[SMB3] Add mfsymlinks support for SMB2.1/SMB3. Part 1 create symlink

Commit Message

Steve French Sept. 16, 2014, 5:52 a.m. UTC

Resending patch series as attachments to avoid mailer issues



On Mon, Sep 15, 2014 at 1:39 PM, Steve French <[e-mail]> wrote:
> Adds support on SMB2.1 and SMB3 mounts for emulation of symlinks
> via the "Minshall/French" symlink format already used for cifs
> mounts when mfsymlinks mount option is used (and also used by Apple).
> http://wiki.samba.org/index.php/UNIX_Extensions#Minshall.2BFrench_symlinks
> This first patch adds support to create them.  The next patch will
> add support for recognizing them and reading them.  Although CIFS/SMB3
> have other types of symlinks, in the many use cases they aren't
> practical (e.g. either require cifs only mounts with unix extensions
> to Samba, or require the user to be Administrator to Windows for SMB3).
> This also helps enable running additional xfstests over SMB3 (since some
> xfstests directly or indirectly require symlink support).
>
> Signed-off-by: Steve French <[e-mail]>
> CC: Stefan Metzmacher <[e-mail]>
> ---
>  fs/cifs/link.c      | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  fs/cifs/smb2ops.c   |  2 ++
>  fs/cifs/smb2proto.h |  4 +++-
>  3 files changed, 68 insertions(+), 1 deletion(-)
>
> diff --git a/fs/cifs/link.c b/fs/cifs/link.c
> index a5c2812..11657f6 100644
> --- a/fs/cifs/link.c
> +++ b/fs/cifs/link.c
> @@ -28,6 +28,7 @@
>  #include "cifsproto.h"
>  #include "cifs_debug.h"
>  #include "cifs_fs_sb.h"
> +#include "smb2proto.h"
>
>  /*
>   * M-F Symlink Functions - Begin
> @@ -398,6 +399,68 @@ cifs_create_mf_symlink(unsigned int xid, struct
> cifs_tcon *tcon,
>      return rc;
>  }
>
> +int
> +smb3_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
> +               struct cifs_sb_info *cifs_sb, const unsigned char *path,
> +               char *pbuf, unsigned int *pbytes_written)
> +{
> +    int rc;
> +    struct cifs_fid fid;
> +    struct cifs_open_parms oparms;
> +    struct cifs_io_parms io_parms;
> +    int create_options = CREATE_NOT_DIR;
> +    __le16 *utf16_path;
> +    __u8 oplock = SMB2_OPLOCK_LEVEL_EXCLUSIVE;
> +    struct kvec iov[2];
> +
> +    if (backup_cred(cifs_sb))
> +        create_options |= CREATE_OPEN_BACKUP_INTENT;
> +
> +    cifs_dbg(FYI, "%s: path: %s\n", __func__, path);
> +
> +    utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
> +    if (!utf16_path)
> +        return -ENOMEM;
> +
> +    oparms.tcon = tcon;
> +    oparms.cifs_sb = cifs_sb;
> +    oparms.desired_access = GENERIC_WRITE;
> +    oparms.create_options = create_options;
> +    oparms.disposition = FILE_CREATE;
> +    oparms.fid = &fid;
> +    oparms.reconnect = false;
> +
> +    rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL);
> +    if (rc) {
> +        kfree(utf16_path);
> +        return rc;
> +    }
> +
> +    io_parms.netfid = fid.netfid;
> +    io_parms.pid = current->tgid;
> +    io_parms.tcon = tcon;
> +    io_parms.offset = 0;
> +    io_parms.length = CIFS_MF_SYMLINK_FILE_SIZE;
> +    io_parms.persistent_fid = fid.persistent_fid;
> +    io_parms.volatile_fid = fid.volatile_fid;
> +
> +    /* iov[0] is reserved for smb header */
> +    iov[1].iov_base = pbuf;
> +    iov[1].iov_len = CIFS_MF_SYMLINK_FILE_SIZE;
> +
> +    rc = SMB2_write(xid, &io_parms, pbytes_written, iov, 1);
> +
> +    /* Make sure we wrote all of the symlink data */
> +    if ((rc == 0) && (*pbytes_written != CIFS_MF_SYMLINK_FILE_SIZE))
> +        rc = -EIO;
> +
> +    SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
> +
> +    kfree(utf16_path);
> +    return rc;
> +}
> +
> +
>  /*
>   * M-F Symlink Functions - End
>   */
> diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
> index f522193..7d3fa29 100644
> --- a/fs/cifs/smb2ops.c
> +++ b/fs/cifs/smb2ops.c
> @@ -1452,6 +1452,7 @@ struct smb_version_operations smb21_operations = {
>      .rename = smb2_rename_path,
>      .create_hardlink = smb2_create_hardlink,
>      .query_symlink = smb2_query_symlink,
> +    .create_mf_symlink = smb3_create_mf_symlink,
>      .open = smb2_open_file,
>      .set_fid = smb2_set_fid,
>      .close = smb2_close_file,
> @@ -1531,6 +1532,7 @@ struct smb_version_operations smb30_operations = {
>      .rename = smb2_rename_path,
>      .create_hardlink = smb2_create_hardlink,
>      .query_symlink = smb2_query_symlink,
> +    .create_mf_symlink = smb3_create_mf_symlink,
>      .open = smb2_open_file,
>      .set_fid = smb2_set_fid,
>      .close = smb2_close_file,
> diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
> index 67e8ce8..e144ecf 100644
> --- a/fs/cifs/smb2proto.h
> +++ b/fs/cifs/smb2proto.h
> @@ -82,7 +82,9 @@ extern int smb2_rename_path(const unsigned int xid,
> struct cifs_tcon *tcon,
>  extern int smb2_create_hardlink(const unsigned int xid, struct cifs_tcon *tcon,
>                  const char *from_name, const char *to_name,
>                  struct cifs_sb_info *cifs_sb);
> -
> +extern int smb3_create_mf_symlink(unsigned int xid, struct cifs_tcon *tcon,
> +            struct cifs_sb_info *cifs_sb, const unsigned char *path,
> +            char *pbuf, unsigned int *pbytes_written);
>  extern int smb2_open_file(const unsigned int xid,
>                struct cifs_open_parms *oparms,
>                __u32 *oplock, FILE_ALL_INFO *buf);
> --
>
> --
> Thanks,
>
> Steve

Patch

From da80659d4aa758dc6935b10ec64513f0b67bc969 Mon Sep 17 00:00:00 2001
From: Steve French <[e-mail]>
Date: Sun, 14 Sep 2014 23:27:09 -0500
Subject: [PATCH 2/4] [SMB3] Fix oops when creating symlinks on smb3

We were not checking for symlink support properly for SMB2/SMB3
mounts so could oops when mounted with mfsymlinks when try
to create symlink when mfsymlinks on smb2/smb3 mounts

Signed-off-by: Steve French <[e-mail]>
Cc: <[e-mail]> # 3.14+
CC: Sachin Prabhu <[e-mail]>
---
 fs/cifs/link.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/link.c b/fs/cifs/link.c
index 68559fd..a5c2812 100644
--- a/fs/cifs/link.c
+++ b/fs/cifs/link.c
@@ -213,8 +213,12 @@  create_mf_symlink(const unsigned int xid, struct cifs_tcon *tcon,
 	if (rc)
 		goto out;
 
-	rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon, cifs_sb,
-					fromName, buf, &bytes_written);
+	if (tcon->ses->server->ops->create_mf_symlink)
+		rc = tcon->ses->server->ops->create_mf_symlink(xid, tcon,
+					cifs_sb, fromName, buf, &bytes_written);
+	else
+		rc = -EOPNOTSUPP;
+
 	if (rc)
 		goto out;
 
-- 
1.9.1