xfs: fix file_path handling in tracepoints

Commit Message

Darrick J. Wong July 11, 2024, 5:43 a.m. UTC

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

Since file_path() takes the output buffer as one of its arguments, we
might as well have it format directly into the tracepoint's char array
instead of wasting stack space.

Fixes: 3934e8ebb7cc6 ("xfs: create a big array data structure")
Fixes: 5076a6040ca16 ("xfs: support in-memory buffer cache targets")
Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Signed-off-by: Darrick J. Wong <[e-mail]>
---
 fs/xfs/scrub/trace.h |   10 ++++------
 fs/xfs/xfs_trace.h   |   10 ++++------
 2 files changed, 8 insertions(+), 12 deletions(-)

Comments

Christoph Hellwig July 24, 2024, 3:36 p.m. UTC | #1

As the discussion didn't really conclude to anything too useful,
except for Steven finding other opportunities to improve the xfs
trace events I think we should go ahead with this:

Reviewed-by: Christoph Hellwig <[e-mail]>

Patch

diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index 92ef4cdc486e9..c886d5d0eb021 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -959,18 +959,16 @@  TRACE_EVENT(xfile_create,
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
 		__field(unsigned long, ino)
-		__array(char, pathname, 256)
+		__array(char, pathname, MAXNAMELEN)
 	),
 	TP_fast_assign(
-		char		pathname[257];
 		char		*path;
 
 		__entry->ino = file_inode(xf->file)->i_ino;
-		memset(pathname, 0, sizeof(pathname));
-		path = file_path(xf->file, pathname, sizeof(pathname) - 1);
+		path = file_path(xf->file, __entry->pathname, MAXNAMELEN);
 		if (IS_ERR(path))
-			path = "(unknown)";
-		strncpy(__entry->pathname, path, sizeof(__entry->pathname));
+			strncpy(__entry->pathname, "(unknown)",
+					sizeof(__entry->pathname));
 	),
 	TP_printk("xfino 0x%lx path '%s'",
 		  __entry->ino,
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 56c8333a470bb..0dfb698a43aa4 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -4715,20 +4715,18 @@  TRACE_EVENT(xmbuf_create,
 	TP_STRUCT__entry(
 		__field(dev_t, dev)
 		__field(unsigned long, ino)
-		__array(char, pathname, 256)
+		__array(char, pathname, MAXNAMELEN)
 	),
 	TP_fast_assign(
-		char		pathname[257];
 		char		*path;
 		struct file	*file = btp->bt_file;
 
 		__entry->dev = btp->bt_mount->m_super->s_dev;
 		__entry->ino = file_inode(file)->i_ino;
-		memset(pathname, 0, sizeof(pathname));
-		path = file_path(file, pathname, sizeof(pathname) - 1);
+		path = file_path(file, __entry->pathname, MAXNAMELEN);
 		if (IS_ERR(path))
-			path = "(unknown)";
-		strncpy(__entry->pathname, path, sizeof(__entry->pathname));
+			strncpy(__entry->pathname, "(unknown)",
+					sizeof(__entry->pathname));
 	),
 	TP_printk("dev %d:%d xmino 0x%lx path '%s'",
 		  MAJOR(__entry->dev), MINOR(__entry->dev),