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Message-Id: <20250712161418.17696-2-pali@kernel.org>
Date: Sat, 12 Jul 2025 18:14:18 +0200
From: Pali Rohár <pali@...nel.org>
To: Steve French <sfrench@...ba.org>,
Paulo Alcantara <pc@...guebit.com>
Cc: linux-cifs@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] cifs: Add support for creating WSL symlinks in version 1 format
Add a new mount option -o symlink=wsl1 which cause that all newly created
symlinks would be of WSL style in layout version 1 format. This type of
symlinks is supported by all WSL versions.
Existing mount option -o symlink=wsl will be now an alias to -o
symlink=wsl2 which creates symlinks in layour version 2 format.
Signed-off-by: Pali Rohár <pali@...nel.org>
---
fs/smb/client/cifsglob.h | 9 +++--
fs/smb/client/fs_context.c | 11 ++++--
fs/smb/client/fs_context.h | 3 +-
fs/smb/client/link.c | 3 +-
fs/smb/client/reparse.c | 73 ++++++++++++++++++++++++++++++++------
5 files changed, 81 insertions(+), 18 deletions(-)
diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 6a84d5eae578..758129ab1302 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -189,7 +189,8 @@ enum cifs_symlink_type {
CIFS_SYMLINK_TYPE_MFSYMLINKS,
CIFS_SYMLINK_TYPE_SFU,
CIFS_SYMLINK_TYPE_NFS,
- CIFS_SYMLINK_TYPE_WSL,
+ CIFS_SYMLINK_TYPE_WSL1,
+ CIFS_SYMLINK_TYPE_WSL2,
};
static inline const char *cifs_symlink_type_str(enum cifs_symlink_type type)
@@ -207,8 +208,10 @@ static inline const char *cifs_symlink_type_str(enum cifs_symlink_type type)
return "sfu";
case CIFS_SYMLINK_TYPE_NFS:
return "nfs";
- case CIFS_SYMLINK_TYPE_WSL:
- return "wsl";
+ case CIFS_SYMLINK_TYPE_WSL1:
+ return "wsl1";
+ case CIFS_SYMLINK_TYPE_WSL2:
+ return "wsl2";
default:
return "unknown";
}
diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c
index a634a34d4086..7808cb224d8c 100644
--- a/fs/smb/client/fs_context.c
+++ b/fs/smb/client/fs_context.c
@@ -377,7 +377,9 @@ static const match_table_t symlink_flavor_tokens = {
{ Opt_symlink_mfsymlinks, "mfsymlinks" },
{ Opt_symlink_sfu, "sfu" },
{ Opt_symlink_nfs, "nfs" },
- { Opt_symlink_wsl, "wsl" },
+ { Opt_symlink_wsl1, "wsl1" },
+ { Opt_symlink_wsl2, "wsl2" },
+ { Opt_symlink_wsl2, "wsl" }, /* wsl - alias for wsl2 */
{ Opt_symlink_err, NULL },
};
@@ -408,8 +410,11 @@ static int parse_symlink_flavor(struct fs_context *fc, char *value,
case Opt_symlink_nfs:
ctx->symlink_type = CIFS_SYMLINK_TYPE_NFS;
break;
- case Opt_symlink_wsl:
- ctx->symlink_type = CIFS_SYMLINK_TYPE_WSL;
+ case Opt_symlink_wsl1:
+ ctx->symlink_type = CIFS_SYMLINK_TYPE_WSL1;
+ break;
+ case Opt_symlink_wsl2:
+ ctx->symlink_type = CIFS_SYMLINK_TYPE_WSL2;
break;
default:
cifs_errorf(fc, "bad symlink= option: %s\n", value);
diff --git a/fs/smb/client/fs_context.h b/fs/smb/client/fs_context.h
index 9e83302ce4b8..0b289237cc81 100644
--- a/fs/smb/client/fs_context.h
+++ b/fs/smb/client/fs_context.h
@@ -72,7 +72,8 @@ enum cifs_symlink_parm {
Opt_symlink_mfsymlinks,
Opt_symlink_sfu,
Opt_symlink_nfs,
