1 files changed, 62 insertions, 1 deletions

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index c5f521bcdee2..568f323665c8 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -1102,6 +1102,64 @@ static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon,
         return rc;
 }
 
+static long smb3_simple_falloc(struct file *file, struct cifs_tcon *tcon,
+                            loff_t off, loff_t len, bool keep_size)
+{
+        struct inode *inode;
+        struct cifsInodeInfo *cifsi;
+        struct cifsFileInfo *cfile = file->private_data;
+        long rc = -EOPNOTSUPP;
+        unsigned int xid;
+
+        xid = get_xid();
+
+        inode = cfile->dentry->d_inode;
+        cifsi = CIFS_I(inode);
+
+        /* if file not oplocked can't be sure whether asking to extend size */
+        if (!CIFS_CACHE_READ(cifsi))
+                if (keep_size == false)
+                        return -EOPNOTSUPP;
+
+        /*
+         * 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
+         */
+        if ((cifsi->cifsAttrs & FILE_ATTRIBUTE_SPARSE_FILE) == 0) {
+                if (keep_size == true)
+                        return 0;
+                /* check if extending file */
+                else if (i_size_read(inode) >= off + len)
+                        /* not extending file and already not sparse */
+                        return 0;
+                /* BB: in future add else clause to extend file */
+                else
+                        return -EOPNOTSUPP;
+        }
+
+        if ((keep_size == true) || (i_size_read(inode) >= off + len)) {
+                /*
+                 * Check if falloc starts within first few pages of file
+                 * and ends within a few pages of the end of file to
+                 * ensure that most of file is being forced to be
+                 * fallocated now. If so then setting whole file sparse
+                 * ie potentially making a few extra pages at the beginning
+                 * or end of the file non-sparse via set_sparse is harmless.
+                 */
+                if ((off > 8192) || (off + len + 8192 < i_size_read(inode)))
+                        return -EOPNOTSUPP;
+
+                rc = smb2_set_sparse(xid, tcon, cfile, inode, false);
+        }
+        /* BB: else ... in future add code to extend file and set sparse */
+
+
+        free_xid(xid);
+        return rc;
+}
+
+
 static long smb3_fallocate(struct file *file, struct cifs_tcon *tcon, int mode,
                            loff_t off, loff_t len)
 {
@@ -1112,7 +1170,10 @@ static long smb3_fallocate(struct file *file, struct cifs_tcon *tcon, int mode,
                 if (mode & FALLOC_FL_KEEP_SIZE)
                         return smb3_zero_range(file, tcon, off, len, true);
                 return smb3_zero_range(file, tcon, off, len, false);
-        }
+        } else if (mode == FALLOC_FL_KEEP_SIZE)
+                return smb3_simple_falloc(file, tcon, off, len, true);
+        else if (mode == 0)
+                return smb3_simple_falloc(file, tcon, off, len, false);
 
         return -EOPNOTSUPP;
 }