cifs: add support for fallocate mode 0 for non-sparse files

RHBZ 1336264

When we extend a file we must also force the size to be updated.

This fixes an issue with holetest in xfs-tests which performs the following
sequence :
1, create a new file
2, use fallocate mode==0 to populate the file
3, mmap the file
4, touch each page by reading the mmapped region.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifsfs.h

@@ -149,6 +149,9 @@ extern ssize_t cifs_file_copychunk_range(unsigned int xid,
 					size_t len, unsigned int flags);
 
 extern long cifs_ioctl(struct file *filep, unsigned int cmd, unsigned long arg);
+extern void cifs_setsize(struct inode *inode, loff_t offset);
+extern int cifs_truncate_page(struct address_space *mapping, loff_t from);
+
 #ifdef CONFIG_CIFS_NFSD_EXPORT
 extern const struct export_operations cifs_export_ops;
 #endif /* CONFIG_CIFS_NFSD_EXPORT */

fs/cifs/inode.c

@@ -2228,7 +2228,7 @@ int cifs_fiemap(struct inode *inode, struct fiemap_extent_info *fei, u64 start,
 	return -ENOTSUPP;
 }
 
-static int cifs_truncate_page(struct address_space *mapping, loff_t from)
+int cifs_truncate_page(struct address_space *mapping, loff_t from)
 {
 	pgoff_t index = from >> PAGE_SHIFT;
 	unsigned offset = from & (PAGE_SIZE - 1);
@@ -2245,7 +2245,7 @@ static int cifs_truncate_page(struct address_space *mapping, loff_t from)
 	return rc;
 }
 
-static void cifs_setsize(struct inode *inode, loff_t offset)
+void cifs_setsize(struct inode *inode, loff_t offset)
 {
 	struct cifsInodeInfo *cifs_i = CIFS_I(inode);
 

fs/cifs/smb2ops.c

@@ -12,6 +12,7 @@
 #include <linux/uuid.h>
 #include <linux/sort.h>
 #include <crypto/aead.h>
+#include "cifsfs.h"
 #include "cifsglob.h"
 #include "smb2pdu.h"
 #include "smb2proto.h"
@@ -3171,29 +3172,33 @@ static long smb3_simple_falloc(struct file *file, struct cifs_tcon *tcon,
 			return rc;
 		}
 
+	/*
+	 * Extending the file
+	 */
+	if ((keep_size == false) && i_size_read(inode) < off + len) {
+		if ((cifsi->cifsAttrs & FILE_ATTRIBUTE_SPARSE_FILE) == 0)
+			smb2_set_sparse(xid, tcon, cfile, inode, false);
+
+		eof = cpu_to_le64(off + len);
+		rc = SMB2_set_eof(xid, tcon, cfile->fid.persistent_fid,
+				  cfile->fid.volatile_fid, cfile->pid, &eof);
+		if (rc == 0) {
+			cifsi->server_eof = off + len;
+			cifs_setsize(inode, off + len);
+			cifs_truncate_page(inode->i_mapping, inode->i_size);
+			truncate_setsize(inode, off + len);
+		}
+		goto out;
+	}
+
 	/*
 	 * Files are non-sparse by default so falloc may be a no-op
-	 * Must check if file sparse. If not sparse, and not extending
-	 * then no need to do anything since file already allocated
+	 * Must check if file sparse. If not sparse, and since we are not
+	 * extending then no need to do anything since file already allocated
 	 */
 	if ((cifsi->cifsAttrs & FILE_ATTRIBUTE_SPARSE_FILE) == 0) {
-		if (keep_size == true)
-			rc = 0;
-		/* check if extending file */
-		else if (i_size_read(inode) >= off + len)
-			/* not extending file and already not sparse */
-			rc = 0;
-		/* BB: in future add else clause to extend file */
-		else
-			rc = -EOPNOTSUPP;
-		if (rc)
-			trace_smb3_falloc_err(xid, cfile->fid.persistent_fid,
-				tcon->tid, tcon->ses->Suid, off, len, rc);
-		else
-			trace_smb3_falloc_done(xid, cfile->fid.persistent_fid,
-				tcon->tid, tcon->ses->Suid, off, len);
-		free_xid(xid);
-		return rc;
+		rc = 0;
+		goto out;
 	}
 
 	if ((keep_size == true) || (i_size_read(inode) >= off + len)) {
@@ -3207,25 +3212,14 @@ static long smb3_simple_falloc(struct file *file, struct cifs_tcon *tcon,
 		 */
 		if ((off > 8192) || (off + len + 8192 < i_size_read(inode))) {
 			rc = -EOPNOTSUPP;
-			trace_smb3_falloc_err(xid, cfile->fid.persistent_fid,
-				tcon->tid, tcon->ses->Suid, off, len, rc);
-			free_xid(xid);
-			return rc;
-		}
-
-		smb2_set_sparse(xid, tcon, cfile, inode, false);
-		rc = 0;
-	} else {
-		smb2_set_sparse(xid, tcon, cfile, inode, false);
-		rc = 0;
-		if (i_size_read(inode) < off + len) {
-			eof = cpu_to_le64(off + len);
-			rc = SMB2_set_eof(xid, tcon, cfile->fid.persistent_fid,
-					  cfile->fid.volatile_fid, cfile->pid,
-					  &eof);
+			goto out;
 		}
 	}
 
+	smb2_set_sparse(xid, tcon, cfile, inode, false);
+	rc = 0;
+
+out:
 	if (rc)
 		trace_smb3_falloc_err(xid, cfile->fid.persistent_fid, tcon->tid,
 				tcon->ses->Suid, off, len, rc);