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authorSteve French <sfrench@us.ibm.com>2009-11-24 22:49:37 +0000
committerSteve French <sfrench@us.ibm.com>2009-11-24 22:52:13 +0000
commitcea62343956c24452700c06cf028b72414c58a74 (patch)
tree961d032aa0d020eaecf04c8be149d96efc17003f /fs
parent8e6c0332d5032aef2d3bc8f41771f999112c8c66 (diff)
[CIFS] Duplicate data on appending to some Samba servers
SMB writes are sent with a starting offset and length. When the server supports the newer SMB trans2 posix open (rather than using the SMB NTCreateX) a file can be opened with SMB_O_APPEND flag, and for that case Samba server assumes that the offset sent in SMBWriteX is unneeded since the write should go to the end of the file - which can cause problems if the write was cached (since the beginning part of a page could be written twice by the client mm). Jeff suggested that masking the flag on posix open on the client is easiest for the time being. Note that recent Samba server also had an unrelated problem with SMB NTCreateX and append (see samba bugzilla bug number 6898) which should not affect current Linux clients (unless cifs Unix Extensions are disabled). The cifs client did not send the O_APPEND flag on posix open before 2.6.29 so the fix is unneeded on early kernels. In the future, for the non-cached case (O_DIRECT, and forcedirectio mounts) it would be possible and useful to send O_APPEND on posix open (for Windows case: FILE_APPEND_DATA but not FILE_WRITE_DATA on SMB NTCreateX) but for cached writes although the vfs sets the offset to end of file it may fragment a write across pages - so we can't send O_APPEND on open (could result in sending part of a page twice). CC: Stable <stable@kernel.org> Reviewed-by: Shirish Pargaonkar <shirishp@us.ibm.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <sfrench@us.ibm.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/cifs/dir.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 32771f581b6..d3a6b07e335 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -214,8 +214,6 @@ int cifs_posix_open(char *full_path, struct inode **pinode,
posix_flags |= SMB_O_EXCL;
if (oflags & O_TRUNC)
posix_flags |= SMB_O_TRUNC;
- if (oflags & O_APPEND)
- posix_flags |= SMB_O_APPEND;
if (oflags & O_SYNC)
posix_flags |= SMB_O_SYNC;
if (oflags & O_DIRECTORY)