[PATCH] mm/shmem: add support for FS_IOC_[SG]ETFLAGS for tmpfs

[PATCH] mm/shmem: add support for FS_IOC_[SG]ETFLAGS for tmpfs

[Theodore Ts'o]

This allows userspace to set flags like FS_APPEND_FL, FS_IMMUTABLE_FL,
FS_NODUMP_FL, etc., like all other standard Linux file systems.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 include/linux/shmem_fs.h | 11 +++++++
 mm/shmem.c               | 65 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index a68f982f22d1..1b6c4013f691 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -25,9 +25,20 @@ struct shmem_inode_info {
 	struct simple_xattrs	xattrs;		/* list of xattrs */
 	atomic_t		stop_eviction;	/* hold when working on inode */
 	struct timespec64	i_crtime;	/* file creation time */
+	unsigned int		fsflags;	/* flags for FS_IOC_[SG]ETFLAGS */
 	struct inode		vfs_inode;
 };
 
+#define SHMEM_FL_USER_VISIBLE FS_FL_USER_VISIBLE
+#define SHMEM_FL_USER_MODIFIABLE FS_FL_USER_MODIFIABLE
+#define SHMEM_FL_INHERITED FS_FL_USER_MODIFIABLE
+
+/* Flags that are appropriate for regular files (all but dir-specific ones). */
+#define SHMEM_REG_FLMASK (~(FS_DIRSYNC_FL | FS_TOPDIR_FL))
+
+/* Flags that are appropriate for non-directories/regular files. */
+#define SHMEM_OTHER_FLMASK (FS_NODUMP_FL | FS_NOATIME_FL)
+
 struct shmem_sb_info {
 	unsigned long max_blocks;   /* How many blocks are allowed */
 	struct percpu_counter used_blocks;  /* How many are allocated */
diff --git a/mm/shmem.c b/mm/shmem.c
index a6f565308133..515a2708d658 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -28,6 +28,7 @@
 #include <linux/ramfs.h>
 #include <linux/pagemap.h>
 #include <linux/file.h>
+#include <linux/fileattr.h>
 #include <linux/mm.h>
 #include <linux/random.h>
 #include <linux/sched/signal.h>
@@ -1058,6 +1059,15 @@ static int shmem_getattr(struct user_namespace *mnt_userns,
 		shmem_recalc_inode(inode);
 		spin_unlock_irq(&info->lock);
 	}
+	if (info->fsflags & EXT2_APPEND_FL)
+		stat->attributes |= STATX_ATTR_APPEND;
+	if (info->fsflags & EXT2_IMMUTABLE_FL)
+		stat->attributes |= STATX_ATTR_IMMUTABLE;
+	if (info->fsflags & EXT2_NODUMP_FL)
+		stat->attributes |= STATX_ATTR_NODUMP;
+	stat->attributes_mask |= (STATX_ATTR_APPEND |
+			STATX_ATTR_IMMUTABLE |
+			STATX_ATTR_NODUMP);
 	generic_fillattr(&init_user_ns, inode, stat);
 
 	if (shmem_is_huge(NULL, inode, 0))
@@ -2272,7 +2282,18 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
 	return 0;
 }
 
-static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
+/* Mask out flags that are inappropriate for the given type of inode. */
+static unsigned shmem_mask_flags(umode_t mode, __u32 flags)
+{
+	if (S_ISDIR(mode))
+		return flags;
+	else if (S_ISREG(mode))
+		return flags & SHMEM_REG_FLMASK;
+	else
+		return flags & SHMEM_OTHER_FLMASK;
+}
+
+static struct inode *shmem_get_inode(struct super_block *sb, struct inode *dir,
 				     umode_t mode, dev_t dev, unsigned long flags)
 {
 	struct inode *inode;
@@ -2297,6 +2318,9 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
 		info->seals = F_SEAL_SEAL;
 		info->flags = flags & VM_NORESERVE;
 		info->i_crtime = inode->i_mtime;
+		info->fsflags = (dir == NULL) ? 0 :
+			SHMEM_I(dir)->fsflags & SHMEM_FL_INHERITED;
+		info->fsflags = shmem_mask_flags(mode, info->fsflags);
 		INIT_LIST_HEAD(&info->shrinklist);
 		INIT_LIST_HEAD(&info->swaplist);
 		simple_xattrs_init(&info->xattrs);
@@ -2813,6 +2837,41 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
 	return error;
 }
 
