xfs
[Top] [All Lists]

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

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: [PATCH 09/18] f2fs: use generic posix ACL infrastructure
From: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>
Date: Mon, 09 Dec 2013 08:28:45 +0900
Cc: viro@xxxxxxxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, linux-btrfs@xxxxxxxxxxxxxxx, linux-ext4@xxxxxxxxxxxxxxx, linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx, linux-mtd@xxxxxxxxxxxxxxxxxxx, Mark Fasheh <mfasheh@xxxxxxxx>, Joel Becker <jlbec@xxxxxxxxxxxx>, reiserfs-devel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx, jfs-discussion@xxxxxxxxxxxxxxxxxxxxx, cluster-devel@xxxxxxxxxx, linux-nfs@xxxxxxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
Dlp-filter: Pass
In-reply-to: <20131208091443.GA13760@xxxxxxxxxxxxx>
Organization: Samsung
References: <20131201115903.910559036@xxxxxxxxxxxxxxxxxxxxxx> <20131201120655.205206019@xxxxxxxxxxxxxxxxxxxxxx> <1386293854.2101.8.camel@kjgkr> <20131208091443.GA13760@xxxxxxxxxxxxx>
Reply-to: jaegeuk.kim@xxxxxxxxxxx
2013-12-08 (ì), 01:14 -0800, Christoph Hellwig:
> 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?

As you guess, there is no race problem, but the problem is on acl
consistency between xattr->mode and inode->mode.

Previously, f2fs_setattr triggers:
              new_mode inode->mode xattr->mode iblock->mode
f2fs_setattr     x    ->    x           y         y       
[update_inode]              x    ---  [ y ]  ---> x
[checkpoint]                x           y         x
__f2fs_setxattr             x     ->    x         x

In this flow, f2fs is able to break the consistency between xattr->mode
and iblock->mode after checkpoint followed by sudden-power-off.

So, fi->mode was introduced to address the problem.
The new f2fs_setattr triggers:
              new_mode inode->mode fi->mode xattr->mode iblock->mode
f2fs_setattr     x    ---  [y]  --->   x          y          y
[update_inode]              y          x          y          y
[checkpoint]                y          x          y          y
__f2fs_setxattr             x    <-    x    ->    x     ->   x

Finally, __f2fs_setxattr synchronizes inode->mode, xattr->mode, and
iblock->mode all together.

The root question is "is it possible to call update_inode in the
i_mutex-covered region like f2fs_setattr?".
The update_inode of f2fs is called from a bunch of places so currently
I'm not sure it can be impossible.

Thanks,

> 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;
>  }
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
Jaegeuk Kim
Samsung

<Prev in Thread] Current Thread [Next in Thread>