On 06/01/2010 04:39 PM, Nick Piggin wrote:
> It appears that I've broken inode time modifications on tmpfs/ext2.
> While ftruncate always updates these attributes, truncate must not
> unless size is changed. I hadn't actually understood that until
> Christoph told me.
>
> Confusion is increased because other filesystems get this wrong.
> Those without ->setattr or ->truncate get it wrong by default.
> Others appear to have problems too.
>
> I haven't gone through many yet, but is there any reason not to
> just do it in the vfs?
>
> ---
> fs/ext2/inode.c | 1 -
> fs/open.c | 3 +++
> fs/ramfs/file-nommu.c | 5 -----
> mm/shmem.c | 5 +++--
> 4 files changed, 6 insertions(+), 8 deletions(-)
>
> Index: linux-2.6/fs/ext2/inode.c
> ===================================================================
> --- linux-2.6.orig/fs/ext2/inode.c
> +++ linux-2.6/fs/ext2/inode.c
> @@ -1203,7 +1203,6 @@ int ext2_setsize(struct inode *inode, lo
>
> __ext2_truncate_blocks(inode, newsize);
>
> - inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
OK I was just investigating this. Please forgive my noviceness here:
So i_mtime is modifications time. i_ctime is creation time?
if I do ftrunc() (like dd skip=x) don't I want modification time changed
but creation time unchanged?
if I do chmod/chown do I want modification-time changed creation not?
open+truncate both m an c changed?
modification-time: is it any aspect of the file has changed? or just the actual data / size?
Confused?
Boaz
> if (inode_needs_sync(inode)) {
> sync_mapping_buffers(inode->i_mapping);
> ext2_sync_inode (inode);
> Index: linux-2.6/fs/open.c
> ===================================================================
> --- linux-2.6.orig/fs/open.c
> +++ linux-2.6/fs/open.c
> @@ -55,6 +55,9 @@ int do_truncate(struct dentry *dentry, l
> newattrs.ia_valid |= ret | ATTR_FORCE;
>
> mutex_lock(&dentry->d_inode->i_mutex);
> + /* Unlike ftruncate, truncate only updates times when size changes */
> + if (length != dentry->d_inode->i_size)
> + newattrs.ia_valid |= ATTR_MTIME|ATTR_CTIME;
> ret = notify_change(dentry, &newattrs);
> mutex_unlock(&dentry->d_inode->i_mutex);
> return ret;
> Index: linux-2.6/mm/shmem.c
> ===================================================================
> --- linux-2.6.orig/mm/shmem.c
> +++ linux-2.6/mm/shmem.c
> @@ -764,10 +764,11 @@ done2:
> static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
> {
> struct inode *inode = dentry->d_inode;
> + loff_t newsize = attr->ia_size;
> int error;
>
> - if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
> - loff_t newsize = attr->ia_size;
> + if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE) &&
> + newsize != inode->i_size) {
> struct page *page = NULL;
>
> if (newsize < inode->i_size) {
> Index: linux-2.6/fs/ramfs/file-nommu.c
> ===================================================================
> --- linux-2.6.orig/fs/ramfs/file-nommu.c
> +++ linux-2.6/fs/ramfs/file-nommu.c
> @@ -175,11 +175,6 @@ static int ramfs_nommu_setattr(struct de
> ret = ramfs_nommu_resize(inode, ia->ia_size, size);
> if (ret < 0 || ia->ia_valid == ATTR_SIZE)
> goto out;
> - } else {
> - /* we skipped the truncate but must still update
> - * timestamps
> - */
> - ia->ia_valid |= ATTR_MTIME|ATTR_CTIME;
> }
> }
>
>
> --
> 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
--
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