+int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+{
+	struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
+
+	fileattr_fill_flags(fa, info->fsflags & SHMEM_FL_USER_VISIBLE);
+
+	return 0;
+}
+
+
+
+int shmem_fileattr_set(struct user_namespace *mnt_userns,
+		       struct dentry *dentry, struct fileattr *fa)
+{
+	struct inode *inode = d_inode(dentry);
+	struct shmem_inode_info *info = SHMEM_I(inode);
+
+	if (fileattr_has_fsx(fa))
+		return -EOPNOTSUPP;
+
+	info->fsflags = (fa->flags & ~SHMEM_FL_USER_MODIFIABLE) |
+		(fa->flags & SHMEM_FL_USER_MODIFIABLE);
+
+	inode->i_flags &= ~(S_APPEND | S_IMMUTABLE | S_NOATIME);
+	if (info->fsflags & FS_APPEND_FL)
+		inode->i_flags |= S_APPEND;
+	if (info->fsflags & FS_IMMUTABLE_FL)
+		inode->i_flags |= S_IMMUTABLE;
+	if (info->fsflags & FS_NOATIME_FL)
+		inode->i_flags |= S_NOATIME;
+
+	inode->i_ctime = current_time(inode);
+	return 0;
+}
+
 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
@@ -3828,6 +3887,8 @@ static const struct inode_operations shmem_inode_operations = {
 #ifdef CONFIG_TMPFS_XATTR
 	.listxattr	= shmem_listxattr,
 	.set_acl	= simple_set_acl,
+	.fileattr_get	= shmem_fileattr_get,
+	.fileattr_set	= shmem_fileattr_set,
 #endif
 };
 
@@ -3847,6 +3908,8 @@ static const struct inode_operations shmem_dir_inode_operations = {
 #endif
 #ifdef CONFIG_TMPFS_XATTR
 	.listxattr	= shmem_listxattr,
+	.fileattr_get	= shmem_fileattr_get,
+	.fileattr_set	= shmem_fileattr_set,
 #endif
 #ifdef CONFIG_TMPFS_POSIX_ACL
 	.setattr	= shmem_setattr,
-- 
2.31.0

Re: [PATCH] mm/shmem: add support for FS_IOC_[SG]ETFLAGS for tmpfs

[Andrew Morton]

On Wed, 13 Jul 2022 10:52:34 -0400 "Theodore Ts'o" <tytso@mit.edu> wrote:

> This allows userspace to set flags like FS_APPEND_FL, FS_IMMUTABLE_FL,
> FS_NODUMP_FL, etc., like all other standard Linux file systems.
> 
> ...
>
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -28,6 +28,7 @@
>  #include <linux/ramfs.h>
>  #include <linux/pagemap.h>
>  #include <linux/file.h>
> +#include <linux/fileattr.h>
>  #include <linux/mm.h>
>  #include <linux/random.h>
>  #include <linux/sched/signal.h>
> @@ -1058,6 +1059,15 @@ static int shmem_getattr(struct user_namespace *mnt_userns,
>  		shmem_recalc_inode(inode);
>  		spin_unlock_irq(&info->lock);
>  	}
> +	if (info->fsflags & EXT2_APPEND_FL)
> +		stat->attributes |= STATX_ATTR_APPEND;
> +	if (info->fsflags & EXT2_IMMUTABLE_FL)
> +		stat->attributes |= STATX_ATTR_IMMUTABLE;
> +	if (info->fsflags & EXT2_NODUMP_FL)
> +		stat->attributes |= STATX_ATTR_NODUMP;
> +	stat->attributes_mask |= (STATX_ATTR_APPEND |
> +			STATX_ATTR_IMMUTABLE |
> +			STATX_ATTR_NODUMP);
>  	generic_fillattr(&init_user_ns, inode, stat);
>  
>  	if (shmem_is_huge(NULL, inode, 0))

hm, how did you even test this?

mm/shmem.c: In function 'shmem_getattr':
mm/shmem.c:1062:29: error: 'EXT2_APPEND_FL' undeclared (first use in this function); did you mean 'FS_APPEND_FL'?
 1062 |         if (info->fsflags & EXT2_APPEND_FL)
      |                             ^~~~~~~~~~~~~~
      |                             FS_APPEND_FL


this

--- a/mm/shmem.c~mm-shmem-add-support-for-fs_ioc_etflags-for-tmpfs-fix-2
+++ a/mm/shmem.c
@@ -40,6 +40,8 @@
 #include <linux/swapfile.h>
 #include "swap.h"
 
+#include <../fs/ext2/ext2.h>
+
 static struct vfsmount *shm_mnt;
 
 #ifdef CONFIG_SHMEM

seems quite wrong.

Re: [PATCH] mm/shmem: add support for FS_IOC_[SG]ETFLAGS for tmpfs

[Theodore Ts'o]

On Wed, Jul 13, 2022 at 12:11:22PM -0700, Andrew Morton wrote:
> 
> hm, how did you even test this?

Sorry, I dropped the -a from "git commit --amend -a".

A corrected version is coming up...

