[PATCH 26/32] xfs: split out handle management helpers a bit

Darrick J. Wong
2024-04-10T01:00:18Z

From: Darrick J. Wong <djwong@kernel.org>

Split out the functions that generate file/fs handles and map them back
into dentries in preparation for the GETPARENTS ioctl next.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/libxfs/xfs_fs.h | 4 ++
fs/xfs/xfs_handle.c | 92 ++++++++++++++++++++++++++++++++----------------
2 files changed, 64 insertions(+), 32 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index 7486dcba8c218..51aa4774f57a2 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -633,7 +633,9 @@ typedef struct xfs_fsop_attrmulti_handlereq {
/*
* per machine unique filesystem identifier types.
*/
-typedef struct { __u32 val[2]; } xfs_fsid_t; /* file system id type */
+typedef struct xfs_fsid {
+ __u32 val[2]; /* file system id type */
+} xfs_fsid_t;

typedef struct xfs_fid {
__u16 fid_len; /* length of remainder */
diff --git a/fs/xfs/xfs_handle.c b/fs/xfs/xfs_handle.c
index a0015dc8cff1a..abeca486a2c91 100644
--- a/fs/xfs/xfs_handle.c
+++ b/fs/xfs/xfs_handle.c
@@ -30,6 +30,35 @@

#include <linux/namei.h>

+static size_t
+xfs_filehandle_init(
+ struct xfs_mount *mp,
+ xfs_ino_t ino,
+ uint32_t gen,
+ struct xfs_handle *handle)
+{
+ memcpy(&handle->ha_fsid, mp->m_fixedfsid, sizeof(struct xfs_fsid));
+
+ handle->ha_fid.fid_len = sizeof(struct xfs_fid) -
+ sizeof(handle->ha_fid.fid_len);
+ handle->ha_fid.fid_pad = 0;
+ handle->ha_fid.fid_gen = gen;
+ handle->ha_fid.fid_ino = ino;
+
+ return sizeof(struct xfs_handle);
+}
+
+static size_t
+xfs_fshandle_init(
+ struct xfs_mount *mp,
+ struct xfs_handle *handle)
+{
+ memcpy(&handle->ha_fsid, mp->m_fixedfsid, sizeof(struct xfs_fsid));
+ memset(&handle->ha_fid, 0, sizeof(handle->ha_fid));
+
+ return sizeof(struct xfs_fsid);
+}
+
/*
* xfs_find_handle maps from userspace xfs_fsop_handlereq structure to
* a file or fs handle.
@@ -84,20 +113,11 @@ xfs_find_handle(

memcpy(&handle.ha_fsid, ip->i_mount->m_fixedfsid, sizeof(xfs_fsid_t));

- if (cmd == XFS_IOC_PATH_TO_FSHANDLE) {
- /*
- * This handle only contains an fsid, zero the rest.
- */
- memset(&handle.ha_fid, 0, sizeof(handle.ha_fid));
- hsize = sizeof(xfs_fsid_t);
- } else {
- handle.ha_fid.fid_len = sizeof(xfs_fid_t) -
- sizeof(handle.ha_fid.fid_len);
- handle.ha_fid.fid_pad = 0;
- handle.ha_fid.fid_gen = inode->i_generation;
- handle.ha_fid.fid_ino = ip->i_ino;
- hsize = sizeof(xfs_handle_t);
- }
+ if (cmd == XFS_IOC_PATH_TO_FSHANDLE)
+ hsize = xfs_fshandle_init(ip->i_mount, &handle);
+ else
+ hsize = xfs_filehandle_init(ip->i_mount, ip->i_ino,
+ inode->i_generation, &handle);

error = -EFAULT;
if (copy_to_user(hreq->ohandle, &handle, hsize) ||
@@ -126,6 +146,32 @@ xfs_handle_acceptable(
return 1;
}

+/* Convert handle already copied to kernel space into a dentry. */
+static struct dentry *
+xfs_khandle_to_dentry(
+ struct file *file,
+ struct xfs_handle *handle)
+{
+ struct xfs_fid64 fid = {
+ .ino = handle->ha_fid.fid_ino,
+ .gen = handle->ha_fid.fid_gen,
+ };
+
+ /*
+ * Only allow handle opens under a directory.
+ */
+ if (!S_ISDIR(file_inode(file)->i_mode))
+ return ERR_PTR(-ENOTDIR);
+
+ if (handle->ha_fid.fid_len !=
+ sizeof(handle->ha_fid) - sizeof(handle->ha_fid.fid_len))
+ return ERR_PTR(-EINVAL);
+
+ return exportfs_decode_fh(file->f_path.mnt, (struct fid *)&fid, 3,
+ FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG,
+ xfs_handle_acceptable, NULL);
+}
+
/*
* Convert userspace handle data into a dentry.
*/
@@ -136,29 +182,13 @@ xfs_handle_to_dentry(
u32 hlen)
{
xfs_handle_t handle;
- struct xfs_fid64 fid;
-
- /*
- * Only allow handle opens under a directory.
- */
- if (!S_ISDIR(file_inode(parfilp)->i_mode))
- return ERR_PTR(-ENOTDIR);

if (hlen != sizeof(xfs_handle_t))
return ERR_PTR(-EINVAL);
if (copy_from_user(&handle, uhandle, hlen))
return ERR_PTR(-EFAULT);
- if (handle.ha_fid.fid_len !=
- sizeof(handle.ha_fid) - sizeof(handle.ha_fid.fid_len))
- return ERR_PTR(-EINVAL);

- memset(&fid, 0, sizeof(struct fid));
- fid.ino = handle.ha_fid.fid_ino;
- fid.gen = handle.ha_fid.fid_gen;
-
- return exportfs_decode_fh(parfilp->f_path.mnt, (struct fid *)&fid, 3,
- FILEID_INO32_GEN | XFS_FILEID_TYPE_64FLAG,
- xfs_handle_acceptable, NULL);
+ return xfs_khandle_to_dentry(parfilp, &handle);
}

STATIC struct dentry *