[24/64] xfs: separate the icreate logic around INIT_XATTRS

Commit Message

Darrick J. Wong Oct. 2, 2024, 1:14 a.m. UTC

From: Darrick J. Wong <[e-mail]>

Source kernel commit: b11b11e3b7a72606cfef527255a9467537bcaaa5

INIT_XATTRS is overloaded here -- it's set during the creat process when
we think that we're immediately going to set some ACL xattrs to save
time.  However, it's also used by the parent pointers code to enable the
attr fork in preparation to receive ppptr xattrs.  This results in
xfs_has_parent() branches scattered around the codebase to turn on
INIT_XATTRS.

Linkable files are created far more commonly than unlinkable temporary
files or directory tree roots, so we should centralize this logic in
xfs_inode_init.  For the three callers that don't want parent pointers
(online repiar tempfiles, unlinkable tempfiles, rootdir creation) we
provide an UNLINKABLE flag to skip attr fork initialization.

Signed-off-by: Darrick J. Wong <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
---
 libxfs/xfs_inode_util.c |   36 ++++++++++++++++++++++++++----------
 libxfs/xfs_inode_util.h |    1 +
 2 files changed, 27 insertions(+), 10 deletions(-)

Patch

diff --git a/libxfs/xfs_inode_util.c b/libxfs/xfs_inode_util.c
index 62af002b2..13c32d114 100644
--- a/libxfs/xfs_inode_util.c
+++ b/libxfs/xfs_inode_util.c
@@ -231,6 +231,31 @@  xfs_inode_inherit_flags2(
 	}
 }
 
+/*
+ * If we need to create attributes immediately after allocating the inode,
+ * initialise an empty attribute fork right now. We use the default fork offset
+ * for attributes here as we don't know exactly what size or how many
+ * attributes we might be adding. We can do this safely here because we know
+ * the data fork is completely empty and this saves us from needing to run a
+ * separate transaction to set the fork offset in the immediate future.
+ *
+ * If we have parent pointers and the caller hasn't told us that the file will
+ * never be linked into a directory tree, we /must/ create the attr fork.
+ */
+static inline bool
+xfs_icreate_want_attrfork(
+	struct xfs_mount		*mp,
+	const struct xfs_icreate_args	*args)
+{
+	if (args->flags & XFS_ICREATE_INIT_XATTRS)
+		return true;
+
+	if (!(args->flags & XFS_ICREATE_UNLINKABLE) && xfs_has_parent(mp))
+		return true;
+
+	return false;
+}
+
 /* Initialise an inode's attributes. */
 void
 xfs_inode_init(
@@ -323,16 +348,7 @@  xfs_inode_init(
 		ASSERT(0);
 	}
 
-	/*
-	 * If we need to create attributes immediately after allocating the
-	 * inode, initialise an empty attribute fork right now. We use the
-	 * default fork offset for attributes here as we don't know exactly what
-	 * size or how many attributes we might be adding. We can do this
-	 * safely here because we know the data fork is completely empty and
-	 * this saves us from needing to run a separate transaction to set the
-	 * fork offset in the immediate future.
-	 */
-	if (args->flags & XFS_ICREATE_INIT_XATTRS) {
+	if (xfs_icreate_want_attrfork(mp, args)) {
 		ip->i_forkoff = xfs_default_attroffset(ip) >> 3;
 		xfs_ifork_init_attr(ip, XFS_DINODE_FMT_EXTENTS, 0);
 
diff --git a/libxfs/xfs_inode_util.h b/libxfs/xfs_inode_util.h
index 50c14ba6c..1c54c3b0c 100644
--- a/libxfs/xfs_inode_util.h
+++ b/libxfs/xfs_inode_util.h
@@ -32,6 +32,7 @@  struct xfs_icreate_args {
 
 #define XFS_ICREATE_TMPFILE	(1U << 0)  /* create an unlinked file */
 #define XFS_ICREATE_INIT_XATTRS	(1U << 1)  /* will set xattrs immediately */
+#define XFS_ICREATE_UNLINKABLE	(1U << 2)  /* cannot link into dir tree */
 	uint16_t		flags;
 };