				- Ted

[PATCH -v2] mm/shmem: support FS_IOC_[SG]ETFLAGS in tmpfs

[Theodore Ts'o]

This allows userspace to set flags like FS_APPEND_FL, FS_IMMUTABLE_FL,
FS_NODUMP_FL, etc., like all other standard Linux file systems.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---

v2:
  - replace use of EXT2_xxx_FL with FS_xxx_FL
  - fix preservation of non-modifiable flags in shmem_fileattr_set()
  - update the commit summary description

 include/linux/shmem_fs.h | 11 +++++++
 mm/shmem.c               | 63 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index a68f982f22d1..1b6c4013f691 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -25,9 +25,20 @@ struct shmem_inode_info {
 	struct simple_xattrs	xattrs;		/* list of xattrs */
 	atomic_t		stop_eviction;	/* hold when working on inode */
 	struct timespec64	i_crtime;	/* file creation time */
+	unsigned int		fsflags;	/* flags for FS_IOC_[SG]ETFLAGS */
 	struct inode		vfs_inode;
 };
 
+#define SHMEM_FL_USER_VISIBLE FS_FL_USER_VISIBLE
+#define SHMEM_FL_USER_MODIFIABLE FS_FL_USER_MODIFIABLE
+#define SHMEM_FL_INHERITED FS_FL_USER_MODIFIABLE
+
+/* Flags that are appropriate for regular files (all but dir-specific ones). */
+#define SHMEM_REG_FLMASK (~(FS_DIRSYNC_FL | FS_TOPDIR_FL))
+
+/* Flags that are appropriate for non-directories/regular files. */
+#define SHMEM_OTHER_FLMASK (FS_NODUMP_FL | FS_NOATIME_FL)
+
 struct shmem_sb_info {
 	unsigned long max_blocks;   /* How many blocks are allowed */
 	struct percpu_counter used_blocks;  /* How many are allocated */
diff --git a/mm/shmem.c b/mm/shmem.c
index a6f565308133..7540e16f6afa 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -28,6 +28,7 @@
 #include <linux/ramfs.h>
 #include <linux/pagemap.h>
 #include <linux/file.h>
+#include <linux/fileattr.h>
 #include <linux/mm.h>
 #include <linux/random.h>
 #include <linux/sched/signal.h>
@@ -1058,6 +1059,15 @@ static int shmem_getattr(struct user_namespace *mnt_userns,
 		shmem_recalc_inode(inode);
 		spin_unlock_irq(&info->lock);
 	}
+	if (info->fsflags & FS_APPEND_FL)
+		stat->attributes |= STATX_ATTR_APPEND;
+	if (info->fsflags & FS_IMMUTABLE_FL)
+		stat->attributes |= STATX_ATTR_IMMUTABLE;
+	if (info->fsflags & FS_NODUMP_FL)
+		stat->attributes |= STATX_ATTR_NODUMP;
+	stat->attributes_mask |= (STATX_ATTR_APPEND |
+			STATX_ATTR_IMMUTABLE |
+			STATX_ATTR_NODUMP);
 	generic_fillattr(&init_user_ns, inode, stat);
 
 	if (shmem_is_huge(NULL, inode, 0))
@@ -2272,7 +2282,18 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
 	return 0;
 }
 
-static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
+/* Mask out flags that are inappropriate for the given type of inode. */
+static unsigned shmem_mask_flags(umode_t mode, __u32 flags)
+{
+	if (S_ISDIR(mode))
+		return flags;
+	else if (S_ISREG(mode))
+		return flags & SHMEM_REG_FLMASK;
+	else
+		return flags & SHMEM_OTHER_FLMASK;
+}
+
+static struct inode *shmem_get_inode(struct super_block *sb, struct inode *dir,
 				     umode_t mode, dev_t dev, unsigned long flags)
 {
 	struct inode *inode;
@@ -2297,6 +2318,9 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
 		info->seals = F_SEAL_SEAL;
 		info->flags = flags & VM_NORESERVE;
 		info->i_crtime = inode->i_mtime;
+		info->fsflags = (dir == NULL) ? 0 :
+			SHMEM_I(dir)->fsflags & SHMEM_FL_INHERITED;
+		info->fsflags = shmem_mask_flags(mode, info->fsflags);
 		INIT_LIST_HEAD(&info->shrinklist);
 		INIT_LIST_HEAD(&info->swaplist);
 		simple_xattrs_init(&info->xattrs);
@@ -2813,6 +2837,39 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
 	return error;
 }
 
