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;
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;
}
}
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