Re: [PATCH] fs/nfsd: fix update of inode attrs in CB_GETATTR

Dai Ngo <dai.ngo@xxxxxxxxxx> · Mon, 26 Aug 2024 09:43:41 -0700

On 8/26/24 9:13 AM, Jeff Layton wrote:
On Mon, 2024-08-26 at 08:31 -0700, Dai Ngo wrote:
On 8/24/24 5:46 AM, Jeff Layton wrote:
Currently, we copy the mtime and ctime to the in-core inode and then
mark the inode dirty. This is fine for certain types of filesystems, but
not all. Some require a real setattr to properly change these values
(e.g. ceph or reexported NFS).

Fix this code to call notify_change() instead, which is the proper way
to effect a setattr. There is one problem though:

In this case, the client is holding a write delegation and has sent us
attributes to update our cache. We don't want to break the delegation
for this since that would defeat the purpose.
I think this won't happen with NFS since nfsd_breaker_owns_lease detects
its own lease and won't break the delegation.

I don't think that works here. In this case, we've gotten a GETATTR
request from a different client than the lease holder. So the breaker
in this case does _not_ own the lease.

Oh yes, the lease breaker in nfsd_breaker_owns_lease is the client
that sends the GETATTR so it is not the same as the lease's owner.

Thanks,
-Dai


   Add a new ATTR_DELEG flag
that makes notify_change bypass the try_break_deleg call.

Fixes: c5967721e106 ("NFSD: handle GETATTR conflict with write delegation")
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
One more CB_GETATTR fix. This one involves a little change at the VFS
layer to avoid breaking the delegation.

Christian, unless you have objections, this should probably go in
via Chuck's tree as this patch depends on a nfsd patch [1] that I sent
yesterday. An A-b or R-b would be welcome though.

[1]: https://lore.kernel.org/linux-nfs/20240823-nfsd-fixes-v1-1-fc99aa16f6a0@xxxxxxxxxx/T/#u
---
   fs/attr.c           |  9 ++++++---
   fs/nfsd/nfs4state.c | 18 +++++++++++++-----
   fs/nfsd/nfs4xdr.c   |  2 +-
   fs/nfsd/state.h     |  2 +-
   include/linux/fs.h  |  1 +
   5 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/fs/attr.c b/fs/attr.c
index 960a310581eb..a40a2fb406f0 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -489,9 +489,12 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
   	error = security_inode_setattr(idmap, dentry, attr);
   	if (error)
   		return error;
-	error = try_break_deleg(inode, delegated_inode);
-	if (error)
-		return error;
+
+	if (!(ia_valid & ATTR_DELEG)) {
+		error = try_break_deleg(inode, delegated_inode);
+		if (error)
+			return error;
+	}
   
   	if (inode->i_op->setattr)
   		error = inode->i_op->setattr(idmap, dentry, attr);
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index dafff707e23a..e0e3d3ca0d45 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -8815,7 +8815,7 @@ nfsd4_get_writestateid(struct nfsd4_compound_state *cstate,
   /**
    * nfsd4_deleg_getattr_conflict - Recall if GETATTR causes conflict
    * @rqstp: RPC transaction context
- * @inode: file to be checked for a conflict
+ * @dentry: dentry of inode to be checked for a conflict
    * @modified: return true if file was modified
    * @size: new size of file if modified is true
    *
@@ -8830,7 +8830,7 @@ nfsd4_get_writestateid(struct nfsd4_compound_state *cstate,
    * code is returned.
    */
   __be32
-nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
+nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
   				bool *modified, u64 *size)
   {
   	__be32 status;
@@ -8840,6 +8840,7 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
   	struct nfs4_delegation *dp;
   	struct iattr attrs;
   	struct nfs4_cb_fattr *ncf;
+	struct inode *inode = d_inode(dentry);
   
   	*modified = false;
   	ctx = locks_inode_context(inode);
@@ -8887,15 +8888,22 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
   					ncf->ncf_cur_fsize != ncf->ncf_cb_fsize))
   				ncf->ncf_file_modified = true;
   			if (ncf->ncf_file_modified) {
+				int err;
+
   				/*
   				 * Per section 10.4.3 of RFC 8881, the server would
   				 * not update the file's metadata with the client's
   				 * modified size
   				 */
   				attrs.ia_mtime = attrs.ia_ctime = current_time(inode);
-				attrs.ia_valid = ATTR_MTIME | ATTR_CTIME;
-				setattr_copy(&nop_mnt_idmap, inode, &attrs);
-				mark_inode_dirty(inode);
+				attrs.ia_valid = ATTR_MTIME | ATTR_CTIME | ATTR_DELEG;
+				inode_lock(inode);
+				err = notify_change(&nop_mnt_idmap, dentry, &attrs, NULL);
+				inode_unlock(inode);
+				if (err) {
+					nfs4_put_stid(&dp->dl_stid);
+					return nfserrno(err);
+				}
   				ncf->ncf_cur_fsize = ncf->ncf_cb_fsize;
   				*size = ncf->ncf_cur_fsize;
   				*modified = true;
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 43ccf6119cf1..97f583777972 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3565,7 +3565,7 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr,
   	}
   	args.size = 0;
   	if (attrmask[0] & (FATTR4_WORD0_CHANGE | FATTR4_WORD0_SIZE)) {
-		status = nfsd4_deleg_getattr_conflict(rqstp, d_inode(dentry),
+		status = nfsd4_deleg_getattr_conflict(rqstp, dentry,
   					&file_modified, &size);
   		if (status)
   			goto out;
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index ffc217099d19..ec4559ecd193 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -781,5 +781,5 @@ static inline bool try_to_expire_client(struct nfs4_client *clp)
   }
   
   extern __be32 nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp,
-		struct inode *inode, bool *file_modified, u64 *size);
+		struct dentry *dentry, bool *file_modified, u64 *size);
   #endif   /* NFSD4_STATE_H */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0283cf366c2a..3fe289c74869 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -208,6 +208,7 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
   #define ATTR_OPEN	(1 << 15) /* Truncating from open(O_TRUNC) */
   #define ATTR_TIMES_SET	(1 << 16)
   #define ATTR_TOUCH	(1 << 17)
+#define ATTR_DELEG	(1 << 18) /* Delegated attrs (don't break) */
   
   /*
    * Whiteout is represented by a char device.  The following constants define the

---
base-commit: a204501e1743d695ca2930ed25a2be9f8ced96d3
change-id: 20240823-nfsd-fixes-61f0c785d125

Best regards,