+int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+{
+	struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
+
+	fileattr_fill_flags(fa, info->fsflags & SHMEM_FL_USER_VISIBLE);
+
+	return 0;
+}
+
+int shmem_fileattr_set(struct user_namespace *mnt_userns,
+		       struct dentry *dentry, struct fileattr *fa)
+{
+	struct inode *inode = d_inode(dentry);
+	struct shmem_inode_info *info = SHMEM_I(inode);
+
+	if (fileattr_has_fsx(fa))
+		return -EOPNOTSUPP;
+
+	info->fsflags = (info->fsflags & ~SHMEM_FL_USER_MODIFIABLE) |
+		(fa->flags & SHMEM_FL_USER_MODIFIABLE);
+
+	inode->i_flags &= ~(S_APPEND | S_IMMUTABLE | S_NOATIME);
+	if (info->fsflags & FS_APPEND_FL)
+		inode->i_flags |= S_APPEND;
+	if (info->fsflags & FS_IMMUTABLE_FL)
+		inode->i_flags |= S_IMMUTABLE;
+	if (info->fsflags & FS_NOATIME_FL)
+		inode->i_flags |= S_NOATIME;
+
+	inode->i_ctime = current_time(inode);
+	return 0;
+}
+
 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
@@ -3828,6 +3885,8 @@ static const struct inode_operations shmem_inode_operations = {
 #ifdef CONFIG_TMPFS_XATTR
 	.listxattr	= shmem_listxattr,
 	.set_acl	= simple_set_acl,
+	.fileattr_get	= shmem_fileattr_get,
+	.fileattr_set	= shmem_fileattr_set,
 #endif
 };
 
@@ -3847,6 +3906,8 @@ static const struct inode_operations shmem_dir_inode_operations = {
 #endif
 #ifdef CONFIG_TMPFS_XATTR
 	.listxattr	= shmem_listxattr,
+	.fileattr_get	= shmem_fileattr_get,
+	.fileattr_set	= shmem_fileattr_set,
 #endif
 #ifdef CONFIG_TMPFS_POSIX_ACL
 	.setattr	= shmem_setattr,
-- 
2.31.0

Re: [PATCH] mm/shmem: add support for FS_IOC_[SG]ETFLAGS for tmpfs

[kernel test robot]

Hi Theodore,

I love your patch! Yet something to improve:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Theodore-Ts-o/mm-shmem-add-support-for-FS_IOC_-SG-ETFLAGS-for-tmpfs/20220713-225257
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
config: hexagon-randconfig-r024-20220714 (https://download.01.org/0day-ci/archive/20220715/202207150617.dHbSxB55-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 5e61b9c556267086ef9b743a0b57df302eef831b)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/2a3164ac6dafb6c7a3cd8a1002e89370eec359c1
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Theodore-Ts-o/mm-shmem-add-support-for-FS_IOC_-SG-ETFLAGS-for-tmpfs/20220713-225257
        git checkout 2a3164ac6dafb6c7a3cd8a1002e89370eec359c1
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All error/warnings (new ones prefixed by >>):

>> mm/shmem.c:1062:22: error: use of undeclared identifier 'EXT2_APPEND_FL'
           if (info->fsflags & EXT2_APPEND_FL)
                               ^
>> mm/shmem.c:1064:22: error: use of undeclared identifier 'EXT2_IMMUTABLE_FL'
           if (info->fsflags & EXT2_IMMUTABLE_FL)
                               ^
>> mm/shmem.c:1066:22: error: use of undeclared identifier 'EXT2_NODUMP_FL'
           if (info->fsflags & EXT2_NODUMP_FL)
                               ^
>> mm/shmem.c:2840:5: warning: no previous prototype for function 'shmem_fileattr_get' [-Wmissing-prototypes]
   int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
       ^
   mm/shmem.c:2840:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
   ^
   static 
>> mm/shmem.c:2851:5: warning: no previous prototype for function 'shmem_fileattr_set' [-Wmissing-prototypes]
   int shmem_fileattr_set(struct user_namespace *mnt_userns,
       ^
   mm/shmem.c:2851:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int shmem_fileattr_set(struct user_namespace *mnt_userns,
   ^
   static 
   2 warnings and 3 errors generated.


vim +/EXT2_APPEND_FL +1062 mm/shmem.c

  1049	
  1050	static int shmem_getattr(struct user_namespace *mnt_userns,
  1051				 const struct path *path, struct kstat *stat,
  1052				 u32 request_mask, unsigned int query_flags)
  1053	{
  1054		struct inode *inode = path->dentry->d_inode;
  1055		struct shmem_inode_info *info = SHMEM_I(inode);
  1056	
  1057		if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
  1058			spin_lock_irq(&info->lock);
  1059			shmem_recalc_inode(inode);
  1060			spin_unlock_irq(&info->lock);
  1061		}
> 1062		if (info->fsflags & EXT2_APPEND_FL)
  1063			stat->attributes |= STATX_ATTR_APPEND;
> 1064		if (info->fsflags & EXT2_IMMUTABLE_FL)
  1065			stat->attributes |= STATX_ATTR_IMMUTABLE;
> 1066		if (info->fsflags & EXT2_NODUMP_FL)
  1067			stat->attributes |= STATX_ATTR_NODUMP;
  1068		stat->attributes_mask |= (STATX_ATTR_APPEND |
  1069				STATX_ATTR_IMMUTABLE |
  1070				STATX_ATTR_NODUMP);
  1071		generic_fillattr(&init_user_ns, inode, stat);
  1072	
  1073		if (shmem_is_huge(NULL, inode, 0))
  1074			stat->blksize = HPAGE_PMD_SIZE;
  1075	
  1076		if (request_mask & STATX_BTIME) {
  1077			stat->result_mask |= STATX_BTIME;
  1078			stat->btime.tv_sec = info->i_crtime.tv_sec;
  1079			stat->btime.tv_nsec = info->i_crtime.tv_nsec;
  1080		}
  1081	
  1082		return 0;
  1083	}
  1084	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

