[PATCH 4/5] xfs: move xfs_update_prealloc_flags() to xfs_pnfs.c

Dave Chinner
2022-01-31T23:39:30Z

The operations that xfs_update_prealloc_flags() perform are now
unique to xfs_fs_map_blocks(), so move xfs_update_prealloc_flags()
to be a static function in xfs_pnfs.c and cut out all the
other functionality that is doesn't use anymore.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_file.c | 32 -------------------------------
fs/xfs/xfs_inode.h | 8 --------
fs/xfs/xfs_pnfs.c | 47 ++++++++++++++++++++++++++++++++++++++++++++--
3 files changed, 45 insertions(+), 42 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 082e3ef81418..cecc5dedddff 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -66,38 +66,6 @@ xfs_is_falloc_aligned(
return !((pos | len) & mask);
}

-int
-xfs_update_prealloc_flags(
- struct xfs_inode *ip,
- enum xfs_prealloc_flags flags)
-{
- struct xfs_trans *tp;
- int error;
-
- error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_writeid,
- 0, 0, 0, &tp);
- if (error)
- return error;
-
- xfs_ilock(ip, XFS_ILOCK_EXCL);
- xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
-
- if (!(flags & XFS_PREALLOC_INVISIBLE)) {
- VFS_I(ip)->i_mode &= ~S_ISUID;
- if (VFS_I(ip)->i_mode & S_IXGRP)
- VFS_I(ip)->i_mode &= ~S_ISGID;
- xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
- }
-
- if (flags & XFS_PREALLOC_SET)
- ip->i_diflags |= XFS_DIFLAG_PREALLOC;
- if (flags & XFS_PREALLOC_CLEAR)
- ip->i_diflags &= ~XFS_DIFLAG_PREALLOC;
-
- xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
- return xfs_trans_commit(tp);
-}
-
/*
* Fsync operations on directories are much simpler than on regular files,
* as there is no file data to flush, and thus also no need for explicit
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 3fc6d77f5be9..b7e8f14d9fca 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -462,14 +462,6 @@ xfs_itruncate_extents(
}

/* from xfs_file.c */
-enum xfs_prealloc_flags {
- XFS_PREALLOC_SET = (1 << 1),
- XFS_PREALLOC_CLEAR = (1 << 2),
- XFS_PREALLOC_INVISIBLE = (1 << 3),
-};
-
-int xfs_update_prealloc_flags(struct xfs_inode *ip,
- enum xfs_prealloc_flags flags);
int xfs_break_layouts(struct inode *inode, uint *iolock,
enum layout_break_reason reason);

diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
index ce6d66f20385..b5e5c7ddfe67 100644
--- a/fs/xfs/xfs_pnfs.c
+++ b/fs/xfs/xfs_pnfs.c
@@ -70,6 +70,49 @@ xfs_fs_get_uuid(
return 0;
}

+/*
+ * We cannot use file based VFS helpers such as file_modified() to update inode
+ * state as PNFS doesn't provide us with an open file context that the VFS
+ * helpers require. Hence we open code a best effort timestamp update and
+ * SUID/SGID stripping here, knowing that server side security in PNFS settings
+ * is largely non-existent as clients have storage level remote write access.
+ * Hence clients have the capability to overwrite filesystem metadata, and so
+ * the filesystem trust domain extends to untrusted, uncontrollable remote
+ * clients. Hence server side enforced filesystem "security" in filesystem
+ * based PNFS block layout settings is pure theatre: friends don't let friends
+ * host executables on PNFS exported XFS volumes, let alone SUID executables.
+ *
+ * We also need to set the inode prealloc flag to ensure that the extents we
+ * allocate beyond the existing EOF and hand to the PNFS client are not removed
+ * by background blockgc scanning, ENOSPC mitigations or inode reclaim before
+ * the PNFS client calls xfs_fs_block_commit() to indicate that data has been
+ * written and the file size can be extended.
+ */
+static int
+xfs_fs_map_update_inode(
+ struct xfs_inode *ip)
+{
+ struct xfs_trans *tp;
+ int error;
+
+ error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_writeid,
+ 0, 0, 0, &tp);
+ if (error)
+ return error;
+
+ xfs_ilock(ip, XFS_ILOCK_EXCL);
+ xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
+
+ VFS_I(ip)->i_mode &= ~S_ISUID;
+ if (VFS_I(ip)->i_mode & S_IXGRP)
+ VFS_I(ip)->i_mode &= ~S_ISGID;
+ xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
+ ip->i_diflags |= XFS_DIFLAG_PREALLOC;
+
+ xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+ return xfs_trans_commit(tp);
+}
+
/*
* Get a layout for the pNFS client.
*/
@@ -164,7 +207,7 @@ xfs_fs_map_blocks(
* that the blocks allocated and handed out to the client are
* guaranteed to be present even after a server crash.
*/
- error = xfs_update_prealloc_flags(ip, XFS_PREALLOC_SET);
+ error = xfs_fs_map_update_inode(ip);
if (!error)
error = xfs_log_force_inode(ip);
if (error)
@@ -257,7 +300,7 @@ xfs_fs_commit_blocks(
length = end - start;
if (!length)
continue;
-
+
/*
* Make sure reads through the pagecache see the new data.
*/
--
2.33.0