| Message ID | 20240826-delstid-v2-5-e8ab5c0e39cc@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | nfsd: implement the "delstid" draft | expand |
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@kernel.org> > --- 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.
On Mon, 2024-08-26 at 15:08 +0200, Christian Brauner wrote: > 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. > Thanks, will fix. > > machinery to respect that value and not to set it to the current time. > > > > Signed-off-by: Jeff Layton <jlayton@kernel.org> > > --- > > Are you set on sending us on a mission to free up ATTR_* bits after > freeing up FMODE_* bits? ;) > Those aren't usually allocated from the heap, so I wouldn't bother, but I get the jest. > 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. > I don't forsee other flags being needed, but you never know. For now I wouldn't bother. > > 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. > Now that you mention it, I suppose we could just key off of ATTR_DELEG instead of declaring a new flag. That should be simpler to reason out for everyone. I'll respin this along those lines instead. Thanks for the review!
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 */ /* * Whiteout is represented by a char device. The following constants define the
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 machinery to respect that value and not to set it to the current time. Signed-off-by: Jeff Layton <jlayton@kernel.org> --- fs/attr.c | 10 +++++++++- include/linux/fs.h | 1 + 2 files changed, 10 insertions(+), 1 deletion(-)