Re: [PATCH] mm/shmem: add support for FS_IOC_[SG]ETFLAGS for tmpfs

[kernel test robot]

Hi Theodore,

I love your patch! Yet something to improve:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Theodore-Ts-o/mm-shmem-add-support-for-FS_IOC_-SG-ETFLAGS-for-tmpfs/20220713-225257
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
config: um-i386_defconfig (https://download.01.org/0day-ci/archive/20220715/202207150754.j4ldkYik-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/2a3164ac6dafb6c7a3cd8a1002e89370eec359c1
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Theodore-Ts-o/mm-shmem-add-support-for-FS_IOC_-SG-ETFLAGS-for-tmpfs/20220713-225257
        git checkout 2a3164ac6dafb6c7a3cd8a1002e89370eec359c1
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=um SUBARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All error/warnings (new ones prefixed by >>):

   mm/shmem.c: In function 'shmem_getattr':
>> mm/shmem.c:1062:29: error: 'EXT2_APPEND_FL' undeclared (first use in this function); did you mean 'FS_APPEND_FL'?
    1062 |         if (info->fsflags & EXT2_APPEND_FL)
         |                             ^~~~~~~~~~~~~~
         |                             FS_APPEND_FL
   mm/shmem.c:1062:29: note: each undeclared identifier is reported only once for each function it appears in
>> mm/shmem.c:1064:29: error: 'EXT2_IMMUTABLE_FL' undeclared (first use in this function); did you mean 'FS_IMMUTABLE_FL'?
    1064 |         if (info->fsflags & EXT2_IMMUTABLE_FL)
         |                             ^~~~~~~~~~~~~~~~~
         |                             FS_IMMUTABLE_FL
>> mm/shmem.c:1066:29: error: 'EXT2_NODUMP_FL' undeclared (first use in this function); did you mean 'FS_NODUMP_FL'?
    1066 |         if (info->fsflags & EXT2_NODUMP_FL)
         |                             ^~~~~~~~~~~~~~
         |                             FS_NODUMP_FL
   mm/shmem.c: At top level:
>> mm/shmem.c:2840:5: warning: no previous prototype for 'shmem_fileattr_get' [-Wmissing-prototypes]
    2840 | int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
         |     ^~~~~~~~~~~~~~~~~~
>> mm/shmem.c:2851:5: warning: no previous prototype for 'shmem_fileattr_set' [-Wmissing-prototypes]
    2851 | int shmem_fileattr_set(struct user_namespace *mnt_userns,
         |     ^~~~~~~~~~~~~~~~~~


vim +1062 mm/shmem.c

  1049	
  1050	static int shmem_getattr(struct user_namespace *mnt_userns,
  1051				 const struct path *path, struct kstat *stat,
  1052				 u32 request_mask, unsigned int query_flags)
  1053	{
  1054		struct inode *inode = path->dentry->d_inode;
  1055		struct shmem_inode_info *info = SHMEM_I(inode);
  1056	
  1057		if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
  1058			spin_lock_irq(&info->lock);
  1059			shmem_recalc_inode(inode);
  1060			spin_unlock_irq(&info->lock);
  1061		}
> 1062		if (info->fsflags & EXT2_APPEND_FL)
  1063			stat->attributes |= STATX_ATTR_APPEND;
> 1064		if (info->fsflags & EXT2_IMMUTABLE_FL)
  1065			stat->attributes |= STATX_ATTR_IMMUTABLE;
> 1066		if (info->fsflags & EXT2_NODUMP_FL)
  1067			stat->attributes |= STATX_ATTR_NODUMP;
  1068		stat->attributes_mask |= (STATX_ATTR_APPEND |
  1069				STATX_ATTR_IMMUTABLE |
  1070				STATX_ATTR_NODUMP);
  1071		generic_fillattr(&init_user_ns, inode, stat);
  1072	
  1073		if (shmem_is_huge(NULL, inode, 0))
  1074			stat->blksize = HPAGE_PMD_SIZE;
  1075	
  1076		if (request_mask & STATX_BTIME) {
  1077			stat->result_mask |= STATX_BTIME;
  1078			stat->btime.tv_sec = info->i_crtime.tv_sec;
  1079			stat->btime.tv_nsec = info->i_crtime.tv_nsec;
  1080		}
  1081	
  1082		return 0;
  1083	}
  1084	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

