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cifs: Rough, incomplete conversion to new fscache API

PATCH New David Howells 1 participant 1 message Nov 18, 2020

Subsystems (3)
VFS SMB client (CIFS) Kernel SMB3 server (ksmbd)
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David Howells

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PATCH 1/1 cifs: Rough, incomplete conversion to new fscache API

Hi Steve,

Here's a rough, but incomplete, conversion of cifs to use the new fscache API, but I've about hit the limit of what I can manage to do. It's built on top of my fscache-iter branch:

https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache-iter

Notes:

(*) I've replaced some code to discard data by reading into a big buffer with
code that uses the ITER_DISCARD iterator instead. See cifs_discard_from_socket().

(*) I've tried to make the ordinary read use an ITER_XARRAY iterator and read
into that directly from the socket, rather than looping through a bunch of pages. This will handle THPs and partial pages for you. However, under some circumstances, readpages_fill_pages() would then be reading from an iterator to an iterator, it appears. Possibly the source iterator can be got rid of, but the code is quite complex.

(*) There's a new function, cifs_req_issue_op(), which the netfs helpers use
to issue a read on part of a request. This looks at current->tgid, but might be running on a workqueue, so needs to get the tgid from somewhere else if not CIFS_MOUNT_RWPIDFORWARD.

(*) cifs_readpage(), cifs_readahead() and cifs_write_begin() now go through
the helpers. cifs_readpages() is obsolete and is removed.

(*) At the completion of a read, netfs_subreq_terminated() is called. As a
future optimisation, we can add a function to do incremental advancement of the pages, unlocking them as we go. The issue is, however, that we have to coordinate with writing larger page lumps to the cache.

(*) The clause in cifs_write_begin() about optimising away a read when we
have an oplock needs dealing with, but I'm not sure how to fit it in.

(*) cifs_writepages() needs to call fscache_write_to_cache() to write to the
cache.

(*) cifs_write_inode() needs to call fscache_unpin_writeback().

David
---

fs/cifs/Kconfig +1 -1
index 441f24bff49c..35aa8324d3dd 100644
@@ -206,7 +206,7 @@ config CIFS_SMB_DIRECT
 
 config CIFS_FSCACHE
 	bool "Provide CIFS client caching support"
-	depends on CIFS=m && FSCACHE_OLD || CIFS=y && FSCACHE_OLD=y
+	depends on CIFS=m || CIFS=y
 	help
 	  Makes CIFS FS-Cache capable. Say Y here if you want your CIFS data
 	  to be cached locally on disk through the general filesystem cache
fs/cifs/cache.c +0 -95

98 lines not on this page · raw message

fs/cifs/cifsfs.c +2 -0
index 472cb7777e3e..e203c7fb9dc4 100644
@@ -372,6 +372,8 @@ static void
 cifs_evict_inode(struct inode *inode)
 {
 	truncate_inode_pages_final(&inode->i_data);
+	if (inode->i_state & I_PINNING_FSCACHE_WB)
+		cifs_fscache_unuse_inode_cookie(inode, true);
 	clear_inode(inode);
 	cifs_fscache_release_inode_cookie(inode);
 }
fs/cifs/cifsglob.h +2 -0
index 484ec2d8c5c9..02392a7cd442 100644
@@ -1367,6 +1367,7 @@ struct cifs_readdata;
 
 /* asynchronous read support */
 struct cifs_readdata {
+	struct netfs_read_subrequest	*subreq;
 	struct kref			refcount;
 	struct list_head		list;
 	struct completion		done;