- Opt_symlink_wsl,
+ Opt_symlink_wsl1,
+ Opt_symlink_wsl2,
Opt_symlink_err
};
diff --git a/fs/smb/client/link.c b/fs/smb/client/link.c
index 2ecd705e9e8c..c27da4a9a74c 100644
--- a/fs/smb/client/link.c
+++ b/fs/smb/client/link.c
@@ -641,7 +641,8 @@ cifs_symlink(struct mnt_idmap *idmap, struct inode *inode,
case CIFS_SYMLINK_TYPE_NATIVE:
case CIFS_SYMLINK_TYPE_NFS:
- case CIFS_SYMLINK_TYPE_WSL:
+ case CIFS_SYMLINK_TYPE_WSL1:
+ case CIFS_SYMLINK_TYPE_WSL2:
if (le32_to_cpu(pTcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS) {
rc = create_reparse_symlink(xid, inode, direntry, pTcon,
full_path, symname);
diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
index 51e476cd4bc9..9c78f217c037 100644
--- a/fs/smb/client/reparse.c
+++ b/fs/smb/client/reparse.c
@@ -22,7 +22,7 @@ static int mknod_nfs(unsigned int xid, struct inode *inode,
static int mknod_wsl(unsigned int xid, struct inode *inode,
struct dentry *dentry, struct cifs_tcon *tcon,
const char *full_path, umode_t mode, dev_t dev,
- const char *symname);
+ const char *symname, int symver);
static int create_native_symlink(const unsigned int xid, struct inode *inode,
struct dentry *dentry, struct cifs_tcon *tcon,
@@ -43,8 +43,10 @@ int create_reparse_symlink(const unsigned int xid, struct inode *inode,
return create_native_symlink(xid, inode, dentry, tcon, full_path, symname);
case CIFS_SYMLINK_TYPE_NFS:
return mknod_nfs(xid, inode, dentry, tcon, full_path, S_IFLNK, 0, symname);
- case CIFS_SYMLINK_TYPE_WSL:
- return mknod_wsl(xid, inode, dentry, tcon, full_path, S_IFLNK, 0, symname);
+ case CIFS_SYMLINK_TYPE_WSL1:
+ return mknod_wsl(xid, inode, dentry, tcon, full_path, S_IFLNK, 0, symname, 1);
+ case CIFS_SYMLINK_TYPE_WSL2:
+ return mknod_wsl(xid, inode, dentry, tcon, full_path, S_IFLNK, 0, symname, 2);
default:
return -EOPNOTSUPP;
}
@@ -534,6 +536,7 @@ static int mknod_nfs(unsigned int xid, struct inode *inode,
static int wsl_set_reparse_buf(struct reparse_data_buffer **buf,
mode_t mode, const char *symname,
+ int symver,
struct cifs_sb_info *cifs_sb,
struct kvec *iov)
{
@@ -569,15 +572,20 @@ static int wsl_set_reparse_buf(struct reparse_data_buffer **buf,
kfree(symname_utf16);
return -ENOMEM;
}
- /* Version field must be set to 2 (MS-FSCC 2.1.2.7) */
- symlink_buf->Version = cpu_to_le32(2);
- /* Target for Version 2 is in UTF-8 but without trailing null-term byte */
+ symlink_buf->Version = cpu_to_le32(symver);
+ /* Target is in UTF-8 but without trailing null-term byte */
symname_utf8_len = utf16s_to_utf8s((wchar_t *)symname_utf16, symname_utf16_len/2,
UTF16_LITTLE_ENDIAN,
symlink_buf->Target,
symname_utf8_maxlen);
*buf = (struct reparse_data_buffer *)symlink_buf;
- buf_len = sizeof(struct reparse_wsl_symlink_data_buffer) + symname_utf8_len;
+ buf_len = sizeof(struct reparse_wsl_symlink_data_buffer);
+ /*
+ * Layout version 2 stores the symlink target in the reparse point buffer.
+ * Layout version 1 stores the symlink target in the data section of the file.
+ */
+ if (symver == 2)
+ buf_len += symname_utf8_len;
kfree(symname_utf16);
break;
default:
@@ -678,7 +686,7 @@ static int wsl_set_xattrs(struct inode *inode, umode_t _mode,
static int mknod_wsl(unsigned int xid, struct inode *inode,
struct dentry *dentry, struct cifs_tcon *tcon,
const char *full_path, umode_t mode, dev_t dev,
- const char *symname)
+ const char *symname, int symver)
{
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
struct cifs_open_info_data data;
@@ -687,6 +695,12 @@ static int mknod_wsl(unsigned int xid, struct inode *inode,
struct inode *new;
unsigned int len;
struct kvec reparse_iov, xattr_iov;
+ struct cifs_open_parms oparms;
+ struct cifs_io_parms io_parms;
+ unsigned int bytes_written;
+ struct kvec symv1_iov[2];
+ struct cifs_fid fid;
+ __u32 oplock;
int rc;
/*
@@ -696,7 +710,7 @@ static int mknod_wsl(unsigned int xid, struct inode *inode,
if (!(le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_EXTENDED_ATTRIBUTES))
return -EOPNOTSUPP;
- rc = wsl_set_reparse_buf(&buf, mode, symname, cifs_sb, &reparse_iov);
+ rc = wsl_set_reparse_buf(&buf, mode, symname, symver, cifs_sb, &reparse_iov);
if (rc)
return rc;
@@ -721,6 +735,45 @@ static int mknod_wsl(unsigned int xid, struct inode *inode,
&data, inode->i_sb,
xid, tcon, full_path, false,
&reparse_iov, &xattr_iov);
+ if (!IS_ERR(new) && mode == S_IFLNK && symver == 1) {
+ /*
+ * WSL symlink layout version 1 stores the symlink target
+ * location into the data section of the file.
+ * Store it now after the reparse point file was created.
+ * The target location was allocated into the buf but iov
+ * size filled in reparse_iov by wsl_set_reparse_buf() was
+ * set to smaller so the created reparse point does not
+ * contain it.
+ */
+ oparms = CIFS_OPARMS(cifs_sb, tcon, full_path, FILE_WRITE_DATA,
+ FILE_OPEN, CREATE_NOT_DIR | OPEN_REPARSE_POINT,
+ ACL_NO_MODE);
+ oparms.fid = &fid;
+ oplock = tcon->ses->server->oplocks ? REQ_OPLOCK : 0;
+ rc = tcon->ses->server->ops->open(xid, &oparms, &oplock, NULL);
+ if (!rc) {
+ symv1_iov[1].iov_base = ((struct reparse_wsl_symlink_data_buffer *)buf)->Target;
+ symv1_iov[1].iov_len = strlen((const char *)symv1_iov[1].iov_base);
+ io_parms = (struct cifs_io_parms) {
+ .netfid = fid.netfid,
+ .pid = current->tgid,
+ .tcon = tcon,
+ .offset = 0,
+ .length = symv1_iov[1].iov_len,
+ };
+ rc = tcon->ses->server->ops->sync_write(xid, &fid, &io_parms,
+ &bytes_written,
+ symv1_iov,
+ ARRAY_SIZE(symv1_iov)-1);
+ if (bytes_written != symv1_iov[1].iov_len)
+ rc = -EIO;
+ tcon->ses->server->ops->close(xid, tcon, &fid);
+ }
+ if (rc) {
+ tcon->ses->server->ops->unlink(xid, tcon, full_path, cifs_sb, NULL);
+ new = ERR_PTR(rc);
+ }
+ }
if (!IS_ERR(new))
d_instantiate(dentry, new);
else
@@ -744,7 +797,7 @@ int mknod_reparse(unsigned int xid, struct inode *inode,
case CIFS_REPARSE_TYPE_NFS:
return mknod_nfs(xid, inode, dentry, tcon, full_path, mode, dev, NULL);
case CIFS_REPARSE_TYPE_WSL:
- return mknod_wsl(xid, inode, dentry, tcon, full_path, mode, dev, NULL);
+ return mknod_wsl(xid, inode, dentry, tcon, full_path, mode, dev, NULL, 0);
default:
return -EOPNOTSUPP;
}
--
2.20.1
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