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authorSteve French <smfrench@gmail.com>2014-08-11 21:05:25 -0500
committerSteve French <smfrench@gmail.com>2014-08-13 13:18:35 -0500
commit3d1a3745d8ca7ccdf00905b01fd5ab42ff523a94 (patch)
tree17ba01e56cbf7238e5ce59967f1e073da95b885b /fs/cifs/smb2pdu.c
parent8ae31240ccc8ff339101e2d023b82cb7c93dd002 (diff)
Add sparse file support to SMB2/SMB3 mounts
Many Linux filesystes make a file "sparse" when extending a file with ftruncate. This does work for CIFS to Samba (only) but not for SMB2/SMB3 (to Samba or Windows) since there is a "set sparse" fsctl which is supposed to be sent to mark a file as sparse. This patch marks a file as sparse by sending this simple set sparse fsctl if it is extended more than 2 pages. It has been tested to Windows 8.1, Samba and various SMB2/SMB3 servers which do support setting sparse (and MacOS which does not appear to support the fsctl yet). If a server share does not support setting a file as sparse, then we do not retry setting sparse on that share. The disk space savings for sparse files can be quite large (even more significant on Windows servers than Samba). Signed-off-by: Steve French <smfrench@gmail.com> Reviewed-by: Shirish Pargaonkar <spargaonkar@suse.com>
Diffstat (limited to 'fs/cifs/smb2pdu.c')
-rw-r--r--fs/cifs/smb2pdu.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 42ebc1a8be6c..74440af59f35 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -1224,7 +1224,9 @@ SMB2_ioctl(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
cifs_dbg(FYI, "SMB2 IOCTL\n");
- *out_data = NULL;
+ if (out_data != NULL)
+ *out_data = NULL;
+
/* zero out returned data len, in case of error */
if (plen)
*plen = 0;