On Mon, Aug 26, 2024 at 08:46:15AM GMT, Jeff Layton wrote: > When updating the ctime on an inode for a setattr with a multigrain > filesystem, we usually want to take the latest time we can get for the > ctime. The exception to this rule is when there is a nfsd write > delegation and the server is proxying timestamps from the client. > > When nfsd gets a CB_GETATTR response, we want to update the timestamp > value in the inode to the values that the client is tracking. The client > doesn't send a ctime value (since that's always determined by the > exported filesystem), but it does send a mtime value. In the case where > it does, then we may also need to update the ctime to a value > commensurate with that. > > Add a ATTR_CTIME_DELEG flag, which tells the underlying setattr Fwiw: disconnect between commit message and actually used ATTR_CTIME_DLG. > machinery to respect that value and not to set it to the current time. > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > --- Are you set on sending us on a mission to free up ATTR_* bits after freeing up FMODE_* bits? ;) If there's going to be more ATTR_*DELEG* flags that modify the behavior when delegation is in effect then we could consider adding another unsigned int ia_deleg field to struct iattr so that you can check: if (ia_valid & ATTR_CTIME) { if (unlikely(iattr->ia_deleg & ATTR_CTIME)) // do some special stuff else // do the regular stuff } or some such variant. > fs/attr.c | 10 +++++++++- > include/linux/fs.h | 1 + > 2 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/fs/attr.c b/fs/attr.c > index 7144b207e715..0eb7b228b94d 100644 > --- a/fs/attr.c > +++ b/fs/attr.c > @@ -295,7 +295,15 @@ static void setattr_copy_mgtime(struct inode *inode, const struct iattr *attr) > return; > } > > - now = inode_set_ctime_current(inode); > + /* > + * In the case of an update for a write delegation, we must respect > + * the value in ia_ctime and not use the current time. > + */ > + if (ia_valid & ATTR_CTIME_DLG) > + inode_set_ctime_to_ts(inode, attr->ia_ctime); > + else > + now = inode_set_ctime_current(inode); > + > if (ia_valid & ATTR_ATIME_SET) > inode_set_atime_to_ts(inode, attr->ia_atime); > else if (ia_valid & ATTR_ATIME) > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 7c1da3c687bd..43a802b2cb0d 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -211,6 +211,7 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset, > #define ATTR_TIMES_SET (1 << 16) > #define ATTR_TOUCH (1 << 17) > #define ATTR_DELEG (1 << 18) /* Delegated attrs (don't break) */ > +#define ATTR_CTIME_DLG (1 << 19) /* Delegation in effect */ What's the interaction between ATTR_DELEG and ATTR_CTIME_DLG? I think that's potentially confusing.