From: Gao Xiang hsiangkao@redhat.com

EROFS has _only one_ ondisk timestamp (ctime is currently documented and recorded, we might also record mtime instead with a new compat feature if needed) for each extended inode since EROFS isn't mainly for archival purposes so no need to keep all timestamps on disk especially for Android scenarios due to security concerns. Also, romfs/cramfs don't have their own on-disk timestamp, and squashfs only records mtime instead.

Let's also derive access time from ondisk timestamp rather than leaving it empty, and if mtime/atime for each file are really needed for specific scenarios as well, we can also use xattrs to record them then.

Reported-by: nl6720 nl6720@gmail.com [ Gao Xiang: It'd be better to backport for user-friendly concern. ] Fixes: 431339ba9042 ("staging: erofs: add inode operations") Cc: stable stable@vger.kernel.org # 4.19+ Signed-off-by: Gao Xiang hsiangkao@redhat.com --- fs/erofs/inode.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c index 139d0bed42f8..3e21c0e8adae 100644 --- a/fs/erofs/inode.c +++ b/fs/erofs/inode.c @@ -107,11 +107,9 @@ static struct page *erofs_read_inode(struct inode *inode, i_gid_write(inode, le32_to_cpu(die->i_gid)); set_nlink(inode, le32_to_cpu(die->i_nlink));

- /* ns timestamp */ - inode->i_mtime.tv_sec = inode->i_ctime.tv_sec = - le64_to_cpu(die->i_ctime); - inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = - le32_to_cpu(die->i_ctime_nsec); + /* extended inode has its own timestamp */ + inode->i_ctime.tv_sec = le64_to_cpu(die->i_ctime); + inode->i_ctime.tv_nsec = le32_to_cpu(die->i_ctime_nsec);

inode->i_size = le64_to_cpu(die->i_size);

@@ -149,11 +147,9 @@ static struct page *erofs_read_inode(struct inode *inode, i_gid_write(inode, le16_to_cpu(dic->i_gid)); set_nlink(inode, le16_to_cpu(dic->i_nlink));

- /* use build time to derive all file time */ - inode->i_mtime.tv_sec = inode->i_ctime.tv_sec = - sbi->build_time; - inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = - sbi->build_time_nsec; + /* use build time for compact inodes */ + inode->i_ctime.tv_sec = sbi->build_time; + inode->i_ctime.tv_nsec = sbi->build_time_nsec;

inode->i_size = le32_to_cpu(dic->i_size); if (erofs_inode_is_data_compressed(vi->datalayout)) @@ -167,6 +163,11 @@ static struct page *erofs_read_inode(struct inode *inode, goto err_out; }

+ inode->i_mtime.tv_sec = inode->i_ctime.tv_sec; + inode->i_atime.tv_sec = inode->i_ctime.tv_sec; + inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec; + inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec; + if (!nblks) /* measure inode.i_blocks as generic filesystems */ inode->i_blocks = roundup(inode->i_size, EROFS_BLKSIZ) >> 9;