@@ -590,7 +589,8 @@ int f2fs_setxattr(struct inode *inode, int name_index, const char *name,
f2fs_balance_fs(sbi);

f2fs_lock_op(sbi);
- err = __f2fs_setxattr(inode, name_index, name, value, value_len, ipage);
+ err = __f2fs_setxattr(inode, name_index, name, value, value_len, ipage,
+ mode);
f2fs_unlock_op(sbi);

return err;
diff --git a/fs/f2fs/xattr.h b/fs/f2fs/xattr.h
index b21d9eb..c73588a 100644
--- a/fs/f2fs/xattr.h
+++ b/fs/f2fs/xattr.h
@@ -114,14 +114,15 @@ extern const struct xattr_handler f2fs_xattr_security_handler;
extern const struct xattr_handler *f2fs_xattr_handlers[];

extern int f2fs_setxattr(struct inode *, int, const char *,
- const void *, size_t, struct page *);
+ const void *, size_t, struct page *, umode_t);
extern int f2fs_getxattr(struct inode *, int, const char *, void *, size_t);
extern ssize_t f2fs_listxattr(struct dentry *, char *, size_t);
#else

#define f2fs_xattr_handlers NULL
static inline int f2fs_setxattr(struct inode *inode, int name_index,
- const char *name, const void *value, size_t value_len)
+ const char *name, const void *value, size_t value_len,
+ umode_t mode)
{
return -EOPNOTSUPP;
}