[PATCH -v3] mm/shmem: support FS_IOC_[SG]ETFLAGS in tmpfs

[Theodore Ts'o]

This allows userspace to set flags like FS_APPEND_FL, FS_IMMUTABLE_FL,
FS_NODUMP_FL, etc., like all other standard Linux file systems.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
v3:
  - declare shmem_fileattr_get() and shmem_fileattr_set() as static functions

v2:
  - replace use of EXT2_xxx_FL with FS_xxx_FL
  - fix preservation of non-modifiable flags in shmem_fileattr_set()
  - update the commit summary description

 include/linux/shmem_fs.h | 11 +++++++
 mm/shmem.c               | 63 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index a68f982f22d1..1b6c4013f691 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -25,9 +25,20 @@ struct shmem_inode_info {
 	struct simple_xattrs	xattrs;		/* list of xattrs */
 	atomic_t		stop_eviction;	/* hold when working on inode */
 	struct timespec64	i_crtime;	/* file creation time */
+	unsigned int		fsflags;	/* flags for FS_IOC_[SG]ETFLAGS */
 	struct inode		vfs_inode;
 };
 
+#define SHMEM_FL_USER_VISIBLE FS_FL_USER_VISIBLE
+#define SHMEM_FL_USER_MODIFIABLE FS_FL_USER_MODIFIABLE
+#define SHMEM_FL_INHERITED FS_FL_USER_MODIFIABLE
+
+/* Flags that are appropriate for regular files (all but dir-specific ones). */
+#define SHMEM_REG_FLMASK (~(FS_DIRSYNC_FL | FS_TOPDIR_FL))
+
+/* Flags that are appropriate for non-directories/regular files. */
+#define SHMEM_OTHER_FLMASK (FS_NODUMP_FL | FS_NOATIME_FL)
+
 struct shmem_sb_info {
 	unsigned long max_blocks;   /* How many blocks are allowed */
 	struct percpu_counter used_blocks;  /* How many are allocated */
diff --git a/mm/shmem.c b/mm/shmem.c
index a6f565308133..fc48680b961a 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -28,6 +28,7 @@
 #include <linux/ramfs.h>
 #include <linux/pagemap.h>
 #include <linux/file.h>
+#include <linux/fileattr.h>
 #include <linux/mm.h>
 #include <linux/random.h>
 #include <linux/sched/signal.h>
@@ -1058,6 +1059,15 @@ static int shmem_getattr(struct user_namespace *mnt_userns,
 		shmem_recalc_inode(inode);
 		spin_unlock_irq(&info->lock);
 	}
+	if (info->fsflags & FS_APPEND_FL)
+		stat->attributes |= STATX_ATTR_APPEND;
+	if (info->fsflags & FS_IMMUTABLE_FL)
+		stat->attributes |= STATX_ATTR_IMMUTABLE;
+	if (info->fsflags & FS_NODUMP_FL)
+		stat->attributes |= STATX_ATTR_NODUMP;
+	stat->attributes_mask |= (STATX_ATTR_APPEND |
+			STATX_ATTR_IMMUTABLE |
+			STATX_ATTR_NODUMP);
 	generic_fillattr(&init_user_ns, inode, stat);
 
 	if (shmem_is_huge(NULL, inode, 0))
@@ -2272,7 +2282,18 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
 	return 0;
 }
 
-static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
+/* Mask out flags that are inappropriate for the given type of inode. */
+static unsigned shmem_mask_flags(umode_t mode, __u32 flags)
+{
+	if (S_ISDIR(mode))
+		return flags;
+	else if (S_ISREG(mode))
+		return flags & SHMEM_REG_FLMASK;
+	else
+		return flags & SHMEM_OTHER_FLMASK;
+}
+
+static struct inode *shmem_get_inode(struct super_block *sb, struct inode *dir,
 				     umode_t mode, dev_t dev, unsigned long flags)
 {
 	struct inode *inode;
@@ -2297,6 +2318,9 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
 		info->seals = F_SEAL_SEAL;
 		info->flags = flags & VM_NORESERVE;
 		info->i_crtime = inode->i_mtime;
+		info->fsflags = (dir == NULL) ? 0 :
+			SHMEM_I(dir)->fsflags & SHMEM_FL_INHERITED;
+		info->fsflags = shmem_mask_flags(mode, info->fsflags);
 		INIT_LIST_HEAD(&info->shrinklist);
 		INIT_LIST_HEAD(&info->swaplist);
 		simple_xattrs_init(&info->xattrs);
@@ -2813,6 +2837,39 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
 	return error;
 }
 
