cifs: enable fscache usage even for files opened as rw

So far, the fscache implementation we had supports only
a small set of use cases. Particularly for files opened
with O_RDONLY.

This commit enables it even for rw based file opens. It
also enables the reuse of cached data in case of mount
option (cache=singleclient) where it is guaranteed that
this is the only client (and server) which operates on
the files. There's also a single line change in fscache.c
to get around a bug seen in fscache.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifsfs.c

@@ -399,7 +399,6 @@ cifs_evict_inode(struct inode *inode)
 {
 	truncate_inode_pages_final(&inode->i_data);
 	clear_inode(inode);
-	cifs_fscache_release_inode_cookie(inode);
 }
 
 static void

fs/cifs/cifssmb.c

@@ -2101,6 +2101,7 @@ cifs_writev_complete(struct work_struct *work)
 		else if (wdata->result < 0)
 			SetPageError(page);
 		end_page_writeback(page);
+		cifs_readpage_to_fscache(inode, page);
 		put_page(page);
 	}
 	if (wdata->result != -EAGAIN)

fs/cifs/file.c

@@ -377,6 +377,8 @@ static void cifsFileInfo_put_final(struct cifsFileInfo *cifs_file)
 	struct cifsLockInfo *li, *tmp;
 	struct super_block *sb = inode->i_sb;
 
+	cifs_fscache_release_inode_cookie(inode);
+
 	/*
 	 * Delete any outstanding lock records. We'll lose them when the file
 	 * is closed anyway.
@@ -882,8 +884,10 @@ int cifs_close(struct inode *inode, struct file *file)
 		if ((cinode->oplock == CIFS_CACHE_RHW_FLG) &&
 		    cinode->lease_granted &&
 		    dclose) {
-			if (test_bit(CIFS_INO_MODIFIED_ATTR, &cinode->flags))
+			if (test_bit(CIFS_INO_MODIFIED_ATTR, &cinode->flags)) {
 				inode->i_ctime = inode->i_mtime = current_time(inode);
+				cifs_fscache_update_inode_cookie(inode);
+			}
 			spin_lock(&cinode->deferred_lock);
 			cifs_add_deferred_close(cfile, dclose);
 			if (cfile->deferred_close_scheduled &&
@@ -4170,6 +4174,10 @@ static vm_fault_t
 cifs_page_mkwrite(struct vm_fault *vmf)
 {
 	struct page *page = vmf->page;
+	struct file *file = vmf->vma->vm_file;
+	struct inode *inode = file_inode(file);
+
+	cifs_fscache_wait_on_page_write(inode, page);
 
 	lock_page(page);
 	return VM_FAULT_LOCKED;
@@ -4235,13 +4243,16 @@ cifs_readv_complete(struct work_struct *work)
 		    (rdata->result == -EAGAIN && got_bytes)) {
 			flush_dcache_page(page);
 			SetPageUptodate(page);
-		}
+		} else
+			SetPageError(page);
 
 		unlock_page(page);
 
 		if (rdata->result == 0 ||
 		    (rdata->result == -EAGAIN && got_bytes))
 			cifs_readpage_to_fscache(rdata->mapping->host, page);
+		else
+			cifs_fscache_uncache_page(rdata->mapping->host, page);
 
 		got_bytes -= min_t(unsigned int, PAGE_SIZE, got_bytes);
 

fs/cifs/fscache.c

@@ -176,28 +176,33 @@ void cifs_fscache_release_inode_cookie(struct inode *inode)
 		auxdata.last_change_time_nsec = cifsi->vfs_inode.i_ctime.tv_nsec;
 
 		cifs_dbg(FYI, "%s: (0x%p)\n", __func__, cifsi->fscache);
+		/* fscache_relinquish_cookie does not seem to update auxdata */
+		fscache_update_cookie(cifsi->fscache, &auxdata);
 		fscache_relinquish_cookie(cifsi->fscache, &auxdata, false);
 		cifsi->fscache = NULL;
 	}
 }
 
-static void cifs_fscache_disable_inode_cookie(struct inode *inode)
+void cifs_fscache_update_inode_cookie(struct inode *inode)
 {
+	struct cifs_fscache_inode_auxdata auxdata;
 	struct cifsInodeInfo *cifsi = CIFS_I(inode);
 
 	if (cifsi->fscache) {
+		memset(&auxdata, 0, sizeof(auxdata));
+		auxdata.eof = cifsi->server_eof;
+		auxdata.last_write_time_sec = cifsi->vfs_inode.i_mtime.tv_sec;
+		auxdata.last_change_time_sec = cifsi->vfs_inode.i_ctime.tv_sec;
+		auxdata.last_write_time_nsec = cifsi->vfs_inode.i_mtime.tv_nsec;
+		auxdata.last_change_time_nsec = cifsi->vfs_inode.i_ctime.tv_nsec;
+
 		cifs_dbg(FYI, "%s: (0x%p)\n", __func__, cifsi->fscache);
-		fscache_uncache_all_inode_pages(cifsi->fscache, inode);
-		fscache_relinquish_cookie(cifsi->fscache, NULL, true);
-		cifsi->fscache = NULL;
+		fscache_update_cookie(cifsi->fscache, &auxdata);
 	}
 }
 
 void cifs_fscache_set_inode_cookie(struct inode *inode, struct file *filp)
 {
-	if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
-		cifs_fscache_disable_inode_cookie(inode);
-	else
 	cifs_fscache_enable_inode_cookie(inode);
 }
 