@@ -1385,6 +1386,7 @@ struct cifs_readdata {
 	int (*copy_into_pages)(struct TCP_Server_Info *server,
 				struct cifs_readdata *rdata,
 				struct iov_iter *iter);
+	struct iov_iter			iter;
 	struct kvec			iov[2];
 	struct TCP_Server_Info		*server;
 #ifdef CONFIG_CIFS_SMB_DIRECT
fs/cifs/cifsproto.h +5 -0
index 24c6f36177ba..c5504ef0f356 100644
@@ -230,10 +230,15 @@ extern unsigned int setup_special_user_owner_ACE(struct cifs_ace *pace);
 extern void dequeue_mid(struct mid_q_entry *mid, bool malformed);
 extern int cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
 			         unsigned int to_read);
+extern ssize_t cifs_discard_from_socket(struct TCP_Server_Info *server,
+					size_t to_read);
 extern int cifs_read_page_from_socket(struct TCP_Server_Info *server,
 					struct page *page,
 					unsigned int page_offset,
 					unsigned int to_read);
+extern int cifs_read_iter_from_socket(struct TCP_Server_Info *server,
+				      struct iov_iter *iter,
+				      unsigned int to_read);
 extern int cifs_setup_cifs_sb(struct smb_vol *pvolume_info,
 			       struct cifs_sb_info *cifs_sb);
 extern int cifs_match_super(struct super_block *, void *);
fs/cifs/cifssmb.c +14 -6
index 0496934feecb..671afc822afc 100644
@@ -36,6 +36,7 @@
 #include <linux/swap.h>
 #include <linux/task_io_accounting_ops.h>
 #include <linux/uaccess.h>
+#include <linux/netfs.h>
 #include "cifspdu.h"
 #include "cifsglob.h"
 #include "cifsacl.h"

@@ -1445,15 +1446,15 @@ int
 cifs_discard_remaining_data(struct TCP_Server_Info *server)
 {
 	unsigned int rfclen = server->pdu_size;
-	int remaining = rfclen + server->vals->header_preamble_size -
+	size_t remaining = rfclen + server->vals->header_preamble_size -
 		server->total_read;
 
 	while (remaining > 0) {
-		int length;
+		ssize_t length;
 
-		length = cifs_read_from_socket(server, server->bigbuf,
-				min_t(unsigned int, remaining,
-				    CIFSMaxBufSize + MAX_HEADER_SIZE(server)));
+		length = cifs_discard_from_socket(server,
+				min_t(size_t, remaining,
+				      CIFSMaxBufSize + MAX_HEADER_SIZE(server)));
 		if (length < 0)
 			return length;
 		server->total_read += length;

@@ -1664,7 +1665,14 @@ cifs_readv_callback(struct mid_q_entry *mid)
 		rdata->result = -EIO;
 	}
 
-	queue_work(cifsiod_wq, &rdata->work);
+	if (rdata->subreq) {
+		netfs_subreq_terminated(rdata->subreq,
+					(rdata->result == 0 || rdata->result == -EAGAIN) ?
+					rdata->got_bytes : rdata->result);
+		kref_put(&rdata->refcount, cifs_readdata_release);
+	} else {
+		queue_work(cifsiod_wq, &rdata->work);
+	}
 	DeleteMidQEntry(mid);
 	add_credits(server, &credits, 0);
 }
fs/cifs/connect.c +25 -0
index c38156f324dd..7dffc05e892d 100644
@@ -754,6 +754,15 @@ cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
 	return cifs_readv_from_socket(server, &smb_msg);
 }
 
+ssize_t
+cifs_discard_from_socket(struct TCP_Server_Info *server, size_t to_read)
+{
+	struct msghdr smb_msg;
+	iov_iter_discard(&smb_msg.msg_iter, READ, to_read);
+
+	return cifs_readv_from_socket(server, &smb_msg);
+}
+
 int
 cifs_read_page_from_socket(struct TCP_Server_Info *server, struct page *page,
 	unsigned int page_offset, unsigned int to_read)

@@ -765,6 +774,22 @@ cifs_read_page_from_socket(struct TCP_Server_Info *server, struct page *page,
 	return cifs_readv_from_socket(server, &smb_msg);
 }
 
+int
+cifs_read_iter_from_socket(struct TCP_Server_Info *server, struct iov_iter *iter,
+			   unsigned int to_read)
+{
+	struct msghdr smb_msg;
+	int ret;
+
+	smb_msg.msg_iter = *iter;
+	if (smb_msg.msg_iter.count > to_read)
+		smb_msg.msg_iter.count = to_read;
+	ret = cifs_readv_from_socket(server, &smb_msg);
+	if (ret > 0)
+		iov_iter_advance(iter, ret);
+	return ret;
+}
+
 static bool
 is_smb_response(struct TCP_Server_Info *server, unsigned char type)
 {
fs/cifs/file.c +199 -417