+static int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
+{
+	struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
+
+	fileattr_fill_flags(fa, info->fsflags & SHMEM_FL_USER_VISIBLE);
+
+	return 0;
+}
+
+static int shmem_fileattr_set(struct user_namespace *mnt_userns,
+			      struct dentry *dentry, struct fileattr *fa)
+{
+	struct inode *inode = d_inode(dentry);
+	struct shmem_inode_info *info = SHMEM_I(inode);
+
+	if (fileattr_has_fsx(fa))
+		return -EOPNOTSUPP;
+
+	info->fsflags = (info->fsflags & ~SHMEM_FL_USER_MODIFIABLE) |
+		(fa->flags & SHMEM_FL_USER_MODIFIABLE);
+
+	inode->i_flags &= ~(S_APPEND | S_IMMUTABLE | S_NOATIME);
+	if (info->fsflags & FS_APPEND_FL)
+		inode->i_flags |= S_APPEND;
+	if (info->fsflags & FS_IMMUTABLE_FL)
+		inode->i_flags |= S_IMMUTABLE;
+	if (info->fsflags & FS_NOATIME_FL)
+		inode->i_flags |= S_NOATIME;
+
+	inode->i_ctime = current_time(inode);
+	return 0;
+}
+
 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
@@ -3828,6 +3885,8 @@ static const struct inode_operations shmem_inode_operations = {
 #ifdef CONFIG_TMPFS_XATTR
 	.listxattr	= shmem_listxattr,
 	.set_acl	= simple_set_acl,
+	.fileattr_get	= shmem_fileattr_get,
+	.fileattr_set	= shmem_fileattr_set,
 #endif
 };
 
@@ -3847,6 +3906,8 @@ static const struct inode_operations shmem_dir_inode_operations = {
 #endif
 #ifdef CONFIG_TMPFS_XATTR
 	.listxattr	= shmem_listxattr,
+	.fileattr_get	= shmem_fileattr_get,
+	.fileattr_set	= shmem_fileattr_set,
 #endif
 #ifdef CONFIG_TMPFS_POSIX_ACL
 	.setattr	= shmem_setattr,
-- 
2.31.0

Re: [PATCH] mm/shmem: add support for FS_IOC_[SG]ETFLAGS for tmpfs

[Arnd Bergmann]

On Fri, Jul 15, 2022 at 1:01 AM kernel test robot <lkp@intel.com> wrote:
>
> >> mm/shmem.c:1062:22: error: use of undeclared identifier 'EXT2_APPEND_FL'
>            if (info->fsflags & EXT2_APPEND_FL)
>                                ^
> >> mm/shmem.c:1064:22: error: use of undeclared identifier 'EXT2_IMMUTABLE_FL'
>            if (info->fsflags & EXT2_IMMUTABLE_FL)
>                                ^
> >> mm/shmem.c:1066:22: error: use of undeclared identifier 'EXT2_NODUMP_FL'
>            if (info->fsflags & EXT2_NODUMP_FL)
>                                ^


I suppose this just needs to use FS_APPEND_FL/FS_IMMUTABLE_FL/FS_NODUMP_FL
instead of the ext2 alias names?

      Arnd

Re: [PATCH] mm/shmem: add support for FS_IOC_[SG]ETFLAGS for tmpfs

[Arnd Bergmann]

[-- Attachment #1: Type: text/plain, Size: 704 bytes --]

On Fri, Jul 15, 2022 at 1:01 AM kernel test robot <lkp@intel.com> wrote:
>
> >> mm/shmem.c:1062:22: error: use of undeclared identifier 'EXT2_APPEND_FL'
>            if (info->fsflags & EXT2_APPEND_FL)
>                                ^
> >> mm/shmem.c:1064:22: error: use of undeclared identifier 'EXT2_IMMUTABLE_FL'
>            if (info->fsflags & EXT2_IMMUTABLE_FL)
>                                ^
> >> mm/shmem.c:1066:22: error: use of undeclared identifier 'EXT2_NODUMP_FL'
>            if (info->fsflags & EXT2_NODUMP_FL)
>                                ^


I suppose this just needs to use FS_APPEND_FL/FS_IMMUTABLE_FL/FS_NODUMP_FL
instead of the ext2 alias names?

      Arnd

Re: [PATCH] mm/shmem: add support for FS_IOC_[SG]ETFLAGS for tmpfs

[Theodore Ts'o]

On Fri, Jul 15, 2022 at 01:09:04PM +0200, Arnd Bergmann wrote:
> On Fri, Jul 15, 2022 at 1:01 AM kernel test robot <lkp@intel.com> wrote:
> >
> > >> mm/shmem.c:1062:22: error: use of undeclared identifier 'EXT2_APPEND_FL'
> >            if (info->fsflags & EXT2_APPEND_FL)
> >                                ^
> > >> mm/shmem.c:1064:22: error: use of undeclared identifier 'EXT2_IMMUTABLE_FL'
> >            if (info->fsflags & EXT2_IMMUTABLE_FL)
> >                                ^
> > >> mm/shmem.c:1066:22: error: use of undeclared identifier 'EXT2_NODUMP_FL'
> >            if (info->fsflags & EXT2_NODUMP_FL)
> >                                ^
> 
> I suppose this just needs to use FS_APPEND_FL/FS_IMMUTABLE_FL/FS_NODUMP_FL
> instead of the ext2 alias names?

The zero day bot was testing the v1 version of the patch.  This was
fixed in the -v2 and -v3 versions.

     	      	     	    	    - Ted

Re: [PATCH] mm/shmem: add support for FS_IOC_[SG]ETFLAGS for tmpfs

[Theodore Ts'o]

[-- Attachment #1: Type: text/plain, Size: 924 bytes --]

On Fri, Jul 15, 2022 at 01:09:04PM +0200, Arnd Bergmann wrote:
> On Fri, Jul 15, 2022 at 1:01 AM kernel test robot <lkp@intel.com> wrote:
> >
> > >> mm/shmem.c:1062:22: error: use of undeclared identifier 'EXT2_APPEND_FL'
> >            if (info->fsflags & EXT2_APPEND_FL)
> >                                ^
> > >> mm/shmem.c:1064:22: error: use of undeclared identifier 'EXT2_IMMUTABLE_FL'
> >            if (info->fsflags & EXT2_IMMUTABLE_FL)
> >                                ^
> > >> mm/shmem.c:1066:22: error: use of undeclared identifier 'EXT2_NODUMP_FL'
> >            if (info->fsflags & EXT2_NODUMP_FL)
> >                                ^
> 
> I suppose this just needs to use FS_APPEND_FL/FS_IMMUTABLE_FL/FS_NODUMP_FL
> instead of the ext2 alias names?

The zero day bot was testing the v1 version of the patch.  This was
fixed in the -v2 and -v3 versions.

     	      	     	    	    - Ted

Re: [PATCH -v3] mm/shmem: support FS_IOC_[SG]ETFLAGS in tmpfs

[Theodore Ts'o]

On Thu, Jul 14, 2022 at 09:59:12PM -0400, Theodore Ts'o wrote:
> This allows userspace to set flags like FS_APPEND_FL, FS_IMMUTABLE_FL,
> FS_NODUMP_FL, etc., like all other standard Linux file systems.
> 
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Hi Andrew,

I notice that in your most recent mm-unstable tree, you still have the
v1 version of the patch plus your fixup:

* c523739526b3 - mm/shmem: support FS_IOC_[SG]ETFLAGS in tmpfs (6 hours ago)
* 2d6c68e33857 - mm-shmem-support-fs_ioc_etflags-in-tmpfs-fix (6 hours ago)

Could you please replace these two patches with the v3 version of the
patch at:

https://lore.kernel.org/all/20220715015912.2560575-1-tytso@mit.edu/

There haven't been any other comments in the past week, so I'm hopeful
this will be the final version of this proposed change.

Many thanks!

					- Ted

Re: [PATCH -v3] mm/shmem: support FS_IOC_[SG]ETFLAGS in tmpfs

[Andrew Morton]

On Wed, 20 Jul 2022 07:10:04 -0400 "Theodore Ts'o" <tytso@mit.edu> wrote:

> On Thu, Jul 14, 2022 at 09:59:12PM -0400, Theodore Ts'o wrote:
> > This allows userspace to set flags like FS_APPEND_FL, FS_IMMUTABLE_FL,
> > FS_NODUMP_FL, etc., like all other standard Linux file systems.
> > 
> > Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> 
> Hi Andrew,
> 
> I notice that in your most recent mm-unstable tree, you still have the
> v1 version of the patch plus your fixup:
> 
> * c523739526b3 - mm/shmem: support FS_IOC_[SG]ETFLAGS in tmpfs (6 hours ago)
> * 2d6c68e33857 - mm-shmem-support-fs_ioc_etflags-in-tmpfs-fix (6 hours ago)

What's there is actually v2, and the fixup which updates that to v3. 
I'll squash the fixup into the base patch before moving the patch into
mm-nonmm-stable (and then mainline) so it all comes good.

> There haven't been any other comments in the past week, so I'm hopeful
> this will be the final version of this proposed change.

Yup.

Re: [PATCH -v3] mm/shmem: support FS_IOC_[SG]ETFLAGS in tmpfs

[Hugh Dickins]

On Thu, 14 Jul 2022, Theodore Ts'o wrote:

> This allows userspace to set flags like FS_APPEND_FL, FS_IMMUTABLE_FL,
> FS_NODUMP_FL, etc., like all other standard Linux file systems.
> 
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Many thanks for adding the chattr support to tmpfs: I'd rather wanted
to do that for a long time, but it's much better coming from you who
actually have a use for it.

But I do have some adjustments to make, coming up now...

Hugh