[RFC PATCH 27/35] netfs: Pass extra write context to write functions

[David Howells <dhowells@redhat.com>]

Allow the filesystem to pass in an extra bit of context to certain write
functions so that netfs_page_mkwrite() and netfs_perform_write() can pass
it back to the filesystem's ->post_modify() function.

This can be used by ceph to pass in a preallocated ceph_cap_flush record.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Viacheslav Dubeyko <slava@dubeyko.com>
cc: Alex Markuze <amarkuze@redhat.com>
cc: Xiubo Li <xiubli@redhat.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: ceph-devel@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
---
 fs/9p/vfs_file.c          |  2 +-
 fs/afs/write.c            |  2 +-
 fs/netfs/buffered_write.c | 21 ++++++++++++---------
 fs/smb/client/file.c      |  4 ++--
 include/linux/netfs.h     |  9 +++++----
 5 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 348cc90bf9c5..838332d5372c 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -477,7 +477,7 @@ v9fs_file_mmap(struct file *filp, struct vm_area_struct *vma)
 static vm_fault_t
 v9fs_vm_page_mkwrite(struct vm_fault *vmf)
 {
-	return netfs_page_mkwrite(vmf, NULL);
+	return netfs_page_mkwrite(vmf, NULL, NULL);
 }
 
 static void v9fs_mmap_vm_close(struct vm_area_struct *vma)
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 18b0a9f1615e..054f3a07d2a5 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -276,7 +276,7 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 
 	if (afs_validate(AFS_FS_I(file_inode(file)), afs_file_key(file)) < 0)
 		return VM_FAULT_SIGBUS;
-	return netfs_page_mkwrite(vmf, NULL);
+	return netfs_page_mkwrite(vmf, NULL, NULL);
 }
 
 /*
diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
index f3370846ba18..0245449b93e3 100644
--- a/fs/netfs/buffered_write.c
+++ b/fs/netfs/buffered_write.c
@@ -86,7 +86,8 @@ static void netfs_update_i_size(struct netfs_inode *ctx, struct inode *inode,
  * netfs_perform_write - Copy data into the pagecache.
  * @iocb: The operation parameters
  * @iter: The source buffer
- * @netfs_group: Grouping for dirty folios (eg. ceph snaps).
+ * @netfs_group: Grouping for dirty folios (eg. ceph snaps)
+ * @fs_priv: Private data to be passed to ->post_modify()
  *
  * Copy data into pagecache folios attached to the inode specified by @iocb.
  * The caller must hold appropriate inode locks.
@@ -97,7 +98,7 @@ static void netfs_update_i_size(struct netfs_inode *ctx, struct inode *inode,
  * a new one is started.
  */
 ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
-			    struct netfs_group *netfs_group)
+			    struct netfs_group *netfs_group, void *fs_priv)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file_inode(file);
@@ -382,7 +383,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 		 */
 		set_bit(NETFS_ICTX_MODIFIED_ATTR, &ctx->flags);
 		if (unlikely(ctx->ops->post_modify))
-			ctx->ops->post_modify(inode);
+			ctx->ops->post_modify(inode, fs_priv);
 	}
 
 	if (unlikely(wreq)) {
@@ -411,7 +412,8 @@ EXPORT_SYMBOL(netfs_perform_write);
  * netfs_buffered_write_iter_locked - write data to a file
  * @iocb:	IO state structure (file, offset, etc.)
  * @from:	iov_iter with data to write
- * @netfs_group: Grouping for dirty folios (eg. ceph snaps).
+ * @netfs_group: Grouping for dirty folios (eg. ceph snaps)
+ * @fs_priv: Private data to be passed to ->post_modify()
  *
  * This function does all the work needed for actually writing data to a
  * file. It does all basic checks, removes SUID from the file, updates
@@ -431,7 +433,7 @@ EXPORT_SYMBOL(netfs_perform_write);
  * * negative error code if no data has been written at all
  */
 ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,
-					 struct netfs_group *netfs_group)
+					 struct netfs_group *netfs_group, void *fs_priv)
 {
 	struct file *file = iocb->ki_filp;
 	ssize_t ret;
@@ -446,7 +448,7 @@ ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *fr
 	if (ret)
 		return ret;
 
-	return netfs_perform_write(iocb, from, netfs_group);
+	return netfs_perform_write(iocb, from, netfs_group, fs_priv);
 }
 EXPORT_SYMBOL(netfs_buffered_write_iter_locked);
 
@@ -485,7 +487,7 @@ ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 
 	ret = generic_write_checks(iocb, from);
 	if (ret > 0)
-		ret = netfs_buffered_write_iter_locked(iocb, from, NULL);
+		ret = netfs_buffered_write_iter_locked(iocb, from, NULL, NULL);
 	netfs_end_io_write(inode);
 	if (ret > 0)
 		ret = generic_write_sync(iocb, ret);
@@ -499,7 +501,8 @@ EXPORT_SYMBOL(netfs_file_write_iter);
  * we only track group on a per-folio basis, so we block more often than
  * we might otherwise.
  */
-vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group)
+vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group,
+			      void *fs_priv)
 {
 	struct netfs_group *group;
 	struct folio *folio = page_folio(vmf->page);
@@ -554,7 +557,7 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr
 	file_update_time(file);
 	set_bit(NETFS_ICTX_MODIFIED_ATTR, &ictx->flags);
 	if (ictx->ops->post_modify)
-		ictx->ops->post_modify(inode);
+		ictx->ops->post_modify(inode, fs_priv);
 	ret = VM_FAULT_LOCKED;
 out:
 	sb_end_pagefault(inode->i_sb);
diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index 8582cf61242c..4329c2bbf74f 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -2779,7 +2779,7 @@ cifs_writev(struct kiocb *iocb, struct iov_iter *from)
 		goto out;
 	}
 
-	rc = netfs_buffered_write_iter_locked(iocb, from, NULL);
+	rc = netfs_buffered_write_iter_locked(iocb, from, NULL, NULL);
 
 out:
 	up_read(&cinode->lock_sem);
@@ -2955,7 +2955,7 @@ cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to)
 
 static vm_fault_t cifs_page_mkwrite(struct vm_fault *vmf)
 {
-	return netfs_page_mkwrite(vmf, NULL);
+	return netfs_page_mkwrite(vmf, NULL, NULL);
 }
 
 static const struct vm_operations_struct cifs_file_vm_ops = {
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index ec1c51697c04..a67297de8a20 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -335,7 +335,7 @@ struct netfs_request_ops {
 
 	/* Modification handling */
 	void (*update_i_size)(struct inode *inode, loff_t i_size);
-	void (*post_modify)(struct inode *inode);
+	void (*post_modify)(struct inode *inode, void *fs_priv);
 
 	/* Write request handling */
 	void (*begin_writeback)(struct netfs_io_request *wreq);
@@ -435,9 +435,9 @@ ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 
 /* High-level write API */
 ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
-			    struct netfs_group *netfs_group);
+			    struct netfs_group *netfs_group, void *fs_priv);
 ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,
-					 struct netfs_group *netfs_group);
+					 struct netfs_group *netfs_group, void *fs_priv);
 ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from);
 ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,
 					   struct netfs_group *netfs_group);
@@ -466,7 +466,8 @@ void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length);
 bool netfs_release_folio(struct folio *folio, gfp_t gfp);
 
 /* VMA operations API. */
-vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group);
+vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group,
+			      void *fs_priv);
 
 /* (Sub)request management API. */
 void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq);