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@xxxxxxx>
---
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
