[PATCH v3] tmpfs: support for file creation time

Xavier Roche
2022-02-28T08:43:10Z

Various filesystems (including ext4) now support file creation time.
This patch adds such support for tmpfs-based filesystems.

Signed-off-by: Xavier Roche <xavier.roche@algolia.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Cc: Xavier Roche <xavier.roche@algolia.com>
Cc: Jean Delvare <jdelvare@suse.de>
---
include/linux/shmem_fs.h | 1 +
mm/shmem.c | 11 +++++++++++
2 files changed, 12 insertions(+)

Index: linux/include/linux/shmem_fs.h
===================================================================
--- linux.orig/include/linux/shmem_fs.h
+++ linux/include/linux/shmem_fs.h
@@ -24,6 +24,7 @@ struct shmem_inode_info {
struct shared_policy policy; /* NUMA memory alloc policy */
struct simple_xattrs xattrs; /* list of xattrs */
atomic_t stop_eviction; /* hold when working on inode */
+ struct timespec64 i_crtime; /* file creation time */
struct inode vfs_inode;
};

Index: linux/mm/shmem.c
===================================================================
--- linux.orig/mm/shmem.c
+++ linux/mm/shmem.c
@@ -476,6 +476,8 @@ bool shmem_is_huge(struct vm_area_struct
{
loff_t i_size;

+ if (!S_ISREG(inode->i_mode))
+ return false;
if (shmem_huge == SHMEM_HUGE_DENY)
return false;
if (vma && ((vma->vm_flags & VM_NOHUGEPAGE) ||
@@ -1061,6 +1063,12 @@ static int shmem_getattr(struct user_nam
if (shmem_is_huge(NULL, inode, 0))
stat->blksize = HPAGE_PMD_SIZE;

+ if (request_mask & STATX_BTIME) {
+ stat->result_mask |= STATX_BTIME;
+ stat->btime.tv_sec = info->i_crtime.tv_sec;
+ stat->btime.tv_nsec = info->i_crtime.tv_nsec;
+ }
+
return 0;
}

@@ -1854,9 +1862,6 @@ repeat:
return 0;
}

- /* Never use a huge page for shmem_symlink() */
- if (S_ISLNK(inode->i_mode))
- goto alloc_nohuge;
if (!shmem_is_huge(vma, inode, index))
goto alloc_nohuge;

@@ -2265,6 +2270,7 @@ static struct inode *shmem_get_inode(str
atomic_set(&info->stop_eviction, 0);
info->seals = F_SEAL_SEAL;
info->flags = flags & VM_NORESERVE;
+ info->i_crtime = inode->i_mtime;
INIT_LIST_HEAD(&info->shrinklist);
INIT_LIST_HEAD(&info->swaplist);
simple_xattrs_init(&info->xattrs);
@@ -3196,6 +3202,7 @@ static ssize_t shmem_listxattr(struct de
#endif /* CONFIG_TMPFS_XATTR */

static const struct inode_operations shmem_short_symlink_operations = {
+ .getattr = shmem_getattr,
.get_link = simple_get_link,
#ifdef CONFIG_TMPFS_XATTR
.listxattr = shmem_listxattr,
@@ -3203,6 +3210,7 @@ static const struct inode_operations shm
};

static const struct inode_operations shmem_symlink_inode_operations = {
+ .getattr = shmem_getattr,
.get_link = shmem_get_link,
#ifdef CONFIG_TMPFS_XATTR
.listxattr = shmem_listxattr,
@@ -3790,6 +3798,7 @@ static const struct inode_operations shm

static const struct inode_operations shmem_dir_inode_operations = {
#ifdef CONFIG_TMPFS
+ .getattr = shmem_getattr,
.create = shmem_create,
.lookup = simple_lookup,
.link = shmem_link,
@@ -3811,6 +3820,7 @@ static const struct inode_operations shm
};

static const struct inode_operations shmem_special_inode_operations = {
+ .getattr = shmem_getattr,
#ifdef CONFIG_TMPFS_XATTR
.listxattr = shmem_listxattr,
#endif