778 lines not on this page · raw message

fs/cifs/fscache.c +52 -204

307 lines not on this page · raw message

fs/cifs/fscache.h +21 -89

140 lines not on this page · raw message

fs/cifs/inode.c +11 -7
index 9ee5f304592f..6232e3e630c7 100644
@@ -1316,10 +1316,7 @@ cifs_iget(struct super_block *sb, struct cifs_fattr *fattr)
 			inode->i_flags |= S_NOATIME | S_NOCMTIME;
 		if (inode->i_state & I_NEW) {
 			inode->i_ino = hash;
-#ifdef CONFIG_CIFS_FSCACHE
-			/* initialize per-inode cache cookie pointer */
-			CIFS_I(inode)->fscache = NULL;
-#endif
+			cifs_fscache_get_inode_cookie(inode);
 			unlock_new_inode(inode);
 		}
 	}

@@ -2213,6 +2210,8 @@ cifs_inode_needs_reval(struct inode *inode)
 int
 cifs_invalidate_mapping(struct inode *inode)
 {
+	struct cifs_fscache_inode_auxdata auxdata;
+	struct cifsInodeInfo *cifsi = CIFS_I(inode);
 	int rc = 0;
 
 	if (inode->i_mapping && inode->i_mapping->nrpages != 0) {

@@ -2222,7 +2221,8 @@ cifs_invalidate_mapping(struct inode *inode)
 				 __func__, inode);
 	}
 
-	cifs_fscache_reset_inode_cookie(inode);
+	cifs_fscache_fill_auxdata(&cifsi->vfs_inode, &auxdata);
+	fscache_invalidate(cifs_inode_cookie(inode), &auxdata, i_size_read(inode), 0);
 	return rc;
 }
 

@@ -2704,8 +2704,10 @@ cifs_setattr_unix(struct dentry *direntry, struct iattr *attrs)
 		goto out;
 
 	if ((attrs->ia_valid & ATTR_SIZE) &&
-	    attrs->ia_size != i_size_read(inode))
+	    attrs->ia_size != i_size_read(inode)) {
 		truncate_setsize(inode, attrs->ia_size);
+		fscache_resize_cookie(cifs_inode_cookie(inode), attrs->ia_size);
+	}
 
 	setattr_copy(inode, attrs);
 	mark_inode_dirty(inode);

@@ -2894,8 +2896,10 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs)
 		goto cifs_setattr_exit;
 
 	if ((attrs->ia_valid & ATTR_SIZE) &&
-	    attrs->ia_size != i_size_read(inode))
+	    attrs->ia_size != i_size_read(inode)) {
 		truncate_setsize(inode, attrs->ia_size);
+		fscache_resize_cookie(cifs_inode_cookie(inode), attrs->ia_size); 
+	}
 
 	setattr_copy(inode, attrs);
 	mark_inode_dirty(inode);
fs/cifs/smb2pdu.c +9 -1
index 445e80862865..42988b6318d6 100644
@@ -36,6 +36,7 @@
 #include <linux/uuid.h>
 #include <linux/pagemap.h>
 #include <linux/xattr.h>
+#include <linux/netfs.h>
 #include "smb2pdu.h"
 #include "cifsglob.h"
 #include "cifsacl.h"

@@ -3975,7 +3976,14 @@ smb2_readv_callback(struct mid_q_entry *mid)
 				     tcon->tid, tcon->ses->Suid,
 				     rdata->offset, rdata->got_bytes);
 
-	queue_work(cifsiod_wq, &rdata->work);
+	if (rdata->subreq) {
+		netfs_subreq_terminated(rdata->subreq,
+					(rdata->result == 0 || rdata->result == -EAGAIN) ?
+					rdata->got_bytes : rdata->result);
+		kref_put(&rdata->refcount, cifs_readdata_release);
+	} else {
+		queue_work(cifsiod_wq, &rdata->work);
+	}
 	DeleteMidQEntry(mid);
 	add_credits(server, &credits, 0);
 }