@@ -310,6 +315,8 @@ void __cifs_readpage_to_fscache(struct inode *inode, struct page *page)
 	struct cifsInodeInfo *cifsi = CIFS_I(inode);
 	int ret;
 
+	WARN_ON(!cifsi->fscache);
+
 	cifs_dbg(FYI, "%s: (fsc: %p, p: %p, i: %p)\n",
 		 __func__, cifsi->fscache, page, inode);
 	ret = fscache_write_page(cifsi->fscache, page,
@@ -334,3 +341,21 @@ void __cifs_fscache_invalidate_page(struct page *page, struct inode *inode)
 	fscache_wait_on_page_write(cookie, page);
 	fscache_uncache_page(cookie, page);
 }
+
+void __cifs_fscache_wait_on_page_write(struct inode *inode, struct page *page)
+{
+	struct cifsInodeInfo *cifsi = CIFS_I(inode);
+	struct fscache_cookie *cookie = cifsi->fscache;
+
+	cifs_dbg(FYI, "%s: (0x%p/0x%p)\n", __func__, page, cookie);
+	fscache_wait_on_page_write(cookie, page);
+}
+
+void __cifs_fscache_uncache_page(struct inode *inode, struct page *page)
+{
+	struct cifsInodeInfo *cifsi = CIFS_I(inode);
+	struct fscache_cookie *cookie = cifsi->fscache;
+
+	cifs_dbg(FYI, "%s: (0x%p/0x%p)\n", __func__, page, cookie);
+	fscache_uncache_page(cookie, page);
+}

fs/cifs/fscache.h

@@ -55,10 +55,13 @@ extern void cifs_fscache_get_super_cookie(struct cifs_tcon *);
 extern void cifs_fscache_release_super_cookie(struct cifs_tcon *);
 
 extern void cifs_fscache_release_inode_cookie(struct inode *);
+extern void cifs_fscache_update_inode_cookie(struct inode *inode);
 extern void cifs_fscache_set_inode_cookie(struct inode *, struct file *);
 extern void cifs_fscache_reset_inode_cookie(struct inode *);
 
 extern void __cifs_fscache_invalidate_page(struct page *, struct inode *);
+extern void __cifs_fscache_wait_on_page_write(struct inode *inode, struct page *page);
+extern void __cifs_fscache_uncache_page(struct inode *inode, struct page *page);
 extern int cifs_fscache_release_page(struct page *page, gfp_t gfp);
 extern int __cifs_readpage_from_fscache(struct inode *, struct page *);
 extern int __cifs_readpages_from_fscache(struct inode *,
@@ -76,6 +79,20 @@ static inline void cifs_fscache_invalidate_page(struct page *page,
 		__cifs_fscache_invalidate_page(page, inode);
 }
 
+static inline void cifs_fscache_wait_on_page_write(struct inode *inode,
+						   struct page *page)
+{
+	if (PageFsCache(page))
+		__cifs_fscache_wait_on_page_write(inode, page);
+}
+
+static inline void cifs_fscache_uncache_page(struct inode *inode,
+						   struct page *page)
+{
+	if (PageFsCache(page))
+		__cifs_fscache_uncache_page(inode, page);
+}
+
 static inline int cifs_readpage_from_fscache(struct inode *inode,
 					     struct page *page)
 {
@@ -123,6 +140,7 @@ static inline void
 cifs_fscache_release_super_cookie(struct cifs_tcon *tcon) {}
 
 static inline void cifs_fscache_release_inode_cookie(struct inode *inode) {}
+static inline void cifs_fscache_update_inode_cookie(struct inode *inode) {}
 static inline void cifs_fscache_set_inode_cookie(struct inode *inode,
 						 struct file *filp) {}
 static inline void cifs_fscache_reset_inode_cookie(struct inode *inode) {}
@@ -133,6 +151,11 @@ static inline int cifs_fscache_release_page(struct page *page, gfp_t gfp)
 
 static inline void cifs_fscache_invalidate_page(struct page *page,
 			struct inode *inode) {}
+static inline void cifs_fscache_wait_on_page_write(struct inode *inode,
+						   struct page *page) {}
+static inline void cifs_fscache_uncache_page(struct inode *inode,
+						   struct page *page) {}
+
 static inline int
 cifs_readpage_from_fscache(struct inode *inode, struct page *page)
 {

fs/cifs/inode.c

@@ -2297,6 +2297,7 @@ cifs_revalidate_mapping(struct inode *inode)
 {
 	int rc;
 	unsigned long *flags = &CIFS_I(inode)->flags;
+	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 
 	/* swapfiles are not supposed to be shared */
 	if (IS_SWAPFILE(inode))
@@ -2308,11 +2309,16 @@ cifs_revalidate_mapping(struct inode *inode)
 		return rc;
 
 	if (test_and_clear_bit(CIFS_INO_INVALID_MAPPING, flags)) {
+		/* for cache=singleclient, do not invalidate */
+		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RW_CACHE)
+			goto skip_invalidate;
+
 		rc = cifs_invalidate_mapping(inode);
 		if (rc)
 			set_bit(CIFS_INO_INVALID_MAPPING, flags);
 	}
 
+skip_invalidate:
 	clear_bit_unlock(CIFS_INO_LOCK, flags);
 	smp_mb__after_atomic();
 	wake_up_bit(flags, CIFS_INO_LOCK);