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authorDarrick J. Wong <djwong@kernel.org>2021-08-18 20:04:44 -0700
committerDarrick J. Wong <djwong@kernel.org>2021-08-19 10:07:11 -0700
commite5f2e54a902de721d9cf4e7f7c35612131654cd7 (patch)
treea817ee673ab65ad8d6734f5128bdd5cdc3267e1a /fs/xfs
parentc03e4b9e6b645a5020f128aeb739a5424c6abe8c (diff)
xfs: start documenting common units and tags used in tracepoints
Because there are a lot of tracepoints that express numeric data with an associated unit and tag, document what they are to help everyone else keep these thigns straight. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/scrub/trace.h4
-rw-r--r--fs/xfs/xfs_trace.h35
2 files changed, 39 insertions, 0 deletions
diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index dfb10966af24..a7bbb84f91a7 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -2,6 +2,10 @@
/*
* Copyright (C) 2017 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <darrick.wong@oracle.com>
+ *
+ * NOTE: none of these tracepoints shall be considered a stable kernel ABI
+ * as they can change at any time. See xfs_trace.h for documentation of
+ * specific units found in tracepoint output.
*/
#undef TRACE_SYSTEM
#define TRACE_SYSTEM xfs_scrub
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 676b66173bb1..6d025a231d3e 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -2,6 +2,41 @@
/*
* Copyright (c) 2009, Christoph Hellwig
* All Rights Reserved.
+ *
+ * NOTE: none of these tracepoints shall be considered a stable kernel ABI
+ * as they can change at any time.
+ *
+ * Current conventions for printing numbers measuring specific units:
+ *
+ * agno: allocation group number
+ *
+ * agino: per-AG inode number
+ * ino: filesystem inode number
+ *
+ * agbno: per-AG block number in fs blocks
+ * startblock: physical block number for file mappings. This is either a
+ * segmented fsblock for data device mappings, or a rfsblock
+ * for realtime device mappings
+ * fsbcount: number of blocks in an extent, in fs blocks
+ *
+ * daddr: physical block number in 512b blocks
+ * bbcount: number of blocks in a physical extent, in 512b blocks
+ *
+ * owner: reverse-mapping owner, usually inodes
+ *
+ * fileoff: file offset, in fs blocks
+ * pos: file offset, in bytes
+ * bytecount: number of bytes
+ *
+ * disize: ondisk file size, in bytes
+ * isize: incore file size, in bytes
+ *
+ * forkoff: inode fork offset, in bytes
+ *
+ * ireccount: number of inode records
+ *
+ * Numbers describing space allocations (blocks, extents, inodes) should be
+ * formatted in hexadecimal.
*/
#undef TRACE_SYSTEM
#define TRACE_SYSTEM xfs